Study on the Mode I Interlaminar Fracture Toughness of Multidirectional Composite Laminates

摘要

The double cantilever beam (DCB) test method and the modified beam theory are adopted to investigate the Mode I interlaminar fracture toughness of multi-directional composite laminates. The test procedure was developed by using a stereoscopic microscope to observe the delamination front tip and a testing machine to record the displacement and load data. A dial indicator was used to eliminate the error due to initial clearance in the clamp. A modified beam theory and a compliance calibration method were used to calculate the interlaminar fracture toughness. The Mode I interlaminar fracture toughness of carbon fiber reinforced bismaleimide resin matrix (BMI) composite laminates with four different interface patterns (0/0, 45/-45, 0/-45 and 0/90, respectively) was obtained. The results show that the patterns of interface ply angles have an obvious influence on Mode I interlaminar fracture toughness of composite laminates.