Intensity of singular stress field for three-dimensional butt joint to evaluate the adhesive strength (original) (raw)
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International Journal of Adhesion and Adhesives, 2020
In our previous study, the adhesive strength of butt joints having three-dimensional (3D) geometries was investigated by using the intensity of singular stress field (ISSF) in two-dimensional modelling. In this paper, by considering the 3D geometry, the ISSF variation along the butt-joint interface side is discussed to explain the experimental results. The results show that the critical ISSF distributions when debonding occur are almost the same and independent of the adhesive bondline thickness. The validity of the 2D modelling is investigated experimentally for two kinds of brittle and ductile adhesives considering the location of the maximum ISSF. It is found that the adhesive strength can be expressed as a constant value of the ISSF at the center side and also at the corner of the adhesive interface.
IOP Conference Series: Materials Science and Engineering
Adhesive joints are widely used although different materials properties cause the singular stress field whose intensity is controlled by the adhesive joint geometry. Our previous studies showed that debonding strength can be expressed as a constant value of the critical intensity of singular stress field (ISSF) by applying two-dimensional modelling. By considering the real adhesive geometry, in this study, the ISSFs along the interface edge of three-dimensional prismatic butt joints are considered by varying the adhesive thicknesses. It is found that the critical ISSF in 3D modelling is almost constant independent of the adhesive thickness. The magnitude and position of the maximum ISSF are discussed by varying the corner fillet radius in comparison with two-dimensional modelling.
International Journal of Adhesion and Adhesives, 2020
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Stress intensity factor in bonded joints: Influence of the geometry
International Journal of Adhesion and Adhesives, 2010
This paper explores the effects of the main geometrical features of an adhesive single lap joint (subjected to tensile stress) on the singular stress field near to the interface end. First, an analysis on a bi-material block is carried out, to evaluate the accuracy obtainable from finite element modelling by comparison with the analytical solution for the singularity given by the Bogy determinant. Then, the study on the lap joint is carried out, by varying both macroscopic (bond length, thickness) and local (edge shape and angle) parameters, for a total of 30 cases. The great importance of the angle to reduce the singular stresses is confirmed, whilst the edge shape plays a lesser role. The bond length has the effect of increasing or decreasing the stress values and the stress intensity factor, and the adhesive thickness has a relevant effect only in case of square edge. Finally, the problem of the significance of the stress intensity factor, representative of the stress distribution only for a given edge angle, is recalled.
Convenient Adhesive Strength Evaluation Method in Terms of the Intensity of Singular Stress Field
International Journal of Computational Methods, 2018
A convenient evaluation method is proposed for the debonding adhesive strength in terms of the intensity of singular stress field (ISSF) appearing at the end of interface. The same FEM mesh pattern is applied to unknown problems and reference problems. It is found that the ISSF is obtained accurately by focussing on the FEM stress at the adhesive corner. Then, the debonding condition can be expressed as a constant value of critical ISSF. The usefulness of the present solution is verified by comparing with the results of the conventional method.
International Journal of Adhesion and Adhesives, 2015
In this study the debonding strength of adhesively bonded joints is investigated in terms of the intensities of the singular stress fields at the ends of the joints. First, a homogeneous and flawless elastic adhesive layer is assumed to evaluate the butt joint strength for carbon steel/epoxy resin, aluminum/araldite, and brass/solder. It is found that the adhesive strength is always expressed as the critical intensities of singular stress. Next, a small fictitious interface edge crack is assumed at the adhesive layer considering double singular stress fields including and excluding the crack. Then the debonding strength is also found to be controlled by the critical interface stress intensity factor of the fictitious crack. A suitable dimension of the fictitious crack is discussed to predict the strength for adhesive joints accurately and conveniently.
International Journal of Adhesion and Adhesives, 2019
Employing mixed adhesive joints has been proven to be very useful. This type of joint leads to improved performance by increasing strength and decreasing stresses in critical areas of the joint. In the same way, the use of the Intensity of Singular Stress Field (ISSF) has been shown to be suitable for adhesive joint calculation, since the adhesive strength can be controlled by the ISSF at the interface end. Four finite element models have been created by combining two epoxy adhesives with different mechanical properties, and therefore with different Young's moduli. New mixed adhesive joints have been compared with respect to only-one adhesive joints in terms of the ISSF. The results show a clear improvement with one of the configurations of mixed adhesive joints.
Evaluation of Adhesive Strength Based on the Intensity of Singular Stress Field of Single Lap Joint
2016
In this study, the adhesive strength for single lap joint is investigated based on the intensity of singular stress field. First, the critical intensity of singular stress at the adhesive dissimilar joint is calculated by using finite element method (FEM) based on the experimental result. It is found that the adhesive strength can be expressed as the critical intensity of singular stress field. Then, a suitable evaluation method of adhesive strength is investigated focusing on the intensity of singular stress field. The effect of specimen geometry on the intensity of singular stress is considered. The results show that the intensity of singular stress field decreases with increasing the adherend thickness, the minimum intensity of singular stress can be obtained when the adherend thickness is large enough. The results of the deformation angle at the interface corner edge show a similar trend as in intensity of singular stress field, and the minimum deformation angle can be obtained ...
Effects of Geometry on Intensity of Singular Stress Fields at the Corner of Single-Lap Joints
World Academy of Science, Engineering and Technology, International Journal of Mechanical, Aerospace, Industrial, Mechatronic and Manufacturing Engineering, 2011
This paper discusses effects of adhesive thickness, overlap length and material combinations on the single-lap joints strength from the point of singular stress fields. A useful method calculating the ratio of intensity of singular stress is proposed using FEM for different adhesive thickness and overlap length. It is found that the intensity of singular stress increases with increasing adhesive thickness, and decreases with increasing overlap length. The increment and decrement are different depending on material combinations between adhesive and adherent. Keywords—Adhesive thickness, Overlap length, Intensity of singular stress, Single-lap joint
Effect of Adhesive Thickness on the Intensity of Singular Stress at the Adhesive Dissimilar Joint
Journal of Solid Mechanics and Materials Engineering, 2010
This paper deals with the singular stress field at the adhesive dissimilar joint, and discusses the effect of material combination and adhesive thickness on the intensity of the singular stress when bonded strip is subjected to tension. A useful method to calculate the intensity of singular stress at the adhesive dissimilar joint is presented with focusing on the stresses at the edge calculated by finite element method. The intensities of singular stress are indicated in charts with varying adhesive thickness t under arbitrary material combinations for adhesive and adherents, and it is found that the intensity of singular stress increases with increasing the adhesive thickness t until t W = , when W is the width of adhesive. The intensity of singular stresses are also charted under arbitrary material combinations which are presented by Dunders' parameters α , β when / 0.001 t W = and / 0.1 t W = , and it is found that for a fixed value β the intensity of singular stress increases with increasing α when α is small while it decreases with increasing α when α is large.