For natural composite materials such as biological tissues, mechanically characterizing the individual constituents and elucidating their roles in supporting structural integrity has remained experimentally challenging since the constituents can often not be isolated without impairment and require non-standard testing devices. Adopting an inverse viewpoint, we examine, in this article, macroscopic samples whose constituent architecture is accessible and investigate whether it is possible to conclude on the stress–strain behaviour of the individual constituents based on experimental measurements from standard material tests. Focussing on isotropic hyperelastic composites, a direct discretization of the constituents’ strain energy densities in terms of global shape functions is explored. In order to assess the local deterministic identifiability of material parameters near an initial estimate, we adopt a sensitivity-based criterion and determine feasible combinations of candidate experiments without recourse to experimental measurements. Both the local identifiability and attainable reidentification accuracy are investigated in detail for a composite truss and a composite sheet whose force–strain responses in uniaxial or biaxial tension tests, respectively, are mainly determined by the constituents’ volume fractions.

中文翻译：

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超弹性复合材料成分应力应变规律的局部可识别性

对于天然复合材料，如生物组织，对单个成分进行机械表征并阐明它们在支持结构完整性方面的作用在实验上仍然具有挑战性，因为这些成分通常无法在不受损的情况下分离，并且需要非标准测试设备。采用相反的观点，我们在本文中检查了其组成结构可访问的宏观样品，并研究是否有可能根据标准材料测试的实验测量得出单个组成部分的应力应变行为的结论。专注于各向同性超弹性复合材料，探索了根据全局形状函数对成分应变能密度的直接离散化。为了评估接近初始估计的材料参数的局部确定性可识别性，我们采用基于灵敏度的标准并确定候选实验的可行组合，而无需求助于实验测量。详细研究了复合桁架和复合板的局部可识别性和可达到的重新识别精度，其在单轴或双轴拉伸试验中的力应变响应分别主要由成分的体积分数决定。