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.

This paper presents an experimental study on the effect of Adhesive thickness on the maximum load of Adhesive Joints under static and impact loading, using the double cantilever beam (DCB) test method. The DCB specimens were prepared with varying Adhesive thicknesses and subjected to impact loading using a drop weight impact tester. The maximum load was recorded for each specimen. The results indicated that the maximum load of the Adhesive Joints increases with increasing Adhesive thickness up to 5 mm, beyond which the maximum load decreases with further increase in Adhesive thickness. Moreover, the failure mode of the Adhesive joint was found to be strongly dependent on the Adhesive thickness, with thicker Adhesive layers exhibiting an Adhesive failure mode but in thinner thicknesses, the Adhesive mode is cohesive. These findings provide important insights into the design and optimization of Adhesive Joints for applications that are subject to impact loading.

Adhesive Joints find numerous applications in various industrial fields. They represent a valid alternative to traditional joining methods. Much of the available scientific literature has focused on the study of Adhesive Joints subjected to tensile loads. There have also been numerous studies concerning the stresses distributions in the Adhesive layer. However, in real case applications, Adhesive Joints could also be subject to cyclic tensile-compression loads and therefore could be subject to buckling phenomena. The objective  of  the  present  paper  is  to  investigate  the  numerical  study  of  the  stress  distribution  in  the Adhesive layer under buckling condition. The study presented develops with the analysis of a single-lap joint  with  a  combination  of  steel  adherends  and  three  different  structural  Adhesives  with  different thickness  and  Young’s  modulus.  The  Joints  are  modeled  using  FE  ANSYS©19  software.  Through numerical  analyzes,  it  is  possible  to  predict  the  value  of  the  critical  load  for  each  single  analyzed combination. Once the critical load is determined, the stresses in the middle plane of the Adhesive layer are determined. The results obtained show that for small Adhesive thicknesses (i.e. 0.30 mm) it is possible to reduce the stress peaks - with the same critical load value - by using structural Adhesives with low elastic modulus (e.g. silicones).

In this paper, we have used numerical simulation to study failure of Adhesive Joints in composite plates. To determine the failure load, Adhesive Joints are subjected to different types of loading and gradual failure of the joint is studied using the finite element method. The composite material failure theory is implemented into the FEM software. Also different geometries for the joint edge are considered and effect of these geometries and fillet chamfer angle on the failure load are investigated.

The design of Adhesive Joints is crucial in industries like aerospace, automotive, and railways, where they offer a lightweight alternative to traditional methods such as welding and bolting. Adhesive Joints distribute stress uniformly and enable the assembly of complex geometries. This review focuses on cutting-edge technologies, highlighting the role of nanomaterials in enhancing fatigue strength and chemical-thermal stability. It also explores the potential of additive manufacturing to create customized joint geometries and enable real-time monitoring through embedded sensors. The paper examines widely used Adhesives, including epoxies and polyurethanes, as well as innovative joint designs, such as sinusoidal profiles and multi-material configurations, which improve stress distribution and structural integrity. Surface preparation techniques and advanced numerical tools, like cohesive zone modeling and artificial intelligence, are also discussed for their role in optimizing joint performance. The study identifies key challenges, including standardization of processes and integration of novel materials, and outlines strategies to enhance the performance of bonded Joints in advanced industrial applications.

Adhesive Joints are becoming increasingly popular in various industrial sectors. However, in spite of numerous recent studies in literature, the design phase of the Adhesive joint is still challenging. The main issue in the design phase is the determination of the stress distribution in the Adhesive layer under external mechanical loads. In the present study, a classical Adhesive joint is analysed in comparison to its modified geometric configuration (i.e. tapered) aimed at reducing the magnitude of stress peaks. In particular, a single-lap joint with steel adherends bonded with a commercial epoxy Adhesive is analysed. A 3D FE analysis is conducted to determine the distribution of normal and shear stresses in the mid-plane of the Adhesive layer. The results obtained from the present study show that the inclusion of a small taper angle (i.e. 5°) leads to a remarkable reduction of normal stresses (up to 30%) compared to the classical configuration. It is observed that the further increase of the taper angle (up to 15°) does not lead to significant reductions of the stress peaks. The trend in shear stresses, on the other hand, is in contrast: an increase in the taper angle leads to an increase in the shear peaks. The method of tapering the adherends is effective in reducing the normal stresses, which are responsible for triggering the failure in the Adhesive joint.

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 this paper, at first stress distribution in a single-lap joint between composite laminates by first order shear deformation theory with and without the presence of longitudinal strain has been evaluated. Adhesive layer supposed to be isotropic and adherents assumed to be orthotropic laminates. A new improved method of displacement theory has been used to determine stresses distribution. The results of this analytical solution have been compared by the results of finite element and it has been revealed that both methods have similar results. The advantage of this new method compared to classic method is that it has a higher Compatibility by finite element results. In shear stress there is no significant improvement. But it obvious that the method has assumed length strain in Adhesive layer has a higher accuracy in its results. In shear stress distribution, considering of length strain has no significant benefit, but in peeling stress this difference will improve the results significantly in a way that the presence of longitudinal strain has a determinative role in peeling stress distribution.

Defects in Adhesive Joints are an important issue in the construction of space structures. In this paper, using lamp waves, suitable properties have been obtained to identify the size and position of the defects of the Adhesive Joints. Using finite element simulations, the effect of the defect on the propagation of the lamp waves has been investigated. Simulations have been performed for three different Adhesive thicknesses, three different sizes of circular defects in 9 different positions, and the effect of each of them on the wave passing through the joint has been investigated. The signals obtained from the faulty connections were compared with the signal obtained from the healthy connection and the desired area was isolated from the total received signal for further analysis. The proper and correct separation of defects requires finding suitable characteristics for it. Therefore, 34 features were examined to differentiate and separate defects. Then, the neural network was used to provide the basis for creating appropriate patterns for the separation of defects. The percentage of correct detection of neural network for Adhesive thickness separation was 93.8%, for defect area separation in terms of size 100% and for defect position separation in X and Y axes were 96.1 and 95.1%, respectively. The obtained results show the efficiency of the improved distance evolution method and the features selected to distinguish the defects of such connections.

Due to high strength and stiffness in comparison with their weights, laminated composite materials are widely used in many structures such as aerospace. Therefore to predict their mechanical response, the understanding of their failure mechanisms is very important. The delamination between composite layers and Adhesive Joints is one of the main damage modes of these materials. In this research, the cohesive zone model is used to predict the damage evaluation of composite wing Adhesive Joints. The advantage of this method is the modeling of delamination growth without any requirements to the presence of initial crack and remeshing. Moreover to predict the probable damage in composite layers the Ladeveze progressive damage model has been implemented in Abaqus using user defined code (Umat) and also the importance of considering the intralaminar failure on the acceleration in damage initiation and propagation in Adhesively bonded Joints have been evaluated. The results verify the proper accuracy of implemented method. Furthermore, the results of solid cohesive elements showed to be more accurate in predicting damage initiation and evaluation in comparison to shell elements. Finally effects of Adhesive properties such as thickness and quality of bonding in load capability of wing structure have been investigated.