Double Notch Flexure Test Method for Mixed Mode II and III Interlaminar Fracture Toughness

摘要

An experimental method to measure mixed mode II and III interlaminar fracture toughness of composite laminates is proposed. A simple bending test by a force in out-of-plane direction produced not only mode III component but also mode II component. By analyzing the both components at the crack tip, the mixed mode fracture toughness of the specimen can be assigned. The twisting force by shear forces applied to the specimen was avoided by making specimen symmetric by introducing two delaminations. Several specimens were tested. The two cracks stably grew with the load increase in almost same manner. Since the profile of the crack was not straight, appropriate analytical methods are necessary to determine the mixed mode fracture toughness.