13th International Conference on Fracture June 16–21, 2013, Beijing, China -2- Figure 1. Model of the CCCD-specimen The stress field in the vicinity of the crack tip of mixed type (I+II) can be represented in the form [8]: . , 2 sin 2 cos 2 2 , 2 3 sin 2 1 sin 2 cos 2 3 cos 2 cos 2 sin 2 1 , 2 3 cos 2 cos 2 sin 2 3 sin 2 1 sin 2 cos 2 1 , 2 3 cos 2 2 cos 2 sin 2 3 sin 2 1 sin 2 cos 2 1 xx zz zz zz II I zz II I xy II I yy xx II I xx T E T T K K r K K r K K r T K K r υ ε θ θ π ν σ θ θ θ θ θ θ π σ θ θ θ θ θ θ π σ θ θ θ θ θ θ π σ = + ⎥ +⎦ ⎤ ⎢⎣ ⎡ − = ⎥ ⎦ ⎤ ⎢ ⎣ ⎡ ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ − ⎟+ ⎠ ⎞ ⎜ ⎝ ⎛ = ⎥ ⎦ ⎤ ⎢ ⎣ ⎡ ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ ⎟+ ⎠ ⎞ ⎜ ⎝ ⎛ + = ⎥ + ⎦ ⎤ ⎢ ⎣ ⎡ ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ + ⎟− ⎠ ⎞ ⎜ ⎝ ⎛ − = (1) where x is the direction formed by the intersection of the plane normal to the crack front and the crack plane, y is the direction orthogonal to the crack plane, z is the direction orthogonal to x and y directions (tangent to crack front); r and θ are the in-plane polar coordinates in plane x0y. Here, E and ν are the elastic modulus and Poisson’s ratio, respectively. The value of the angle α and the corresponding parameters Me, which characterize loading mode mixity, for the specimen under consideration are shown in Table 1. Note that in the case of mode I crack (KII=0) Me=1, in the case of mode II crack (KI=0) Me=0. ( ) 2 II I e K K M arctg π = (2)
RkJQdWJsaXNoZXIy MjM0NDE=