Thermomechanical Cracking in Coated Media Due to High Speed Asperity Excitation.
Technical rept. Jan 86-Jun 87,
NEW MEXICO UNIV ALBUQUERQUE BUREAU OF ENGINEERING RESEARCH
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This investigation considers the thermo-mechanical effects of an asperity traversing at a high speed over a semi-infinite medium with a thin hard coating surface. The general analytical solutions of the mechanical stress state, the temperature field and the thermal stress state are obtained and expressed in Fourier transform space. The asperity speed is sufficiently high such that the thermal stress is much larger than that caused by the mechanical traction of asperity pressure and friction. The analysis emphasizes the heating effect of the friction force, which leads to the initiation of the thermo-mechanical cracking, or heat-cracking in the surface layer, the substrate or their interface. For hard coating layers, the initiation of a crack will occur at a depth eta sub max where the maximum principal thermal stresses occur. The depth is found to be controlled principally by the Peclet number. Keywords Parametric analysis Integral transforms.
- Coatings, Colorants and Finishes