Abstract:Stress distributions at interfaces of adhesive lap joints have been widely studied to optimize overall structural strength. However, these studies focussed mainly on the mechanics of adhesive layers. In this paper, a novel concept for a double lap adhesive joint is proposed by introducing a slot in its inner adherend. Numerical simulations employing a finite-element method are used to validate the proposed concept. The results show that the introduction of the slots can smooth the stress distributions along th… Show more
“…Roughly 400 elements were used for the cohesive region. This model was developed to be similar to previous works on adhesive joints [18], [19]. The model can be seen in Figure 7.Figure 7FEM model of a simplified joint.…”
In this work, aluminium–carbon-fibre reinforced plastic joints have been studied. Three types of samples were designed as double lap joints where the aluminium inserts were fabricated using both classical methods (milling) and additive manufacturing. Two versions of the joint were fabricated using additive manufacturing, one flat, and the other with small teeth designed to hook into the carbon-fibre plies. The joints were characterised using a non-linear, dual-energy computed tomography method to evaluate the bond between the composite and the metal inserts. The mechanical strength of the bonds was evaluated, both through tensile tests and four-point bending. A simple finite element model was used to discuss the joints behaviour. It was found that the joints fabricated using additive manufactured inserts were more resistant to peel stress than the milled inserts. In four-point bending tests the moment that the joint could withstand was increased by roughly 300% with the use of additive manufacturing and 400% with the use of additive manufacturing and small teeth. However, in tensile tests it was found that the teeth design reduced the maximum load capacity of the joints by roughly 30% due to porosity. Further, it was found that the additive manufactured samples did not add to the capability of withstanding shear stress. The information gained with the dual-energy computed tomography method was highly valuable as the behaviour of the joints would have been difficult to explain without the porosity information.
“…Roughly 400 elements were used for the cohesive region. This model was developed to be similar to previous works on adhesive joints [18], [19]. The model can be seen in Figure 7.Figure 7FEM model of a simplified joint.…”
In this work, aluminium–carbon-fibre reinforced plastic joints have been studied. Three types of samples were designed as double lap joints where the aluminium inserts were fabricated using both classical methods (milling) and additive manufacturing. Two versions of the joint were fabricated using additive manufacturing, one flat, and the other with small teeth designed to hook into the carbon-fibre plies. The joints were characterised using a non-linear, dual-energy computed tomography method to evaluate the bond between the composite and the metal inserts. The mechanical strength of the bonds was evaluated, both through tensile tests and four-point bending. A simple finite element model was used to discuss the joints behaviour. It was found that the joints fabricated using additive manufactured inserts were more resistant to peel stress than the milled inserts. In four-point bending tests the moment that the joint could withstand was increased by roughly 300% with the use of additive manufacturing and 400% with the use of additive manufacturing and small teeth. However, in tensile tests it was found that the teeth design reduced the maximum load capacity of the joints by roughly 30% due to porosity. Further, it was found that the additive manufactured samples did not add to the capability of withstanding shear stress. The information gained with the dual-energy computed tomography method was highly valuable as the behaviour of the joints would have been difficult to explain without the porosity information.
“…The effects of tapering adherends were investigated by Sancaktar and Nirantar [27]. Hou et al [28] have shown that the insertion of a defect in the internal adhesion of a double lap type joint led to a reduction of the stress peaks recorded at the edges of the adhesive region while reducing the overall weight of the joint.…”
Section: Problem Statementmentioning
confidence: 99%
“…In this paper the dynamic behavior of a DLJ is investigated, using an epoxy adhesive with both normal and cracked adherends, considering the geometries considered in literature [28]. The geometry is shown in Figure 1.…”
“…Peel stress is more critical to the adhesive lap joint compared with shear stress, since it is considered to dominate the failure of the joint [26]. The maximum peel stress is negative in section I, representing that the left end of the bonding region is subjected to a compressive load.…”
Section: Parametric Studymentioning
confidence: 99%
“…Moya-Sanz et al [25] developed a 2-D numerical model in the Abaqus/Standard to investigate the effects of geometry such as recessing and chamfering of the adherends and adhesive on the failure load of a single-lap joint under uniaxial tensile force, using the cohesive zone model. Hou et al [26] proposed a novel concept to reduce the stress concentration at both ends of the bonding region in a double lap joint by making a slot in the inner adherend using finite element numerical simulation. Santos et al [3] employed a numerical method based on XFEM to predict the stress distribution, strength and damage propagation in the adhesively bonded joints.…”
The use of adhesively bonded joints in place of traditional joining techniques such as bolted or rivet joints is becoming greatly popular in recent years. Interfacial stress in the adhesive is critical to the strength of adhesively bonded joints. It is necessary to predict the interfacial stresses accurately to ensure the safety of joints. In this work, an analytical model is explicitly presented to evaluate the stresses in a double lap joint. The equilibrium equations in the adhesive overlap region are derived on the basis of elasticity theory. The governing equations are presented in terms of shear and peel stresses in the adhesive. Analytical solutions are derived for the shear and peel stresses, which are considered to be the main reason for the failure of the double lap joint. To verify the analytical solutions, the finite element method is conducted using the commercial package ANSYS. Results from the analytical solution agree well with finite element results and numerical investigations available in the literature. The effect of the adhesive thickness, shear modulus, adherend Young’s modulus and bonding length on the shear and peel stresses in the adhesive of the double lap joint are studied. Numerical results demonstrate that both the maximum shear and peel stress occur at both ends of the bonding region. The maximum values of the shear and peel stresses increase as the adhesive thickness decreases and as the adhesive shear modulus increases provided that the adhesive thickness is sufficiently small. The simplicity and capability to obtain analytical expressions of the shear and peel stresses for double lap adhesive bonded joints makes the proposed analytical model applicable for the stress analysis and preliminary structural design.
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