Viscoelastic fracture of multiple cracks in functionally graded materials

In this paper, the viscoelastic fracture of multiple cracks in a functionally graded strip is studied. The solution of linear elastic crack tip field is investigated at first, using the finite element method. Both applied stress load and applied strain load are taken into account. The effects of the crack length, crack spacing, material gradient index and the loading condition on the crack tip field intensity factor are plotted and discussed. According to the correspondence principle, the viscoelastic crack tip field under applied strain is obtained from the linear elastic results. Variation of stress intensity factor of the viscoelastic functionally graded strip is analyzed. Some useful information for the design of functionally graded materials is provided.