Performance Enhancement of a Hole in a Plate Through Residual Stress Induced by Thermal Autofrettage

Abstract

This article presents an investigation of the reinforcement of lughole structures, particularly a hole in an infinite (very large) plate widely employed across aerospace, automobile, and marine industries. The study focuses on augmenting the load-carrying capacity of these structures by inducing the compressive residual stresses surrounding the holes by using the method of thermal autofrettage. A thermo-mechanically coupled temperature displacement finite element approach implemented in abaqus is used to capture the effects of plastically deforming autofrettage temperature gradients on the mechanical response in the vicinity of the hole. The plasticity is incorporated using the von Mises yield criterion to capture the yielding and plastic deformation behavior of the material in the vicinity of the hole in the plate under plane stress conditions. The residual stresses upon the removal of the temperature gradients are analyzed and the corresponding load-carrying capacity is assessed. It is found that the residual stress induced by thermal autofrettage around the hole in the plate can drastically reduce the total resultant tensile stress in the vicinity of the hole when loaded in axial tension as well as in pin loading. For instance, the maximum net axial tensile stress induced at the autofrettaged hole surface due to a far-field applied axial tensile stress of 18 MPa is only 5 MPa, which is significantly lesser as compared to 53.5 MPa induced in the corresponding non-autofrettaged hole for the same far-field applied stress.