The effects of thickness and Poisson’s ratio on 3D mixed-mode fracture

The effects of specimen thickness and Poisson’s ratio are investigated on mixed mode fracture parameters of a test sample using numerical analyses. A large number of three dimensional finite element models of semicircular bend specimen containing an inclined edge crack are analyzed to compute mixed mode fracture parameters (i.e. KI, KII and T). While for the two dimensional models the fracture parameters are independent of thickness and Poisson’s ratio, the three dimensional results showed that the stress intensity factors (KI and KII) and the T-stress are generally increased by increasing Poisson’s ratio. The T-stress decreases when the thickness of specimens is increased. A comparison between the two and three dimensional solutions shows that the available KI, KII and T results obtained from two dimensional conditions, present lower estimate data for the real three dimensional cracked semicircular bend specimen. Also, the influence of specimen thickness and Poisson’s ratio, is more pronounced for dominantly mode I condition in the semicircular bend specimen.

► 3-D mixed mode fracture parameters were obtained numerically for the SCB specimen.
► Extensive finite element analyses were performed for various loading conditions.
► KI, KII and T were dependent to the specimen thickness and Poisson’s ratio in the 3-D SCB specimen.
► 2-D data provide lower estimate results for the fracture parameters of real 3-D SCB specimens.
► The differences between 2-D and 3-D data are more pronounced for dominantly mode I conditions.