Effect of plate thickness on stress state at sharp notches and the strength paradox of thick plates

Abstract

Notched plates are often found in various applications ranging from microelectronic devices to large-scale civil structures. Stress analysis of plate components wherein the loading is uniformly distributed over the thickness, parallel to the plane of the plate, is normally based on plane stress or plane strain assumptions. Three-dimensional effects, such as the influence of the plate thickness on stress components, are largely ignored or considered as negligible for all practical purposes. This paper summarizes recent theoretical and numerical studies and discusses some important features of the three-dimensional singular solutions for sharp notches obtained within linear elasticity. Taking into account dimensionless considerations, the relationships between the intensities of the singular stress states corresponding to the three-dimensional linear elastic solutions and the plate thickness are established. The obtained relationships have many intriguing implications for the failure assessment of notched plates made of sufficiently brittle material. For example, based on a similar argument to the one used in classical linear-elastic fracture mechanics, it can be shown that a sufficiently thick plate with a sharp re-entrant corner should have virtually zero strength when subjected to antisymmetric (or mixed mode) loading. The theoretical conclusions drawn in this paper have direct applications to fracture testing and fracture assessment of plate components, and they set new goals for further experimental studies.