|Budget Amount *help
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1995 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1994 : ¥1,300,000 (Direct Cost : ¥1,300,000)
In this study, J-integral of interfacial crack in the bonded joint which is composed of the materials with different mechanical properties, is studied. J-values of two type of bonded joints under the uniformly tensile stress and the three-point bending load are calculated by finite element method. One type is the bi-materials joint, in which the material B is bonded directly to the material A,and the other type is the tri-materials joint, in which the material B is bonded to the material A by using the insert material C.The effect of several factors (Young's modulus ratio of material A and B,difference in coefficient of linear expansion of material A and B,crack length etc.) on J-value is discussed. Furthermore, fracture tests are carried out using specimens that are bonded using an insert materials.
The results obtained are as follows.
1. It is clarified that the normalized J-values of bi-materials joint, J/J_<A=B> are able to be determined by the ratio of Young's modulus of both materials, E_A/E_B and difference in coefficient of linear expansion, (alpha_A-alpha_B). J_<A=B> is the J-value of same material joint. This is affected only by crack length.
2. J-values of tri-materials joint are affected by the thickness of insert materials, d, and the ratio of E_A/E_B and E_C/E_B. J-values can be calculated by the followed equation.
3. Critical J-value is analyzed from breaking load of fracture test by using J-values which is calculated by above equation. It is found that the critical J-value is reasonable parameter for evaluating bonding strength of dissimilar material joints.