低应变下PP/nano-TiO_2复合材料拉伸力学行为的有限元模拟

Numerial Simulation of Tensile Behaviors in the Elastic Region for PP/Nano-TiO_2 Composites

通过双螺杆挤出机制备了聚丙烯/二氧化钛纳米复合材料,在材料连续介质力学模型假设基础上,建立了复合材料的有限元模型,求解发现:低应变下,二维平面模型较三维体积元模型能够更好地拟合实际材料的应力应变曲线;当无机纳米粒子较少时,单个粒子的微区应力场受其它粒子影响不大,微区应力场重叠或交叉现象不明显;而在不同载荷作用下,无机粒子与聚丙烯相互作用区域应力首先达到最大,当达到某一临界值时,界面层脱粘。

Polypropylene（PP）/nano-TiO2 composites were prepared by the melt intercalation molding.Based on the assumption of continuum mechanics model for materials,a finite element analysis model for the composites was constructed using ANSYS 11.0 finite element analysis software.In the stage of deformation（pre-yield regime） the response mechanism of the stress and the strain for composites was investigated,and we also simulated the von mises stress field of the PP/nano-TiO2 composites.It is found that the simulation results are consistent with the testing results at low volume strain level.Comparing with the 3D model,the results simulated using the 2D model is more accurate with the experimental results.If the volume fraction of particles is less,other particles have little influence on the local stress field of a certain particle,no obvious overlap or cross of the stress field could be found between two neighboring particles.While applying different loads,the stress jumps to maximum stress value in the interaction region of the two phases firstly,and then it occurrs that the particles debond with the matrix.