Theoretical and Experimental Investigations of Fracture Mechanical Graded Materials

With the focus on innovative manufacturing and application-oriented products considering lightweight construction functional graded materials become more and more interesting. Due to the application matched functional gradation different local demands such as absorbability, abrasion and fatigue of structures are met. However the gradation has a remarkable influence on the crack propagation behaviour. According to the different fracture mechanical graded materials the area of stable crack growth is more or less distinct and the crack velocity changes. In addition the crack propagation direction can be influenced by the gradation. Within this contribution the influence of a fracture mechanical gradation on the crack growth rate, the area of stable fatigue crack growth and the crack propagation direction is investigated. For the prediction of the crack growth behaviour in fracture mechanical graded materials considering different loading situations (Mode I, Mixed Mode) a new concept was developed. This TSSR-concept can be applied to sharp as well as smooth material gradations. In addition results of experimental investigations of crack growth considering fracture mechanical graded materials are discussed.