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This paper reports a study on the use of response inverse filtering (RIF) methodology for crash pulse prediction. RIF is based on the finite impulse response (FIR) and inverse filtering (IF) methods. The FIR coefficients obtained by the digital convolution theory and the least squared error approach serve to transfer response from the input (impacting or excitation) side to the output (non-impacting or receiving) side. The FIR method, a process of low pass filtering (e.g. truck body mount), is commonly used in predicting the non-impacting side (e.g. truck body or cab) response with the input excitation in the impacting side (e.g. truck frame). The accuracy in the validation and prediction via FIR transfer function depends on the frequency contents of the input and output accelerometer data from which the transfer function is developed. The prediction accuracy is low if the output data contain higher frequency components than the input.

In vehicle crash tests, an unbelted occupant's kinetic energy is absorbed by the restraints such as an air bag and/or knee bolster and by the vehicle structure during occupant ride-down with the deforming structure. Both the restraint energy absorbed by the restraints and the ride-down energy absorbed by the structure through restraint coupling were studied in time and displacement domains using crash test data and a simple vehicle-occupant model. Using the vehicle and occupant accelerometers and/or load cell data from the 31 mph barrier crash tests, the restraint and ride-down energy components were computed for the lower extremity, such as the femur, for the light truck and passenger car respectively.

Computer simulations of occupant dynamics in frontal crashes have pretty much been done like sled tests, in that crash-induced deformation of the interior — which may be significant for the occupant — has usually not been accounted for. The object of occupant dynamics simulation studies is often to assess the effect of changes in vehicle front-end parameters on occupant response. But these parameter variations may influence the amount of interior deformation. In order to simulate more accurately occupant dynamics in very severe crashes, the interior deformation caused by engine intrusion should concurrently be simulated. Crash test results over a range of speeds were used in a computer simulation study of occupant compartment intrusion in high speed barrier crash tests. It was found that intrusion has a significant effect on occupant response and where appropriate should be included in crash simulations.

This paper describes an interactive graphics processor, VIEW2D, for the MVMA-2D occupant crash simulation model. VIEW2D simplifies the use and operation of the MVM-2D by processing and displaying any of the hundreds of input and output response variables. VXEW2D displays the occupant and vehicle interior on a graphics terminal before program execution for verifying or revising the input data file. It also displays the kinematics and the dynamic responses of the dummy and vehicle at times selected by the user. The main functions and features of V1EW2D are described, and the procedures to make animation on a graphics terminal with refresh mode are presented. Finally, to illustrate the applications of the MVMA-2D and VIEW2D, a study of front structure intrusion effects on occupant kinematics and dynamic responses is discussed.

The vehicle-occupant impact dynamics during a crash are studied using a simple mathematical model. The model yields explicit analytical relationships between occupant responses and physical parameters of the vehicle structure and occupant restraint system. These parametric relationships, verified by experimental crash tests of the total system, are useful in describing the physical concepts of the impact event, and predicting occupant dynamic behavior during a vehicle crash. The limitations of the model are discussed and the design procedures using the equations and “carpet” plots are presented to aid the designer in the selection of a restraint system and vehicle structural parameters to meet predetermined design criteria. The application of the “carpet” plot in studying the sensitivity of the occupant response to the vehicle structural parameters is also demonstrated.

It is frequently desirable to construct a characterization of vehicle deceleration which is significantly simplified from its actual time history. A number of interesting techniques have been developed to perform this characterization based upon polynomial and Fourier-type series approximations and utilizing goodness of fit criteria related to both least squared error and the satisfaction of boundary conditions. Extensive mathematical occupant simulations indicate that characterizations involving as few as four parameters are adequate to describe the primary effects of complex vehicle deceleration time histories as they influence occupant dynamics with conventional restraint systems.

This paper reports a study of the dynamic characteristics of body mounts in body on frame vehicles and their effects on structural and occupant CAE results. The body mount stiffness and damping are computed from spring-damper models and component test results. The model parameters are converted to those used in the full vehicle structural model to simulate the vehicle crash performance. An effective body mount in a CAE crash model requires a set of coordinated damping and stiffness to transfer the frame pulse to the body. The ability of the pulse transfer, defined as transient transmissibility[1]1, is crucial in the early part of the crash pulse prediction using a structural model such as Radioss[2]. Traditionally, CAE users input into the model the force-deflection data of the body mount obtained from the component and/or full vehicle tests. In this practice, the body mount in the CAE model is essentially represented by a spring with the prescribed force-deflection data.

This paper reports a study of the impact dynamic characteristics of body mounts in a body-on-frame vehicle. Two methods of dynamic analyses are utilized. One method is direct impact; and the other excitation on the body mount. Using a series of component test data, the direct impact method yields the natural frequency, f, and damping factor, ζ, for a spring-mass-damper model of a body mount. The functional relationship between the g-force versus deflection curve and f, ζ, and v (impact speed) is examined. Given a frame impulse, the excitation method predicts the body response by the convolution integral. The transient transmissibility (TT), the ability of a body mount to transmit shock impulse from the frame to the body in the early part of crash duration, is investigated. The degree of front-loadedness on the body pulse is determined by TT and thus it affects the occupant/vehicle crash response.