Strength Of Single Lap Adhesive Joints Research Articles

The effect of co-creation of notches and recesses in the adhered material on the strength of single-lap adhesive joints: Experimental and numerical analysis

For decaces, many different adhesive joint geometries have been used in aerospace and automotive applications, with the idea that adhesively-bonded joints can be an alternative to traditional joining methods in aerospace applications. The single-lap joint geometry is today one of the most frequently used joint geometries in research. In this joint geometry, due to eccentric loading, peel stresses occur, which cause damage in the overlap region. Reducing these stresses increases joint strength. In this study, the strengths of single-lap joints (SLJ) obtained by creating notches and recesses of different lengths and depths in the adhered material were investigated experimentally and numerically. First, the strengths of the SLJ obtained by using different lengths and thicknesses of recesses and notches of different widths and depths in the adherend were investigated. After this examination, the strength of the joints with the best recess and notch joints together in terms of joint strength were examined. As a result, making a recess of the adherend on the outer part of the overlap region in single-lap joints increases the joint strength by approximately 29%, and making a notch increases the strength of the connection by approximately 27%. These increases in the joint strength vary according to the geometry of the recess and notch formed in the adherend. In addition, the use of both the notch and the recess in the joint improves the joint strength further. Additionally, in the presented study, experimental data were compared with numerical analysis and it was observed that the data were quite consistent with each other.

The effect of inclusions embedded in the adhesive on the stress distribution and strength of single-lap adhesive joints: analytical and numerical analysis

In this study, an analytical analysis and a finite element method (FEM) study of the overall strength and interfacial stress distribution of single lap joints with an embedded inclusion in the adhesive layer were performed. The stress analysis model for the single lap adhesive joints including inclusion layers was firstly established, and the effects of the thickness and stiffness of the inclusions on their mechanical strength were discussed in detail. The results show that the bond strength of the adhesive joints is highly dependent on the geometric parameters and properties of the inclusions, and increases with the inclusion thickness and stiffness. When the stiffness of inclusions is lower than that of the adhesive layers, their introduction degrades the bond strength of the single lap adhesive joints. The interface stress distribution and failure mechanism caused by the inclusion layers are intuitively analyzed by FEM, which is in good agreement with the analytical analysis.

Experimental investigation of the effects of adhesive defects on the strength and creep behavior of single-lap adhesive joints at various temperatures

ABSTRACT In this article, the creep behavior and strength of single-lap adhesive joints ( s) including defects have been studied, and the effect of the position of defects on the creep behavior and strength of s have been investigated. The defects were created on various sides of the Araldite 2011 adhesive layer and joints were subjected to the tensile and creep tests. The creep tests were done at three different temperatures; 23 ℃ (Room Temperature), 45 ℃, and 55 ℃. The results showed that the presence of a defect in the adhesive layer caused the greatest decrease in the strength of the joints in the defective joint with the defect in the middle and both sides. Also, the presence of a defect in the adhesive layer increases the creep displacement, which is much higher than the amount of this displacement in the joint without a defect. Increasing temperature to 45 ℃, and 55 ℃ has increased the creep displacement by almost 90%, compared to the creep displacement at room temperature (RT). Based on the results, the presence of defects on both sides has the greatest effect on reducing the strength of the joint (defect in the middle) and increasing the creep displacement (defect in the edge).

The Influence of Sandblasting Process Parameters of Aerospace Aluminium Alloy Sheets on Adhesive Joints Strength.

