一种预测颗粒增强复合材料界面力学性能的新方法

界面在颗粒增强复合材料中起到传递载荷的关键作用, 界面性能对复合材料整体力学行为产生重要影响. 然而由于复合材料内部结构较为复杂, 颗粒与基体间的界面强度和界面断裂韧性难以确定, 尤其是法向与切向界面强度的分别预测缺乏有效方法. 本文以氧化锆颗粒增强聚二甲基硅氧烷(PDMS)复合材料为研究对象, 提出一种预测颗粒增强复合材料界面力学性能的新方法. 首先, 实验获得纯PDMS基体材料及单颗粒填充PDMS试样的单轴拉伸应力$\!-\!$应变曲线, 标定出PDMS基体材料的单轴拉伸超弹性本构关系; 其次, 建立与单颗粒填充试样一致的有限元模型, 选择特定的黏结区模型描述界面力学行为, 通过样品不同阶段拉伸力学响应的实验与数值结果对比, 分别给出颗粒与基体界面的法向强度、切向强度及界面断裂韧性; 进一步应用标定的界面力学参数, 开展不同尺寸及不同数目颗粒填充试样的实验与数值结果比较, 验证界面性能预测结果的合理性. 本文提出的界面力学性能预测方法简便、易操作、精度高, 对定量预测颗粒增强复合材料的力学性能具有一定帮助, 亦对定量预测纤维增强复合材料的界面性能具有一定参考意义. 

A NEW METHOD FOR PREDICTING THE INTERFACIAL MECHANICAL PROPERTY IN PARTICLE-REINFORCED COMPOSITES

Interfaces play a key role in the load transfer of particle reinforced composites, and the interface properties have an important impact on the overall mechanical behavior of composites. However, due to the complex internal structure of composites, it is difficult to determine the interfacial strength and fracture toughness, especially for the respective prediction of normal and tangential interfacial strength. In this paper, a new method is proposed to predict the interfacial mechanical properties of particle-reinforced composites based on zirconia particle (ZrO) reinforced polydimethylsiloxane (PDMS) composite materials. Firstly, the uniaxial tensile stress-strain curves of pure PDMS matrix material and single particle filled PDMS sample are obtained, and the uniaxial tensile constitutive relationship of the PDMS matrix material is achieved. Secondly, the finite element model (FEM) consistent with single particle filled sample is established, and a specific cohesive zone model is chosen to describe the mechanical behavior of interface. Comparison of the experimental and numerical results of tensile mechanical response of samples at different stages can yield the normal strength, tangential strength and fracture toughness of the interface, respectively. The achieved interfacial mechanical parameters are further adopted in FEM calculations of samples filled with different sizes and numbers of particles. The rationality of the proposed method of predicting interfacial properties is verified by comparing the corresponding experimental and numerical results. Such a method is simple, easy to operate and has high accuracy, which should be helpful to quantitatively predict the mechanical property of particle reinforced composites, and also has certain reference significance to quantitatively predict the interfacial properties of fiber reinforced composites.