Development of Hybrid Stress Measurement Technique Using Thermoelasticity and Photoelasticity and Its Application to Experimental Investigation of Fetting Problems.

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The present project developed a new experimental technique of full-field stress separation measurement based on the hybrid use of thermoelasticity and photoelasticity. Several experimental investigations were carried out for measuring stress field around notches and cracks using the developed technique. The results obtained are summarized as follows.1. A hybrid measurement technique using both of thermoelastic stress analysis (TSA) and photoelastic stress analysis (PSA) developed for stress separation. The sum of principal stresses can be measured by TSA, while the difference of p***pal stresses and direction of principal stress can be measured by PSA. All of the stress components can be determined from the Mohr's stress circle.2. Stress separation of a loaded plate with a circular hole was investigated. The experimental results were compared with results of boundary element method analysis. It was found that the stress components experimentally obtained by the proposed technique coincided with those obtained by the boundary element analysis. Feasibility of the proposed hybrid measurement for stress separation is demonstrated.3. The developed hybrid stress separation measurement technique was applied for determining distribution of all individual stress components in cracked plates subjected to mechanical load. The experimental results were compared with results of boundary element method analysis. It was found that the all individual stress components around the center crack and the edge crack can be accurately determined. Stress intensity factors and the J-integrals were calculated from the measured stress distribution. For the accurate evaluation of J-integral, near tip exclusive domain integral method was newly proposed. It was found that these fracture mechanics parameters can be evaluated with good accuracies by the present techniques.