The following papers have been presented by HVE Users during the HVE White Paper Session at the annual HVE Forum. These papers may present information on any of the following topics:
- HVE Case Studies
- Innovative Tips and Techniques Using HVE
- Any application of HVE showcasing its capabilities (especially events involving important 3-dimensional vehicle behavior)
|"Simulating Train Collisions with Highway Vehicles using EDSMAC4 and other programs"
Lawrence Jackson, Kristin M. Bolte, Ph.D. -- National Transportation Safety Board
ABSTRACT: This paper describes the successful application of the HVE system, EDSMAC4 and additional software to simulate highway-rail grade crossing crashes.
|"The Importance of Crash Pulse Data When Analyzing Occupant Kinematics Using Simulations"
Wesley D. Grimes -- Collision Engineering Associates, Inc.
ABSTRACT: Computer simulations are frequently used to analyze occupant kinematics in motor vehicle crashes, including what they collide with during the crash and the severity of these internal collisions. From study of such occupant simulations, it is then possible to infer how the actual human occupants may have been injured in a crash. When using a simulation to study how occupants react in a vehicle crash, a crash-pulse is usually required as input to the occupant simulation model. This crash-pulse is typically generated from a study of the vehicle motion and acceleration during a crash. There are several different methods for obtaining such a crash-pulse which are in common use. Each of these methods produces a different shape for the crash-pulse, even with identical velocity changes for the vehicle. The time duration, maximum acceleration, and general shape of the crash-pulse may influence the predicted motion of the occupants. In this research, the GATB (Graphical Articulated Total Body) computer simulation model is used to study basic occupant kinematics using a variety of shapes for the crash-pulse, in order to determine how the specific shape of the crash-pulse affects the predicted occupant kinematics.
|"Development of HVE 3-D Surface Data through AutoCAD Land Development Desktop"
William E. Dickinson -- Wolf Technical Services, Inc.
ABSTRACT: Engineering Dynamics Corporation's 3-Dimensional Human, Vehicle and Envrionment (HVE 3-D) analysis package is an ideal tool to evaluate the dynamic response of a vehicle to various environmental conditions. Many different types of 3-Dimensional (3-D) vehicle models are readily available in the HVE 3-D vehicle library. These vehicle models can be customized to match the characteristics of the particular vehicle being evaluated. However, the second important piece of the analysis, the environment, must be recorded and developed by the user. Many different approaches to the measurement and development of a 3-D surface environment are available. These measurement techniques range from the use of state of the art total station surveying equipment to manually recording measurements of the physical geometry using measuring wheels, measuring tapes and levels. Whatever measurement technique is utilized, the 3-D environment topography or terrain data must be developed and processed into 3-D surface data and thereafter transferred into the HVE 3-D analysis package where it will interact with the HVE 3-D vehicle model. This paper describes an approach for the development and processing of the 3-D environment's topography or terrain data from various sources using a simple spreadsheet. A comma delimited point file is developed for the 3-D surface and the files are imported into an AutoCAD Land Development Desktop (LDD), which is used to develop the various 3-D surfaces associated with the vehicle-environment analysis. Once the terrain model is developed in LDD, it can be exported as a 3-D Studio file into HVE-3D. A graphical presentation of the analysis can be created using HVE 3-D or the data can be transferred into a high order rendering program to develop the graphical presentation.
|"Dynamics and Roll Stability of a loaded Class 8 Tractor-Livestock Semi-Trailer: An EDVDS Application"
Dan A. Fittanto, Ruhl and Associates -- Forensic, Inc.
ABSTRACT: Concern has been expressed for the effect of cattle movement upon the dynamic performance of the loaded Class 8 tractor-livestock trailer assembly. Loading guidelines exist for cattle that attempt to prevent injury or debilitation during transit, and literature exists on the orientation and some kinematics of loaded cattle.
Considerable literature exists on the effect of liquid slosh in tankers and swinging beef carcasses suspended from hooks in refrigerated van trailers on the dynamic response and roll stability of those vehicles. However, no research is reported on the case of a loaded livestock trailer, although it is analogized (incorrectly) to the above. The research that is outlined herein focuses specifically on loaded Class 8 tractors and livestock semi-trailers.
The authors have engaged in an extensive program involving the five following components:
Results of this research verify the stability of Class 8 livestock trailers and validate the use of EDVDS as tool for analysis.
|"Using Motion Layers to Analyze Pre-Accident Event Timelines"
Patrick M. Fay -- Fay Engineering Corporation
ABSTRACT: This paper presents a technique for using HVE’s Playback Editor to analyze automobile accidents where one of two conditions exists. The first is when an analysis of the pre-accident timing or visibility is necessary. For example, a vehicle may momentarily hinder visibility as it passes between two others that then collide. The second is when the boundaries of two vehicles overlap during some portion of the event, but do not come in contact. For example, a car may pass beneath some portion of a semi-trailer without making contact. The technique involves superimposing two vehicles in the same scene and manipulating their positions relative to each other by changing a time delay.
|"Building Vehicles for HVE"
J. Travis Garvey -- Engineering Dynamics Corporation
ABSTRACT: The accuracy of any vehicle simulation software depends upon the accuracy of the data used to create the vehicles. It is therefore essential to follow a consistent, documented process in gathering and entering data used for the mathematical dynamics model and visual representation. The vehicle data file consists of all the data that makes up the dynamic model, where as, the geometry file is the visual representation of the vehicle. This paper presents an overview of the entire process of creating a vehicle to be used in the HVE vehicle database. An in depth review of the information that resides in the vehicle data file is given. The collection of physical data from the desired vehicle is discussed. In addition, the objectives and process for digitizing a vehicle for HVE are explained. Finally the process of orienting the vehicle geometry file to the coincided with the vehicle data file is discussed.
|"Vehicle Trajectory Following Steering Disconnect Investigated by Application of HVE-VSM Steering DOF Capability"
William Blythe -- William Blythe, Inc.
ABSTRACT: A single vehicle run-off-the-road accident occurred on a major highway in Sonora State, Mexico. It was daylight and the road was dry. The accident initially was attributed to tire failure, but subsequent investigation indicated no tire damage.
Approximately one year after the accident the driver of the Dodge pickup, a citizen of the US living in Southern California, received a recall notice from the manufacturer indicating a possible steering column separation problem.
A lawsuit was filed against the manufacturer, claiming the loss of control was due to steering column separation. The car had been destroyed in Mexico before the lawsuit was filed.
The Defense claimed that the path followed by the car was inconsistent with steering column separation and only could have been achieved with steering input. Therefore, the loss of control was due to inattentive driving and inappropriate steer input by the driver.
The recently-introduced steer degree of freedom (DOF) capability of VSM was used to investigate the claims of both the plaintiff and the defense.
|"Collection of Field Data and Special Effects to Enhance HVE Simulations of Large Commercial Vehicle Collisions"
Lawrence Jackson, P.E., Kristin M. Bolte, Ph.D., Shane Lack
ABSTRACT: Many of the highway crash investigations undertaken by the National Transportation Safety Board involve collisions of several large vehicles, large vehicle rollovers, or other highly dynamic and complex scenarios. The collision simulations were enhanced with detailed scene and vehicle documentation. A variety of tools were used in an effort to best replicate the physical evidence at the scene and the crush characteristics of the vehicles within the HVE system. The purpose of this paper was to detail the large commercial vehicle crashes simulated using HVE and associated "special effects" in an effort to address safety issues.
|"Creating Three Dimensional Environments from As-Built Plans"
Kenneth S. Baker and James P. Sneddon -- Northwestern University Center for Public Safety
ABSTRACT: Creating three dimensional environments requires significantly more point data than an orthographic two dimensional diagram. Ideally, this point data is acquired through a total station survey of the site. Circumstances occur when a survey is not possible. The roadway improvements may have changed since the date of the accident, or regulatory and safety issues prevent you from performing a survey.
Construction plans exist for the majority of paved streets and highways in the United States. Changes made during construction are often recorded on a set of revised plans called As-Built plans. Three dimensional environments can be generated from these plans in lieu of a site survey.
Third party software such as AutoCAD is necessary to create the environment, which can then be imported into HVE. The user constructs a "virtual" roadway in a computer environment. The process is similar to what occurs when the actual roadway is built. First the roadway is staked, then cut to grade, and finally the surfaces are poured.
