X-Ray Residual Stress Measurements of Shot Peened Components

Author:  Dr. David Kirk, Coventry University, U.K.
Source:  The Shot Peener magazine, Vol 19 / Issue 1, Winter 2005
Doc ID:  2005146
Year of Publication:  2005
Abstract:  
INTRODUCTION It is a paradox that we cannot measure residual stresses directly. Measurements of strain can be made, which are then converted into stress using available elastic constant values. This procedure is familiar to anyone involved in strain-gage analysis. Tiny changes in some physical property (that is proportional to strain) are monitored - such as resistance changes in the fine wire of strain gages or of interplanar spacing for x-ray analysis. There is a vast literature on x-ray stress analysis. The intention with this article is to present only the basic engineering principles that are relevant for understanding how residual stresses can be measured in shot peened components. An example is given to show how x-ray studies can reveal variations in residual stress with distance from a peened area.