Modal Responses of Mechanical Structures Under Thermo Mechanical Loads PhD

Cranfield University

The research in this doctoral opportunity will investigate the relation between the strain energy and the change in modal response of a structure under thermo-mechanical loads. Sub-surface fatigue in mechanical structures affecting their fundamental modes within conventional sensing limits. As per published research, these effects are mostly investigated under dynamic loads on different boundary conditions. Analytical, numerical and empirical studies clearly indicate that the dissipated strain energy during crack propagation affects the modal values of the structure. However, there is still need to perform comprehensive research that can relate the mentioned parameters specifically under thermo-mechanical loads. The cyclic thermal loads along with dynamic loading may represent a more practical loading scheme as experienced on mechanical components or structures. In this research, empirical setup will be developed by using a modal exciter and a mini cartridge or induction heating mechanism to provide both the dynamic and thermal loading on a mechanical structure simultaneously. Instrumentation involving accelerometers, acoustic sensors and data acquisition will allow the measurement of the modal response together with the dissipated strain energy. Empirical testing schemes will be pursued under a pre-set boundary condition and more likely to be in a free-fixed mode. The data acquired will be used to relate the strain energy and modal response of the structure when subjected to sub-surface fatigue.