Strength Prediction of Composite Π Joints Under Tensile Load

Abstract

Application of an all-composite π joint as a structural connector for integrated aircraft structures can potentially enable both weight and assembly cost benefits while retaining good load carrying capability. This article is concerned with the behavior of an all-composite π joint under a static, tensile load. The damage onset, propagation, and ultimate collapse of the composite π joint are simulated by a progressive damage method. A progressive damage model, which includes three aspects: a three dimensional finite element model of composite π joint for stress analysis, a modified maximum stress failure criterion to assess damage/failure, and a material degradation model to simulate the structural stiffness reduction, is presented to predict strength of composite π joint. Stress distributions are characterized and the load transfer path in the joint is traced. Failure mechanisms are identified and failure progression between the first and final failures is outlined for the composite π joint. Experimental results show good agreement with the predictions from the numerical models.