The path of the roadway is established by a survey line or centerline. This centerline provides the spine from which the roadway can by constructed. Initially, the centerline is plotted using only horizontal data. After which adjustments for grade and vertical curves are made.
Typical cross sections define the roadway crown, curb and gutter, and super-elevation. There may be multiple cross sections, which apply to various locations along the centerline. Cross sections are place along the centerline at points where changes occur in the centerline’s traverse.
Using the centerline and cross sections as a skeleton, entities are drawn to establish roadway edges, curbs and gutters. Intersecting roadways, drives and alleys are added. Finally, surfaces are constructed between the centerline and roadway edge or curb and gutter. Roadside features and pavement markings are added before the environment is exported.
|"Extracting Tire Model Parameters From Test Data"
Wesley D. Grimes and Eric Hunter, Collision Engineering Associates, Inc.
ABSTRACT: Computer models used to study crashes require data describing the vehicles. Data such as weight, length, wheelbase, tire locations, crush stiffness, tire parameters, etc. all require some source of information. Usually the tire parameters are difficult to obtain and analysts will routinely use default or "typical" values. Engineering Dynamics Corp. (EDC), with support from many in the field of crash reconstruction, conducted a tire test series in 1999 to obtain tire data that will be used in studying motor vehicle performance. The computer simulations in use today require some type of tire data coefficients or lookup tables that must be extracted from the raw collected data. This paper presents a basic overview of the tire test data and presents a technique for extracting the required tire parameters for use in computer simulation modeling.
|"Yaw Stability of Single Versus Tandem Axle Tractors"
Dan A. Fittanto -- Ruhl Forensic, Inc.
ABSTRACT: Yaw instability was studied for five tractor-semitrailer configurations using EDVDS and SIMON in the HVE 4.10 operating system. Steady-state analyses were performed on the vehicle configurations by implementing a series of trapezoidal steer inputs, roll angles, articulation angle and forward velocity were recorded. Steer angles were incrementally increased until the vehicle experienced yaw divergence, rollover or steer tire saturation.
The five vehicle configurations were:
Handling diagrams were prepared for each vehicle configuration using the data obtained from EDVDS and SIMON. The five vehicle configurations were compared to each other using EDVDS data and again using SIMON data. Relative stability of each configuration was compared.
The results for each individual configuration as reported by EDVDS and SIMON were also compared.
SIMON and EDVDS revealed similar trends among the vehicle configurations. EDVDS and SIMON demonstrated rather different responses within the sensitivity of the handling diagrams. The vehicles modeled in SIMON tended to be more neutral steer than those modeled in EDVDS. That is, 2-axle tractor configurations exhibited more oversteer in EDVDS than in SIMON and 3-axle tractor configurations tended to exhibit more understeer in EDVDS than in SIMON.
A unique characteristic of the vehicle response was observed in the SIMON runs. Between approximately .07 and .12 g’s, a spike in the yaw rate was observed in all five runs.
|"Introduction to Creating HVE Environments with Rhinoceros"
James P. Sneddon -- Northwestern University Center for Public Safety
ABSTRACT: Since HVE’s introduction, users have employed third party software to create environments for import. Numerous computer aided drafting and 3-D modeling programs are available, and the user’s choice is influenced by many factors. Some of the more significant factors concerning HVE users are:
Modeling an HVE environment requires three dimensional point data that is typically acquired from a site survey. HVE’s Environment Editor was intended to import surfaces constructed from this data, using either computer aided drafting or 3-D modeling software. Creating surfaces that accurately match the point data is largely dependant upon the software’s surface tools. Similarly, ensuring “watertight” seams between adjacent surfaces is a function of the software’s capability.
Additionally, the direction of surface normals is critical to HVE calculation models. Surface normal directions are established by the CAD or 3-D modeling software. The method by which normals are oriented vary among programs and file formats, and have caused problems for HVE users. Finally, the software must be able to export a file format supported by HVE. If not, a translator must be available, or another piece of software purchased solely for this purpose.
This white paper provides an introduction to using Rhinoceros® (a.k.a. Rhino) as it applies to these issues.
|"Predicting and Analyzing Vehicle Dynamics in a Train-Passenger Vehicle Collision Using EDSMAC"
James S. Sobek and William E. Dickinson, Wolf Technical Services, Inc.
ABSTRACT: This paper describes the successful application of EDSMAC to “pre-construct” a staged car/train collision. The paper compares the real-world results of that April 1996 collision with the EDSMAC predictions and with a recent re-analysis of the collision using the HVE system and the current EDSMAC4 program.
Wolf Technical Services, Inc. (WOLF), Indiana Rail Road, WRTV Channel 6, Teen Challenge and Operation Lifesaver worked together to stage a grade crossing collision involving a 1984 Cadillac deVille and an EMD GP-16 locomotive. The purpose of the event was to produce a news program geared to educate the public on the dangers of railroad grade crossings. To ensure that the filming was completed in a safe manner, WOLF was asked to design the collision configuration. WOLF personnel used the EDVAP EDSMAC vehicle dynamics program to determine how to place the car on the grade crossing and to predict the dynamics of the collision once the train struck the car. The vehicle C.G. (center of gravity) position was established at the site. The car post-impact path and rest position were "right on track" and were predicted within inches, showing the accuracy of the EDSMAC program in both reconstruction and pre-construction. Crash dummies and video cameras were in the car. Channel 6 and WOLF provided video coverage from a variety of other viewpoints. Excerpts from that coverage will be shown . . .
As a demonstration of the ability to use HVE for the same purpose, we used the same general techniques in EDSMAC4 to reanalyze the collision.
|"Downhill Commercial Vehicle Simulations - Part A (Tractor/Semi-trailer Brake Fade)"
Lawrence Jackson, PE, MS and Kristin Poland, PhD, -- National Transportation Safety Board
ABSTRACT: The purpose of this paper is to present a simulation of a large, commercial vehicle during a mountainous descent using the SIMON physics program contained in the Human Vehicle Environment (HVE) system. This paper discusses the simulation of a brake fade for a fully loaded tractor/semi-trailer in Mountainburg, Arkansas as it negotiated a long, mountainous descent. The simulation required SIMON to apply aerodynamic forces on the vehicle and to simulate the forces due to braking. The Mountainburg tractor/semi-trailer was built in 1989 reflecting older commercial vehicle technologies that are still on the road. The brakes were not adjusted properly as discovered through post-accident inspection.
SIMON has several unique features that were needed to refine the simulation. The aerodynamic drag was used to slow the vehicle as it descended the mountain and to calibrate the drag in gear. Brake Designer was needed to account for the hot brake linings and to simulate brake fade.
|"Downhill Commercial Vehicle Simulations - Part B (Intercity Bus Equipped with an Engine Data Recorder)"
Lawrence Jackson, PE, MS, and Kristin Poland, PhD, -- National Transportation Safety Board
ABSTRACT: The purpose of this paper is to present a simulation of a large, commercial intercity-bus during a mountainous descent using the SIMON physics program contained in the Human Vehicle Environment (HVE) system. This paper discusses the simulation of a run-off-the-road intercity bus accident in Canon City, Colorado. The accident involved a commercial vehicle braking on a long, mountainous descent. The simulation required SIMON to estimate the aerodynamic forces on the vehicle, to simulate the forces due to braking on a slippery surface during cornering and to simulate the loss of lateral control. The Canon City intercity bus was built in 1999, reflecting current commercial vehicle technologies including a DDEC IV engine recorder, ABS, and a transmission retarder.
SIMON has several unique features that were needed to refine the simulations. The aerodynamic drag was used to slow these vehicles as they descended the mountain and to calibrate the drag in and out of gear. In the Canon City simulation, the robust tire and suspension models were needed during the two loss-of-control events and also when brakes and the retarder were applied, especially during cornering.
|"Reconstruction of Real World Side Impact Vehicle Collisions Using HVE - A Case Series of Pediatric Pelvic Fracture"
Rajiv A. Menon, Yoganand S. Ghati, Shresta B. Marigowda and Kristy Abrogast
Flaura K. Winston -- University of Pennsylvania
ABSTRACT: This paper describes the application of HVE software to reconstruction of a series of side impact automobile crashes resulting in pelvic fracture to pediatric case occupants. This paper compares crash dynamics, injury mechanisms and occupant kinematics from on-site crash investigations, with reconstruction of these cases using HVE.
