Studies in the matrix dominated failures of composite joints

The potential use of composites for weight savings is now widely recognised and they are extensively used in both aircraft control surfaces and doors. However, if major weight savings are to be realised it is essential that composites be used in ʹprimaryʹ structural components, i.e. wing and fuselage skins. Before this can be achieved it must be shown that means of transmitting the load from the composite structure to the underlying, or adjacent structure, are both safe and meet the FAA damage tolerance certification requirements. For stiffened composite panels, one potential failure mechanism is the separation of the skin from the stilTeners: resulting from excessive ʹthrough the thicknessʹ stresses. This failure mechanism is also present in bonded composite joints and composite repairs. Currently, failure prediction due to in-plane loading appears to be relatively well handled. Unfortunately, this is not yet true for matrix dominated failures. Consequently, it is essential that a valid certification methodology, which addresses all of the possible failure mechanisms, including failure due to interlaminar failure, be developed. To aid in the understanding of such failures the present paper outlines the results of a series of experimental, analytical and numerical studies into the matrix dominated failures of bonded joints, composite repairs and rib stiffened post buckled structures. © 1999 Elsevier Science Ltd. All rights reserved.