Abstract The variation in the apparent strength of a lamina in a laminate depending on the stacking sequence and thicknesses of the laminas of the laminate has been a matter of interest since the initiation of the extension of the applicability of composites. This fact led to the concept of in-situ strength, the problem itself being covered as a scale effect. In this paper this question is revisited moving towards the level where the damage appears, that is the micromechanical level. As the origin of the effect under consideration, the variation of thickness, takes place at a different level (mesomechanical), a multi-scale model is developed. It is possible in this model to vary the thickness of the lamina under consideration and to observe its effect on the damage. In this paper, only the first stage of damage, which appears in form of debondings between fibres and matrix, is taken into consideration. The analysis carried out shows that there is no scale effect at this first stage of the damage, which is corroborated by experimental evidences.

中文翻译：

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复合材料损伤第一阶段尺度效应影响的微观力学研究

摘要 自从复合材料的适用性扩展开始以来，层压板中层压板的表观强度的变化取决于层压板的层压顺序和厚度，这一直是一个令人感兴趣的问题。这一事实导致了原位强度的概念，该问题本身被视为规模效应。在本文中，这个问题被重新讨论到损伤出现的层次，即微观机械层次。作为所考虑的效应的起源，厚度的变化发生在不同的水平（细观力学），因此开发了一个多尺度模型。在这个模型中可以改变所考虑的薄板的厚度并观察其对损坏的影响。在本文中，只有第一阶段的损害，以纤维和基体之间的脱粘形式出现的这种情况被考虑在内。进行的分析表明，在损伤的第一阶段没有规模效应，这得到了实验证据的证实。