微粒填充流变材料界面开裂的局部临界应力及尺寸效应的理论分析

研究了以等轴粒子填充流变材料的边界开裂机理，采用能量准则导出了以界面能表示的界面开裂局部临界应力的简洁表达式。由于临界应力正比于１√α，从而可以非常方便地研究粒子开裂的尺寸效应，以碳酸钙微粒填充的聚丙烯复合材料为例进行了理论分析，通过比较界面开裂的能量准则和张应力准则得出结论：即使按照保守的方法估算，即在界面强度等于基体强度的条件下，只要粒径不超过０．２微米，若能量准则得到满足，则张应力准则也会得

THEORETICAL ANALYSIS ON THE LOCAL CRITICAL STRESS AND SIZE EFFECT FOR INTERFACIAL DEBONDING IN PARTICLE REINFORCED RHEOLOGICAL MATERIALS

The mechanisms of interfacial debonding of particle reinforced rheological materials are studied. Based on an energy criterion, a simple formula of local critical stress for interfacial debonding is derived and expressed in terms of the interfacial energy. The particle size effect on interface debonding can then be analyzed easily due to the fact that critical stress is inversely proportional to the square root of particle radius. By taking PP/CaCO 3 system as an example, the present energy criterion is compared with mechanical debonding criterion, and it is found that under the condition that bonding strength equal to matrix strength and particle radius is not over 0.2 mm, the mechanical debonding criterion can be automatically satisfied if energy criterion is satisfied. From the above discussion, a relation between critical time and interface energy is calculated by using the energy criterion. The influences of particle volume fraction, the size distribution, loading rate and relaxation time of the matrix on critical time of interfacial debonding are also discussed.