Models for unidirectional fiber-reinforced hybrid composites of a regular periodic structure that allow one to determine the yield loci for fibrous composites are constructed. The plane stress state in all components of compositions having different tensile and compressive strengths is considered. Components of the compositions are homogeneous and isotropic, and their mechanical behavior is described by the associated flow rule for rigidplastic bodies with piecewise linear yield states of Johansen, Hu, and Tresca–Hu types. Analytical expressions for the equations of yield loci convenient for a further analysis and application are obtained. It is proved that the plastic flow in the reinforced medium is associated with the yield loci constructed. It is shown that, in contrast to the structural model with a one-dimensional stress state in fibers (Nemirovsky and Mruz–Shamiev models), considering the complex stress state in the reinforcement in the case of different yield stresses of composite components, in the general case, leads to yield loci with more than six regimes of plastic flow.

中文翻译：

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考虑纤维二维应力状态的刚塑性非等抗材料加固板的屈服轨迹 I. 单向加固

构建了规则周期结构的单向纤维增强混合复合材料模型，可以确定纤维复合材料的屈服轨迹。考虑了具有不同拉伸和压缩强度的组合物的所有组分的平面应力状态。组合物的组分是均质和各向同性的，它们的机械行为由具有 Johansen、Hu 和 Tresca-Hu 型分段线性屈服状态的刚塑性体的相关流动规则描述。得到了便于进一步分析和应用的屈服轨迹方程的解析表达式。证明了增强介质中的塑性流动与构造的屈服轨迹有关。结果表明，