A Whole-Structure Approach to the Influence of Residual Stress on Fracture 12th International Conference on Fracture held on

摘要

It is known that the presence of tensile residual stress in a cracked structure can result in the load carrying capacity of the structure being much lower than that of an identical structure with no residual stress. Various researchers have carried out tests to assess the influence of residual stress on the fracture of cracked components. Others have considered the problem of how to treat residual stresses in the fracture assessment of these components. However, in engineering practice, a component is combined with other components to form a structure. This raises the possibility of long-range residual stresses being introduced in the structure as a result of misfits between components. In order to assess how the strength of a structure containing a cracked component is influenced by these long-range residual stresses, a whole-structure level approach (rather than a component-level approach) is required. The degree of change in load carrying capacity of such a structure depends not just on the initial level of long-range residual stress but also on how the residual stress changes as plastic deformation occurs in the structure prior to fracture. This paper explores the influence of these long-range residual stresses on fracture from a whole-structure perspective. An idealised structure is described and results from whole-structure experiments, based on the idealised model, are presented. It is shown that the change in the load carrying capacity of the structure depends not only on the level of initial residual stress but also on the relative stiffness of the uncracked and cracked parts of the structure, as well as on the level of plastic crack mouth opening displacement (CMOD) prior to fracture.