Intensity of Singular Stress Field at the Corner of Adhesive Layer in Bonded Plate

In this paper the strength of adhesive joint under tension and bending is discussed on the basis of intensity of singular stress by the application of FEM. A useful method is presented with focusing on the stress at the edge of interface between the adhesive and adherent obtained by FEM. After analyzing the adhesive joint strength with all material combinations, it is found that to improve the interface strength, thin adhesive layers are desirable because the intensity of singular stress decreases with decreasing the thickness. Keywords—Adhesive, Adherent, Intensity of singular stress, Bonded strip I. NTRODUCTION ITH the widely used of adhesive joint, the evaluation of adhesive joint strength also be paid more and more (a) (b) (c) Fig.1 Adhesive joint under (a) tension, (b) bending (c ) with different adherents under tension N.A.N. Author is with the Department of Mechanical Engineering, Kyushu Institute of Technology, Kitakyushu, CO 8048550 Japan (phone: 093-884-3124 fax:093-884-3124;e-mail: [email protected]). Y.Z. Author is with the Department of Mechanical Engineering, Kyushu Institute of Technology, Kitakyushu, CO 8048550 Japan (phone: 093-884-3124 fax:093-884-3124;e-mail: [email protected]). T. T. Author is with the Department of Mechanical Engineering, Kyushu Institute of Technology, Kitakyushu, CO 8048550 Japan (phone: 093-884-3124 fax:093-884-3124; e-mail:[email protected]). H.S. Author is with the Department of Mechanical Engineering, Kyushu Institute of Technology, Kitakyushu, CO 8048550 Japan (phone: 093-884-3124 fax:093-884-3124; e-mail:[email protected]). (a) (b) Fig.2 Bonded strip under (a) tension, (b) bending attention to. About the adhesive joint strength many researches have been done [1],[2], but most of them are limited in the experiments, and the most popular experiments are the adhesive joint subjected to the tension and bending, for example, the mode shown in Fig.1 (a) could describe the micro-tensile bond test , which is a laboratory procedure frequently employed today in an attempt to predict the clinical effectiveness of adhesive used for bonding composite restorations to the dental substrate. In this paper, adhesive joint with the same adherent materials under tension shown Fig.1 (a) and under bending shown in Fig.1(b), and adhesive joint with different adherent materials under tension shown in Fig.1 (c) will be analyzed on the basis of intensity of singular stress using the solutions for the reference problem shown in Fig.2 (a) and (b). Here, , r are polar coordinates around the interface edge, and , , W l t are dimensionless of the adhesive joint with the width W , the height l , and the adhesive thickness t . II.ANALYSIS METHOD For the adhesive joint as shown in Fig.1, it is known that the interface stress ( , , ) ij ij rr r goes to infinity at the edge of joint and has singularity of 1 1 ij r when ( 2 ) , 0 where , are Dunders’ parameters ; Besides, when 2 , the order of singularity at the joint of interface can be expressed by the following equation[3],[4]. 2 2 2 2 2 2 2 2 2 2 2 sin 2 sin 1 2 2 sin 0 4 (1) Nao-Aki Noda, Yu Zhang, and Ken-Tarou Takaishi, Hiroyuki Shibahara Intensity of Singular Stress Field at the Corner of Adhesive Layer in Bonded Plate