Determination of linear and nonlinear parameters of combustion chamber wall materials

A study for the determination of elastic and elastoplastic parameters of a typical combustion chamber material (Cu alloy) with different test sample geometries is presented. Based on the experimental results of elastic and elasto-plastic tests of three sample geometries the appropriate elasto-plastic parameters such as yield stress and hardening parameters are determined. Furthermore, details about the loading during the tests, the advantages and disadvantages of each of the sample geometries and of the appropriate range of testing are pointed out. Cyclic fatigue calculations using FEM which assumes either kinematic hardening or isotropic hardening showed that neither of the methods alone was able to reproduce the experimentally determined material behavior. Finally, by the use of a combination of nonlinear kinematic and multi linear isotropic hardening, a satisfying agreement between experiment and FEM predictions could be obtained.