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The University of Virginia is investigating the use of a magnetohydrodynamic (MHD) angular rate sensor to measure head angular acceleration in impact testing. Output from the sensor, which measures angular velocity, must be differentiated to produce angular acceleration. As a precursor to their use in actual testing, a torsional pendulum was developed to analyze an MHD sensor's effectiveness in operating under impact conditions. Differentiated and digitally filtered sensor data provided a good match with the vibratory response of the pendulum for various magnitudes of angular acceleration. Subsequent head drop tests verified that MHD sensors are suitable for measuring head angular acceleration in impact testing.

This paper describes the development of an automated Door Test Facility for implementing the Door Component Test Methodology for side impact analysis. The automated targeting and loading of the door inner/trim panels with Side Impact Dummy (SID) ribcage, pelvis, and leg rams will greatly improve its test-to-test repeatability and expedite door/trim/armrest development/evaluation for verification with the dynamic side impact test of FMVSS 214 (Occupant Side Impact Protection). This test facility, which is capable of evaluating up to four (4) doors per day, provides a quick evaluation of door systems. The results generated from this test methodology provide accurate input data necessary for a MADYMO Side Impact Simulation Model. The test procedure and simulation results will be discussed.

The objective of this study was to determine dynamic tensile characteristics of various door trim materials and to recommend a practical test methodology. In this study, Polypropylene (PP) and Acrilonitryl Butadiene Styrene (ABS) door trim materials were tested. Slow speed (quasi-static-0.021 mm/s) and high speed tests were conducted on a closed loop servo-hydraulic MTS system. The maximum stress of these materials increased from quasi-static to dynamic test conditions (as much as 100%). The dynamic stiffness of PP increased two times from quasi-static tests. No significant change in stiffness was observed for ABS during quasi-static and dynamic tests at different strain-rates. Quasi-static and medium strain-rate (10-20 mm/mm/s) tests may be adequate in providing data for characterizing the dynamic behavior of trim materials for CAE applications. Strain gages can be used to measure the quasi-static and in some cases, dynamic strain.

A constitutive model is developed for strain rate dependent foam and implemented in an explicit dynamic finite element code. The constitutive model is developed in conjunction with a Lagrangian hexahedral solid element with twenty four degrees of freedom. A number of dynamic impact problems involving strain rate dependent foam are analyzed and results are compared with experimental data. In all cases, numerical predictions show excellent agreement with the experiments.

Various foam models are developed using LS-DYNA3D and the model predictions were validated against experiments. Dynamic and static stress-strain relations are obtained experimentally for crushable and resilient foam materials and used as inputs to the finite element analyses. Numerous simulations were carried out for foams subjected to different loading conditions including static compression and indentation, and dynamic impacts with a rigid featureless and a rigid spherical headform. Comparisons of the results obtained from different foam models with test data show appropriate correlations for all the cases studied. Parametric studies of the effects of tensile properties of foam material and the interface parameters on foam performance are also presented.

This report describes an experimental validation of an ellipsoid-to-foam contact model. A series of static foam tests was conducted using Side Impact Dummy rib cage, pelvis, upper leg, and wooden ellipsoids as impactors to validate a theoretical foam contact model previously developed. Predicted results of contact forces, calculated using the uni-axial stress-strain relationship and contact areas, yield good correlation with the test data. These studies used CFC foams and were conducted prior to switching to water-blown foam material development. The ellipsoid-to-foam contact model is being integrated into a MADYMO side impact model. The MADYMO/foam simulation model can then be used to help evaluate design variable tradeoffs (e.g., door thickness vs. body side structures and foam padding requirement vs. interior package) thereby reducing the current dependency on testing, bolster development time, and cost.

This paper deals with the constitutive modeling of energy absorbing foams. Two mechanical-analog hyper-elastoplastic models are constructed for simulating the characteristics of semi-rigid and rigid foams. These piecewise linear models are suitable for describing the loading as well as the unloading behavior of material. The result from quasi-static compression tests are used to determine the three parameters of the models. It is observed that the models can be used in the prediction of stress-strain behavior as well as the energy absorption characteristics.

This paper describes further developments of the MVMA-2D model including program modifications of the air bag and the energy absorbing steering assembly submodels. The air bag submodel and the steering assembly submodel in the MVMA-2D crash victim simulation are independently formulated. No coupling exists between these two submodels to permit simulation of the kinematics of an anthropomorphic dummy restrained by a driver air bag restraint system mounted on a collapsible steering column. The development effort of integrating both submodels to provide the MVMA-2D model with such a capability is presented. The integrated model has been successfully utilized in simulating dynamic responses, in frontal impact situations, of a dummy restrained by a driver air bag restraint system mounted on a collapsible steering column. Validations of the model were made by comparing simulation results with experimental test data.