This work undertakes the analysis of continuous media that carry simultaneously two different material or geometric structures in the same material substrate. Even when these two structures are individually perfectly uniform and homogeneous, their combination may result in a non-uniform assembly. Thus, in contradistinction to the classical interpretation of material defectivity as a manifestation of material inhomogeneity, the lack of uniformity of a composite is physically interpreted as the presence of a different kind of continuously distributed material defects. Various quantitative measures of misalignment and lack of uniformity are proposed associated with solid constituents of different symmetry types. Finally, from a more formal point of view, the use of double groupoids and their associated double Lie algebroids is suggested as the natural setting for further developments of the theory.

这项工作对在同一材料基材中同时携带两种不同材料或几何结构的连续介质进行分析。即使当这两种结构单独完全一致和同质时，它们的组合也可能导致不均匀的组装。因此，与将材料缺陷作为材料不均匀性表现的经典解释相反，复合材料的不均匀性在物理上被解释为存在不同类型的连续分布的材料缺陷。提出了与不同对称类型的固体成分相关的各种未对准和缺乏均匀性的定量测量。最后，从更正式的角度来看，