Effect of Adhesive Type and Overlap Length on the Mechanical Resistance of a Simple Overlap Adhesive Joint (original) (raw)
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Stress and Strength Evaluation of Double Lap Adhesive Joint
— This paper summarizes the evaluation of stress and strength of double lap adhesive joint. Stress and deformation of the double lap adhesive joint is obtained by finite element analysis using ANSYS and strength is obtained by experimental method. Joint failure is one of the main causes of interruption of rotating or stationary machinery operation. This generally leads to unscheduled shut down thereby increasing the cost of operations. One of the major concerns in adhesive joint is the detection of the rupture initiation and strength of joint before it develops into a failure of material. The ability to achieve strength of adhesive joint is essential to the optimal maintenance of whole system with respect to cost and productivity. The effects of the length of adherend, width of adherend, the overlapping length of the joint, the thickness of the adhesive layer and the initial impact velocity of the impacted mass on the double lap adhesive joint are studied. Early detection of the stresses and rupture in the joint are crucial for the prevention of damage to the system.
Strength assessment of adhesive-bonded joints
Computational Materials Science, 2008
This paper deals with non-linear analyses of adhesively bonded joints under tensile lap shear loading. 3D FEM models are taken into account. The effect of the number of elements through the adhesive layer thickness is considered. Tensile true stress-true strain curves are used as models of the adherend and adhesive materials. The single lap joints are tested to validated the numerical analyses.
Non-linear three dimensional (3-D) finite element analyses (FEA) of the single lap joints (SLJs) having pre-existing rectangular adhesion failure in the interface of the strap adherend and the adhesive have been carried out. The effect of the size, the shape and the aspect ratio of the pre-existing rectangular adhesion failure on (i) the strength, (ii) the interfacial stresses and (iii) the strain energy release rates (SERRs) in the vicinity of the adhesion failure front have been presented in this research work. The SLJ is subjected to uniformly applied tensile load. The adherends are made with very high strength steels and the adhesive is a commercially available AV119. The analyses of the adhesion failure propagation have been carried out by sequentially releasing the constraints of the nodes ahead of the pre-existing adhesion failure front in finite element model. The SERR values in the vicinity of the adhesion failure fronts are computed using the virtual crack closure technique (VCCT) for assessment of the structural integrity of the SLJ. The strength of the SLJ, the interfacial stresses, and the three modes of strain energy release rates (SERRs) have been found to be significantly affected by the shape and size of adhesion failures. The SERRs and interfacial stresses along the rectangular adhesion failure front are compared with the corresponding values around the circular adhesion failure front of same area, pre-existing in the SLJ. It is observed that the circular and rectangular adhesion failures of the same area will have dissimilar growth rate and the mode II is the dominant failure mode. The total strain energy release rate and the failure strength, computed from the 3-D FEA of the SLJ is in good agreement with the experimental fracture toughness of the AV119 adhesive and the experimentally obtained failure loads, respectively.
Mathematical and Computational Applications, 2011
This paper examines the failures and strengths of joints bonded by a Neoxil CE92 N8 adhesive at different overlap lengths and different taper angles. The study was carried out both as experimental and numerical. In the experimental stage, lap-shear tests on Single-Lap Joints (SLJs) with different taper angles and overlap lengths were conducted. The stress analyses in the SLJs were obtained using a linear Finite Element Analysis (FEA) in numerical stage. It is assumed that adhesive and adherend have both geometrical nonlinearity and linear material behaviour. Scrutinising carefully the surfaces of the SLJs, two different failure types, cohesive failures (CF) and special cohesive failures (SCF) were observed. The obtained numerical results were compared with experimental ones. Results indicate that the increasing of both overlap length and taper angle increase the joint strength and, in particular, the highest strength values in all joint geometries are attained by specimens having a taper angle of 15°.
Local evaluation of adhesive failure in similar and dissimilar single-lap joints
Engineering Fracture Mechanics, 2017
Single-lap joints made of aluminium and carbon fibre adherends are tested to understand better the behaviour of such dissimilar joints. Local deformation fields are monitored by using the digital image correlation method (DIC). Over the overlap length strain gauges are emulated as to measure properly the strains in the adhesive. Peeling and shearing strains are investigated, emphasizing that peeling is important in the region where failure is initiated, towards the extremity of the overlap region. Cohesive Zone Modelling (CZM) available in Abaqus Ò was used to simulate the behaviour and strength of dissimilar single-lap adhesively bonded joints. A linear elastic FEM was used. A distinct CZM model is used to show the variation of normalized stresses and damage in the process zone of the single-lap joint. Experiments show that the use of dissimilar aluminium-carbon and carbon-carbon adherends is reducing the strength and stiffness of the joints as the delamination and pull-out of the carbon fibres compromises their integrity. Numerical simulations overestimate the experimental strength and stiffness of the joints. FEM model has to be improved as to consider a refined laminate modelling.
