Gartsev, Sergey; Fraunhofer IKTS; Germany
Gartsev, S.; Fraunhofer Institute for Ceramic Technologies and Systems IKTS; Germany
Rjelka, M.; Fraunhofer Institute for Ceramic Technologies and Systems IKTS; Germany
Barth, M.; Fraunhofer Institute for Ceramic Technologies and Systems IKTS; Germany
Koehler, B.; Fraunhofer Institute for Ceramic Technologies and Systems IKTS; Germany
Session: Nonlinear Ultrasonics 3
Time: 09:40 - 10:00
Aero-engine parts are exposed to severe environmental conditions like high temperatures and mechanical stresses, which require robust materials. Therefore, they are produced from superalloys, and their surfaces receive an additional mechanical treatment, e.g. by shot-peening, a procedure in which small metal beads are shot upon the surface. This process introduces residual stresses which are held in the specimen by dislocations. In the course of the fatigue lifetime these dislocations will form slip bands, which will move on to the surface and generate micro-cracks there. Such cracks in turn lead to a modification of the elastic constants. To measure the state of stress by the acousto-elastic effect, the elastic constants of third order (TOEC) have to be known. In this paper overview for TOEC surface measurements with 2 approaches is presented. One of the methods is the acousto-elastic constants (AEC) determination. Results of AEC measurements with velocity dispersion for Inconel 718 are shown. In the other part utilization of surface acoustic waves (SAW) mixing for TOEC determination is preliminary examined. Results of acoustic nonlinear parameter measurements for Ti6246 are presented.