Prediction of brittle fracture in notched specimens under cyclic loading

Abstract

Brittle fractures in steel can have devastating effects during its use, such as the collapse of buildings during earthquakes. This paper describes the effects of cyclic loading on the occurrence of brittle fracture and presents a brittle fracture prediction method. Notched specimens of steels with low and high fracture toughness were tested under monotonic and cyclic loading. A cumulative ductility estimation method was developed to predict the occurrence of brittle fracture using the Coffin–Manson law and Miner's rule. This method is based on the empirical relationship between the ductility amplitude or Weibull stress and the number of cycles at brittle fracture. Cumulative damage theory was also used to consider different cyclic amplitudes. The proposed approach can be employed to predict cumulative ductility at brittle fracture and showed a relatively high correlation coefficient between the calculated and experimental results. In addition, this approach can be used to predict brittle fracture using data from samples with different toughness and notch shapes in a unified manner, unlike many previous methods.