In this study, the influence of sandblasting process parameters as a surface preparation method on the strength of single-lap adhesive joints of EN AW 2024 T3 aerospace aluminium alloy sheets was determined. Eleven sets of sandblasting parameters were used, which were determined according to a determined experimental plan. The variable factors in the sandblasting process were pressure, nozzle distance, and workpiece displacement speed. The sand jet incidence angle was constant. Garnet 80 E+ was the abrasive material that was used. The joints were made using an epoxy adhesive composition of Epidian 5 epoxy resin and a PAC curing agent. The influence of the surface preparation method on the surface roughness and contact angle to determine the surface free energy was evaluated. The shear strength of the adhesive joints was also determined, which finally allowed the evaluation of the applied surface treatment variants. The obtained results were subjected to statistical analysis, which indicated that the highest shear strength of the adhesive joints was obtained for samples whose surfaces were treated by sandblasting at parameter configurations in which the pressure was 5–6 × 105 Pa; the distance between the nozzle and the sandblasted surface should not be greater than 97 mm, and the speed at which the workpiece moves in relation to the nozzle should not be greater than 75 mm/min.

Bending strength of single-lap adhesive joints under hygrothermal aging combined with cyclic thermal shocks

ABSTRACT Adhesive joints in the aeronautical sector are exposed to hostile environments, which may combine different temperatures and/or moisture conditions. Both subjects are conveniently reported in the open literature, but when they act together there is no consolidated knowledge about their effect on the mechanical strength of adhesive joints. Therefore, this work will study the effect of hygrothermal aging combined with cyclic thermal shocks on the flexural properties of single-lap adhesive joints. Adhesive joints involving ductile and brittle adhesives were exposed to different number of cycles, which combine two sequences of 12 hr with constant temperatures but different environments (water and air). It was possible to conclude, independently of the adhesive, that higher hygrothermal aging temperatures promote higher decreases of the failure load and maximum failure displacement, but they are only marginally affected by thermal shocks in air. Finally, a significant degradation of flexural properties occurs with the number of hygrothermal shocks, but the water/air environments reveals to be much more severe than water/water ones.

Effect of the geometry in the strength of single-lap adhesive joints of composite laminates under uniaxial tensile load

Adhesively bonded joints are widely used in structures manufactured with composite laminates. Single-lap adhesive joints are the common most used due to their simple geometry and structural efficiency. In this study, a 2D numerical model has been developed in Abaqus/Standard to evaluate the influence of variations in the geometry of the adherends and the adhesive on the mechanical strength of a single-lap joint subjected to uniaxial tensile load, using the Cohesive Zone Model (CZM). Different geometrical configurations of single-lap joints have been studied, such as adherend recessing and chamfering of the adherends and adhesive. The objective is to analyse the effect of these variations with respect to the mechanical strength of the adhesive joint. In this sense, the vertical displacement of the adherends, the peak peel stress, the distribution of peel stress on the overlap length, and the failure load have been studied, identifying the chamfer in the adherends and adhesive as the most influential parameter governing the strength of the adhesive joint.

Comparative Analysis of Shear Strength of Single-Lap Adhesive Joints after "Thermal Shock"

The paper presents a comparative analysis of static shear strength of single-lap adhesive joints of 316L steel, before and after mechanical treatment with a coated abrasive tool. The research was of comparative nature and focused on adhesive joints subjected to variable thermal stress and adhesive joints not subjected to such shock. Adhesives based on epoxy resins were used. The results of static shear strength tests of single-lap adhesive joints for different variations of material preparing were analysed. The obtained results were analysed statistically and in compliance with relevant scientific standards. The scope of tests covered a relatively short fatigue cycle, i.e. 200 cycles in the range of temperatures between-40°C and +60°C. The main aim of the research was to determine the relation between joint strength and thermal fatigue. The paper presents conclusions resulting from the conducted research.

Mechanical Behavior of Single-Lap Adhesive Joints with Reinforced Pins

An approach to increasing the loading ability of adhesive joints by adding reinforced pins is presented. Following procedures are taken for making adhesive joints with reinforced pins: At first, holes are drilled at the overlap region of adherends, and then one hole is filled with a metal pin and adhesive. At the same time, adhesive is also applied on the surfaces of the overlap of adherends. After cured, the metal pin and the adhesive in one hole form an adhesive-metal reinforced pin. In this study, strengths of single-lap adhesive joints with the reinforced pins were measured experimentally. It is found that to well-bonded joints, (1) the strength of single-lap adhesive joints with adhesive-metal pins are obviously greater than those without adhesive-metal pins; (2) the strength of single-lap adhesive joints with adhesive-metal pins is highest when the pins are located at the positions of 5mm from the two ends of the overlap segment, the strength of single-lap adhesive joints with adhesive-metal pins is lowest when the pins are located at the middle of the overlap segment, about 10mm from the two ends of the overlap segment.

