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An important requisite for an effective use of numerical tools in occupant safety assessment is that suitable models of crash victims are available. Reliable well validated multibody models of several crash dummies have been developed in the last two decades. Flexible parts are modeled as rigid bodies interconnected by joints that account for the flexibility. Recently the finite element method has been used for modeling such parts. In this paper an alternative method is proposed namely as a flexible body with distributed mass and stiffness. To evaluate these methods, three models of a rib module of a EUROSID-1 dummy are compared with the rib modeled as: a chain of nine rigid bodies interconnected by revolute joints, and torsional springs and dampers, one flexible body with the deformation approximated by one predefined displacement mode, a finite element model using triangular shell elements with a linear elastic material behavior and mass proportional Rayleigh damping.

An important assumption of conventional belt models is that the belt can slide over points that are fixed to bodies or the inertial space. Using finite elements sliding of the belt in all directions can be modelled. A study comparing both belt modelling techniques using the MADYMO program is described. A mid-severity frontal impact sled test using a 50th percentile Hybrid III dummy is simulated. In addition, a performance study for oblique impact situations is presented to determine the effect of multi-directional belt slip of the shoulder belt. For the situations studied, it was found that both belt models can be used if belt roll-out at the shoulder does not occur. However CPU times are significantly higher for the simulations with finite element belts. An efficient approach for those cases where multi-directional belt slip of the shoulder belt occurs is to apply the finite element belt model only after a parameter study using the conventional belt model.

Simple, as well as more sophisticated empirical airbag models have been developed since the early seventies. By discretization of the fabric skin of the airbag in finite elements, phenomena like the inertia effects due to the motion of the different parts of the fabric, bag slap, and pressure forces on penetrating objects are accounted for, also during the deployment phase of the airbag. In most cases relatively simple thermodynamics, i.e. a lumped parameter approach, can be used. For an out-of-position occupant however a complication can arise if the gas jet coming out of the inflator is directed towards the occupant. A relatively simple analytical model to account for the gas jet effects in combination with a lumped parameter approach is implemented in the MADYMO finite element module. A model validation using a pendulum test with a passenger side airbag shows a good agreement between the measured and calculated results, only when the gas jet effects are included in the analysis.

MADYMO is a well accepted multibody program for crash analyses. The main emphasis of the program is the prediction of the kinematics and dynamic behaviour of crash victims during a crash. A brief description of the MADYMO history and theory is presented as well as recently developed couplings with explicit finite element programs for non-linear structural analyses. The development of dummy databases is described with special emphasis on the development of the EUROSID dummy database using a new multibody module. This module is based on a recursive algorithm and allows modelling of other kinematic joints in addition to the currently available ball and socket joints. The use of MADYMO in impact biomechanics is illustrated with examples from the area of vehicle safety and sports biomechanics. The use of MADYMO for structural modelling is illustrated by a side-impact simulation using MADYMO to model both car and occupant.