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The viscous criterion (V*C) has been proposed by biomechanics researchers as a generic biomechanical index for potential soft tissue injury. It is defined by the product of the velocity of deformation and the instantaneous compression of torso and abdomen. This criterion requires calculation and differentiation of measured torso/abdomen compression data. Various computational algorithms for calculating viscous criterion are reviewed and evaluated in this paper. These include methods developed by Wayne State University (WSU), NHTSA (DOT) and Ford. An evaluation has been conducted considering the accuracy of these algorithms with both theoretical and experimental data from dummy rib compressions obtained during a crash test. Based on these results, it is found that: V*C results depend on the scheme used in the computation process, the sampling rate and filtering of original raw data. The NHTSA method yields the lowest V*C value.

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 the development of a Dynamic Door Component Test Methodology (DDCTM) for side impact simulation. A feasibility study of the methodology was conducted using a MADYMO computer model by taking parameters such as door pre-crush, door-to-SID (Side Impact Dummy) contact velocity and the deceleration profile into consideration. The prove-out tests of this methodology was carried out on a dynamic sled test facility. The DDCTM has been validated for various carlines. In addition, various existing dynamic component test methods are reviewed. In our approach, a pre-crushed door, mounted on a sled, strikes a stationary SID at a pre-determined velocity. A programmable hydraulic decelerator is used to decelerate the sled to simulate the barrier/door deceleration pulse during door-to-SID contact period. This test procedure provides excellent correlation of the SID responses between the component test and the full-scale vehicle test.

Various foam models are developed using LS-DYNA3D and 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. Comparisons of the results obtained from different foam models with test data show excellent correlations for all the cases studied.

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 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.

Currently, the three (3) methods for calculating the HIC-value are: 1) direct computation method, 2) utilization of maximization requirement approach developed by Chou and Nyquist, and 3) a partitioning technique. A method which involves the adoption of an optimization approach for HIC calculation is discussed in this study. This optimization technique, which has previously been applied to Boundary Element Method (BEM), employs an improved constrained variable metric method in recursive quadratic programming. This technique was applied to three theoretical and ten experimental acceleration pulses; the results compare extremely well with exact solution and/or other numerical methods. It is concluded that this optimization scheme provides accurate HIC calculations. A study is planned to investigate the feasibility of extending the application of this optimization technique to an integrated trim/foam/sheet metal pillar system for improved interior head impact protection study.

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.