Accession Number : ADA307039

Title :   Development and Application of a Photoelasto-Plastic Method to Study Stress Distributions in Vicinity of a Simulated Crack.

Descriptive Note : Contract rept.,

Corporate Author : LOCKHEED AIRCRAFT CORP SUNNYVALE CA

Personal Author(s) : Hunter, A. R. ; Schwarz, M. E.

PDF Url : ADA307039

Report Date : DEC 1966

Pagination or Media Count : 144

Abstract : The photoelasto-plastic method utilizes the creep and 'frozen' stress characteristics exhibited by epoxy resins and other polymer materials when subjected to a thermal cycle whose maximum temperature is significantly less than the 'critical' temperature of the material. The resulting "frozen" stress-strain behavior is characterized by the generation of nonlinear effective stress-strain curves. Effective stress-strain curves of this nature were generated for two polymer materials, an epoxy and a polycarbonate for various thermal cycles in order to arrive at a material and associated thermal cycle which could be used to simulate the stress-strain behavior of an aluminum alloy. Also the associated birefringence was determined (calibration). Stress-strain similarity was established by use of the Ramberg-Osgood method of stress-strain representation. Upon selection of an appropriate model material and thermal cycle, elasto-plastic stress distributions were determined for infinite plates with centrally located holes to verify the usefulness of the method. This photoelasto-plastic method of stress analysis was then applied to study stress distributions in the vicinity of a simulated crack.

Descriptors :   *POLYMERS, *EPOXY RESINS, *THERMAL STRESSES, *POLYCARBONATES, *PHOTOELASTICITY, *ELASTOPLASTICITY, STRESS STRAIN RELATIONS, STRESS ANALYSIS, ALUMINUM ALLOYS, ELASTIC PROPERTIES, CRITICAL TEMPERATURE, CRACK PROPAGATION, FREEZING, CREEP, BIREFRINGENCE, PLASTIC PROPERTIES, THERMAL CYCLING TESTS, CYCLIC LOADS.

Subject Categories : Plastics
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE