Investigation of the ratcheting phenomenon for dominating bending loads Original Research Article

For components subjected to strong mechanical and cyclically thermal loads, proof of a limitation of permanent strain is of great significance due to the danger of deformation progressing from cycle to cycle (ratcheting). Within the framework of investigations concerning the load situation of the first wall of a fusion reactor, experimental and theoretical studies on ratcheting were carried out. Progressive deflections were identified under suitable conditions on internally cooled beam-shaped components subjected to cyclic heating and a bending load. A simple beam model can be used for systematic theoretical analysis in this case. Its treatment leads to the development of so-called Bree diagrams with which the structural behaviour can be characterized as a function of the applied primary and secondary stresses. The peculiarities arising under predominant bending loads will be discussed.