玻纤增强微发泡注塑薄壁结构件的力学性能多尺度研究

发布时间：2018-05-06 14:10

本文选题：均匀化方法 + 代表性体积单元　；参考：《上海交通大学》2015年硕士论文

【摘要】：玻璃纤维增强树脂基复合材料凭借其强度高、质量轻、绝缘耐温性、耐蚀性好等优点,广泛应用于各行各业,尤其在汽车工业(零部件)中。但是,由于其复杂多变的内部结构,在表现出优异且复杂力学性能的同时,往往也给广大研究工作者带来巨大的挑战。然而,基于双尺度渐近展开均匀化方法的兴起,给复合材料力学性能的研究提供了新的思路,许多对单向连续纤维增强复合材料力学参数的研究结果表明,均匀化方法相较于其它方法往往能给出很好的预测。首先,本文以长玻纤增强注塑样条为研究对象,基于其断面的玻纤分布显微观察,建立了相应的RVE模型,通过均匀化方法的有限元求解,获得了长玻纤增强复合材料的弹性力学性能,并与样条拉伸模量对比分析,研究了运用均匀化方法预测非连续长玻纤增强PP弹性力学性能的可行性。同时,研究了玻纤增强结构件和发泡材料的构形规律,并参数化分析了各组分弹性模量、泊松比、玻纤取向等因素对其力学性能的影响。随后,本文以微发泡注塑薄壁门板切割样条为研究对象,基于其断面结构显微观察建立表皮层和发泡层的RVE模型,然后将均匀化方法与ABAQUS模拟仿真相结合,分别获得表皮层和发泡层的弹性力学参数,先后进行了玻纤增强PP发泡结构样条在实体单元和壳单元下的弯曲仿真线弹性分析,并与实验结果比较。对比结果表明,壳单元仿真结果具有较高的准确度。此外,本文在壳单元模型基础上,初步研究了玻纤增强PP微发泡注塑结构件的非线性性能,并与弯曲试验曲线对比,拟合出发泡层的简化两段刚度力学参数。研究表明:均匀化方法预测非连续长玻纤增强注塑件的等效弹性力学性能具有较高的工程可行性,能进一步为玻纤增强注塑件的结构服役性能分析提供科学依据;本文提出的RVE建模方法考虑了纤维两端PP的长度,较传统的连续纤维RVE模型更为合理;运用ABAQUS分析发泡层的弹性模量具有较高的可靠性;壳单元模型仿真较实体单元更为准确,且灵活度更高。
[Abstract]:Glass fiber reinforced resin matrix composites are widely used in various industries, especially in automobile industry, because of their advantages of high strength, light weight, good insulation and temperature resistance and good corrosion resistance. However, because of its complex and changeable internal structure, its excellent and complex mechanical properties often bring great challenges to the majority of researchers at the same time. However, based on the emergence of two-scale asymptotic expansion homogenization method, a new idea is provided for the study of mechanical properties of composites. Many studies on mechanical parameters of unidirectional continuous fiber reinforced composites show that, Compared with other methods, the homogenization method can give a good prediction. Firstly, the long glass fiber reinforced injection spline is taken as the research object. Based on the microscopic observation of the glass fiber distribution in the section, the corresponding RVE model is established and solved by the finite element method of homogenization. The elastic properties of long glass fiber reinforced composites were obtained and compared with the tensile modulus of spline. The feasibility of using homogenization method to predict the elastic properties of PP reinforced by long glass fiber was studied. At the same time, the configuration of glass fiber reinforced structural parts and foamed materials was studied, and the effects of elastic modulus, Poisson's ratio and glass fiber orientation on the mechanical properties were analyzed parameterized. Then, the RVE model of the surface layer and foaming layer is established based on the microscopic observation of micro-foaming injection molding thin-walled door plate, and then the homogenization method is combined with the simulation of ABAQUS. The elastic mechanical parameters of the epidermis and foamed layer were obtained, and the linear elastic analysis of fiberglass reinforced PP foamed structure spline under solid element and shell element was carried out successively, and the results were compared with the experimental results. The comparison results show that the simulation results of shell element have high accuracy. In addition, on the basis of shell element model, the nonlinear properties of glass fiber reinforced PP microfoamed injection molded parts are preliminarily studied, and compared with the bending test curves, the simplified two-stage stiffness mechanical parameters of foamed layer are fitted. The results show that the homogenization method has high engineering feasibility in predicting the equivalent elastic mechanical properties of discontinuous long glass fiber reinforced injection molded parts, and can provide scientific basis for the analysis of the structural service performance of glass fiber reinforced injection molded parts. The RVE modeling method proposed in this paper takes into account the length of PP at both ends of the fiber, which is more reasonable than the traditional continuous fiber RVE model, the elastic modulus of foamed layer is more reliable by using ABAQUS, and the simulation of shell element model is more accurate than that of solid element. And the flexibility is higher.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB332

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