Mechanical design of mussel byssus: material yield enhances attachment strength
Mechanical design of mussel byssus: material yield enhances attachment strength
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发表时间：
1996-04
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通讯作者：
E. C. Bell;J. Gosline
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作者：
E. C. Bell;J. Gosline
贻贝在波浪冲刷的岩石潮间带的竞争优势，部分是由于他们的能力，以保持一个安全的附件。贻贝通过足分泌的大量细胞外胶原丝组成的足丝束缚在基底上。每根深渊线有三个连续排列的部分：一个波纹状的近端区域，一个光滑的远端区域和一个粘性斑块。本研究探讨了三种贻贝（Mytilus californianus、M. trossulus和M. galloprovincialis。拉伸试验通常显示不同种属之间的材料特性相似：近端区域的初始模量较低，极限应力较低，极限应变高于远端区域。远侧区域在远低于其极限值的应力下也屈服。在全螺纹测试中，近端区域和粘合剂斑块是结构失效的常见部位，并且在强度上紧密匹配，而远端区域似乎过于坚固。我们认为远端区域的高强度是设计用于在结构失效发生之前屈服和延伸的材料的副产品。实验和理论证据表明，线程的屈服和延伸性提供了两个重要的机制，用于增加贻贝的整体附着强度：（1）重新取向的线程对施加的负载的方向，和（2）的“招聘”更多的线程进入张力和随之而来的分布在一个更大的横截面积上的施加的负载，从而减少对每个线程的应力。这种远区屈服行为对M.这可能是它在极端波浪环境中成功的关键。
The competitive dominance of mussels in the wave-swept rocky intertidal zone is in part due to their ability to maintain a secure attachment. Mussels are tethered to the substratum by a byssus composed of numerous extracellular, collagenous threads secreted by the foot. Each byssal thread has three serially arranged parts: a corrugated proximal region, a smooth distal region and an adhesive plaque. This study examines the material and structural properties of the byssal threads of three mussel species: Mytilus californianus, M. trossulus, and M. galloprovincialis. Tensile tests in general reveal similar material properties among species: the proximal region has a lower initial modulus, a lower ultimate stress and a higher ultimate strain than the distal region. The distal region also yields at a stress well below its ultimate value. In whole thread tests, the proximal region and adhesive plaque are common sites of structural failure and are closely matched in strength, while the distal region appears to be excessively strong. We propose that the high strength of the distal region is the byproduct of a material designed to yield and extend before structural failure occurs. Experimental and theoretical evidence is presented suggesting that thread yield and extensibility provide two important mechanisms for increasing the overall attachment strength of the mussel: (1) the reorientation of threads towards the direction of applied load, and (2) the 'recruitment' of more threads into tension and the consequent distribution of applied load over a larger cross-sectional area, thereby reducing the stress on each thread. This distal region yield behavior is most striking for M. californianus and may be a key to its success in extreme wave-swept environments.