Introduction to Measurement and Prediction of Residual Stresses with the Help of Inherent Strains

In this chapter, using a simple three-bar model as adopted in Chapter 1 , the basic theory of the inherent strain method with the application to measurement and prediction of residual stresses is presented. The most key issue is how to identify inherent strains from experiments, theoretical analysis, etc. First, effective and noneffective inherent strain are defined. The theory explains how to calculate inherent strains from limited numbers of measured stresses with the aid of the elastic response matrix that is explicitly illustrated. For the case where the measurement contains some errors, an extended theory is introduced to calculate the most provable value of effective inherent strains. The basic concept of measuring procedures of two- and three-dimensional residual stresses is illustrated. The prediction method of residual stress is outlined. The theory of the inherent strain method presented here is in a general form. Practical applications are presented in Sections 7.7 and 7.9 Section 7.7 Section 7.9 , and also Sections A.2.2 and A.2.3 Section A.2.2 Section A.2.3 of Appendix A.