Off-Axis Ratcheting Behavior of Unidirectional Carbon/Epoxy Laminate under Asymmetric Cyclic Loading at High Temperature
TSUKUBA UNIV IBARAKI (JAPAN)
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Development of an engineering model for predicting the off-axis ratcheting behavior of a unidirectional CFRP laminate has been attempted. For this purpose, the ratcheting behavior of a unidirectional carbonepoxy laminate under off-axis cyclic loading at high temperature is studied with emphasis on its dependence on load waveform i.e. stress ratio and fiber orientation. First, off-axis ratcheting tests with different levels of maximum and non-zero mean stresses are performed on coupon specimens with different fiber orientations, respectively. The experimental results show that the accumulation of ratcheting strain occurs in the unidirectional CFRP laminate, regardless of fiber orientation, and the off-axis ratcheting behavior is similar to the off-axis transient creep behavior in all aspects of its stress, time and fiber orientation dependence. It is shown that the proposed model allows adequately predicting the off-axis ratcheting behavior of the unidirectional CFRP laminate for different stress ratios as well as for different fiber orientations.
- Laminates and Composite Materials