Validierung von dehnratenabhängigem Schaummaterial für verschiedene Temperaturen

In order to design pedestrian protection systems with the aid of numerical simulation, an exact depiction of materials used in the front end of vehicles is necessary. Materials used are simulated according to law at room temperature for the passive pedestrian protection design only. Active pedestrian protection systems, e.g. systems with an active bonnet, work partly with contact sensors which are built into the front end and are not visible from the outside. The effectiveness of the contact sensors depends on for example the determining of pressure, intrusion, acceleration, deformation etc.. The sensor signals and their strengths depend above all on the stiffness of the components built into the front end. Material simulation needs to be carried out at varying operating temperatures of the vehicle because the strength of plastic material is in turn strongly affected by it's temperature. The material from type *MAT_083 (*MAT_FU_CHANG_FOAM) in LS-DYNA depicts strain rate dependent foams (e.g. EPS, EPP etc.), and how they are generally used with bumper foam. There are various approaches with varying test methods in order to generate a material card. One approach for the determining of material behaviour involves quasistatic pressure tests and dynamic tests for various strain rates on the drop tower. The force travel curves determined and the acceleration travel curves respectively are entered directly into the card after a processing phase as tension-strain curves for various strain rates. The following paper discusses an efficient methodology from testing and generation through to material card verification for various temperatures in addition to the approach and problems which occur and their solutions.

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