玻纤增强注塑件的均匀化弹性力学参数研究

基于均匀化方法,根据长玻纤增强聚丙烯(LGFR-PP)的微观特征,建立了非连续长玻纤增强复合材料的代表性体积单元(RVE),通过有限元方法模拟预测了复合材料的宏观等效弹性力学参数,与注塑样条拉伸性能测试结果进行了比较。研究表明,通过在玻纤两侧增加聚丙烯(PP)分布,所采用的RVE较传统连续纤维的有限元模型更为合理;当玻纤成单一取向时,玻纤增强聚丙烯为一种横观各向同性材料;改变玻纤取向与拉伸方向之间的角度,拉伸方向的等效模量先微幅减小,再迅速降低,而后趋于稳定。利用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。

Elastic properties of glass fiber reinforced injection moldings based on homogenization method

Based on homogenization method, a representative volume element (RVE) of discontinuous long glass fiber reinforced composites was constructed according to the microstructure of the composites. The equivalent elastic mechanical properties of the composites were obtained based on a numerical simulation on the RVE, and were then compared with the experimental data of the tensile properties of injected spline. Numerical results show that it is more reasonable based on the new finite element model built by adding polypropylene(PP) at both ends of glass fiber than on the traditional one which applied on continuous fiber reinforced composites. Glass fiber reinforced polypropylene is transversely isotropic when glass fibers are unidirectional. In addition, the equivalent elastic modulus in the tensile direction first decreases slightly, then drops rapidly, and then turns stable with the increase of the angle between fiber orientation and tensile direction. In conclusion, homogenization theory is very useful for the prediction of the equivalent elastic mechanical properties of discontinuous glass fiber reinforced moldings in engineering, and is significant to provide the scientific evidence for the analysis of structure service performance of the moldings.