CYCLIC INELASTIC DEFORMATION AND LIFE PREDICTION OF CFRP

Abstract

Fiber reinforced composite materials are widely used in many structures. It is well known that composite materials inelastically deform. Although there are some researches on fatigue failure, damage and crack propagation of composite materials, cyclic inelastic behavior of composite materials subjected to cyclic loading whose direction is different from that of the fiber has not been investigated in detail. In this paper, in order to investigate the cyclic inelastic behavior and the fatigue failure of composite materials, cyclic tension-compression loading under several conditions are carried out using laminated graphite/epoxy tubular specimens. The definition of fatigue failure is also discussed based on the test results. It is found that the CFRP subjected to cyclic loading shows the characteristic cyclic inelastic deformation. Moreover, using the concept of the plastic strain energy density and the concerned definition of fatigue failure, the relationship between the number of fatigue failure and the plastic strain energy density can be expressed by a formula.