In-depth investigations of eight near side impacts crashes involving children (8-15 years old) with pelvic fractures were conducted. Vehicle dynamics and vehicle damage were reconstructed using the EDSMAC4 program. The acceleration pulse generated from the EDSMAC4 program was then input into the GATB module to predict the child occupant kinematics in these crashes. The results confirmed the vehicle dynamics and damage pattern as measured in the crash investigations. The HVE reconstructions of occupant kinematics suggested that initial orientation and subsequent rotation of the pelvis during the intrusion influenced the likelihood of injury.
|"Investigating the Use of Simulation Model Non-linear (SIMON) for the 'Virtual Testing' of Road Humps"
Iwan Parry BSc (Hons) MIHT, Fabian Marsh BEng, and Nicola Cripps
ABSTRACT: This paper presents the results of a study which involved the measurement of various vehicles response to being driven over various types of road hump at a range of speeds. As part of this project, computer simulation runs were conducted using SIMON to investigate the use of this program for the 'virtual testing' of future road hump designs.
This paper compares the results of physical tests and 'virtual tests' for five different vehicle types traveling over four different designs of road hump, with each vehicle being tested at speeds of up to 40 mph. Vehicle types include a passenger car with independent suspension, a taxi and a minibus, both with solid axle suspensions, and a bus and ambulance with airbag suspensions. The methods by which input parameters were measured for each vehicle are described.
Results are presented for COG vertical acceleration, wheel vertical displacement and pitch angle/rate. These show good consistency between physical and test data. It was found that sensitivity tests of key variables allowed a 'best fit' between the simulation and physical test results to be developed. The paper comments on issues arising from the use of measured vehicle parameters, and the sensitivity tests that were undertaken to generate a 'best fit' between virtual and physical tests.
|"Constructing Detailed Road Surfaces for Vehicle Dynamics Simulation Using 3D Laser Scanning Techniques"
Iwan Parry BSc (Hons) MIHT and Fabian Marsh BEng
ABSTRACT: The Investigations and Risk Management Group of TRL Limited has been researching and developing applications for 3D laser scanning technology in traffic accident investigation and reconstruction, crime scene preservation, and transport related infrastructure investigations. One such application of this technology is the detailed measurement of road surface, verge and/or kerb line geometry.
Laser scan data has been used to generate detailed road surface models, in the form of a dense three dimensional mesh, for vehicle dynamics simulations where the precise geometry of the road surface in important to the simulation, or where detailed road geometric information is difficult, or impractical, to measure using other means.
The paper describes the methods used to generate detailed road surface models from laser scan data. Examples are provided in which road surface models have been created from data captured in heavily trafficked road environments, and in which laser scan data has been used to construct a complex 3D surface for a vehicle dynamics simulation.
The use of laser scanning systems at incident sites will invariably involve the measurement of areas surrounding the road such as topography, buildings, vegetation, etc. This information can be used to enhance visualisations by allowing detailed models of the environment surrounding the road to be constructed.
|"Human Performance - Can Visual Phenomena Be Recreated in HVE?"
Lawrence E. Jackson, P.E., M.S., ACTAR, and Kristin M. Poland, Ph.D., and Paula Sind-Prunier, Ph.D.
ABSTRACT: On Saturday, October 13, 2001, at about 2:00 pm, a 22-year-old male was driving a 2000 Thomas 78-passenger school bus westbound on Nebraska State Route 6 at about 40 mph, and was approaching a bridge. The roadway was under construction. Witness statements and Safety Board observations on-scene indicated that the school bus driver might have perceived that one of the three oncoming vehicles veered into his lane thus causing him to steer rapidly to the right to avoid a collision.
A simulation was developed to replicate the school bus motion and also that of the oncoming traffic. This simulation resulted in the observation of several visual phenomena, which may have contributed to the accident. The purpose of this paper is to present a simulation of a school bus negotiating a narrow, curvy roadway in a construction zone with oncoming traffic and to detail visual phenomenon contributing to the accident.
|"Creating an HVE Vehicle Geometry from Orthographic Diagrams"
James P. Sneddon -- Baker Sneddon Consulting
ABSTRACT: The vehicle geometry file provides a graphic visualization of a vehicle and damage profile in HVE simulations. Many users prefer specific vehicle geometries over generic for use in video exhibits. An increased need for specific vehicle geometries occurred with the release of the DYMESH option in SIMON. Unlike EDSMAC4, the vehicle geometry is an integral part of the collision simulation in DYMESH.
Currently, there are over 150 vehicle geometry files included with the HVE system software, and additional models are added with each release. Most users will periodically require a vehicle that is not included in the database. If a generic vehicle geometry will not suffice, the user can order the vehicle from EDC, purchase the vehicle geometry from a third party, or build the vehicle geometry file using 3D modeling software.
Building a vehicle geometry requires three dimensional point data. This data is best acquired by using a digitizing arm, survey instrument or photogrammetry. However, some vehicle configurations can be built from orthographic diagrams. This whitepaper will provide an introduction to this method.
|"Comparison between EDVSM and SIMON: Automobile Handling Characteristics "
Daniel A. Fittanto, M.S.M.E., P.E. and Adam Senalik, M.S.G.E., P.E. -- Ruhl Forensic, Inc.
ABSTRACT: Steady-state directional control was studied for several passenger cars and two sport utility vehicles using EDVSM and SIMON in the HVE 4.4 operating system. Constant velocity, variable steer tests were performed and relevant data recorded and analyzed.
The modeled vehicles are taken directly from the HVE Vehicle Database. These vehicles represented various class categories. Two vehicles were modified by selecting different tires from within the HVE Tire Database. The modeled vehicle configurations were as follows:
Steering diagrams and/or handling diagrams were generated from the results of these simulated tests and the understeer characteristics were analyzed. Relative comparisons were made between vehicles both in EDVSM and SIMON. Similarities and differences between EDVSM and SIMON responses for each vehicle were also observed and discussed.
Vehicles exhibited intuitive and expected relative understeer characteristics within both EDVSM and SIMON. For each vehicle, the SIMON-modeled vehicle exhibited a greater level of understeer than the EDVSM-modeled vehicle. Aerodynamic forces were found to only slightly influence the vehicle responses in SIMON.
|"Computerised simulation of car and 4WD impacts into alternative median barrier profiles using the DyMESH collision algorithm within the HVE simulation environment"
Grant Johnston and Iwan Parry, TRL Limited
Clint Bradley, Grant Johnston Consulting Engineers Pty Limited
ABSTRACT: This paper presents a cost effective alternative to repetitive finite element modelling of vehicle to barrier impacts using Engineering Dynamics Corporation's HVE 3D Simulation system. Whilst it is not claimed this system is suitable for full NCHRP compliance testing it was found to provide a cost effective and fast alternative for preliminary testing of alternative barrier profiles. A pre-beta release of the DyMesh Collision Algorithm was used to simulate a series of vehicle to barrier impacts for a blackspot location in Sydney, Australia. An alternative barrier profile had to be considered due to road width limitations preventing the footprint of a standard "New Jersey" profile barrier.
|"HVE Data Inputs Based on Testing for a Wet Pavement Accident Involving an Intercity Bus and an SUV"
Lawrence E. Jackson, PE, MS, ACTAR, David Rayburn, Dan Walsh, PE, Jennifer Russert, National Transportation Safety Board
ABSTRACT: This paper will discuss the technique used to simulate a wet pavement accident. It will discuss the weather data, the environment data and the surface friction inputs and the bus tire friction inputs used for an HVE SIMON loss-of-control simulation on wet pavement. By knowing the rain intensity, texture, drainage path length and cross slope of the pavement, it could be determined that the surface was flooded. The surface was documented with an ASTM skid trailer using a treaded and a smooth tire. This data showed that for smooth tires the friction changed both longitudinally every 0.1-mile and laterally between wheel paths, which created a split coefficient of friction. Five of the accident bus’s 8 tires were tested at the General Dynamics Tire Research Facility (TIRF), on a smooth surface selected to match the accident site, for cornering and longitudinal friction at different speeds, and with different water depths. The surface used on the TIRF was validated with the ASTM ribbed and smooth tires. The results of these tire tests are presented. Finally, the data inputs for the surface friction factors and the tire in-use factors will be discussed.
