纤维增强陶瓷基复合材料疲劳迟滞回线模型研究

INVESTIGATION ON FATIGUE HYSTERESIS LOOPS MODELS OF FIBRE-REINFORCED CERAMIC-MATRIX COMPOSITES

纤维增强陶瓷基复合材料初始加载到疲劳峰值应力时,基体出现裂纹,纤维/基体界面发生脱粘.在疲劳载荷作用下,纤维相对基体在界面脱粘区往复滑移使得陶瓷基复合材料出现疲劳迟滞现象.建立了纤维陶瓷基复合材料疲劳迟滞回线细观力学模型,采用断裂力学方法确定了初始加载纤维/基体界面脱粘长度、卸载界面反向滑移长度与重新加载新界面滑移长度,分析了4种不同界面滑移情况的疲劳迟滞回线.假设正交铺设与编织陶瓷基复合材料疲劳迟滞回线主要受0?铺层、轴向纱线内纤维/基体界面滑移的影响,预测了单向、正交铺设与编织陶瓷基复合材料在不同峰值应力与不同循环的疲劳迟滞回线,与试验结果吻合.

When the fibre-reinforced ceramic-matrix composites(CMCs) are first loading to the fatigue peak stress, the matrix cracking and fibre/matrix interface debonding occur. Under the fatigue loading, the stress-strain hysteresis loops appear due to the fibre sliding relative to matrix in the fiber/matrix interface debonded region. The micromechanical hysteresis loops models for the fibre-reinforced CMCs have been developed in present analysis. The fibre/matrix interface debonded length upon first loading, the unloading interface counter-slip length and the reloading interface new slip length were determined by the fracture mechanics approach. The hysteresis loops of four different interface slip cases have been analysed. By assuming that the mechanical hysteresis behavior of cross-ply and woven CMCs was mainly controlled by the fiber/matrix interface slip in the 0o ply or the longitudinal yarns, the hysteresis loops of unidirectional, cross-ply and woven CMCs corresponding to different peak stresses and different cycles have been predicted, respectively. The predicted results agreed with the experimental data.