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Technical Paper

An Investigation of Thermal Effects on the Hybrid III Thorax Utilizing Finite Element Method

2001-03-05
2001-01-0767
The advent of the Hybrid III crash test dummy marked the beginning of biofidelic anthropomorphic test devices. During the development of its critical components, notably the head, neck, knee, and thorax, biomechanical cadaver test results were incorporated into the design. The result was a dummy that represented the 50th percentile male during idealized impacts. In order to achieve a more biofidelic response from the components, many exotic materials and unique designs were utilized. The thorax, for instance, incorporates a spring steel rib design laminated with a viscoelastic polymeric composite material to damp the response. This combination results in the proper hysteretic losses necessary to model the human thorax under impact loading conditions. The disadvantage of this design is that the damping material properties are highly sensitive to temperature. A variation of more than 5 degrees Fahrenheit dramatically affects the response of the thorax.
Technical Paper

A Validation Study of Vehicle Dynamics Simulations for Heavy Truck Handling Maneuvers

2001-03-05
2001-01-0139
This paper deals with the ongoing efforts at The Vehicle Research and Test Center (VRTC) in East Liberty, Ohio in promoting the safe operation of heavy trucks. The associated research evaluated two vehicle dynamics simulations for their accuracy in predicting tractor-trailer handling metrics. The goals of the research were threefold: 1. Establish a generic “benchmark” parametric data set for the three-axle truck/two-axle trailer vehicle 2. Demonstrate the accuracy of experimental data that was collected for the tractor-trailer vehicle of this study 3. Demonstrate the accuracy of two vehicle simulations by comparing their predicted responses to experimentally observed vehicle responses and metrics.
Technical Paper

Improving Steering Feel for the National Advanced Driving Simulator

1997-02-24
970567
The National Highway Traffic Safety Administration's Vehicle Research and Test Center (VRTC) plans to evolve the state-of-the-art of steering system modeling for driving simulators with the ultimate goal being the development of a high fidelity steering feel model for the National Advanced Driving Simulator (NADS). The VRTC plans on developing reliable research tools that can be used to determine the necessary features for a steering model that will provide good objective and subjective steering feel. This paper reviews past and continuing work conducted at the VRTC and provides a plan for future work that will achieve this goal.
Technical Paper

Validation Results from Using NADSdyna Vehicle Dynamics Simulation

1997-02-24
970565
This paper presents an evaluation of a vehicle dynamics model intended to be used for the National Advanced Driving Simulator (NADS). Dynamic validation for high performance simulation is not merely a comparison between experimental and simulation plots. It involves strong insight of vehicle's subsystems mechanics, limitations of the mathematical formulations, and experimental predictions. Lateral, longitudinal, and ride dynamics are evaluated using field test data, and analytical diagnostics. The evaluation includes linear and non-linear range of vehicle dynamics response.
Technical Paper

Parameter Measurement and Development of a NADSdyna Validation Data Set for a 1994 Ford Taurus

1997-02-24
970564
This paper discusses the development of a 1994 Ford Taurus vehicle model for the National Advanced Driving Simulator's planned vehicle dynamics simulation, NADSdyna. The front and rear suspensions of the Taurus are modeled using recursive rigid body dynamics formulations. To complement vehicle dynamics, subsystems models that include steering, braking, and tire forces are included. These models provide state-of-the-art high fidelity vehicle handling dynamics for real-time simulation. The realism of a particular formulation depend heavily on how the parameters are obtained from the physical system. Therefore, the development of a data set for a particular model is as important as the model itself. The methodology for generating the Taurus data set is presented. The power train model is not yet included, so the simulation is run with the vehicle either at constant speed or decelerating.
Technical Paper

Methodology for Validating the National Advanced Driving Simulator's Vehicle Dynamics (NADSdyna)

1997-02-24
970562
This paper presents an overview of work performed by the National Highway Traffic Safety Administration's (NHTSA) Vehicle Research and Test Center (VRTC) to test, validate, and improve the planned National Advanced Driving Simulator's (NADS) vehicle dynamics simulation. This vehicle dynamics simulation, called NADSdyna, was developed by the University of Iowa's Center for Computer-Aided Design (CCAD) NADSdyna is based upon CCAD's general purpose, real-time, multi-body dynamics software, referred to as the Real-Time Recursive Dynamics (RTRD), supplemented by vehicle dynamics specific submodules VRTC has “beta tested” NADSdyna, making certain that the software both works as computer code and that it correctly models vehicle dynamics. This paper gives an overview of VRTC's beta test work with NADSdyna. The paper explains the methodology used by VRTC to validate NADSdyna.
Technical Paper

Evaluation of Angular Displacement Measurement Techniques for Tracking the Motion of Anthropomorphic Test Devices

