Accession Number : ADA193311

Title :   Thermo-Mechanical Cracking in Coated Media with a Cavity by a Moving Asperity Friction.

Descriptive Note : Technical rept.,

Corporate Author : NEW MEXICO UNIV ALBUQUERQUE DEPT OF MECHANICAL ENGINEERING

Personal Author(s) : Ju, Frederick D ; Chen, Tsu-Yen

PDF Url : ADA193311

Report Date : Mar 1988

Pagination or Media Count : 192

Abstract : The research deals with the problem of asperity excited thermomechanical field in a medium with a surface layer and a near surface void defect. The thermomechanical field governs the mode of cracking, which leads to failure in the wear surface. The presence and location of the void defect is most critical. This investigation obtained the solutions for the temperature distribution and the stress state in a layered medium with a rectangular cavity. This temperature distribution and stress state result when the solid medium is subjected to Coulomb frictional loading from an asperity moving at a moderately high speed (of approximately 10-15 m/s). In the analysis, the coated medium was represented by a solid half space, with a thin top surface-layer of solid wear material. The cavity defect required a mathematical model in terms of the material coordinates. The corresponding governing differential equations were time-explicit and transient. A general finite difference formulation was developed to calculate both the temperature and the stress fields. The energy balance method was applied at the corners of the rectangular cavity to resolve the problem of singularities in the temperature field.

Descriptors :   *COATINGS, *CRACKS, *FRICTION, *THERMOMECHANICS, *THERMAL STRESSES, BALANCE, CAVITIES, COORDINATES, DIFFERENTIAL EQUATIONS, DISTRIBUTION, ENERGY, FINITE DIFFERENCE THEORY, FORMULAS(MATHEMATICS), LAYERS, MATHEMATICAL MODELS, RECTANGULAR BODIES, SOLIDS, STRESSES, SURFACES, TEMPERATURE, WEAR, PRESSURE DISTRIBUTION, TENSILE STRESS, INTERFACES, DEFECTS(MATERIALS), SUBSTRATES, SURFACE ROUGHNESS, SUBSURFACE, VOIDS, MOTION, HIGH RATE, FAILURE(MECHANICS), COBALT ALLOYS

Subject Categories : Mechanics
      Coatings, Colorants and Finishes
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE