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Comparison of Faceted Vs Ellipsoid Dummies In Frontal Crash Simulations

An improved Hybrid-III 50th %ile crash test dummy model has been developed in MADYMO. Advanced multibody techniques have been used to obtain fast computation times with the geometry and potential accuracy of CPU intensive finite element models. So-called facet surfaces have been used in combination with flexible bodies and rigid bodies. The MADYMO contact algorithm has been enhanced with options to separately describe the non-linear compliance of two contacting objects such as a dummy and a seat and orthotropic, penetration-dependent friction has been implemented to capture of ‘belt pocketing’ in the dummy flesh. The available set of component and full dummy validations has been extended with load cases representing the latest restraint system designs and test procedures. A systematic validation has been performed using objective rating techniques to compare the enhanced facet model to the standard ellipsoid model. Objective rating showed that the enhanced facet model provides significant benefits in particular for chest deflections. INTRODUCTION FMVSS 208 and European legislation force OEM’s to develop restraint systems to work under an increased number of conditions. Consumer tests demand injury values below regulated levels, and new injury criteria are being introduced for instance for the neck and for the extremities. Restraint system performance is to be evaluated for the mid size male and small female dummies, and the risk of airbag induced injury is to be evaluated with small female and child dummies. FMVSS 208 requires belted and unbelted evaluations and various speeds (16mph, 22mph, 25mph, 30mph, 35mph) and various level of deployment thresholds are generally considered for robust restraint performance in frontal impact. Numerical techniques such as DOE, optimisation and stochastics yield increasing numbers of simulations and this requires CPU efficient and robust solutions. Predictive models of the regulated crash test dummies are a key component in restraint system optimisation. Multibody Hybrid III models with ellipsoid surfaces have proven to be highly effective in restraint system design. This paper presents a next level in multibody dummy modelling. An advanced facet model of the Hybrid III dummy is introduced as well as several recent MADYMO features which improve usability of this model. Finally objective rating is used to quantify the accuracy of both the new facet model and the standard ellipsoid model.

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