Failure analysis of notched composite plates with bushings

Abstract

Fiber reinforced composite structures are widely used in the aerospace, aircraft, civil and automotive applications due to their high specific modulus and high specific strength. These applications require the joining of the composite structures. In mechanically fastened joints holes should be drilled, and the stress concentration around the holes leads to significant reduction in the strength of composite laminates. Bushings are installed to improve the strength of the laminates. Based on finite element calculations, the effect of bushing installation on the failure characteristics of laminates was investigated in this thesis. The Tsai-Wu failure criterion was used for failure calculations. A carbon epoxy laminate subjected to 0.4 mm pin displacement was simulated through different models with and without bushing. Also, the established samples had different orientations which were [0 45 -45 90]s and [90 45 -45 0]s in order to study the influence of stacking sequence of layers on the laminate strength. The results showed a great improvement in load carrying capacity of samples with bushing due to the introduced bushing compressive load which postponed the failure. Moreover, the laminate with bushing and [90 45 -45 0]s orientation showed higher strength compared to the [0 45 -45 90]s laminate. The obtained results of the laminate orientation effect were matched with experimental test results.