|"Heavy Truck Brake Designer Validation Testing"
Thomas H. Vadnais, P.E., Vadnais, Wood & Rivers
ABSTRACT: In late August 2004, a week-long series of well-documented heavy truck braking tests was conducted at Transportation Research Center (TRC) in East Liberty, OH. Using the same tractor and flatbed semi-trailer, tests were performed with and without ABS, on wet and dry surfaces, loaded and unloaded, and at both 30 and 60 mph. Additional tests were done with the semi-trailer’s ABS disabled, with only the tractor’s ABS system cross-wired, with some of the tractor and trailer brakes out of adjustment, and with the bobtail tractor alone. Both the tractor and semi-trailer were documented to allow creation of an accurate HVE vehicle model, including all brake components. For this initial paper, SIMON runs, using the Brake Designer, were made of several actual test runs to validate the software against the actual test data. These were compared to similar simulations using generic vehicles. For this paper, only loaded, non-ABS, 60 mph tests were modeled, with all brakes in adjustment, and some out of adjustment.
|"SIMON and EDVDS Validation Study: Steady State and Transient Handling"
Daniel A. Fittanto, M.S.M.E., P.E. and Adam Senalik, M.S.G.E., P.E.
ABSTRACT: This research compares the responses of vehicle modeled in SIMON and EDVDS in the HVE simulation operating system against instrumented responses of a 3-axle tractor, 2-axle semi-trailer combination. The instrumented tests were previously described in SAE 2001-01-0139 and SAE 2003-01-1324. The vehicle inertial parameters were measured by UMTRI (University of Michigan Transportation Research Institute). The tire data was provided by Smithers Scientific Services, Inc. and UMTRI. The series of tests discussed herein compares the modeled and instrumented vehicle responses during quasi-steady state and transient handling maneuvers. The time response of the following variables is compared graphically:
SIMON and EDVDS simulated responses are found to reasonably follow the trends of the instrumented vehicle. SIMON is found to more closely simulate the truck dynamics of the experimental vehicle than EDVDS. SIMON responses correlated well to the experimental values in both step steer transient phases and steady state phases in all tests except for the steady state phase of the Step Steer at 20 m/sec.
|"Simulation of a Side Impact and Vehicle Rollover Using EDVSM and EDSMAC4 within HVE"
James E. Flynn, Stephen Harper, Howard Underwood, Robert Buckert and Phillip Parks
ABSTRACT: EDVSM and EDSMAC4 were used to determine impact speeds, vehicle changes in velocity and vehicle rollover mechanics during the analysis of a side impact collision. On the date of the incident, a 1997 Ford Crown Victoria was parked facing westerly on the northerly shoulder of the No. 2 westbound lane of a four lane, east-west directed roadway. The driver of the Crown Victoria initiated a U-turning maneuver from the shoulder with the reported intent of crossing the center earthen median and proceeding easterly within the eastbound lanes of the roadway. As the Crown Victoria crossed into the No. 1 westbound lane, it was collided with at the left front fender and left front wheel by a westbound 1991 Chevrolet S-10 Blazer. Subsequent to the collision, the Crown Victoria was propelled in a westerly direction while rotating clockwise to its point of rest. The Crown Victoria came to rest facing southerly on the line striping separating the No. 1 and No. 2 westbound lanes. The collision deflected the Blazer in a southwesterly direction after which it exited the No. 1 lane and traveled onto the earthen median where it rolled over and came to rest on its top while facing northerly. The right front occupant of the Blazer was ejected and sustained a severe brain injury during the rollover process. The use of EDVSM and EDSMAC4 allowed for successful modeling of both pre and post impact vehicle dynamics. Tire marks produced by the model were found to match those imported from the post-collision scene survey. Vehicle crush, including that resulting from secondary vehicle to vehicle contact, matched damages documented during the inspections of the vehicles. The rollover simulation was found to correlate well with the vehicle rollover damages and the Blazer's documented final orientation and point of rest.
|"Investigating the Sensitivity of Vehicle Response to Inter-Vehicle Friction Values for Broadside Collisions utilizing HVE (EDSMAC4 Algorithm)"
Jubal D Hamernik, Ph.D., Douglas M. Schuler, MS, Brendan C. Rudack, David E. Wittekind and Brian P. Tholl
ABSTRACT: In this research, Engineering Dynamics Corporation’s Human Vehicle Environment (HVE) software was utilized to model a series of broadside impacts where the inter-vehicle friction coefficient, relative vehicle mass ratio, and contact alignment were allowed to vary. The sensitivity of these parameters was examined by comparing the relative final rest positions, as predicted by EDSMAC4, when each parameter was individually varied. The research consisted of utilizing two identical vehicle models for all simulations where only the weight of the bullet vehicle weight was modified. All simulations are based on a stationary target vehicle, where a bullet vehicle traveling at 40-mph contacts the stationary vehicle at a 90-degree configuration. Results obtained from the target vehicle during simulation are presented for delta-V, change in heading, post-contact travel distance, CDC, and PDOF are presented and compared. The findings of this research are useful to aid HVE EDSMAC4 users in their understanding and application of inter-vehicle friction coefficients when simulating an array of broadside collisions.
|"Simulation of Tire Interaction with Curbs and Irregular Terrain"
Terry D. Day, Engineering Dynamics Corporation
ABSTRACT: The reconstruction of vehicular loss of control often involves a path that includes irregular terrain, such as pavement edges, curbs and soft soils. Depending on the angle of impact and soil characteristics, these irregularities can significantly influence the vehicle’s trajectory. To draw proper conclusions regarding accident causation requires an understanding of how such irregularities may have affected the trajectory or contributed to the loss of control. This paper describes a new tire-terrain model that includes the capability of simulating tire interaction with irregular terrain. In addition to simulating non-homogeneous pressure distributions at the contact patch, the model also simulates the forces and moments produced by tire sidewall interaction with pavement edges, curbs and soft soils. This paper presents the details of the modeling approach. Examples are provided illustrating the use of these models, including tire interaction with a curb, pavement edge and soft soil. The new model is compared with the existing point contact tire model.
|"Presentation of HVE Validation Studies"
Eric Deyerl, P.E. -- Quan, Smith & Associates
Fawzi P. Bayan, P.E., Anthony D. Cornetto, III, P.E. and Jonathan Anderson -- SEA, Ltd.
ABSTRACT: HVE users are regularly required to provide explanation as to how the various HVE simulation programs operate and how they have been validated. This paper presents a method by which HVE validation studies may be visually depicted so that a viewer may gain a rapid understanding of what the HVE programs do and the methods by which they have been validated.
In this method, EDSMAC4 validation simulations are used to create movie files with viewpoints and effective frame rates similar to those of the cameras used to document full-scale dynamic vehicle tests. The viewer is provided with a visual comparison of the motion of the simulated vehicles played adjacent to the films of the full-scale crash tests. It is contended that this technique provides a more concise and understandable explanation of the program' s operation and validation than would a verbal description alone.
|"Tractor-Semitrailer Handling Analysis Using EDVDS and EDVTS"
Daniel A. Fittanto, M.S., P.E. and Louis V. Inendino, M.S., P.E. -- Ruhl Forensic, Inc.
ABSTRACT: A 2005 HVE Forum Whitepaper compared simulated responses in SIMON and EDVDS against instrumented responses for a tractor-semitrailer combination. The instrumented tests involved a three-axle tractor with an unloaded two-axle trailer in a series of handling maneuvers.
In this research the same series of tests are simulated using EDVTS. Simulated results are compared to experimental results and previously reported EDVDS results. The time response of the following variables is compared graphically:
The initial EDVTS results are found to more closely correlate with EDVDS than with SIMON from the past series of tests.
For EDVDS and EDVTS, the steering gain (steering gear ratio) was varied, without changing the shape of the steering profile or changing vehicle parameters to determine if simulated vehicle responses similar to the experimental tests could be found. Simulated results for trailer lateral acceleration were also compared with experimental results for EDVDS.
