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.

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.

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 study, analytical models considering different material and geometry for both single and double-lap bolted joints were reviewed for better understand how to select the proper model for a particular application. The survey indicates that the analytic models selected for the adhesively single or double bolted lap joints, as well as T, scarf, and stepped joints, with linear material properties are mostly two dimensional and the studies on stress distribution and/or failure of the joint are performed either experimentally, analytically or by finite element method. The results seem to be generally accurate and adequate. Additionally, it was shown that any increase in the bolt-hole clearance leads to an increase in bolt rotation, as well as a decrease in bolt-hole contact area, and hence, a reduction in joint stiffness. Moreover, studies on hybrid joints have revealed that the proper choice of adhesive material in conjunction with bolts or rivets in a joint, allows for significant increase in the static and fatigue strength compared to similar pure bonded joints. Additionally, the results on hybrid scarf joints showed that it is vital to place fasteners closer to the ends of the overlap to suppress the peak peeling stresses and hence, delay the effects of early crack initiation in the adhesive layer. Experimental studies on fatigue behavior and strength of bolted joints have shown that compared to clearance fit specimens, clamping force increases the fatigue life of a bolted joint. Moreover, higher tightening torque, in general, results in higher fatigue lives in bolted joints.

In this study, behavior of pin-loaded glass fiber reinforced with polyethylene laminated composites with different stacking sequence and different dimensions has been observed experimentally and stress analysis was performed using ANSYS software. The aim is to investigate stresses, failure strength and failure mode of composite laminates containing a pin loaded hole, when the material exhibits linear elastic behavior. The logical methodology for modeling the joint problem uses the two major steps: failure analysis and stress analysis. Failure analysis is done experimentally and stress analysis is done by using ANSYS software. To investigate and verify to the analytical predictions of mechanical behavior, and to observe the failure characteristics of the pin-loaded composites, a series of experiments were performed with eight different material configurations, in all, over 36 specimens. The edge distance-to-hole diameter ratios and width-tohole diameter ratios of plates were changed. For this part of study, layered composite materials were manufactured in our Institute. The stress distribution around the hole in pin-loaded glass-fiber with polyethylene laminate was performed, and in addition, ANSYS was performed to compare effects of different boundary conditions used to simulate the pin load on stress distributions around the hole.

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.

Pipelines are commonly used in various industries such as oil and gas, water supplies and petrochemical. composite Pipes are appropriate choice due to some properties including high strength, lightness and high corrosion resistance. It is necessary to employ Nondestructive Tests (NDT) during construction as well as maintenance of such pipelines, in order to reduce costs. One of the damages that may occur on composite pipes is joint failure which normally happens during construction and operation of the pipes. Furthermore, the most common method of joints in composite pipes is adhesive joint. Ultrasonic Guided Wave (UGW) is suitable method of NDT. In this research, a numerical simulation of L(0, 1) guided mode is carried out in order to inspect the adhesive joint between two composite pipes. A parametric study is performed on damage length variation in order to extract suitable feature from damaged pipe signals for damaged joint identification. Using two sensors which are located before and after the adhesive joint, with the purpose of receiving the reflected and transmitted ultrasound wave from the joint, two signals energy indices have been developed for damaged joint identification.

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.

joints are the most important parts of composite structures, because of their more sensitivity to load transmission, stress concentration and adherents differences (in materials, geometries and boundary conditions). Numerical analysis of all mechanical joints in big structures is costly in time and memory usage. In big structures, precise numerical analysis of mechanical joints needs to an appropriate criterion to find the critical joint. In this paper different modeling methods on analysis of mechanical joints are compared to each others. The numerical analysis is done by means of ABAQUS-6.11.1 finite element (FE) code. Predicted elastic modulus, the joint strength (maximum force) and load-displacement trends are compared with experimental results and time cost of modeling are compared to each others. Result study shown that the elastic modulus and the joint strength are better predicted in the improved Solid-Shell model. Beam-Shell model predicted a good elastic modulus in the joint, although the joint strength is predicted less than experiments. The final suggestion of this paper to time saving purpose in joint analysis of a big structure with many joints is to start the analysis of all joints with Beam-Shell model and finding the failed mechanical joints. In second step, just the failed joints should be re-model with improved Shell-Solid model and the structure should be checked for joint failure again.

Considering the importance of composite connections, this study evaluated two experimental and numerical methods for bolted joints of epoxy-glass composite plates. Then, using an artificial neural network, a model was defined between experimental and numerical results. The results of this study showed that the maximum force tolerated by bolted joints was various at several distances and its maximum value was tolerated by the connection at 4cm equal to 5332 and 7093N, for two specimens. Comparison of numerical and experimental results of Von-Mises stress for distances of 2, 3, and 4cm was done. The Von-Mises stress for these distances was 313.59, 217.57, and 177.71MPa, respectively. In this research, the connection of epoxy-glass plates using M6-bolt was studied, and by increasing the coverage of two composite plates, the Von-Mises stress in the connection was raised. Concerning the determination of the stress measuring path, from the internal edge of the critical notch to the end of the defined range with a smaller mesh, the Von-Mises stress was extracted, which in distance equal to 3cm with the vertical arrangement, maximum stress was equal to 513MPa. The minimum stored energy of the numerical method in the connection was related to the bolted joint with a two-bolt in the vertical position.