The Distribution of Fracture Toughness: Data for D6ac Steel.

摘要

A.R.L. have recently applied reliability theory to structural fatigue, allowing estimation of safe inspection intervals in service. The method recognises various inputs which influence the risk of failure. One input is the distribution of residual strength of structures all cracked to the same extent. This is important in view of the high variability in fracture toughness for some materials, and the corresponding variability in residual strength for a given crack size. The feasibility of applying the method was investigated using the example of an aircraft having many components made from D6ac steel heat treated to strength levels of 220-240 k.s.i. Five locations in D6ac components were considered possible sites for fatigue failures. Much fracture toughness data for D6ac steel was available. This was analysed to identify its distribution, and to estimate its parameters at each failure site. This report presents this analysis.