Search

To evaluate and analyze the pedestrian injury risk of automobiles, the finite element models of headform impactors are used. In this study, a modeling method that can accurately estimate the peak of the headform impactor impact pulse and head injury criterion (HIC) was developed. The headform impactor skin has the characteristics of both hyperelasticity and viscoelasticity. Therefore, compression tests, stress relaxation tests, and rheometer tests were conducted, and the hyperelastic and viscoelastic models were developed. The models were combined and used in the finite element analysis. The new headform impactor model was verified to accurately estimate the peak of impact pulse and HIC at the certification test of the headform impactor. [ABSTRACT FROM AUTHOR]

Hood stiffness scanning tests were conducted and numerical modeling of hoods was implemented to simulate hoods having the same stiffness as the test results in order to predict the hood surface deflections occurring during the dipping process among automobile manufacturing processes through the finite element analysis (FEA). The flow stress of the mastic sealer and the hemming sealer was measured through viscosity tests to express the material properties of the adhesive and decreases in the thickness of inner panels were reflected in order to accurately calculate surface deflections. The yield stress of the hemming part and the width of the master sealer were selected as virtual joining properties so that joint complexity and singularity could be compensated for. The virtual joining properties were applied to a total of six hood models and tendencies that correspond to individual hood models were analyzed to define tendency functions thereby presenting a method of predicting virtual properties without undergoing stiffness scanning test and analysis processes. When the results of analyses that predicted surface deflections after dipping processes were compared to 3D-scanning results, the results of analyses were found to have accuracy not lower than 85%. In addition, analyses to predict surface deflections after the dipping process were conducted using numerical models that reflected inner panels with reinforced stiffness and decreases in surface deflections were identified according to the results. Therefore, the fact that designs for reducing surface deflections after the dipping process could be made utilizing the technique implemented in the present study to predict permanent deformation of hoods was proved. [ABSTRACT FROM AUTHOR]