Limiting the probability of failure for components containing flaws

Abstract

A new methodology is proposed for determining the probability of failure of an arbitrarily loaded component with an arbitrary shape, containing internal flaws. An important application area of the proposed equation is developing optimised designs and loading, associated with low probability of failure. Methods have also been developed for specifying the maximum acceptable level of the flaw number density and the maximum size of the stressed volume to guarantee that the probability of failure triggered by flaws remains below a maximum acceptable level. An important parameter called detrimental factor has been introduced to characterise components with internal flaws. Components with identical geometry and material, with the same detrimental factors, are characterised by the same probability of failure. The methods are based on derived equations related to the probability of triggering failure by flaws and the probability of clustering of flaws following a homogeneous Poisson process. Using the developed models a new technique has been created for setting reliability requirements regarding the flaw number density bounds which limit the risk of failure below a maximum acceptable level and minimise the total losses.