Comparison of three different methods for determination of damage in solid materials

Abstract

Material failure is most often caused by cyclic fatigue loading. Prior to failure, material damage growth can be observed by means of various methods. Through experimental research, it has been determined that individual methods are appropriate only for specific types of materials and that analysis results also depend on the method of material loading. Therefore, a question is being raised on which method to choose for a specific material and method of loading. For this purpose, the paper presents the results of the damage initiation process and damage growth for high yield strength material Armox 500T, as well as for annealed low yield strength steel 42CrMo4. The measured data on material response are evaluated by means of three different methods which are based on the elastic modulus, plastic strain energy, and maximum stress.Parameters and damage values were obtained from the measurement data by means of various damage evaluation methods. After that, an overview was made of the differences between these methods. The results were used to determine the deficiencies and benefits of each method and the most appropriate method for subsequent tests was selected. The most frequently applied damage identification method, i.e. the elastic modulus method, proves to be inappropriate for high yield strength materials.