In a previous study (Asp et al., 1995) the experimentally observed low strains to transverse tensile failure of unidirectional (UD) polymer matrix composites were explained as an effect of triaxial (composite- like) stress state in the epoxy matrix. Assuming cavitation as an underlying mechanism for brittle cracking under triaxial stress states, a dilatation energy density based criterion was put forth (Asp et al., 1996) and was shown to predict well the transverse failure of epoxy based UD composites (Asp et al., 1996). The assumption of cavitation in the epoxy matrix has hitherto not been supported by a mechanism study. The current study attempts to provide a systematic clarification of the cavitation mechanism by molecular dynamic simulation. By imposing uniaxial, equi-biaxial and equi-triaxial tension on a simulation cell of a crosslinked epoxy, the degrees of cavitation at various stages of the stress- strain response are revealed. The results show that triaxiality of the stress states is a governing factor in cavitation of epoxies.

在先前的研究（Asp等，1995）中，实验观察到的单向（UD）聚合物基复合材料横向拉伸破坏的低应变被解释为环氧基体中三轴（复合材料）应力状态的影响。假设空化是三轴应力状态下脆性开裂的潜在机理，提出了基于膨胀能量密度的判据（Asp等，1996），并被证明可以很好地预测环氧基UD复合材料的横向破坏（Asp等。 （1996年）。迄今为止，机理研究尚未支持在环氧基质中产生气穴的假设。当前的研究试图通过分子动力学模拟提供系统化的空化机理的解释。通过施加单轴，在交联环氧树脂的模拟单元上的等双轴和等三轴张力，揭示了应力应变响应各个阶段的空化程度。结果表明，应力状态的三轴性是影响环氧树脂空化的主要因素。