Thermomechanische Ermüdung von bauteilnahen zylindrischen Hohlkörpern

Research output: ThesisDiploma Thesis

Authors

Abstract

The aim of this work is to expand the field for thermo-mechanical fatigue (TMF). The introduced TMF-test shows compared to the isothermal fatigue test a better accordance of the real load. To increase this accordance component-near TMF-tests should be the target. Influencing factors coming from the structure are not recorded by the perfectly manufactured standard specimen (cylindrical solid with polished surface). Component testing on the other hand is a considerable effort, therefore we decided to conduced tests which are near to components with tubes. The TMF-test rig is modified to perform the task of testing tubes with an outer diameter of 23 mm and a wall thickness of 1 mm. The main components are adapted to use this test rig for tube specimen. These components are the clamping system, the induction coil and the measuring technique of the temperature. The experiments under thermo-mechanical fatigue are performed by equal parameters for standard and tube specimen. The phase relation from thermal Strain to mechanical Strain is at first inphase (IP). Furthermore, out of phase tests (OoP) have been performed. The test schedule comprised the influence of the maximum temperature and of the strain constraint factor to the lifetime behavior for both types of specimens at IP and OoP. The arising time dependent stress and strain progressions are investigated and compared. The stress progression by OoP shows for both specimen types the same hardening behavior. For the IP test mode the stress progressions are contrary. The next part is to study the formation of the stress-strain-hysteresis. The compared lifetime between both specimens shows a 3 times reduced number of cycles at the tubes. The comparative lifetimes from different test parameters are similar. The final analysis of the fracture surface from both types of specimen shows similar principles for the damage pattern and the crack growth.

Details

Translated title of the contributionThermo-mechanical Fatigue of tube test specimen
Original languageGerman
QualificationDipl.-Ing.
Supervisors/Advisors
Award date28 Jun 2013
Publication statusPublished - 2013