Investigation of curved and scarf lap joints subjected to tensile loads using the cohesive zone model (original) (raw)
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Experimental and 3D non-linear stress analysis of adhesively bonded curved and scarf lap joints
2020
Adhesive bonding is an excellent alternative to traditional joining techniques such as welding, riveting, and is commonly used in almost every sector of the industry. However, there are many factors that have to be accounted for during joint design to accurately predict strength of the joint. One of these is the design of adhesively bonded joints. The objective of this work is to study the influence of curvature on strength of adhesively bonded curved-lap joints. For that, different radii of curvature were introduced to the end zones of an aluminium sheet to which the adhesive is applied. Then, a scarf lap joint was obtained by increasing the radius of curvature for the same overlap length, and mechanical behaviour of curved and scarf lap joints was studied experimentally. Additionally, in the analyses, the Extended Drucker-Prager material model was used and to verify the finite element model, experiments were carried out. The results show that thickness, overlap length and curvatur...
3D numerical investigation of tensile loaded lap bonded joint of aircraft structure
Journal of KONES, 2006
Adhesive bonding is becoming one of the most popular joining techniques in automotive and aircraft industry. The adhesively bonded joints need to be designed to minimize tensile stress. The most widely used method of an adhesive joint strength test is the lap-shear test. Single lap joints create bending loads in the adherends and tensile stress in the adhesive. The mechanism of shear deformation of the adhesive and adherend layers and separation occurring at the adherend/adhesive interface are discussed in this paper. Uniaxial tensile test of a lap bonded joint and numerical simulations were carried out. 3D numerical model of single lap bonded joint consists of three components described as separate solids. Glue contact is defined between the joined layers. This approach allows to determine and compare stress distribution along the adhesive and the adherend bondline. Experimental data are used to establish the engineering stress-strain curves for the aluminium adherends and the epox...
On the static strength of aluminium and carbon fibre aircraft lap joint repairs
Composite Structures, 2018
The behaviour of various aircraft lap joint repair configurations is investigated experimentally and numerically under static loading. The lap joints consist of aluminium alloy (AA) 2024-T3 substrates repaired with twin single-sided AA 2024-T3 or Carbon Fibre Reinforced Epoxy (CFRE) doublers. Pure riveted, pure bonded and hybrid (riveted and bonded) joints of metal-metal and metal-composite configurations are investigated. From experimental results, joints with adhesive bond showed nearly 5 times higher average strength than pure riveted joints, while hybrid joints performed better than riveted and bonded joints because of higher stiffness. On the other hand, hybrid metal-metal joint has 70% higher average strength compared to hybrid metal-composite joint. Rivet-shear has caused failure of riveted joints, and adhesive failure is observed in pure bonded joints. Hybrid joints with metal doublers have failed initially due to adhesive failure and later rivet shear. Interestingly, net-section failure is observed in composite doublers with breakage of doublers due to the presence of holes in the doublers. Experimental results are complemented with numerical analysis using commercial finite element code ABAQUS. Load-displacement curves obtained from the numerical results are in good agreement with experiments within a marginal error of 2%. In addition to load-displacement curves, a detailed stress analysis is performed numerically on metal-metal and metal-composite joints under riveted, bonded and hybrid configurations to study stress distribution on substrate and doublers. Numerical analysis showed hybrid and bonded joints have lower stresses in substrate and doublers compared to the riveted joints. Bonded joints have smoother load transfer due to the adhesive spread over a larger area. And finally, Stress Intensity Factors (SIFs) analysis is performed numerically for un-reinforced and reinforced metal substrate with a crack length of 1, 5 and 10 mm with metal and composite doublers under riveted and bonded configuration. For crack of 10 mm, 35% reduction in SIFs is observed for reinforced substrate with bonded metal or composite doublers compared to the un-reinforced cracked substrate.
2017
Adhesively-bonded joints are increasingly used in aeronautical industry. Adhesive joints permit to join complex shapes and reduce the weight of structures. Adhesively bonded lap joints are used increasingly in the spacecraft and aerospace application to join structural component of metallic material. The influence of the parameter like Adhesive thickness, Adherend thickness, Lap length, Adhesive mechanical properties and Static load has been investigated. A two dimensional finite element model (FEM) based on plane strain assumption including the geometrical nonlinear analysis was utilized to investigate the joint stiffness and stress distribution. To explore the effect of boundary conditions on the elastic stress distribution in a single lap joint.
Structures built from several components require some means of joining. In this context, bonding with adhesives has several advantages compared to traditional joining methods, e.g. reduction of stress concentrations, reduced weight penalty and easy manufacturing. Adhesives can be strong and brittle (e.g., Araldite ® AV138) or less strong and ductile (e.g., Araldite ® 2015). A new family of polyurethane adhesives combines high strength and ductility (e.g., Sikaforce ® 7888). In this work, the performance of the three above mentioned adhesives was tested in single-lap joints with varying values of overlap length (L O). The experimental work carried out is accompanied by a detailed numerical analysis by Finite Elements, based on Cohesive Zone Models (CZM). This procedure enabled detailing the performance of this predictive technique applied to bonded joints. Moreover, it was possible to evaluate which family of adhesives is more suited for each joint geometry. CZM revealed to be highly accurate, except for largely ductile adhesives, although this could be circumvented with a different cohesive law.
Procedia Engineering, 2015
Structures built from several components require some means of joining. In this context, bonding with adhesives has several advantages compared to traditional joining methods, e.g. reduction of stress concentrations, reduced weight penalty and easy manufacturing. Adhesives can be strong and brittle (e.g., Araldite ® AV138) or less strong and ductile (e.g., Araldite ® 2015). A new family of polyurethane adhesives combines high strength and ductility (e.g., Sikaforce ® 7888). In this work, the performance of the three above mentioned adhesives was tested in single-lap joints with varying values of overlap length (L O). The experimental work carried out is accompanied by a detailed numerical analysis by Finite Elements, based on Cohesive Zone Models (CZM). This procedure enabled detailing the performance of this predictive technique applied to bonded joints. Moreover, it was possible to evaluate which family of adhesives is more suited for each joint geometry. CZM revealed to be highly accurate, except for largely ductile adhesives, although this could be circumvented with a different cohesive law.
Archives of Metallurgy and Materials, 2017
The contemporary demands in different branches of engineering require application of new multi-component materials and structural systems. Appropriately chosen joining technology can offer significant enhancement of structural system performance in terms of effectiveness, reliability, safety and other design criteria. The modern applications of complex joints are of great technological interest as they permit to combine and to enhance the individual effects of each kind of joint. This is of great importance for modern applications in different branches of engineering: aerospace, mechanical and civil. Therefore in this paper we will focus on the analysis of mechanical response of adhesive joint of aluminium strips reinforced by rivets. The aim of the paper is to investigate experimentally the mechanical behaviour of adhesive joint of aluminium strips reinforced by rivets for industrial applications in aerospace. The considered joint was subjected to uniaxial loading. The tests in thi...
Applied Mechanics and Materials, 2011
This paper presents an experimental investigation on the behaviour of structural adhesive bonding under quasi-static and moderately high loading rates. It addresses the effects of the loading rate on the strength of the adhesively bonded joints under dynamic tensile. A comparison has been achieved between the strength and the damage of specimens' made of aluminium and lamina substrates. High rate tests showed ringing in the force/displacement curves.
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.