Analysis of the residual stress around a cold-expanded fastener hole in a finite plate

In this paper, we present results of residual stresses around a cold-worked fastener hole in a thin, finite plate. An analytical model, with plane stress conditions, elastic nonlinear-plastic loading and unloading taken into account, is explicitly presented and has been developed from existing analytical models and methodologies. The solution also accounts for elastic deformation of the mandrel, and is applicable to different sizes of hole and mandrel. A parametric study of the strain-hardening exponent, plate size, Bauschinger parameter and expansion ratio was carried out in the context of the present solution. A sample study of a plate subjected to 4% hole-cold expansion was performed to compare this model with other analytical predictions, finite element simulation and X-ray diffraction experimental results. A brief review of related issues is given. This work is intended to present completely the closed-form equations able to generate residual stress profiles with ease around a cold-expanded hole in a thin, finite plate where boundary conditions are at issue.