Influence of Adherend Surface Roughness on the Adhesive Bond Strength (original) (raw)
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Adherend surface roughness effect on the mechanical response of adhesive joints
arXiv: Applied Physics, 2020
The present contribution focuses on the effect of adherend surface roughness on the strength of adhesive joints, which are particularly cost-effective and extensively applied in a wide range of industrial applications. However, the reliability of such solutions is a critical concern for the integrity of commercial products. To gain a deeper understanding on the effect of roughness, an extensive experimental campaign is proposed, where thermoplastic substrates are produced with a specified roughness, whose characterization has been performed using a confocal profilometer. Elastic strips are then bonded onto such substrates using Silicone adhesive while controlling the adhesive thickness. Peeling tests are finally carried out and the effects of joint parameters such as surface roughness, adhesive thickness, and loading rate are discussed in detail. Eventually, it is demonstrated that the surface roughness can increase the adhesion energy of joints depending on the value of a ratio bet...
Mechanics Based Design of Structures and Machines, 2020
Surface roughness obtained from different preparation processes such as sanding, shot blasting, and sand blasting were considered in this study. The effects of surface roughness on shear strength of single-lap adhesive joint were examined. 2024-T3 aluminum sheets were cut into standard pieces and then sanded with seven sandpapers with different mesh, shot blasted for four different duration times and sandblasted under four different pressures. Pairs of prepared surfaces were attached using Araldite 2015 adhesive with high viscosity and HPL1012/HPH112 epoxy adhesive with low viscosity. Results show that the ultimate lap shear strength of the sanded samples initially increase and then decrease as surface roughness is increased. The lap joint strength continuously increases as the surface roughness of shot blasted and sand blasted samples are increased. In sanding, the optimum surface roughness is different for both high and low viscosity adhesives. However, for shot blasting and sand blasting, the optimum surface roughness is the same for both adhesive types. The maximum ultimate lap shear strength of joints for both types of adhesives obtained for sand blasting under 0.6 MPa pressure with 0.6 lm surface roughness.
Influence of Acrylic Adhesive Viscosity and Surface Roughness on the Properties of Adhesive Joint
The Journal of Adhesion, 2015
The aim of this paper is to study the influence of viscosity and surface roughness on the wetting and their effect on the bond strength. For this purpose, an acrylic adhesive with different viscosities was synthesized and some properties, such as viscosity and surface tension, were studied before adhesive curing took place. Furthermore, the contact angle and the lap-shear strength were analyzed using aluminum adherends with two different roughnesses. Scanning electron microscopy was used to determine the effect of the viscosity and the roughness on the joint interface. The results showed that the adhesive exhibits an optimal value of viscosity. Below this value, at low viscosities, the low neoprene content produces poor bond strength due to the reduced toughness of the adhesive. Additionally, it also produces a high shrinkage during curing, which leads to the apparition of residual stresses that weakens the interfacial strength. However, once the optimum value, an increase in the viscosity produces a negative effect on the joint strength as a result of an important decrease in the wettability.
U.Porto Journal of Engineering
A two-component high-ductility adhesive (acrylic and catalyst based), SikaFast® - 5211 NT, was used to bond single overlap joints with mild steel adherends and 25 mm of overlap. One joint configuration used treated bonding surfaces while the other was did not employ treatment of the adherend surfaces, with the aim of studying the influence of the material surface treatment. The specimens were tensile tested in a INSTRON® universal testing machine and the non-treated surface have shown a strength four times lower than the treated surface. Several analytical methods were used to predict joint strength, with two methods achieving reasonably accurate failure load predictions.
This work deals with an experimental investigation on the effect of mechanical surface treatments of adhesive bonded joints. The behaviour of an adhesively bonded joint can be considered good if cohesive failure is achieved, while when interfacial failure occurs the performances are normally much worse. A key parameter which drives the failure type is the surface treatment applied to the adherends. This work analyzes, by means of a structured experimental campaign, which surface mechanical treatment gives the best performance. The design of the experimental approach used involves different materials, joint geometries, and surface treatments. The results are investigated in terms of force, energy, and stresses in the joints and the performance of the several mechanical treatments tested is assessed, showing that a simple correlation with the surface roughness is not sufficient to predict the best joint performances. The reliable results obtained prove that sandpapering or sandblasting the adherends gives a strong improvement in terms of performance and leads to a higher probability of cohesive failure.
