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依据纤维丝束带复合材料的相关几何结构参数值和所确定的纤维丝束带特征体积单元(RVE)模型几何结构尺寸,以有限元软件MSC.Patran/Nastran为平台建立纤维丝束带复合材料RVE有限元模型并在模型中置入相应的制备缺陷。各类制备缺陷的置入均采用删除网格单元的方法,置入裂纹型制备缺陷时偏移裂纹两侧单元相对面以获得当前裂纹宽度,置入孔洞型制备缺陷时尽量模拟其真实形貌。根据复合材料力学关于材料各性能参数的定义和细观力学基本理论推导了有限元计算细观力学(FECM)方法预测复合材料有效弹性性能和有效热膨胀性能的过程。根据FECM方法预测了不含制备缺陷、含单一制备缺陷和含各类制备缺陷时的弹性常数和有效热膨胀系数。结果表明:各类制备缺陷的存在均会使弹性模量和剪切模量减小,泊松比和热膨胀系数可能增大也可能减小。通过与实验测试结果对比分析可知,数值预测结果普遍比实验测试结果偏大,但总体效果较为理想,最大相对误差为6.04%。
According to the geometrical parameters of fiber ribbon composite material and the determined geometrical structure dimension of the fiber volumetric ribbon (RVE) model, a fiber-ribbon composite material was set up based on finite element software MSC.Patran / Nastran RVE finite element model and put into the corresponding preparation defects in the model. All kinds of preparation defects were placed using grid cell removal method, into crack-type preparation defects on both sides of offset cracks on both sides of the unit to obtain the current crack width, into the hole preparation defects to simulate the true shape . According to the definition of material performance parameters and the basic theory of meso mechanics, the process of finite element analysis mesomechanics (FECM) is used to predict the effective elastic properties and effective thermal expansion properties of composites. According to the FECM method, the elastic constants and effective coefficients of thermal expansion without preparation defects, with single preparation defects and with various preparation defects were predicted. The results show that the existence of all kinds of preparation defects will reduce the elastic modulus and shear modulus, Poisson’s ratio and thermal expansion coefficient may increase or decrease. Compared with the experimental test results, we can see that the numerical prediction results are generally larger than the experimental test results, but the overall effect is ideal, the maximum relative error is 6.04%.