Strength and interface failure mechanism of adhesive joints

Abstract

a b s t r a c tAdhesive joints have a wide range of applications in the civil engineering, automotive and aircraft industries. In the present research, we use the finite element method to systematically study the overall strength and interface failure mechanism of single lap joints, which are subjected to tensile loading, focusing on the effects of various system parameters including fracture energy of the adhesive layer, overlap length and adhesive layer thickness on the load-bearing capability of the joints. The results show that the overlap length and the adhesive fracture energy have combined influences on the load-bearing capability. On the other hand, a preliminary damage analysis of the adhesive layer is carried out, considering the situations when the loads arrive to the peak values. Furthermore, the interface behavior is investigated, including the interface stress analysis and interface slip. The rotation of the joint during loading and its influence factors are studied as well. Obtained results suggest that the interface stress distributions are related to the slip and the rotation angle.Crown

Numerical analysis on load-bearing capacity and damage of double scarf adhesive joints subjected to combined loadings of tension and bending

“…In addition, failure was demonstrated to take place progressively as energy dissipates gradually at the crack tip [4,[7][8][9][10][11]13]. Furthermore, failure generally occurs in the adhesive layer with a lower stiffness than that of the adherends, which has been proved by previous investigations [4,[8][9][10][11][14][15]. The onset of damage can be predicted without requiring any initial crack using the existing stress-or strain-based criteria [13].…”

“…Based on the Traction-Separation (T-S) law, CZM is widely used to analyze the de-cohesion in composite structures [8][9][10][11][13][14][15]. It must be pointed out that the adhesive layer using CZM is a generalized interface phase rather than a material.…”

“…T-S curve can be considered as a representation of the constitutive relation of the equivalent interface [9]. A bilinear assumption model [25][26][27], in which a critical energy release rate G c and a cohesive strength s u are vital to capture the interface separation behavior [9][10][11]15,28], is employed in this study. Owing to the combined loadings, a complex stress state of the joint is present with mixed-mode (Mode I and II) damage propagation, as shown in Fig.…”

“…Failure of adhesive joints is dictated by the mechanical properties of the adhesive [7][8][9][10][11] and the stress states of the adhesive layer controlled by the geometrical configurations and constraint effects [4,12]. In addition, failure was demonstrated to take place progressively as energy dissipates gradually at the crack tip [4,[7][8][9][10][11]13].…”

“…Owing to the complex failure behavior of the adhesive joint, it is difficult to obtain a universal failure criterion to various situations. Alternatively, cohesive zone models (CZM) can simulate the damage onset and growth with mesh independence and dispensable initial crack, maintaining the possibility to characterize the behavior of the structure up to failure [7][8][9][10][11][12][13][14][15]. Especially, an efficient finite element computational method with the core of CZM was certified by Castagnetti et al [18], which showed that the socalled Tied Mesh method has the advantage of numerical precision and computational speed.…”