Accession Number : ADA184176

Title :   Thermomechanical Cracking in Coated Media Due to High Speed Asperity Excitation.

Descriptive Note : Technical rept. Jan 86-Jun 87,

Corporate Author : NEW MEXICO UNIV ALBUQUERQUE BUREAU OF ENGINEERING RESEARCH

Personal Author(s) : Ju, Frederick D ; Liu, Jew-Chy

PDF Url : ADA184176

Report Date : Apr 1987

Pagination or Media Count : 82

Abstract : 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.

Descriptors :   *CRACKS, *COATINGS, *THERMAL STRESSES, *FRICTION, LAYERS, INTEGRAL TRANSFORMS, MECHANICAL PROPERTIES, TRACTION, SUBSTRATES, TEMPERATURE, SOLUTIONS(GENERAL), HEATING, STRESSES, PARAMETRIC ANALYSIS, SURFACES, THERMOMECHANICS, HARDNESS, THINNESS

Subject Categories : Coatings, Colorants and Finishes

Distribution Statement : APPROVED FOR PUBLIC RELEASE