This work deals with the fiber ends debonding-induced elastic moduli degradation of a short fiber reinforced composite (SFRC). The strain fields of the matrix in a representative volume element (RVE) of the SFRC are determined from an imaginary fiber technique. By using the debonding boundary conditions, the debonded modulus of the composite is derived, which is affected by not only the far-field but also the transient solutions for the longitudinal strain of the matrix. Particularly, the imaginary fiber technique provides unbounded solution for a moderately large fiber aspect ratio. This is resolved by separating the RVE along the fiber direction into two domains. Combining the longitudinal strains in both domains, the longitudinal modulus is determined, and the longitudinal bridging tensor element in the micromechanics Bridging Model is amended. Five elastic moduli of an SFRC after the fiber end debonding are obtained on the amended Bridging Model. The effects of the fiber volume fraction, fiber aspect ratio, and fiber-to-matrix modulus ratio on the end-debonded longitudinal modulus, transverse modulus, and longitudinal Poisson’s ratio are investigated.

中文翻译：

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纤维端部界面脱粘的短纤维复合材料的弹性模量预测

这项工作涉及短纤维增强复合材料（SFRC）的纤维端部脱粘引起的弹性模量下降。SFRC 的代表性体积单元 (RVE) 中的矩阵应变场是通过假想纤维技术确定的。通过使用脱粘边界条件，推导出复合材料的脱粘模量，该模量不仅受到远场的影响，还受到基体纵向应变瞬态解的影响。特别是，假想纤维技术为适度大的纤维纵横比提供了无限的解决方案。这是通过将 RVE 沿光纤方向分成两个域来解决的。结合两个域中的纵向应变，确定纵向模量，并修正微力学桥接模型中的纵向桥接张量单元。在修正的桥接模型上获得了纤维端部脱粘后 SFRC 的五个弹性模量。研究了纤维体积分数、纤维长径比和纤维与基体模量比对端部脱粘纵向模量、横向模量和纵向泊松比的影响。