Study of g value of Edge Crack Existing along Bond Line of Joint Composed of Dissimilar Materials

Study of Specimen Size for Estimating Joint Strength of Dissimilar Materials (Part 2)

Abstract

The energy release rate, g, used for estimating the joint strength of dissimilar material joints with defect has been investigated by means of a boundary element method (BEM). Size and material parameters of g value in both load and residual stress fields were derived. The main conclusions are as follows:
1) In a thermal stress filed, the relation between g value and material properties is given by the following equation;
For the case of Poisson's ratios of dissimilar materials being equal,
g/E^A{(α^A-α^B)T}²a=f(E^B/E^A, v^A=v^B)
where E is Young's modulus. ν is Poissons' ratio. α is a coefficientof linear expansion.
T is temperature difference. α is half length of crack.
Suffix A and B mean materials A and B. For the case of ν^A being different from ν^B,
g/E^A(α^AT)²α=g(E^B/E^A, ν^A, ν^B, α^B/α^A)
2) When the height of specimen, h, is greater than the width of specimen, b, h, hardly affects g value in both load and residual stress fields.
3) When b is greater than twice of h, g value is almost constant in both fields.