Papers by Keyword: Adhesive Joint

Abstract: This research investigated the effect of the thickness of adhesive to the stiffness (Young’s modulus) of adhesive butt joint at high strain rate loading. A split Hopkinson pressure bar (SHPB) test is used to obtain the stress-strain response of join specimen at strain rate of 530±10 s^-1. The joint is composed of aluminum adherend bonded by epoxy adhesive with 0.5, 1, 2, and 3 millimeter of thickness variation. The results show that the joint deformed elastically and the stiffness increases with the increase of adhesive thickness. However, the rate at which the stiffness increases with thickness decreases at thick adhesive layer. The facts of this research are important for the improvement of the crashworthiness of structure such as automobile structures.

Abstract: Adhesive sandwich structures with the honeycomb core of the metallic foil, polymeric papers and composites are widely and effectively used in the units of aerospace engineering and in the other industries owing to a number of undeniable advantages, including high specific strength and stiffness. In the process of designing and manufacturing of abovementioned structures, it is necessary to ensure high strength and reliability of the adhesive joint of the bearing skins and honeycomb core at a small area of their contact. The decisive factors influencing the bearing capacity of such joint are the technological parameters of the bonding process. Using the finite element modeling, the paper deals with the bearing capacity of the adhesive joint of bearing skins with the honeycomb core based on the aluminium foil and polymeric paper Nomex at transversal tearing for the key factors of the bonding process. The pattern of the adhesive joint failure (on the adhesive of honeycombs) has been revealed, depending on the depth of penetration of honeycombs ends in the adhesive, physical and mechanical characteristics of honeycombs, modulus of elasticity and tearing strength of the adhesive and thickness of the adhesive layer. Peculiar features of behavior of adhesive joints of the bearing skins with the honeycomb core based on the aluminium foil and polymeric paper Nomex under the load have been established, which should be taken into account in designing and manufacturing of honeycomb structures. The recommendations are given with regard to choosing of parameters of the process of honeycomb structure bonding, which allow providing with the acceptable accuracy the optimal depth of penetration of ends of the honeycomb core faces in the adhesive layer of specified depth.

Abstract: The study of the steel/steel adhesive joint using digital image correlation method has been carried out. A correlation between the evolution of distributions of deformation regions on the surface of the adhesive joint and the stages on the deformation curve is revealed. It has been found that a destruction along the adhesive seam begins when the adhesive joint reaches total deformations of about 0.5%. The analysis of deformation fields on the steel surface have allowed revealing the formation of extensive tension regions with greatest deformations at the interface of loaded plates. An increase in the values of compression deformations at the ends of the patch and a significant increase in the areas of these regions have been revealed.

Abstract: The research of the deflected mode of the construction, composed of two coaxially-glued cylindrical pipes, is done. Pipes are considered as thin-walled axisymmetric shells, which are joined by adhesive layer of a certain thickness. The shearing stresses in the glue are considered to be constant over the thickness of the adhesive layer, and normal stresses are linearly dependent on the radial coordinate. The shearing stresses in the adhesive layer are considered to be proportional to the difference in the longitudinal displacements of the shell sides that are faced to the adhesive layer. Normal stresses are proportional to the difference in radial displacement of the shells. It is supposed that the change in the adhesive layer thickness under deformation does not affect the stress, that is, the linear model is considered. The problem of the joint deflected mode finding is reduced to the system of four ordinary differential equations relative to the radial and longitudinal displacements of the layers. The system is solved by the matrix method. Displacements of layers outside of the adherent area can be found by the classical theory of axisymmetric shells. Satisfaction of boundary conditions and conjugation conditions leads to a system of twenty two linear equations with twenty two unknown coefficients. The model problem is solved; the results are compared with the computation made by the finite element method. The tangential and normal stresses in the glue reach the maximum values at the edges of the adhesive line. It is shown that the proposed model describes the stressed state of the joint with high accuracy, and this joint has an influx of glue residues at the ends of the adhesive line but can not be applied in the absence of adhesive influxes. Because in this case, the tangential stresses due to the parity rule reach maximum values not on the edge, but at some distance from the edge of the line. As a result, the distribution of normal stresses at the edge of the line also substantially changes. Thus, the proposed model with certain restrictions has sufficient accuracy for engineering problems and can be used to solve design problems.

Abstract: In sheet metal industries, press-formed sheet elements are usually adhesively bonded together at the final stage of assembly. Instead of such a conventional process, the present authors proposed a new technique that first flat sheets are adhesively bonded together and then press-formed into the final products. In previous study, the problem of the die-bending (V-bending and hat-shaped bending) with symmetrical shape has studied. In this study, asymmetric-shaped bending of adhesively bonded sheet metals was investigated by experiments and FEM analysis method. In the case of asymmetric-shaped bending, it was found that the timing of contact from the die corner to the die hypotenuse is early in the press-forming process compared with symmetrical bending (V-bending and hat-shaped bending). For the FEM analysis results, the maximum shear strain in asymmetric-shaped bending was smaller than that in symmetric-shaped bending at the hat-shaped side. Thus, the shape of the die has a large influence on the die-bending of adhesively bonded sheet metals.

Abstract: In this study, we developed a new conceptual test method of adhesive joining using aluminum circular pipes with sloping bonded surfaces to evaluate the failure strength of the adhesive layer under a multiaxial stress state. In our experiment, we prepared several test specimens made of A5052 aluminum with cross-sectional surfaces possessing angles of inclination varying from 0–90 degrees. We then carried out uniaxial tensile tests, employing paired aluminum pipe halves joined by adhesives. From the load‒displacement curves, we estimated the first invariant of the stress tensor and the second invariant of the deviatoric stress tensor, and we applied two kinds of criteria, both of which effectively represent the failure stress of the adhesive joint. According to the failure criteria, the thickness-dependent strength of the adhesive layer and its power law are discussed.

Abstract: 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.

Abstract: This paper presents the experimental investigation on adhesive joint under three loading angles using a modified Arcan jig. Fracture test was performed using the fabricated Arcan specimens and Araldite adhesive with loading angle of 0°, 90° and 45° to represent Mode I, Mode II and mixed Mode loading, respectively. Eighteen specimens were prepared with adhesive thickness of 6 mm and nine of them with interface crack length of 5 mm. The result shows the stress intensity factor, K is influenced by the loading angle and the initial crack-line directions. KI was found greater than KII .

Abstract: This paper presents a literature review on the influence of heat treatment and surface roughness to the adherent surface and its effect on adhesion strength and covers some article published from 1992 to 2013. The paper is divided into several related topics such as types of adhesive bonding failure, effect of surface roughness, and effects of heat treatment. The objective of this paper is to reveal the underlying scientific phenomena, relationships, and arguements on the related topics. The paper is concluded by highlighting the significant topics that drives future research.

Abstract: A damage model for thin adhesively bonded joints is presented, which predicts the time to creep-fatigue failure of the joint subjected to combined static and cyclic sustained loadings with constant or variable amplitudes. The influences of particular model parameters on the predicted lifetime are elaborated suggesting the proposed stepwise parameter identification strategy by means of creep and Wöhler fatigue tests until rupture. The parameters are identified and computationally optimized. As a conclusion, the model prediction is verified and validated.