Surface Traction and Crack Propagation in Delamination Wear.
Final rept. Feb 78-Sep 81,
MASSACHUSETTS INST OF TECH CAMBRIDGE LAB FOR MFG AND PRODUCTIVITY
Pagination or Media Count:
The mechanisms of surface traction and crack propagation and their functional relation to sliding wear are investigated experimentally and theoretically. According to the delamination theory of wear, the wear of materials strongly depends on friction because of the effect of surface traction on subsurface deformation and crack nucleation and propagation rates. Experimental studies using the cylinder-on-cylinder sliding arrangement with the iron based metals show that the coefficient of friction varies with the sliding distance and the environment. It is postulated that it is due to the changing contributions of three components of friction due to the deforming asperities plowing by wear particles and hard surface asperities and adhesion. At any given loading contact only one of these mechanisms may operate and therefore, the local surface traction can vary from contact to contact, affecting the crack nucleation and propagation processes. The three mechanisms responsible for the generation of friction are analyzed using plasticity theory. The finite element analyses for the elastic and elastic-plsatic solids with subsurface cracks indicate that the cracks in sliding wear propagate in a ductile manner. Such fracture parameters as the crack-tip sliding displacement and the fracture strain are found to be useful in characterizing crack propagation.
- Physical Chemistry
- Properties of Metals and Alloys
- Numerical Mathematics