Some applications of combined thermoelastic-photoelastic stress analysis

Abstract

Combined thermoelasticity-photoelasticity integrates the use of reflection photoelasticity to determine the difference in the principal stresses with thermoelastic stress analysis to evaluate the sum of the principal stresses, the advantage gained from this combination being the independent separation of the principal stresses at all points in the field of view. The principle has been established in prior research and suitable instrumentation designed and employed on classical test specimens. This work is extended here with the analysis of two more complex components, namely a composite panel subject to a biaxial strain field and a compressor blade excited at approximately 250 Hz. The methodology for applying combined thermoelasticity-photoelasticity under these conditions is described and the difficulties encountered highlighted and discussed. The results demonstrate that the technique and instrumentation are relatively robust and can be successfully used in these demanding applications.