Using an Optical Measuring System for Identification of Material Parameters for Finite Element Analysis

Finite element simulations in passive safety applications for the automotive industry have reached the status of a major development tool. Therefore, the prediction, gained by simulation, has reached high levels of quality. Load paths, loads and energy absorption have to be detected correctly by simulation to reach the necessary level of real life prediction. The modeling of a finite element simulation has to be done carefully. Modeling may be divided into 4 areas, the modeling of geometry, of material behavior, of connecting techniques and of numerical parameters. In this paper, material characterization and modeling of plastics are described. Deformation and failure behavior of the plastic material have to be modeled correctly to calculate load paths and energy absorption. Stress-strain and failure mechanisms of materials need to be known for the modeling of the material behavior. Those values depend on strain, strain rate and temperature. The material characterization, the description of the behavior under given loads, is the base for the choice of an appropriate material model. Experimental data is used for the material characterization and the determination of the necessary parameters within a material model. The Accredited test Center "ATC" of EDAG in Fulda, which is accredited according to ISO 9000, is performing such experiments for some years. The introduction of an optical measuring system to evaluate the stress-strain behavior is described in this paper.