变厚度复合材料U型零件固化变形仿真预测与结构影响因素

Prediction and analysis of cure-induced deformation of composite U-shaped parts with variable thickness

为了准确预测变厚度CCF800H/AC531碳纤维/环氧树脂复合材料U型零件的固化变形,并分析弯边以及变厚区参数对变形的影响。首先,利用自洽方法确定了单层复合材料力学性能,采用细观有限元方法预测了层合板的整体性能以避免仿真建模时复杂的铺层设置。而后结合固化硬化瞬时线弹性模型建立了零件的固化变形预测方法并进行了验证。变厚区对相邻区域的变形的影响规律由变厚区结构参数确定,与铺层方式和材料种类无关。运用Box-Behnken响应面方法,拟合了两个二次模型以分析弯边参数和变厚度结构参数对固化变形的影响规律。变厚区对较薄区域的影响较大,变形最大减小幅度达15%,而对较厚区域的影响可以忽略。采用方差分析比较了不同因素的影响,变厚区的宽度变化对变形的影响较小。当截面距变厚区的距离大于150 mm时,变厚区对较薄区域的影响接近为0。

The micromechanics and the finite element analysis method(FEA)were used to predict the cureinduced deformation(CID)of CCF800H/AC531 carbon fiber/epoxy composite U-shaped parts with variable thickness.The effects of flange and various thickness area parameters on CID were studied by response surface methodology(RSM).The material properties of unidirectional composite were determined by self-consistent method,and the equivalent properties of laminates were calculated by FEA based micromechanical model to avoid the complex layer division and direction definition of the numerical model.The CID of U-shaped parts was predicted by the curing hardening instantaneous linear elastic model(CHILE).A case part was manufactured to verify the accuracy of the FEA.It can be found that the lay-ups and material types have no influence on the law of variable thickness area’s effect on adjacent areas.Then two plans were designed by the Box-Behnken RSM method to analyze the influence of flange parameters and variable thickness area parameters,and two quadratic regression models were fitted,respectively.The investigation reveals that the variable thickness area greatly influences the thinner area,with a maximum reduction of CID of about 15%.The variable thickness area has little effect on the thicker area.Besides,the CID is unaffected by the width of the variable thickness area.The variable thickness area has no effect on the CID of a cross section if it is 150 mm or more away from the cross section.