The role of meso-scale structure on the mechanical response of soft musculoskeletal tissues

肌肉和肌腱是具有明显结构相似性的特别庞大的肌肉骨骼组织：分层管状结构和细长结构沿优选方向沿着的主要单轴排列。这使它们在结构方面与体内其他组织区分开来。肌肉和肌腱组织对压缩载荷的响应与它们的拉伸行为相比得到了很少的关注，尽管这两种组织在体内都受到压缩状态。申请人最近的工作揭示了这些组织的压缩响应中的特定各向异性，并表明细胞外基质结构的分层组织在稳定纤维样组分中的重要作用。这些观察有助于提高这些组织的负荷转移的理解，并有影响建模和simulation.The当前项目的目的是全面了解的结构特征和机制，管理的肌肉骨骼组织的多轴负荷的特殊反应。为此，肌肉和肌腱组织的力学行为的细胞外基质形成的中尺度结构的作用进行了详细研究，重点是几个不对称的拉伸和压缩载荷的响应之间。将对不同长度尺度进行一系列全面的专用实验，以确定多轴载荷下的非线性组织和中尺度材料特性。将在不同载荷下制备组织学组织切片，并用于构建多尺度有限元模拟的计算机模型。将基于非线性光学显微镜进行原位实验，将细观结构的变化与组织尺度上施加的载荷联系起来。最后，实验结果以及从详细的有限元计算中获得的理解将被用来定义一类连续本构模型，适合于代表肌肉骨骼组织的非线性各向异性行为。

Muscle and tendon are particular bulky musculoskeletal tissues with a pronounced structural similarity: a hierarchical tubular architecture and a predominantly uniaxial alignment of elongated structures along a preferred direction. This distinguishes them in terms of structure from other tissues in the body. The response of muscle and tendon tissues to compressive loads has gained little attention compared to their tensile behaviour although both tissues are subjected to compressive states in-vivo. Recent work by the applicants revealed a particular anisotropy in the compressive response of these tissues and suggests an important role of the hierarchical organisation of extracellular matrix structures in stabilising the fibre-like components. These observations help improving the understanding of load transfer in these tissues and have implications for modelling and simulation.The aim of the current project is a comprehensive understanding of the structural features and mechanisms that govern the peculiar response of musculoskeletal tissues to multiaxial loads. To this end, the role of meso-scale structures formed by the extracellular matrix for the mechanical behaviour of muscle and tendon tissues is investigated in detail, with a focus on several asymmetries between the responses to tensile and compressive loads. A comprehensive set of dedicated experiments on different length-scales will be performed to determine non-linear tissue and meso-scale material properties under multiaxial loads. Histological tissue sections will be prepared under different loads and used to build computer models for multi-scale finite element simulations. In-situ experiments will be performed based on non-linear optical microscopy to connect the change of meso-structure with loads applied on tissue-scale. Finally, the experimental results together with the understanding gained from detailed finite element computations will be used to define a class of continuum constitutive models suitable to represent the non-linear anisotropic behaviour of musculoskeletal tissues.