Estimation of Fracture Toughness with Small Specimens Based on TSM Model

Abstract

Fracture toughness is an important parameter in industry for measuring material properties. In order to obtain the fracture toughness of standard thickness materials it is necessary to go through a large number of fracture toughness experiments, but the cost is high. And in practice there are not that many eligible experimental materials to be able to conduct the experiment. If fracture toughness data are obtained for small specimens. Fracture toughness data for large and thick specimens can be predicted by the toughness scaling model (TSM). The relationship between fracture toughness based on Weibull’s principle of stress equivalence. Can effectively make up for the defect of the specimen’s own constraint degree is insufficient. The parameters of the Toughness scaling model are decisive for the accuracy of the predicted fracture toughness data. The traditional TSM calibration procedure is complex. Using a simplified Toughness scaling model can reduce many arithmetic steps in engineering. And this method was applied to calibrate the parameters for three materials. It was found that the predicted probability of failure-fracture toughness curves at a crack tip of 0.02 mm–0.03 mm for the low constraint specimens were informative although there was some error. Also, the linear relationship between the magnitude of the Weibull stress and the fracture toughness is independent of the material type. It is only related to the magnitude of parameter m.