Fatigue of materials
Fatigue failure occurs when the structure or the test sample is subjected to cyclic loading, which results in plastic deformation in the locations stress concentration. Progressing and accumulating material damage may lead to fatigue fracture or eventual overall failure. Fatigue failure progression depends on the character and number of loading cycles. Materials are tested on the special testing devices enabling to apply various types of loading.
We focus on two types of fatigue failure testing. The first one is expressed by standard testing of fatigue properties of metal and ceramic materials. By using electro-resonance loading machines we are able to determine fatigue properties in the area of high-cycle fatigue, including detailed identification of stages of fatigue failure using the method of acoustic emission and analysis of changes in load frequency. The second one is represented by analysis of contact fatigue. We analyse propagation of contact fatigue of metal and ceramic materials using axial and radial testing machines (e.g. due to different lubrication conditions). We also determine service life of radial and axial bearings. In that case, we also use method of acoustic emission to monitor initiation and propagation of the damage.