Stress concentration phenomena in the vicinity of composite plate-doubler junctions by a layerwise analysis approach

This paper presents an analysis method for the determination of displacements, strains and stresses in a laminated composite plate subjected to tensile load that is reinforced by a doubler. The analysis approach consists of two parts. Firstly, a 'global' solution that is based on Classical Laminated Plate Theory (CLPT) is introduced. Secondly, a 'local' model is derived that enables the assessment of the three-dimensional stress state near the plate-doubler junction. The local solution employs a discretization of the physical layers into a number of mathematical layers which necessitates the numerical treatment of a quadratic eigenvalue problem. Consequently, the current approach can be classified as being a semi-analytical layerwise analysis method. Results are generated for several different plate-doubler configurations, and it is found that the current analysis model delivers excellent results when compared to finite element simulations, however with only a fraction of the computational time and effort that are needed for the FEM analyses.