Selecting designs with high resistance to overstress failure initiated by flaws

A powerful new technology is proposed for creating reliable and robust designs, characterized by a high resistance to failure. The new technology is based on a new mixed-mode failure criterion, and computationally very efficient simulation technique for calculating the probability of failure of a component with complex shape.The new technology handles design alternatives with complex shape and arbitrary loading. For each design shape or a loading alternative, a finite element model is created by using a standard finite element package. Next, a specially designed postprocessor reads the output files from the static stress analyses and calculates the probability of failure associated with each design alternative. Finally, the design alternative characterised by the smallest probability of failure is selected.Limitations of existing approaches to statistics of failure locally initiated by flaws are also discussed. Central to the traditional approaches is the assumption that the number density of the critical flaws is a power function of the applied stress. In this paper, on the basis of counter-examples, we show that for a material with flaws, the power law assumption does not hold in common cases, such as spherical flaws in a homogeneous matrix.