Beam analysis of the double cantilever beam specimen with fibre bridging

Abstract

The fibre bridging phenomenon commonly seen in double cantilever beam tests is considered an artifact of the standard unidirectional specimen. Therefore, it limits the scope of the test to the measurement of the critical strain energy release rate G_{I c} for crack initiation. This paper presents a beam model based on a linear traction–separation law that has been shown to be a good approximation to the early stages of fibre bridging. The present model enables the evaluation of accurate propagation G_{I c} values through the fitting of experimental load–displacement curves. Furthermore, fairly good fits can be obtained without employing sophisticated optimization algorithms by considering simple relations between model parameters and curve features. Therefore, the present model is able to extract a broader set of results from a single test, thereby increasing the confidence in toughness measurements.