A new analytical method for determining J-integral-crack opening displacement curve of DCB specimen with large scale fiber bridging

The fiber bridging is an important toughening mechanism, and J-integral theory is usually used to determine the bridging stress. To achieve the determination of bridging stress, the calculation of J-integral-crack opening displacement J(δ) curve is the key. A new analytical method is proposed to calculate the J(δ) curve, which only requires the experimentally recorded load–displacement data. Compared with the traditional analytical method based on equivalent crack length, the proposed method has more physical significance. Two independent parameters, i.e. initial fracture toughness J_init and the crack opening displacement corresponding to initial damage δ₀ can be directly extracted from the calculated J(δ) curve. In addition, the bridging stress with a multi-linear function can be determined. Experimental cases with large scale fiber bridging are used to verify the validity of the analytical method. The proposed method is simple and effective, and can provide support for investigating the fiber bridging phenomenon of mode I delamination.