Mechanical Strength Of Adhesive Joints Research Articles

Investigating the mechanical strength of adhesive joints at different concentration of nanoparticles

The mechanical properties of a single lap bonds that had been formed by integrating two dissimilar materials, aluminium plate of Al 6061 and steel plate of SAE 1055 grades using the Bisphenol-A grade epoxy resin (along with the HY 5200 hardener) were investigated, whereas the shearing stress state had been maintained. In addition, the impact that incorporating nano-silica into the epoxy in different quantities on the mechanical properties of the joints had been investigated. During the shearing stress condition, the overlapping distance was decided as being 2.5 cm, and the fractions of nano-silica were chosen to be 0.25, 0.5 and 1.0 percentages in epoxy, correspondingly. When the results of the experiments have been reviewed, it was discovered that the deployment of nano-silica in Bisphenol-A resulted in a considerable increase in the overall average destructive load connected with the process. As a result of the tests, it had been found that the concentration of nano-silica particles, which was found to be the most beneficial for increasing the mechanical characteristics strength of adhesion bonds identified was 0.5%, and the augmentation in frequency of failure stress rise had been recorded as 52.16%. Furthermore, it was demonstrated that the straining of the nano-sized particles had a significant effect in determining the shearing properties of the adhesion connections. Moreover, it was being demonstrated that the elongation of the interface may be improved by introducing nano-silica particles within the bond. When the gluing interactions of the samples were being evaluated, it was found that there was deterioration in the form of adhesion decoupling. On the other hand, nano-silica restocking had been found to be a mix of adhesion and cohesion qualities.

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 structural reinforcement of composite adherends on the mechanical strength of adhesive joints

AbstractThis study proposes a novel method to strengthen fiber reinforced plastic (FRP) adherends in a single lap joint (SLJ) by using Kevlar threads. The adherend reinforcement procedure consists of applying a zigzag thread in the fiber glass layers that comprise the adherend in order to subsequently manufacture the adherends using the vacuum infusion method. For this study, three single lap joint configurations were used: Adherends without Kevlar reinforcement (SLJ1), adherends with Kevlar reinforcement with a medium step zigzag (SLJ2) and adherends with Kevlar reinforcement with a small step zigzag (SLJ3). Mechanical tensile tests were carried out to determine the ultimate strength and displacement of the single lap joint configurations studied. Adherends reinforced by Kevlar threads increase the strength and displacement of the single lap joint. However, the influence of the step size of zigzag threads on the adherend does not significantly influence the strength, but significantly affects the maximum displacement of the single lap joint.

Mechanical Behavior Analysis of Apus Bamboo (<i>Gygantochloa sp</i>) Thin Plate Composite due to Adhesive Joint and Water Absorption Using Experimental and Finite Element Method

The mechanics of adhesive-lap joints of apus bamboo thin plate composite were investigated experimentally and numerically. Tensile load were applied to determine mechanical strength of adhesive joint overlaps. Modal analysis were employed to determine natural frequency of bamboo apus single-lap joint for different overlap and plate thickness configurations. This research found the strength of bamboo adhesive joints decreased 11% due to the effect of 24 hours water immersion. Natural frequencies of single-lap adhesive joint configuration were equivalently decreased in decreament of overlap joint and thickness plate. Finite element models using ABAQUS Software were developed for static and dynamic analysis and compared with the experimental results. Compared to experimental results, numerical analysis gives the prediction with 4% difference for the mean shear stress at failure, and 7-12% difference for the natural frequencies.

A new hybrid bonding technique: Adhesive-soft soldered joints

Joining of components is usually accomplished by mechanical fastening, welding, or adhesive bonding. Apart from the classical methods, various hybrid methods applied with adhesives are widely used in industry to bond mechanical parts. This study describes a new hybrid bonding method as an alternative to currently used hybrid methods: adhesive-soft soldered joints. In this new hybrid technique, joints are made by adding various (5 wt%, 15 wt%, 25 wt%, and 50 wt%) amounts of soft soldering alloy powder into the adhesive at two different temperatures (180℃ and 200℃). The strength of the joints is measured by tensile shear tests. The mechanical strength of adhesive joints carried out by adding soft soldering powder melted at 200℃ is higher than that of joints with only adhesives and unmelted soft soldering powders. The developed hybrid method is applied to attach the insert to cutting tools used in the machining industry and the feasibility of the method is investigated with experiments.

Use of Functionalized Nanosilica to Improve Thermo-Mechanical Properties of Epoxy Adhesive Joint Bonding Aluminium Substrates

The present work is concerned with the improvement of thermal properties and mechanical strength of adhesive joints consisting of an epoxy adhesive layer bonding aluminium substrates by grafted nanosilica. Epoxy resin/silica nanocomposites were prepared by using functionalized silica. Silica was functionalized by amine group (SiO2-NH2). It was identified by Raman and Fourier Transform Infrared (FTIR). Effects of silica on viscoelastic properties for epoxy resin and its assemblies with aluminium substrates were studied by Dynamical Mechanical Analysis (DMA). Particles distribution was characterized by Scanning Electron Microscope (SEM). Our experimental results showed that functionalized silica presents a better distribution in the matrix than the pure silica. Our results also showed that grafting of functionalized silica improves the glass transition temperature (Tg) and the ultimate strength of aluminium/epoxy/aluminium assembly.

Shear strength of adhesively bonded polyolefins with minimal surface preparation

Interest in polyethylene and polypropylene bonding has increased in the last years. However, adhesive joints with adherends which are of low surface energy and which are chemically inert present several difficulties. Generally, their high degree of chemical resistance to solvents and dissimilar solubility parameters limit the usefulness of solvent bonding as a viable assembly technique. One successful approach to adhesive bonding of these materials involves proper selection of surface pre-treatment prior to bonding. With the correct pre-treatment it is possible to glue these materials with one or more of several adhesives required by the applications involved. A second approach is the use of adhesives without surface pre-treatment, such as hot melts, high tack pressure-sensitive adhesives, solvent-based specialty adhesives and, more recently, structural acrylic adhesives as such 3M DP-8005 ® and Loctite 3030 ®. In this paper, the shear strengths of two acrylic adhesives were evaluated using the lap shear test method ASTM D3163 and the block shear test method ASTM D4501. Two different industrial polyolefins (polyethylene and polypropylene) were used for adherends. However, the focus of this study was to measure the shear strength of polyethylene joints with acrylic adhesives. The effect of abrasion was also studied. Some test specimens were manually abraded using 180 and 320 grade abrasive paper. An additional goal of this work was to examine the effect of temperature and moisture on mechanical strength of adhesive joints.

Influence of nanoporous structure on mechanical strength of aluminium and aluminiumalloy adhesive structural joints

The influence of surface treatments on the mechanical strength of adhesive joints wasinvestigated. The attention was focused on AA2024 alloy because it is extensively used inboth the automotive and aerospace industries. Adhesive joints fabricated with purealuminium were also investigated in order to evidence possible differences in the surfacefeatures after identical treatments. Before joining with a commercial epoxy adhesive, metalsubstrates were subjected to different kinds of treatment and the surfaces werecharacterized by SEM analysis. The formation of a microporous surface in the AA2024alloy, upon etching and anodizing, is discussed on the basis of the role of the intermetallicparticles and their electrochemical behaviour with respect to the aluminium matrix.Moreover, nanostructured porous oxide layers on both type of substrate were also formed,as a consequence of the anodizing process. Differences in their morphologies were revealedas a function of both the applied voltage and the presence of alloying elements. Onthis basis, an explanation of the different values of fracture energy measured bymeans of T-peel tests carried out on the corresponding joints was attempted.