1997-02-24
971055
The measurement of angular rotation has many applications in crash testing, particularly in tracking the motion of crash dummies. There are currently a few devices for determining angular rotation. These include accelerometer arrays, magnetohydrodynamic (MHD) sensors, potentiometers, and high speed films. However, there are problems associated with all of these methods. Systron Donner has developed a new device called a “Quartz Rate Sensor” or “QRS”. The QRS utilizes a piezoelectric chip which produces a DC voltage proportional to the rate of rotation of the sensor about its sensitive axis. Angular displacement can then be determined from a simple integration. Results of preliminary tests performed at The U.S. Department of Transportation's Vehicle Research and Test Center suggest that the QRS's yield very accurate results.
Technical Paper

The Design of a Vehicle Inertia Measurement Facility

1995-02-01
950309
This paper describes the design of a vehicle inertia measurement facility (VIMF): a facility used to measure vehicle center of gravity position; vehicle roll, pitch, and yaw mass moments of inertia; and vehicle roll/yaw mass product of inertia. The rationale for general design decisions and the methods used to arrive at the decisions are discussed. The design is inspired by the desire to have minimal measurement error and short test time. The design was guided by analytical error analyses of the contributions of individual system errors to the overall measurement error. A National Highway Traffic Safety Administration (NHTSA) database of center of gravity position and mass moment of inertia data for over 300 vehicles was used in conjunction with the error analyses to design various VIMF components, such as the roll and yaw spring sizes.
Technical Paper

A Study of Vehicle Class Segregation Using Linear Handling Models

1995-02-01
950307
The handling, stability, and rollover resistance of vehicles is presently being studied by both the automotive industry and the National Highway and Traffic Safety Administration (NHTSA). However, to study the handling and rollover behavior of each vehicle on the road is not feasible. The ability to categorize and compare the rollover and handling behavior of various vehicles is a subject of considerable research interest. This paper examines the possibility of characterizing vehicle classes through the use of a three degree-of-freedom linear model. Initially, segregation is studied by evaluating the eigenvalue location in the complex domain for vehicle sideslip velocity, yaw rate, and roll angle. Then the influence of numerator dynamics on vehicle behavior is studied and vehicle class segregation is attempted through evaluation of the amplitude ratio of the frequency responses for sideslip velocity, yaw rate, and roll angle.
Technical Paper

Modeling of Dynamic Characteristics of Tire Lateral and Longitudinal Force Responses to Dynamic Inputs

1995-02-01
950314
This paper presents the development of a tire model for use in the simulation of vehicle dynamics. The model was developed to predict tire lateral and longitudinal force responses to dynamic inputs. In this new tire model, the contact patch of a tire is lumped into a number of elements to study the dynamic behavior of the displacement of the tire contact patch in the lateral and longitudinal directions. For each displacement, a differential equation governing the dynamic behavior of the displacement to the dynamic inputs is derived. Based on the differential equations for the lateral and longitudinal displacements, difference equations are derived for the purpose of simulating tire output responses. Since system parameters, such as mass, damping and stiffness, in the difference equations are unknown, estimation of system parameters is performed using the differential equations and experimental data measured for this research.
Technical Paper

The Application of Pulse Input Techniques to the Study of Tire Lateral Force and Self-Aligning Moment Dynamics in the Frequency Domain

1995-02-01
950317
This paper presents the application of pulse input techniques to study tire dynamics in the frequency domain. Many tire researchers analyze tire dynamics by means of studying the frequency response of tire output responses to sinusoidal frequency inputs, for example, the frequency response of tire lateral force to sinusoidal slip angle input. To replace expensive and time-consuming sinusoidal frequency tests, pulse techniques are applied to obtain frequency responses. A series of slip angle pulse input tests in various conditions (several normal forces, speeds and magnitudes of slip angle inputs) are executed on a pneumatic tire. The tire output responses to the slip angle pulse inputs are transformed into the frequency domain using discrete Fourier transform. Several rules of Fourier transform related to the study of tire dynamics are detailed. The frequency responses obtained by pulse techniques are validated by comparison with the results from sinusoidal frequency tests.
Technical Paper

Sprung/Unsprung Mass Properties Determination without Vehicle Diassembly

1996-02-01
960183
This paper presents a method of measuring a vehicle's sprung mass without vehicle disassembly. The method involves measuring whole vehicle properties at different trim heights. The accuracy of the method is tested using results for several vehicles. As an extension of the sprung mass determination, this paper also demonstrates the feasibility of determining the inertial properties of a vehicle's sprung mass without vehicle disassembly. Lastly, measured vehicle roll/yaw product of inertia values are presented for a selection of vehicles.
Technical Paper

Spot Weld Failure Analysis for Accident Reconstruction

1994-03-01
940570
Adequacy of resistance spot welds in low carbon steels in relation to structural integrity can become an issue in the reconstruction of automotive accidents. Because formation of a plug (or button or slug) in a peel test is used as a quality control criterion for welds, it is sometimes assumed conversely that a weld which failed is defective if no plug is present. Spot welds do not necessarily form a plug when fractured. Fracture behavior of spot welds both by overload and fatigue is reviewed. Then techniques for examination of field failures are discussed. Finally two case histories are discussed.
Technical Paper