Adhesive Joints Subjected to Impact Loading: A Review
International Journal of Materials Engineering, 2019
Adhesive joints have widely been used in many engineering applications due to their outstanding advantages over conventional joining methods. Developing strong adhesive bonds lead adhesive joints to be a very popular joining methods in the applications subjected to impact loadings. Especially, the automotive industry uses adhesive joints in order to reduce the weight of vehicles by bonding multilayer lightweight materials. Understanding the performance of adhesive joints subjected to impact loadings is significant to apply them into the applications that may be exposed to high loading rates. Even though there are many researches on characterizing the performance of adhesive joints subjected to quasi-static loading in the literature, there are few studies focused on the performance of adhesive joints under impact loading. In this paper, the researches on adhesive joints under high loading rates are reviewed. The different testing techniques of adhesive joints subjected to impact load...
Durability of structural adhesive joints
International Journal of Adhesion and Adhesives, 1984
Single lap joint specimens bonded with two commercial epoxy-based film adhesives, FM-73 and FM-3OOK, ware exposed to combinations of different types of "load" ie mechanical load, temperature and moisture/water. The applied mechanical load was high -90% of the nominal strength of the specimen (as determined in tensile experiments). The initial strength of the joint and the residual strength at various time intervals were then determined. The specimens Ware not influenced by a single type of "load" or even by a combination of two types of "load'. However, combining all three "loads" caused spontaneous failure of the specimen. When applying a constant load of up to 60% of the nominal strength, no spontaneous failures Ware observed within 30 days (even after exposure to hot-wet environment).
Stress-Strain Analysis of Single-Lap Tensile Loaded Adhesive Joints
2007
Both, experimental investigation and finite element analysis of single-lap adhesive joints subjected to tension have been done to find out an optimal overlap length. As the adherend material aluminum was considered with the two component high-strength engineering adhesive for the bonding of the layers. The thickness of the sheet metal layer was 1,95 mm, while adhesive was 0,15 mm thick. The width of all thin plates was 30 mm, but the overlap length varied as 15, 20, 30, 40 and 60 mm. Real mechanical properties of all materials in the joint have been determined experimentally. Obtained results proved that the overlap length affects directly the joint tensile strength, where an optimum value of overlap length can be defined. Finite element analysis of stress and strain fields could help to determine the moment when the crack initiates at the joint overlap end. In such a manner, complex mechanisms of failure of adhesive joints could be better understood.
Systematic Evaluation of Bonding Strengths and Fracture Toughnesses of Adhesive Joints
Journal of Adhesion, 2011
A systematic experimental investigation to determine the shear, tensile, and fracture properties of adhesive joints with bonded same-materials (polymer-polymer) and bi-materials (metal-polymer) is reported. Full-field optical techniques including photoelasticity and coherent gradient sensing (CGS) are employed to record the stress development and failure in these adhesive joints. Five types of strong and weak adhesives are used in conjunction with five different types of materials [aluminum, steel, polymethylmethacrylate (PMMA), polycarbonate, and Homalite®-100] to produce a variety of bonded material systems. Weld-on®-10 and a polyester bonding consistently show higher tensile and shear bonding strengths. Bi-material systems in shear and fracture report lower properties than the same-material systems due to a higher property mismatch in the former. The resulting complete experimental data are expected to be immensely helpful to computational mechanists in simulating failure mechanics of adhesive joints.
Interfacial failure in adhesive joints: Experiments and predictions
International Journal of Adhesion and Adhesives, 2013
The aim of this paper is the development of a method to predict interfacial failure in adhesive joints. The main originality of the paper resides on the application of a twofold criterion involving stress and energy conditions simultaneously to predict adhesive failure onset in different geometries of adhesive joints subjected to diverse loadings. Butt joints and double lap joints made of linear elastic materials are tested in torsion and tension. The failure onset predictions are based on finite element calculations and a twofold criterion which considers a novel stress condition. These predictions are accurate and prove the validity of the method to predict adhesive failure for different adhesive joint configurations and loadings.