A comparative study of two experimental techniques for the measurement of residual stresses in circular rods and tubes of perspex

Two experimental techniques have been used to measure residual stresses in circular rods and tubes of perspex, i.e., polymethyl methacrylate (PMMA). The first technique, based on photoelasticity, is non-destructive and easy to apply. It gives distribution of stresses over the entire cross-section. The analysis of this technique has been improved to relax some restrictions. The other technique is the layer removal technique. A serious drawback of this technique is that it fails to give the distribution of stresses over the entire cross-section and its accuracy for thin walled tubes is doubtful. A simplification of this technique is possible if the kinematic assumption introduced by Nishimura is replaced by one using the sum rule of stresses.