Experimental and Numerical Study of Composite T-Joints

Abstract

The present paper deals with experimental and nonlinear finite element analysis of sandwich T-joints which are formed by two panels connected by lap joints. Such joints are for instance commonly used in high-speed marine vehicles, and the joints considered herein are typical for such structures. This study is concerned with T-joints subjected to tension (pull-out) force and the behaviour up to ultimate failure. The behaviour of such sandwich joints is very complex, since it involves several types of materials such as GRP, glue filler as well as foam material, and a geometry with potential high stress concentrations. Also, nonlinear material and geometrical effects may influence the ultimate behaviour. In this study experimental specimens have been produced and tested to failure. A nonlinear finite element method is adopted throughout the T-joint, which is taking into account the possible high-stress concentration positions, the nonlinear properties of both the core and the glue materials and the nonlinear displacement deformation of the T-joint. In this way we succeeded in making a significant contribution to furthering the understanding of the response and failure of sandwich T-joints. The effect of some design parameters of such joints affecting joint strength and flexibility is also investigated.

Adhesively bonded joints in composite materials: An overview

“…8). Various improved T-joints have been designed and investigated [37][38][39][40][41][42][43][44][45][46]; some with focus on improved strength and others on reduced weight. Also, T-joint connection can have foam fillets in the form of a pad or two triangular inserts combined with overlaminates [40].…”

“…Linear finite-element analyses of composite sandwich T-joints were developed by Shenoi and Violette [40], Dodkins et al [42], and Phillips and Shenoi [44]. Non-linear analyses are provided in references [38], [39], [41], and [43] and may include damage in the form of delamination [42] or cracks [44].…”

“…Theotokoglou [38,39,43] developed a non-linear finite-element model to predict joint performance of composite sandwich T-joints under pull-off load. The behaviour of the sandwich T-joint in tension was shown to be characterized by geometric nonlinearities due to out-of-plane loads and by material non-linearities due to local yielding.…”

Analytical determination of the ultimate strength of sandwich beams

“…Mfy ~-afy(btd), (11) where My u is the moment of the beam which causes tensile or compressive failure of the faces. The compression face of a sandwich beam may fail by local buckling or wrinkling.…”

“…Two failure modes are observed [9,11]. The ultimate loads and the corresponding failure modes are given in Table III.…”