The Research On Mechanical Property Of Vehicle Crash Test Dummy Ribs

Experiment and simulation are two important methods in the research of vehicle crash safety. Anthropomorphic test dummy and its finite element model are indispensable when above-mentioned research methods are used. Recently, dummy development technology is monopolized by foreign enterprise. Our state is lack of fundamental research and self-developing capability for dummy. The rib is a main undertaker of thorax response, therefore, the mechanical properties of it were studied in this thesis. The research was divided into two parts, firstly, the influence of internal geometrical parameters of ribs on the dummy thorax calibration response was studied. Secondly, based on experiment and simulation, material parameters of rib spring steel and damping material were studied.LSTC verified dummy model was used to build dummy thorax high and low speed calibration simulation model. A parameter study of the thickness of rib steel, the thickness of rib damping material and the width of rib was conducted based on that finite element model and orthogonal experiment design method. It suggested that increasing the thickness of rib steel leads to an augment of total rib stiffness, which results in an increase of peak resistance force, a decrease of the chest compression, and a decrease of the internal hysteresis. The decrease of damping material thickness reduces the stiffness of rib and its hysteresis effect. The change of rib width insignificantly affects the internal hysteresis. The interaction effect between the thickness of steel and that of damping material has a significant effect on the chest compression in high and low speed thorax calibration, while internal hysteresis is just sensitive to that interaction effect in high speed.Integrating the experiment and simulation method, the properties and material parameters of rib material were studied. Testing program of these two materials were determined in accordance with regulations. According to the literature research, using elastic material model represents rib spring steel, and using Ogden material model represents damping material. Preparing specimen of rib spring steel and damping material, uniaxial tensile test of two speeds were conducted on the spring steel specimen, uniaxial compression test of three speeds were conducted on the damping material specimen. Initial material parameters were calculat ed using 1st Opt in accordance with experiment results and constitutive equations of material model and optimized in LS-Opt. Optimum value of material parameters which fit for finite element model was obtained.Single rib steel, single rib, a complete set o f rib impact test and dummy thorax calibration test in high and low speed were conducted to obtain experimental data which was used to verify the material parameter. The material parameter of LSTC dummy rib was set to the reverse value, and these model was used to do some simulation in accordance with the above-mentioned test. The simulation results and experimental results were compared. The result was shown that the simulation curves and experiment curves are conformity, and mostly the error rate between them is less than 10%. It indicates that material parameters which are gained by reverse technology have high accuracy.