基于VCCT复合材料柔性梁疲劳寿命研究

Fatigue Life Research of Composite Flexbeam Based on VCCT

建立了直升机复合材料柔性梁的二维有限元模型,计算了在离心力和挥舞弯矩载荷作用下柔性梁的应力-应变场;应变计算值与试验值基本一致,说明该模型是合理的。针对柔性梁内部断层引起的分层,引入了虚拟裂纹闭合技术;考虑分层尖端前后单元长度不等和大转动的影响,修正了应变能释放率的计算公式。结合有限元模型和虚拟裂纹闭合技术,计算了分层扩展时的应变能释放率。利用应变能释放率的最大值预测了柔性梁的分层疲劳寿命,预测结果与试验值相一致。

The paper built a 2D finite element model of helicopter composite flexbeam, and calculated the flexbeam strain--stress field under combination load of centrifugal force and flapping moment. The calculated strains are identical with experimental values, which proves the finite element model is right. At the same time, for the delamination of flexbeam because of inner ply--drop, the paper introduced VCCT; for the effect of varied element length in the delamination tip and large rotation,the strain energy release rate calculation formulae were modified. Based on VCCT, the strain energy release rate was calculated during the simulation of the delamination. The maximum of the strain energy release rate was used to calculate fatigue life of flexbeam,and a good agreement is found between the predictions and the experimental values.