This study focuses on the effects of an adhesive defect and ADHEREND type and material on stress distribution in laminated composite tubular joints sustaining axial tensile loads. The tubular joint comprised two hollow tubes joined by a layer of adhesive to form a simple lap joint, hosting a cylindrical void or debond. The ADHERENDs were assumed to be either isotropic, quasi-isotropic, orthotropic, or transversely isotropic. Applying linear elasticity, the equilibrium equations were derived and solved using the differential quadrature method. Furthermore, finite element models of the joint were prepared and solved to support the semi-analytical solutions. Good agreements were observed between the results of both methods. Based on the results, for a defect-free joint with a bond length of 30 mm, nearly 80% of the bond length experienced zero peel stress (σr), while this value was about 20% for the peak interfacial shear stress (τrx)max. Additionally, among the selected types of glass/epoxy outer tubes, the [08] lamination setup minimized (τrx)max while (σr)max was the least for the quasi-isotropic arrangement of [0/90/-45/45]S. Moreover, replacing the aluminum inner tube with steel, reduced the tensile peak peel stress by 38% and increased the peak shear stresses by 12%. However, compared to a defect-free joint, a void/debond in the adhesive layer highly affected the magnitudes and locations of the adhesive peak interfacial shear and the tensile peel stresses. Additional results showed that in a defective adhesive hosting a void, the application of [08] transversely isotropic carbon/epoxy can reduce the adhesive peak shear stresses by 200% compared to glass/epoxy.

In this paper by employing ANSYS Workbench software and three-dimensional finite element simulation, failure analysis of hybrid bonded and bolted single and double lap joints with laminated composite ADHERENDs subjected to axial, shear and bending loads were performed. In order to select an appropriate and optimized element number, the convergence behavior of single and double lap joints were investigated. Then the failure study of each single and double lap hybrid composite joints for the three time dependent loading cases were performed. To demonstrate the validity and precision of the presented simulations, the obtained results were compared with the results presented in the available literatures. The results of this research indicated that, in the single lap joint subjected to axial load, the replacement of hybrid bonded bolted joint instead of adhesive joint leads to significant increase of 56% in the load bearing capacity of the joint.

This paper presents a novel formulation and numerical solutions for adhesively bonded composite joints with non-linear (softening) adhesive behaviour. The presented approach has the capability of choosing arbitrary loadings and boundary conditions. In this model ADHERENDs are orthotropic laminates that obey classical lamination theory. The stacking sequences can be either symmetric or asymmetric. Adhesive layer (s) is (are) homogenous and isotropic material. They are modeled as continuously distributed nonlinear (softening) tension/compression and shear springs. In this method by employing constitutive, kinematics and equilibrium equations, sets of differential equations for each inside and outside of overlap zones are derived. In the inside of overlap zone, the set of differential equations is non-linear, that is solved numerically. By solving these equations, shear and peel stresses in adhesive layer (s) as well as deflections, stress resultants and moment resultants in the ADHERENDs are determined. Most of adhesives have non-linear behavior, therefore unlike previous methods, in which the adhesive layers are modeled as linear materials, in the presented approach the non-linear behavior is assumed for the adhesive layer and can be used to analyze the most of adhesive joints. The numerical results reveal that in the inside of overlap zone, magnitudes of shear forces are considerably large due to high rate of variation in the bending moments. The developed results are successfully compared with those obtained by finite element analysis using ANSYS. The comparisons demonstrate the accuracy and effectiveness of the aforementioned methods.

Nowadays there are an increasing number of industrial fields in which adhesive technology finds application. The main reason for their growing interest in both science and production is due to the high structural efficiency of this type of joining. Numerous studies have investigated the stress distribution in the adhesive layer under unreinforced conditions. The present work analyzes the elastic shear stress distribution in double-lap adhesive joints between timber and float glass ADHERENDs, both in the classical configuration and with an introduction of a nylon reinforcement in the two-component (2K) structural epoxy adhesives layers. In particular, three geometric configurations were investigated: nylon placed on the inner ADHEREND, outer ADHEREND and both. The result showed how the presence of the nylon inclusion changes the stress distribution in the joint. Numerical modelling of the joints was carried out using FE ANSYS©19 software. The greatest reduction in peak adhesive stresses is achieved by placing the reinforcement at both interfaces of the ADHERENDs with the adhesives. In general, it can be observed that the insertion of the reinforcement layer leads to a reduction in peak shear stresses, resulting in a potential increase in the ultimate strength of the joint.

