On inception of cracking in composite materials with brittle matrix

The primary mechanism that leads to failure in composite materials with brittle matrix is the formation of macrocracks. In general, the specification of the conditions at the onset of cracking requires an elaborate analysis of the stress field throughout the domain. Such an analysis is not always feasible in view of the complexity of the problem. In this work, an attempt is made to formulate some macroscopic criteria that define the conditions at the inception of macrocracks. The approach involves generating a set of data from a homogenization analysis that is subsequently used for the identification of closed-form criteria derived based on critical plane approach and/or microstructure tensor approach. The methodology is illustrated using an example of reinforced concrete specimen subjected to different loading conditions. A numerical study is conducted to examine the efficiency of this approach. The primary focus is on assessment of the influence of volume fraction of the reinforcement and its orientation (relative to the loading direction) on the onset of macrocracking. It is noted that the proposed approach can be employed for other composite materials, such as fiber-reinforced composites with ceramic or brittle polymeric matrix.