The Application of Advanced Surface Preparation Methods in the Adhesive Bonding Process
Biuletyn Instytutu Spawalnictwa, 2019
An important part in the process of adhesive bonding is played by the appropriate preparation of surfaces to be subjected to adhesive bonding. The objective of the tests discussed in the article was to identify the effect of various surface preparation methods, including cleaning, grinding, atmospheric plasma treatment and the ATOP method on the strength of adhesive-bonded joints. The tests involved the use of specimens made of aluminium alloy EN AW 5754 as well as specimens made of glass fibre-reinforced epoxy-based plastics. The specimens were subjected to overlap adhesive bonding involving the use of Araldite two-component epoxy adhesive (Huntsman). The article presents results of the static shear test (of the overlap joints) in relation to a given surface preparation method applied before the adhesive bonding process. The highest strength of the adhesive-bonded joints made in the aluminium alloy was obtained in relation to the ATOP method-based treatment. In addition, the above-named method makes it possible to properly prepare a cleaned surface by forming a protective layer ensuring proper surface preparation for several months. In turn, the highest strength of the adhesive-bonded joints made of glass fibre-reinforced plastics was obtained in relation to the surface treatment performed using atmospheric plasma.
Use of thin adherends in adhesively bonded joints under different loading modes
Science and Technology of Welding and Joining, 2003
The adhesive bonding technique is especially suited to the joining of thin materials. An adhesive joint consists of a structural adhesive and an adherend. When designing the joint, focusing on the behaviour of the adhesive is important. However, if the material to be joined is thin, then it becomes much more important to concentrate on the material properties. In the present work, two adhesives with different mechanical behaviour and two thin adherend materials, steel and aluminium, were selected for the production of adhesive joints. The single lap joint con guration was subjected to tests under bending load and also under tensile load. The results show that adherend plasticity plays an important part in the joint failure; specimens under bending load experienced high plastic deformation of adherends, depending on the strength of the adherend material. Overlap increase did not seem to affect the joint strength. When the joints were tested under tensile loading, it was observed that the load bearing capacity of adhesives was an important parameter in uencing the joint strength, and that an increase in overlap seemed to contribute to the joint performance. In general, the results obtained imply that it is vital that the adherends used remain in their elastic deformation region to obtain a joint strength that re ects the mechanical behaviour of the adhesive used.
VW Applied Sciences, 2019
Adhesive bonding is getting more attention for research and considered as most promising and well-known technique for joining the two materials which may be similar or dissimilar naturally polymers, metals etc. and to be utilized in light weight structures for reduced stress distribution. Adhesion bonding consisting on intrinsic bonding force which plays vital role to make the joint withstand more strength. To fabricate an effective griped joint between the components, good adhesion strength is compulsory attainment factor for long life of structures. Recently, along with metallic materials polymers and their composites are also trending in multiple industries. All materials always have forces of attraction between their atoms/molecules which extremely crucial role to ensure stronger bond strength and often dependent on roughness of surface of material which are taking part to fabricate the joint. Consequently, surface roughness and surface morphology are most important parameters to decide the joint strength and life of bonded joints of polymeric composites. In this review article, mechanical interlocking mechanism, surface roughness effects on wettability, surface energy estimation and various bonding theories including adsorption theory, diffusion theory, boundary layer theory and chemical theory are discussed briefly to emphasize the various technological & industrial developments VW Applied Sciences
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.
Study of the Impact of Surface Topography on Selected Mechanical Properties of Adhesive Joints
Coatings, 2024
Manufacturers of adhesives for industrial use determine the strength of adhesive joints during shear tests. Most often, components made of the same material are joined. In contrast, the roughness of the surfaces to be joined results from the use of a specific surface treatment technology. In adhesive manufacturers’ recommendations for metal-to-metal joints, surface technologies can be found without specifying numerical requirements for roughness. Modern techniques for shaping the geometric accuracy of components allow the formation of determined irregularities on the surface, which are characterised by their height and mutual distribution. Furthermore, regular irregularities can be obtained by using the appropriate tool and technological machining parameters. In this way, surfaces with similar load-bearing capacity, core volume, texture or expected hydrophobic properties can be produced by various methods. However, a basic prerequisite is the careful definition of the numerical requirements, both for the basic roughness indices and those of a complementary nature. As a rule, the strength of the adhesive joint is also lower than the strength of the adhesive itself. The strength of an adhesive joint depends on the ‘mechanical anchorage’ of the adhesive and the adhesion phenomenon on the surface. The research assumes that it is possible to induce an interaction between the geometric state of the surface and the properties of the adhesive, so as to guarantee the maximum strength of the adhesive joint. To verify this, a series of experimental tests were developed and carried out for two different adhesives characterised by different viscosities and offered bond strength. Based on the tests carried out, recommendations were made to the designers of adhesive joints, where, in addition to the height of the surface irregularities, the properties related to fluid retention and the shape of the irregularities in the valleys should be determined.