Adhesive joints represent a viable alternative to traditional joining methods. The analysis of frequencies and modal shapes is fundamental to predict the vibrational behaviour of a structural component subjected to dynamic stress. There are numerous studies in the literature to determine the trend of stresses in the bonded region. It has been proved that the introduction of a slot in the inner ADHEREND allows to reduce the stress concentration at the edges of the adhesive region. In this paper, the influence of imperfections in the central ADHEREND is investigated by FEM analysis. The FE software ANSYS©19 is used for the modal analysis of the double lap adhesive joints and the first five modes are considered. The results show the influence of Young’s modulus and density ratio on the natural frequencies, varying with the material. Moreover, the introduction of the imperfection is found to influence the vibrational behavior as the frequency increases. It is also observed that the mass reduction due to the introduction of the crack does not change the shape and modal frequency for the most significant modes, while it causes more important changes for the last vibrational mode. Therefore the introduction of the crack does not significantly change the dynamic behaviour of the joint and allows to realize a more even distribution of stresses, reducing the stress peaks values.

A novel semi analytical method is developed for transient analysis of single-lap adhesive joints with laminated composite ADHERENDs subjected to dynamical loads. The presented approach has the capability of choosing arbitrary loadings and boundary conditions. In this model, ADHERENDs are assumed to be orthotropic plates that pursuant to the classical lamination theory. Stacking sequences can be either symmetric or asymmetric. The adhesive layer is homogenous and isotropic material and modelled as continuously distributed normal and shear springs. By applying constitutive, kinematics, and equations of motions, sets of governing differential equations for each inside and outside of overlap zones are acquired. By solving these equations, the time dependent shear and peel stresses in adhesive layer as well as deflections, stress resultants, and moment resultants in the ADHERENDs are computed. The developed results are successfully compared with the experimental research presented in available literates. It is observed that the time variations of adhesive peel and shear stress diagrams are asymmetric for the case of symmetric applied load with high variation rate. Moreover, it is reported that although the magnitude of applied transverse shear force is reduced to 10% of applied axial force, however a significant increase of 40% in the maximum peel stress attained.

In the present study, the transient stress distribution caused by a break in the fibers of an adhesive bonding is investigated. Transient stress is a dynamic response of the system to any discontinuity in the fibers from detachment time till their equilibrium state (or steady state). To derive the governing dynamic equilibrium equations shear lag model is used. Here, it is assumed that the tensile load is supported only by the fibers. Employing dimensionless equations, initial conditions and proper boundary conditions, the differential-difference equations are solved using explicit finite difference method and the transient stress distribution is obtained in the presence of discontinuities. The present work aims to investigate the transient stress distribution in a single-lap joint, caused by the fiber breakage in a single layer of the adhesive joint. For this purpose, the effect of different number of broken fibers (including mid fiber) in the ADHEREND on load distribution in other intact filaments, the location of fiber breaks in the ADHEREND, and the effect of adhesive length is studied on the overall joint behavior. The results show that a the fiber is broken away, the amount of initial shock (maximum load) into the fiber and thus the dynamic overshoot is reduced. Maximum amount of shock in the lateral fibers is broken at this point due to breakage in the thirteenth fiber maximum axial load and shock are introduce to the fourteenth fiber.

The goal of this research is to optimize the design of single-lap joints made by joining composite material to metals. The single-lap joint under both out-of-plane load and tensile load was examined. It is observed that designing a joint for one kind of load is not always satisfactory because for other load cases, different stresses would govern the design. Local stress peaks were investigated in order to find ways to decrease these peaks. An approach for optimizing the joint was chosen so the stress peaks at each end could be minimized (peel, axial and shear stress). By tapering the titanium ADHEREND inside and outside, the stress distribution in the adhesive can be significantly changed at the tapered end and all three important stresses that governed the design (peel, axial and shear stress) are decreased for a joint under tension and out-of-plane load. For dissimilar ADHERENDs, the numerically largest stresses always occur in the adhesive at the edge of the overlap adjacent to the ADHEREND with the lower value of flexural stiffness and the relative difference in these peaks is a function of the relative flexural stiffness of two ADHERENDs. Using an outer bead of adhesive decreases the stress peak at composite edge. Thus, two methods are used to reduce adhesive stresses: tapering and addition of adhesive beads. Having completed a finite element stress analysis, the results are used to predict the strength of a given joint. A strain energy based on failure criteria was evaluated, which addressed the problem of stress singularities in the finite element method. Three point bending tests were performed using different bonding configurations to verify the strength of the adhesive joint and to evaluate the failure criterion. Optimization of the parameters of the joint geometry was achieved from the results of this study.