Failure Analysis of Laminates Single-Lap Adhesive Joints under Uniaxial Tensile Loading

Tension tests on three different types of T700/EXOPY unidirectional laminates single-lap adhesive joints under uniaxial tensile loading were performed and effect of adherend thickness and spew fillets on strength of single-lap adhesive joints were analyzed in this paper. According to the experimental results, it is found that joint strength was not linear with the adherend thickness and much affected by spew fillets in overlap ends. At the same time, finite element simulations are carried out to analyze the peel/shear stress fields along joint interfaces and the intermediate layer of adhesive. The simulation results show that it is the main factor to leading to joint failure that the maximum peel/shear stress is occurred at overlap area edges and peel/shear stress of joints with spew fillet at the overlap area edges is less than that of joints with no spew fillet. Good agreements between the present simulations and the experimental results are found.

551 静的曲げモーメントを受ける被着体が竹板である単純重ね合わせ接着継手の応力と強度(接着接合の力学I)

551 静的曲げモーメントを受ける被着体が竹板である単純重ね合わせ接着継手の応力と強度(接着接合の力学I)

551 静的曲げモーメントを受ける被着体が竹板である単純重ね合わせ接着継手の応力と強度(接着接合の力業)

551 静的曲げモーメントを受ける被着体が竹板である単純重ね合わせ接着継手の応力と強度(接着接合の力業)

Effect of Adhesive Type and Thickness on the Lap Shear Strength

The effect of the adhesive thickness on the bond strength of single-lap adhesive joints is still not perfectly understood. The classical elastic analyses predict that the strength increases with the adhesive thickness, whereas experimental results show the opposite. Various theories have been proposed to explain this discrepancy, but more experimental tests are necessary to understand all the variables. The objective of the present study was to assess the effect of the adhesive thickness on the strength of single-lap joints for different kinds of adhesives. Three different adhesives were selected and tested in bulk. The strain to failure in tension ranged from 1.3% for the most brittle adhesive to 44% for the most ductile adhesive. The adherend selected was a high-strength steel to keep the adherends in the elastic range and simplify the analysis. Three thicknesses were studied for each adhesive: 0.2, 0.5, and 1 mm. A statistical analysis of the experimental results shows that the lap shear strength increases as the bondline gets thinner and the adhesive gets tougher.

A Two-dimensional Stress Analysis and Strength of Single-lap Adhesive Joints of Dissimilar Adherends Subjected to External Bending Moments

The stress distributions of single-lap adhesive joints of dissimilar adherends subjected to external bending moments are analyzed as a three-body contact problem by using a two-dimensional theory of elasticity (plane strain). In the analysis, dissimilar adherends and an adhesive are replaced by finite strips. In the numerical calculations, the effects of the ratio of Young's moduli of adherends, the adherend thickness ratio and the adherend length ratio between dissimilar adherends on the stress distributions at the interfaces are examined. The results show that the stress singularity occurs at the ends of the interfaces, and its intensity is greater at the interface of the adherend with smaller Young's modulus. It is also noted that the singular stress is greater at the interface of the thinner adherend. It is found that the effect of the adherend length ratio on the stress singularity at the interfaces is very small. Joint strength is predicted by using the interface stress and it was measured by experiments. From the analysis and the experiments, it is found that the joint strength increases as Young's modulus of adherends and the adherend thickness increase while the effect of the adherend lengths on the joint strength is small. For verification of the analysis, a finite element analysis (FEA) is carried out. A fairly good agreement of the interface stress distribution is seen between the analytical and the FEA results.