Modifications were then made to the tire data as used by EDVTS and EDVDS to more closely approximate the lateral tire forces that would have occurred during full-scale tire testing. The maneuvers were rerun in EDVTS and good agreement was found with the experimental data without modification to the steering gear ratio. EDVDS results were improved.
Several observations regarding the lateral and yaw responses of the three HVE tractor-semitrailer simulation programs, SIMON, EDVDS and EDVTS are discussed.
|"Application of HVE SIMON to the Analysis of Lateral Wind Loadings on High-sided Vehicles"
William Blythe, P.E., Ph.D. -- William Blythe, Inc.
ABSTRACT: The SIMON simulation model, part of the HVE simulation environment, automatically calculates longitudinal wind forces as a function of vehicle speed and user-specified drag coefficients. Lateral wind loads are not calculated at the present time, but may be constructed by the user. Modifications to the SIMON program are suggested.
Tractor-trailer rollover due to high crosswinds is a well-recognized accident type. Some highway jurisdictions limit high-profile vehicle travel under certain weather conditions in certain locations to reduce the probability of rollover or other loss of control. The research literature relating to this issue has been reviewed and reported.
|"Validation of Collision Reconstruction Opinion Utilizing EDSMAC4"
Steven Day -- California Highway Patrol
ABSTRACT: This paper describes the use of old and new technologies to validate a collision reconstruction opinion regarding the relation of undocumented tire friction marks to a fatal collision.
The collision occurred on a rural two lane mountainous roadway in which an Acura NSX crossed into the opposing traffic lane, from behind a pickup truck, and struck a Volkswagen Beetle head-on. Responding California Highway Patrol (CHP) officers documented specific items of physical evidence utilizing a station line, but discounted four distinct curvilinear tire friction marks present at the collision scene they believed were not associated with the fatal collision. Photographs of the scene were taken, but were limited in their coverage. Approximately 22 months following the collision, a CHP MAIT (Multi-disciplinary Accident Investigation Team) investigation was initiated to confirm or eliminate the tire friction marks as part of the fatal collision as well as determine vehicle speeds at and prior to impact if possible.
Photogrammetry reconstruction methodologies were used in conjunction with a traditional site survey and a 3-D laser scan of the collision site to re-establish the tire friction marks in question in relation to the roadway. The data from the photogrammetry reconstruction, site survey, and site scan were imported into AutoCAD where a traditional collision reconstruction was completed.
To validate the opinions of the traditional collision reconstruction, a three dimensional environment and the tire marks were imported into HVE and an EDSMAC4 event was created in an attempt to reconstruct the collision event. The EDSMAC4 event provided additional confirmation that the tire marks in question were indeed related to the collision event and deposited by the errant vehicle while in a steering induced yaw. An additional EDSMAC4 event, created per the errant driver's statement, refuted his claim that the yaw marks were created by an emergency brake only application due to a mechanical failure of the vehicle's braking system.
|"Computer Simulation of Staged Motorcycle-Vehicle Collisions Using EDSMAC4"
Eric Deyerl --Dial Engineering
ABSTRACT: The use of computer simulation to analyze motorcycleinto- vehicle collisions is examined and presented. The software program EDSMAC4 within the HVE-2D suite, developed for the simulation of vehicle-to-vehicle collisions, is extended in this study to the analysis of collisions between motorcycles and other vehicles. Simulation results are compared to the results of the series of full-scale staged collisions between motorcycles and passenger vehicles previously published in SAE paper 2002-01-0551, "Seventeen Motorcycle Crash Tests Into Vehicles and a Barrier" by Adamson, et. al.
The rest positions, damage ranges, and speed changes of the test vehicles in the simulations and those in the full-scale tests are presented in numerical and graphical formats. This effort achieved good to excellent correlation between the simulated and test results, thereby providing support for the use of this simulation technique for the type of motorcycle-vehicle collisions examined in this study. In the set of 10 crash tests analyzed, 10 motorcycles moving at speeds between 25 and 49 miles per hour were guided into 2 stopped passenger vehicles. The simulations of these full-scale tests calculated the rest locations of the test automobiles to within approximately 1 foot or less in 7 out of the 10 tests, the changes in the automobile headings to within 4 degrees in all 10 of the tests, the automobiles' speed changes to within 2 ½ miles per hour in 8 of the 10 tests, the motorcycle speed changes to within 3 miles per hour in 7 out of the 10 tests, and the average automobile damage depths to within 2 inches in 7 out of the 10 tests.
|"A Procedure for Modeling Tire Behavior on Wet Surfaces in HVE"
William Blythe -- William Blythe, Inc.
ABSTRACT: A method to account for tire-roadway friction changes due to wet road conditions is presented. The method is empirical and is based upon flat-bed tire test data. The procedure is being incorporated into the "hydroplaning" model in HVE, for use initially in SIMON and possibly later in EDSMAC4 and is known as the Blythe-Day model.
|"Use of Aerial Photographs from Internet Sources for HVE-2D Environment"
R. Torrey Roberts, P.E. and Dave L. Jakovac, P.E., -- FDJ Engineering
ABSTRACT: There are multiple aerial photograph sources on the internet that contain high quality images capable of being successfully imported into HVE-2D and used for environment backgrounds. This paper will discuss a process that can be quickly utilized to import aerial photographs into HVE-2D to create accident simulation environments. Software required includes HVE/HVE-2D, a PDF editor with dimension feature, Microsoft Word, and Internet Explorer or other browser. The imported aerial photographs need to be scaled to on-site tangible dimensions with a PDF editor before being used as an environment. Site diagram information can be added to the aerial photograph with the PDF editor before importing to HVE. The aerial photograph can then be saved as a .tif file, and imported into the HVE environmental editor as an object texture on a slab of the same dimensions as the scaled aerial photograph. Camera and vehicle positions can then be manipulated in HVE without change of environment scale. This paper will discuss this process in detail and provide examples of imported HVE environments.
|"Evaluation of the Automatic Transmission Model in HVE Version 7.1"
Eric S. Deyerl, P.E. and Michael J. Fitch -- Dial Engineering
ABSTRACT: The Automatic Transmission Model in HVE Version 7.1 is evaluated via simulation of the motion of a full-scale test vehicle subjected to straight line acceleration runs. Fidelity of the simulated output data to measured vehicle parameters is discussed, as are limitations of the Automatic Transmission Model, which presently lacks the incorporation of drivetrain slip in the form of a clutch or torque converter model.
|"Modeling a Pothole Impact of an Agricultural Tractor Using HVE and SIMON"
Ciro Ramirez, PhD, PE, CSHO and R. Joe Thornhill, PhD, PE, CSHO -- Thornhill, Ramirez & Associates, Inc..
ABSTRACT: This paper presents an HVE study of the dynamics of a cabbed agricultural tractor pulling a large rotary shredder when impacting a deep pothole. The study was conducted using the SIMON physics module as part of an effort to quantify the way in which a tractor operator could be ejected from the tractor cab, possibly resulting in serious injuries from the shredder. The HVE radial spring tire model was used to predict tractor bounce as it encountered the hole at a variety of attack offsets and two different speeds. Unique vehicle features modeled for this study included agricultural tires and a rigid, unsprung front axle mounted on a pivot and angle limiting stops. A follow-up study was conducted by combining the SIMON soft soil model and field measurements to estimate the coasting distance of the tractor and shredder at the incident site if engine fuel flow is stopped.
|"Introduction to HVE 3D Environments with Google SketchUp"
R. Torrey Roberts, P.E., Anthony D. Cornetto III, P.E. and Ronny Wahba, P.E. -- SEA Limited
ABSTRACT: Creating an accurate and appealing 3D model for use in HVE is an important part of accident reconstruction simulation. Google has released software in recent years, which can be utilized to create 3D models for HVE environments. SketchUp (SU) is a 3D drawing program by Google that is supported by Google Earth s (GE) Digital Elevation Model (DEM), Aerial Photography and 3D Warehouse (3DW). DEM data can be imported from GE with overlaid aerial photography and used in SU as a starting point for 3D accident scene modeling. 3DW provides pre-made models of environmental objects and vehicles submitted by other users of SU. The accident scene model created with SU can be imported into HVE as a 3D environment. The 3D model can also be exported to a .kmz file and viewed with GE software. This paper will discuss the use of SU as a 3D environment-modeling tool and give some examples of its application.
|"Hydroplaning During Steady-State Cornering Maneuvers"
L. D. Metz -- Metz Engineering and Racing, LLC
ABSTRACT: Vehicles running in wet conditions may experience hydroplaning of one or more tires. Hydroplaning can, and often does, change vehicle braking, acceleration and handling characteristics dramatically. Proper analysis of this behavior requires accommodating the clearing of paths for the rear tires that may result from the front tires engaging the water-coated surface first. In this work, tire overlap and associated hydroplaning behavior are theoretically and experimentally examined.
|"A Method for Creating Photograph Textured Planes and Camera Positions in HVE Simulations"
Brad R. Shults -- Ponderosa Associates.
