Definition and Modeling of Critical Flaws in Graphite Fiber Reinforced Resin Matrix Composite Materials

摘要

An analytical and experimental study was conducted to determine criticality of interlaminar disbonds by NDE methods. Criticality of such flaws in a shear environment (action of shear near support) was defined in terms of crack propagation and was analyzed by principles and methods of fracture mechanics. Growth of disbonds under cylic loading was also studied. Failure under compressive loading in presence of a disbond was defined in terms of buckling and an elastic stability analysis was utilized for assessing criticality. Analytical predictions were compared with experimental results in both cases. Utrasonic 'C' scans were used for detection and tracking of the flaws. Preliminary wave propagation studies were conducted for estimating changes in storage and loss moduli induced by moisture conditioning to examine the possibility of using such measurements as NDT techniques for damage assessment. (Author)