Effects of Loading on Vehicle Handling

1998-02-23
980228
This paper explores the effects of changes in vehicle loading on vehicle inertial properties (center-of-gravity location and moments of inertia values) and handling responses. The motivation for the work is to gain better understanding of the importance vehicle loading has in regard to vehicle safety. A computer simulation is used to predict the understeer changes for three different vehicles under three loading conditions. An extension of this loading study includes the effects of moving occupants, which are modeled for inclusion in the simulation. A two-mass model for occupants/cargo, with lateral translational and rotational degrees of freedom, has been developed and is included in the full vehicle model. Using the simulation, the effects that moving occupants have on vehicle dynamics are studied.
Technical Paper

Computer Accident Simulation - Pretty Pictures and the Real World

1991-02-01
910368
A Computer Accident Simulation (CAS) is the application of dynamics to known physical evidence to yield a best approximation of the interactions of vehicles and other objects during the real world accident scenario. The simulation is based upon the reconstruction after an engineer's examination of the vehicles involved, the roadway (i.e., skid marks and gouges), and any substantiated evidence from witnesses. Examples of various cases are presented to illustrate the engineer's accident reconstruction and how the reconstruction is used to establish the computer simulation. The cases are used to explain the accuracy, features, advantages, and disadvantages of developing a computer accident simulation. During the interaction of the engineer and the graphics specialist, extra information such as witness viewpoint needs to be attained to make the computer simulation.
Technical Paper

The Effects of Suspension Stiffness on Handling Responses

1991-09-01
911928
The purpose of this paper is to investigate the influence of suspension roll stiffness on handling responses. A linear mathematical model is utilized to scrutinize responses on sideslip, yaw velocity and roll angle. Due to different sensitivity to suspension roll stiffness, the influence on an oversteer and an understeer vehicle is very distinct. An oversteer vehicle possesses high sensitivity to suspension stiffness at high speeds. Forward speed also plays an important role. Responses in root locus plots and steady state gains are illustrated in this study.
Technical Paper

Effect of Lateral Tire Flexibility on the Steering System Dynamic Behavior

1991-02-01
910239
The purpose of this paper is to investigate the influence of tire lateral flexibility on the steering system dynamic behavior. Individually, the steering models and the lateral flexible models have been investigated for a long time. However, the combination of both hasn't yet drawn much attention. The inclusion of the lateral (rigid) tire model has shown to be of great importance. This study attempts to scrutinize the influence of a more practical tire model on the steering dynamic performance. Included in the study, Transient response as well as frequency response are illustrated by tables and figures.
Technical Paper

Practical Application of Vehicle Speed Determination from Crush Measurements

1987-02-01
870498
The use of vehicle damage measurements has been proven to be an effective technique in the determination of impact energy and pre-collision speeds. However, as with any analytical technique, the quality of the speed estimate is highly dependent on the accuracy of the measurements. This relationship suggests a need to employ intricate and exacting measurement schemes to obtain useable data. This approach is often difficult to implement in a routine accident investigation where a tape measure may be the only available measuring device. In the current study, vehicle damage resulting from collisions with a known speed is measured with techniques of increasing sophistication and the results are compared. These measurements are then used in conjunction with the CRASH III computer program to estimate the pre-impact vehicle speeds. The analysis technique used by CRASH III is also reviewed to provide a summary understanding of how the crush measurements are used in the program.
Technical Paper

Response of Brake Light Filaments to Impact

1988-02-01
880234
Taillight lamp filaments provide valuable information on their illumination status during a collision. This information is contained in the shape of filament deformation, extent and nature of filament fracture, and filament oxidation. The degree of deformation of these filaments, a quantity which may be useful in determining velocities prior to impact, has been documented for headlights but has not been closely examined for taillights. In this paper, a study of the quantification of automobile taillight filament response when subjected to low speed impacts is presented. These studies include two different brands, five velocities up to approximately 19 miles per hour, three filament orientations, and two different deceleration pulses. Recommendations are given for further study in order to provide sufficient data for practical application and use in accident reconstruction.
Technical Paper

Two Dimensional Thoracic Modeling Considerations

1989-02-01
890605
There is currently a considerable effort being devoted to the development of anthropomorphic test devices for the measurement of thoracic side impact response. Both the SID and EUROSID have been proposed as viable candidates for this test device. In addition, the thorax of the three year old Fart 572 has been shown to be useful in simulating side impact while used in the frontal orientation. This apparent anomaly suggests that the intuitive differences between the frontal and side geometries of the thorax may not be significant. To date, all useable thoracic models have been unidirectional. For the most part, these have been frontal models. This paper discusses some of the difficulties inherent in the development of a two dimensional thoracic model and ways these difficulties can be addressed. Based on these considerations, a single thoracic impact model is proposed for simulation of both frontal and lateral impact without adjustment of model parameters for impact direction.
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