三维粘弹性复合材料层合板固化残余应力研究

Research on process-induced residual stress for composite laminates based on three-dimensional viscoelasticity

应用改进的有限元算法,综合考虑了碳纤维复合材料固化过程中树脂的化学收缩、应力松弛、材料的热收缩,建立了一个基于三维线性粘弹性的积分模型对复合材料层合板热压罐成型工艺过程中产生的残余应力进行了研究。结果表明：本文提出的方法能够完整地模拟树脂的固化过程并计算层合板的固化残余应力;对于文中的正交对称层合板而言,热收缩是影响残余应力大小的主要因素;固化完成后,0°铺层内的中面中心区域层间残余应力值接近于0,边缘区域会迅速增加,容易发生分层破坏;任意点处,轴向应力比其他两个方向的应力高出1~2个数量级;残余应力值沿厚度方向有较大变化;树脂的应力松弛行为会在一定程度上降低残余应力。

Process-induced residual stress for autoclaved composite laminates is investigated with modified finite element method based on three-dimensional viscoelasticity, taking chemical shrinkage, stress relaxation behavior and thermal expansion into account. The results show that the present method considers the whole curing process and can obtain the residual stress and strain of autoclaved composite laminates. To the orthogonal symmetric laminate mentioned in the paper, thermal shrinkage is the key factor that affects residual stress. After finishing the curing process, in central zone, the interlaminar normal stress in the middle surface of 0°layer is close to 0. But it will mushroom in marginal area, where it is prone to delamination damage. At any point, the axial stress is one or two orders higher than transverse stress and interlaminar stress. The stress changes along the thickness direction. Stress relaxation behavior can reduce residual stress to a certain extent.