Exploration of the Weibull Modulus as a Function of Surface Preparation and Flexure Testing Conditions

Weibull characteristic strength and modulus were studied as a function of machining severity and orientation. The characteristic strength decreased as machining conditions were more aggressive, and longitudinally machined specimens were consistently stronger than transversely machined specimens. The Weibull modulus did not vary systematically with machining conditions, but after pooling data from sets machined under identical conditions, a low Weibull modulus and a poor fit to the Weibull distribution was obtained. The results showed that the lack of reliability of the machining process effectively decreased the Weibull modulus, a critical parameter to be used in the life prediction of machined components.