A semi-analytical method for determining the mode-I delamination R-curve and fiber bridging traction-separation law of Double-double laminates

Abstract

Delamination, as one of the most prevalent failure modes of composites, was significantly influenced by the interface angles. In contrast to the limited combinations of interface angles found in traditional laminates, DD laminates, with unique sequence [±Φ/±Ψ]rT and diverse interface angles , urgently required extensive experiments and high-precision simulation analyses to delve into the complexities and unique properties of their interlayer performance. However, the calculation process of current method for determining the R-curve and the bridging traction-separation law was time-consuming. This study proposed a simplified semi-analytical method based on the Euler–Bernoulli beam theory that only required recording initial crack length, final crack length, initial compliance and final compliance. The method validation showed that the deviation between the results obtained from the semi-analytical method and the MBT method averaged no more than 2%. In addition, a tri-linear cohesive zone model based on the delamination fracture micro-mechanism was developed combining semi-analytical method. Both the initial load and ultimate load errors between the simulation and experimental results were within 5N, showing the accuracy of the model and the semi-analytical method. This method provided a simple and effective way to study the delamination propagation behaviors of DD laminates.