ABSTRACT: A method for creating photograph backgrounds in HVE is presented. This method is useful for comparing simulation results to accident photographs evidencing the scene. Through the use of survey equipment, photogrammetry software, and CAD software, a user may calculate the photograph plane and respective camera position in three-dimensional space of a particular photograph. A process for determining the three-dimensional camera position and photograph plane center is presented. A process for creating the photograph texture for HVE is presented. After presenting the above processes, an example crash from the 2011 ARC-CSI Crash Conference is presented. Additionally, a case study photograph background is presented. Finally, results are discussed and recommendations for future work are presented.
|"An Introduction to the Vehiclemetrics HVE Vehicle Database"
Ron Jadischke and Joe McCarthy -- Vehiclemetrics/McCarthy Engineering Inc.
ABSTRACT: Vehiclemetrics is compiling a new vehicle database for use in HVE to increase the number of vehicles for use in HVE drastically. The procedure currently used by EDC for building vehicle geometry, as well as various input mechanical parameters for the vehicles, has been published by Garvey (2000) and Day (1995) and is also presented annually at the HVE Forum. The goal of this paper is not to repeat a discussion of the various input parameters. Rather, it is to present not only an overview of the process that Vehiclemetrics uses to generate vehicle interior and exterior geometry but also a mechanical property dataset for use in HVE. We have highlighted areas where Vehiclemetrics' method and EDC's method differ. The intent of the Vehiclemetrics vehicle database is to supply modern vehicle mechanical datasets that are vehicle specific and, in turn, minimize the use of generic data. At this time, all vehicle parameters cannot be measured within budget constraints, and notes are made regarding planned areas of improvement and future research areas.
|"Using HVE to Simulate a Nine Vehicle Accident Involving a Heavy Truck"
Eric Rossetter, Benjamin Ewers III, Bradford Coburn, Yomi Agunbiade -- Principia Engineering, Inc.
ABSTRACT: Multi-vehicle high-speed accidents that have a high number of vehicle collisions and interaction with a fixed obstacle in the environment are ideally suited for simulation. This paper covers a nine-vehicle collision involving a heavy truck and eight passenger vehicles. We constructed a 3-D environment in AutoCAD based on survey data, along with custom vehicle geometries not available in the HVE database. The final simulation using HVE's EDSMAC4 algorithm matched the physical evidence remarkably well. In addition, HVE allowed us to compare various impact speeds to show why certain scenarios did not match the physical evidence. The resulting simulations were used successfully in trial.
|"SIMON/DyMESH Validation Preview" (Oral Presentation Only)
Eric Deyerl, P.E. -- Dial Engineering
ABSTRACT: This presentation provides a summary of the development history of SIMON/DyMESH. Prior validation studies and their results are discussed and a preview of a planned future suite of validation studies of Version 3.0 of DyMESH is presented.
|"Restitution in Frontal Impact Simulations Using the EDSMAC4 and SIMON/DyMESH Collision Models"
Micky Marine, Joseph Cuadrado and Stephen Werner
ABSTRACT: In this study, the restitution (i.e., structural recovery) models within the EDSMAC4 and SIMON (via DyMESH) physics modules of the HVE program are examined. By way of background, the methodologies for handling structural recovery within these physics modules are reviewed. Results from simulation studies using these modules are presented. In these simulation studies, the effective coefficient of restitution values from a series of frontal vehicle-tobarrier impact simulations and a series of vehicle-to-vehicle collinear frontal impact simulations are determined from the program output and compared to results from publicly available full-scale vehicle crash tests. Studies were also conducted to evaluate simulation sensitivities vis-à-vis changes of the user-supplied parameters that directly control the respective structural recovery algorithms.
|"Analysis of Tire Rub Rail Interaction"
Dirk Smith, Ph.D., P.E. -- Rimkus Consulting Group, Inc.
ABSTRACT: On December 20, 2010, a Mine Safety and Health Administration (MSHA) inspector issued a citation at a mine site because the side railings on the driveover- scale were not mid-axle height of the largest piece of equipment to use the scale. The side railings were 5 inch diameter tubing with the top of the rail 10 inches high. HVE SIMON was used to model the interaction of a tractor-trailer and a straight truck with the side railing. Based on the speed of trucks on the scales, the method of operation on the scales, truck dynamics and driver control, the HVE analysis revealed that the height of the side rails on the subject scale was sufficient to give feedback to the driver and keep the truck on the scale. The MHSA judge agreed with this analysis and dismissed the citation.
|"Linear Error Analysis and HVE"
Scott B. Anderson, Ph.D. -- Anderson-Lee Applied Science
SUMMARY: Many non-linear dynamical systems will behave linearly with respect to small perturbations of their initial conditions. The usual goal for an HVE user is to determine the initial state given the final state. The example presented in this monograph is from an actual collision involving a semi and two cars and it clearly illustrates how linear error analysis can be applied to refine an HVE run.
|"A Method to Determine Non-Linear Crush for Use in HVE" (Oral Presentation Only)
Brian Gilbert, Ron Jadischke and Joe McCarthy -- McCarthy Engineering/Vehiclemetrics
SUMMARY: The potential advantages of using non-linear crush coefficients include the ability to better model vehicle structural changes and also improved accuracy of simulation results over a range of crush depths. The purpose of the present work is to develop a method to calculate the A, B, C and D stiffness coefficents utilized by the DyMESH 3-D collision model. The proposed methodologies are evaluated using crash test results from the NHTSA database for the 2002-2007 Jeep Liberty SUV in comparison with SIMON/DyMESH simulations.
|"Evaluation of DyMESH Wheel Impact in a Rollover Collision" (Oral Presentation Only)
Eric Deyerl, P.E. and Mu-Hua Cheng -- Dial Engineering
SUMMARY: An evaluation of the performance of the wheel impact model within SIMON/DyMESH by simulating a rollover crash test involving significant interaction between the wheel of the bullet vehicle and the body of the target vehicle. The rollover crash test used in this evaluation was conducted by W. R. Haight at the 2012 ARC-CSI Crash Conference and involved a 2011 Jeep Grand Cherokee SUV that was induced to roll over by driving up and over a 1987 Bertone (Fiat) X1/9 sports car.
|"Observational Validation of the SIMON Steer Degree-of-Freedom Model: A Case Study"
Maximilian Lee and Cline Young
INTRODUCTION: An accident occurred near Eureka Springs, AR, in which a motorhome rolled out of control down an embankment, across a flat basin, and into a vertical cliff face, resulting in a total loss of the vehicle. The owner had been driving the motorhome eastbound through difficult and hilly terrain on a US highway. He claims to have experienced some problems with the brakes and was barely able to bring the vehicle to a stop on the eastbound shoulder. He decided to take his Jeep, which was attached to the rear of the motorhome, into Eureka Springs to look for a mechanic to repair his brakes. Shortly after setting his parking brake and detaching his Jeep from the motorhome the brakes were claimed to have failed completely and the motorhome rolled freely down the embankment. Numerous photographs were taken documenting the position of the Jeep at the detachment location and the position of the motorhome at point of rest.
Upon further inspection, the motorhome's brakes, which were S-Cam air brakes with springs, were found to be functioning normally. Furthermore, there was a southbound roadway which formed a T-intersection with the aforementioned eastbound road. The point of rest of the motor home was directly opposite the extended centerline of the southbound road. The owner's story of brake failure described that of a hydraulic system, which was not on the motorhome. Thus the police, wrecker driver, and claims agent all suspected that the vehicle had been started into the drainage basin deliberately from the southbound road with nobody inside to attempt braking. In other words, there was every reason to believe that was a case of insurance fraud.
