DETERMINATION OF NONLINEAR MATERIAL PARAMETERS OF A TYPICAL COMBUSTION CHAMBER MATERIAL BY MEANS OF OPTIMIZATION METHODS

A study for the determination of elasto-plastic parameters of a typical combustion chamber material (Cu alloy) with different test sample ge-ometries is presented. Based on the experimen-tal results of elasto-plastic tests of three sample geometries, the appropriate elasto-plastic pa-rameters such as yield stress and hardening parameters are determined. Cyclic fatigue calculations using FEM which as-sumes either kinematic hardening or isotropic hardening showed that neither of the methods alone was able to reproduce the experimentally determined material behavior for a cyclic defor-mation of one of the test samples. By the use of a combination of non-linear kinematic and multi linear isotropic hardening, a satisfying agreement between experiment and FEM predictions can be obtained. For the majority of the tests (cyclic tests, biaxial tests), optimization algorithms had to be applied in order to determine the material parameters from the test results