An assessment of a model method for predicting the fracture of cracked components

Abstract

Three-point-bend (3PB) specimens with real cracks and very sharp notches have been manufactured from Araldite CT200 with HT907 hardener. The plane strain fracture toughness, K_IC, has been obtained from cracked specimen tests and the apparent plane strain fracture toughness, K^App_IC, has been obtained for various very sharp notched widths. A systematic variation of apparent fracture toughness with notch width has been observed.

Burst tests have also been performed on cylinders with similar, very sharp, axially aligned, external, semi-circular notches. It has been shown that the burst pressure for the cylinders, with different depths of crack, can be predicted from the corresponding 3PB apparent fracture toughness data. The notches in the cylinders and 3PB specimens must be very sharp, and manufactured in a similar way, for the predictions to be accurate. Therefore, by loading model components containing very sharp crack-like flaws to obtain the failure loads, the failure loads of similar actual components having a real crack and behaving in a brittle manner can be predicted.

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