The office of Cline Young, Consulting Engineer was contacted and asked to determine how a driverless vehicle would perform under the various slopes and grades. More specifically, the question that was posed dealt directly with determining if the motor home were indeed initially parked parallel to the drainage basin, on the eastbound shoulder of the US highway, or had it begun its travel on the intersecting southbound roadway.
|"Comparison of HVE simulations to NHTSA full-frontal barrier testing: an analysis of 3D and 2D stiffness coefficients in SIMON and EDSMAC4"
Jeffrey Suway -- Biomechanical Research and Testing, LLC.
ABSTRACT: Previous work by Cornetto, et al. has shown a method for calculating three-dimensional (3D) stiffness coefficients for SIMON, based on existing crash test data. In the methods presented by Cornetto, et al., the resulting crash pulse and deflection-time history, as predicted by SIMON using the derived 3D stiffness coefficients, are compared to the data from NHSTA crash tests. This white paper will compare the SIMON simulations using A, B, C, and D stiffness coefficients from this method to SIMON simulations with the default HVE vehicle stiffness parameters as well as EDSMAC4 simulations with default stiffness parameters with the same vehicles. The three types of HVE simulations will be compared with the NHTSA crash test data with a focus on the crash pulse duration, shape, and peak, as well as the crush over time and maximum crush.
The same vehicles used in Cornetto, et al. will be used in this white paper. This includes vehicles in several different categories, including passenger vehicles, pickup trucks, minivans, and SUVs. The curves will be compared by applying the Object Rating Method (ORM).
|"Using Barrier Load Cell Data to Generate Stiffness Coefficients"
Brian Gilbert, Ron Jadischke, Joe McCarthy -- McCarthy Engineering Inc. / Vehiclemetrics Inc.
ABSTRACT: The analysis and modeling of vehicle crush in accident reconstruction has traditionally been based upon the use of linear crush-based, stiffness coefficients. Residual crush is used to develop these coefficients.
This paper expands upon a technique used to generate non-linear stiffness coefficients (Pressure model) previously presented by Gilbert et al. This pressure model uses time-specific load cell and accelerometer data from frontal barrier crash tests along with the undamaged vehicle geometry to develop a pressure versus deflection curve for that vehicle. This curve is then used to generate the stiffness coefficients for the vehicle.
The array of barrier load cells provides a means to establish stiffness coefficients for specific areas of the frontal portion of a vehicle. This creates the potential to generate multiple crush zones which could be beneficial in modeling pole impacts or override/underride collisions. Modifications to HVE would be required to accommodate multiple crush zones. Recommendations are suggested which would allow DyMESH to utilize this model better.
|"SIMON Simulation of Non-Automotive Vehicle Free Rolling Response"
Ciro Ramirez, PhD, PE, CSHO, C. L. Long, Jr., P.E., and R. Joe Thornhill, PhD, PE, CSHO
ABSTRACT: Although the HVE SIMON physics module provides the ability to perform sophisticated simulations of crashes involving automobiles and trucks, it can also be used with other types of four wheeled vehicles. This paper describes the methodology used to study the free rolling response of a large commercial lawn mower after the unit lost power and rolled down a steep slope. The mower ultimately overturned, fatally injuring the operator. The unique challenges associated with modeling this type of machine are discussed, and avoidance scenarios studied are described. Specialized testing was used to provide appropriate values for some of the vehicle and site parameters needed for the HVE simulation.
|"The Performance of Photo Based Vehicle Models using HVE's DyMesh Algorithm"
Eric Rossetter, Benjamin Ewers III, Yomi Agunbiade
ABSTRACT: HVE's DyMesh algorithm uses 3-dimensional vehicle models to simulate vehicle contact and the resulting collision forces and vehicle motion. The authors compare the performance of custom vehicles made using photographs and Photomodeler (a commercially available photogrammetry software) with vehicles available in the HVE database. The results show that the basic vehicle geometry obtained from this technique is sufficient to closely match the results obtained from HVE vehicles. Further improvement, especially in acceleration profiles, can be achieved through tessellation of the Photomodeler derived vehicles.
|"HVE Vehicle Accelerometers: Validation and Sensitivity"
Kent W. McKee, M.E.Sc., P.Eng., Matthew Arbour, B.A.Sc., Roger Bortolin, P.Eng., and James R. Hrycay, M.A.Sc., P.Eng.
ABSTRACT: An understanding of the acceleration experienced at various seating positions in a vehicle is important for predicting occupant dynamics during an event. In most accident reconstructions there may not be an opportunity to instrument the accident vehicle with accelerometers and perform tests at the accident site. Therefore, it is desirable to simulate accelerometers using HVE and when doing so it is important to know that the output data is valid. The output data is highly dependent on the input parameters and an understanding of how the available input parameters affect the output data is important.
This paper compares the results of physical tests and SIMON simulations over two different sizes of flat-top speed bumps at targeted speeds of 10 km/h and 20 km/h. In addition, three different accelerometer positions were used in the physical testing and the SIMON simulations. The vehicle used in both physical and virtual testing was a 2007 Ford Focus SE hatchback. The methods by which the input and output parameters were measured for each condition are described.
|"Evaluation of the Automatic Transmission Model in HVE Version 10.1"
Eric S. Deyerl, P.E.
ABSTRACT: Prompted by the addition of a driveline slip algorithm, the performance of the SIMON Automatic Transmission Model (ATM) within Version 10.1 of the HVE suite is revisited in this follow-up to a 2010 study by the author. SIMON's ATM is evaluated against test data acquired from a vehicle equipped with an automatic transmission, thereby assessing the performance of the ATM driveline slip algorithm, which was introduced after the prior study. Correlation parameters examined include vehicle speed, engine speed, engine throttle, transmission gear, driveline slip, as well as brake pressure. Good correlation was found between the simulation model and the test data in the case of a wide open throttle test run, thereby verifying the functionality of the driveline slip feature within the SIMON ATM under this condition.
|"Application and Use of Linear Interpolation Models: A Case Study"
Eric Hunter, P.E.
ABSTRACT: Computer simulations are often used to analyze vehicle motion and impact forces in accidents. In cases where vehicles have interacted with roadway objects the simulation models may not have the capability of modeling the interaction. Some cases involve an object penetrating the vehicle in such a way that the forces are so minimal that they do not need to be calculated, but that the specific motion of the object and vehicle can be modeled through the use of multiple simulations. This case study is a look at using the SIMON simulation model in conjunction with EDGEN or similar linear interpolation programs to solve specific collision sequences and collision trends.
|"Analysis of SIMON/DYMESH Simulations for Underride Collisions"
Christian R. Sax, P.E., PTOE. and Charles O. Funk, Ph.D., P.E.
ABSTRACT: Underride impacts present a challenge to traditional reconstruction methods, such as conservation of energy, crush analyses, and two-dimensional simulation models (e.g. EDSMAC4 and EDCRASH), where the structural components of the involved vehicles are partially contacted or not contacted and there is deformation to the cosmetic vehicle components. SIMON/DYMESH provide the combination of three-dimensional vehicle dynamics and collision algorithms within the commercially available HVE simulation package to account for the bumper mismatch in underride collisions. Several staged vehicle-into-barriers and vehicle-into-vehicle collisions were evaluated. The post-impact damage to the underride vehicle, pre-impact travel speed, and peak accelerations from the simulations were compared with the measured values in the staged collisions. The effect of relaxation length and stiffness coefficient conversion height is presented.
|"Incorporating UAV Generated Deliverables into HVE Simulation Software"
ABSTRACT: It's a well-established fact that demonstrative evidence is a critical component with effectively presenting a case to the trier of fact. Studies have demonstrated the combination of verbal and demonstrative evidence is six times more effective than a verbal delivery alone. In addition, many jurors have an expectation for some type of forensic evidence and analysis. This has often been referred to as the "CSI Effect." Regardless if the CSI Effect really exists, a National Institute for Justice Report stated there is a belief that a broader "tech effect" exists that influences juror expectations and demands.
In order to be an effective expert witness, crash reconstructionists should be cognizant of the proper use of demonstrative evidence and technology when presenting their findings to the finder of fact.
HVE is a powerful tool for the crash reconstructionist, allowing the user to simulate and model various types of collisions. HVE users have the ability to incorporate different types of backgrounds and environments into their simulations. This ability provides the users flexibility and the control to produce a highly effective work product. Once the collision is modeled, the results of the simulation may be visualized in an output file using the Playback Editor, producing highly accurate, physics based computer generated movies.
Over the last 20 years, technology has allowed collision investigators to improve their ability to accurately measure the geometry of 3- dimensional environments of traffic collisions. This technology includes laser based systems, total station technology, photogrammetry, terrestrial scanners, and now Unmanned Aerial Vehicles (UAVs).
The intent of this paper is to provide a basic description of the deliverables generated from professional mapping UAV systems and how to incorporate them into HVE simulations.
|"Development of a 12-Node Thermodynamic Simulation Model of a Disc Brake Assembly"
Terry D. Day, P.E.
ABSTRACT: Overheated brakes on a heavy truck can lead to a loss of braking and subsequent crash. This typically occurs after prolonged braking on a downhill grade. The problem is often accompanied by improper brake adjustment, causing one or more of the actuators to reach the end of travel due to thermal expansion. Reconstruction of this type of crash requires the consideration of overheated brakes. A thermodynamic model of a drum-type foundation brake is included in the HVE simulation environment and has been used successfully to study this phenomenon. However, newer on-highway trucks are often fitted with disc brakes. A similar thermodynamic model for a heavy truck disc brake does not exist, making the problem described above difficult to address. This paper describes a new thermodynamic model of a disc foundation brake, such as those often fitted on newer heavy trucks. The model is based on classic thermodynamic heat transfer principles that describe the rate of heat flow through the brake rotor and pads as a function of time and location within the rotor and pad materials. Simulation results are used to compare the new disc brake model with the existing drum brake model.
|"Simulation of a Four-Car Collision Using SIMON/DyMESH"
James R. Loumiet
ABSTRACT: This paper describes the reconstruction of a four-car collision using the SIMON 3D vehicle dynamics model and the DyMESH 3D crush damage model that are part of the HVE suite. The collision included an underride impact between two of the vehicles so that 2D methods of reconstruction were not viable in this study. The use of HVE's "Show Skidmarks" option is also discussed in this study.
|"A Person and His Bicycle are Struck by a Pickup Truck, but was He Riding or Walking the Bicycle?"
Thomas Jenkyn, PhD PEng
ABSTRACT: A pickup truck is leaving a doughnut shop drive-thru. The driver checks the traffic and turns left onto the main roadway. The roadway has two lanes in each direction separated by a double yellow line. At the same time, a person with a bicycle leaves a side road on the opposite side of the main roadway and illegally begins to cross the main roadway, with the intent of getting to the other side. The pickup truck strikes the person and the person and his bicycle are knocked to the ground.
The person claimed that he was walking his bicycle at the time of the collision and that he was well-visible and not moving quickly. Since he was walking his bicycle there was no reason to wear a bicycle helmet. The driver of the pickup truck claimed the person was actually riding his bicycle at high speed without due care and that he should have been wearing a helmet.
Several simulations were conducted using HVE and GATB. There was good evidence as to the rest positions of the person and his bicycle after the collision. By simulating the motion of the person's body after impact and comparing the diagnosed injuries with loading on the human model, it was determined that the person could have been either riding his bicycle or walking it. In both scenarios he would have struck his head forcefully on the hood of the pickup.
|"Three Vehicle Chain Reaction Collision Injures an NHL Hockey Player"
Thomas Jenkyn, PhD PEng
ABSTRACT: Two roadways meet at a traffic light-controlled intersection. In all directions the roadways have two lanes in each direction separated by grass medians. There are left turn lanes in all directions. Stopped at a red light in the westbound left turn lane is a small sedan (V1) driven by a minor league hockey player who is being actively scouted by NHL teams. Waiting to turn left in the southbound left turn lane is a small sedan (V2). Approaching the intersection heading northbound is a midsize sedan (V3) that has the intention of continuing straight through the intersection.
As V3 approaches, V2 starts to turn left. But V2 strikes the front left corner of V3 and causes V3 to veer off toward the northeast and into V1. V3 strikes the left front corner of the stopped V1. This second impact moves V1 backward and to the right by about 8 feet and rotates the car to the right by 45 degrees. Airbags deploy in all vehicles. The hockey player in V1 suffers a neck injury and a concussion. Unfortunately, his post-concussion symptoms force him to retire from hockey and he never makes the NHL.
A series of simulations were done using HVE and EDSMAC4 to determine the range of speeds V3 could have been approaching the intersection and the range of circumstances that V2 could have made her left turn in safety. The simulations showed that V2 initiated her left turn with a very narrow window of safety and should not have proceeded.
|"Computer Simulation of a Vehicle-Verses-Dummy Collision via GATB"
Eric Deyerl, P.E. and Mu-Hua Cheng, M.S.M.E.
ABSTRACT: A staged collision between a 2002 Toyota Camry and an adult pedestrian dummy was modeled via the GATB physics module within the HVE software suite to evaluate the performance of GATB in modeling such an impact configuration. During the test, the upright and stationary dummy was struck by the front of the Toyota, which was traveling at approximately 20 miles per hour while undergoing hard braking. During the collision sequence the dummy experienced a typical wrap trajectory, rotating onto the hood of the vehicle while being accelerated in the direction of travel of the vehicle. As the vehicle continued to brake, the dummy separated from the car, landing on the pavement with its center of gravity approximately 24 feet ahead of the point of impact. The GATB computer model was used to simulate the collision and its output was visually compared against high speed video of the staged test. It was found that, to model the motion of the dummy accurately, the default slope for the unloading portion of the force-deflection relation for the dummy's segments needed to be increased by a factor of approximately two. The resulting simulated motion of the test dummy matched that of the test dummy well, including its trajectory, limb movement, as well as its contact locations and point of rest. No other modifications to the dummy's default parameters were required.
|"Using HVE to Study Vehicle Dynamics: An Example"
L. D. Metz
ABSTRACT: In this paper we examine some handling metrics of vehicles equipped with space-saver tires and compare the metrics with performance of the vehicles on standard OEM tires using vehicle data available in HVE/SIMON. Vehicle data for 162 vehicles contained in the HVE vehicle data base was used and various linear handling characteristics were calculated for each vehicle. Tire performance data for representative space-saver tires were developed on a well-known and validated tire test machine and understeer gradient and initial step steer behavior showed that space-saver tires are reasonably capable substitutes for OEM tires under many linear handling conditions.
|"Validation of Accident Reconstruction Formulas Using HVE"
ABSTRACT: Starting with the classic speed-to-stop formula, two formulas used in accident reconstruction are examined using HVE to validate them and their domain of applicability. These include formulas for spinning vehicles and sliding vehicles. A discussion of each formula is presented and along with the results of the relevant HVE validation simulations.
|"Performing Reverse Projection Photogrammetry of Surveillance Video with HVE"
James P. Sneddon
ABSTRACT: The presence of video cameras in urban areas is becoming commonplace. The availability of low cost, high capacity digital storage provides a means to record weeks or months of continuous video surveillance. This has resulted in an increase of traffic events being photographically captured. Using photogrammetric methods, the positions of vehicles or other objects of interest can be located. Their change in position can be established between sequential frames and used in conjunction with the frame rate to calculate velocities and accelerations.
One photogrammetric method used for this purpose is Reverse Projection Photogrammetry. This method involves superimposing an image of the event over the event site. Using objects that appear in the image which are still present at the traffic site, the camera location, optical axis and effective focal length of the lens can be established. The location of an object of interest can be identified by intersecting a ray from the camera location with a definable surface such as the roadway. In the past, this method was performed using a transparency of the image and a "dummy" camera. Object locations were manually sighted and measured at the site. This is no longer necessary.
Instead, a three-dimensional computer model of the environment can be built, and the camera location and optical axis established virtually. Vehicle positions can be sighted by moving a computer model of the vehicle over the environment surfaces. HVE has proved to be useful for this purpose.