How the Cucumber Tendril Coils and Overwinds
How the Cucumber Tendril Coils and Overwinds
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DOI：
10.1126/science.1223304
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发表时间：
2012-08-31
期刊：
影响因子：
56.9
通讯作者：
Mahadevan, L.
中科院分区：
文献类型：
--
作者：
Gerbode, Sharon J.;Puzey, Joshua R.;Mahadevan, L.
几个世纪以来，植物卷须的螺旋状卷曲一直吸引着科学家，但其背后的机制仍然难以捉摸。此外，尽管达尔文将卷曲的卷须解释为软弹簧被广泛接受，但它们的机械行为仍然未知。我们对黄瓜卷须的实验表明卷须卷曲是通过特化细胞内部纤维带的不对称收缩发生的。在张力下，提取的纤维带和老卷须表现出无捻过卷，而不是退绕，与最初的软响应，然后在大的扩展强大的应变硬化。我们解释这种行为使用物理模型的预应变橡胶条，几何参数，和数学模型的弹性长丝。总的来说，我们的研究阐明了卷须卷曲的起源，量化了达尔文的原始提议，并建议设计具有可调机械响应的仿生无扭弹簧。
The helical coiling of plant tendrils has fascinated scientists for centuries, yet the underlying mechanism remains elusive. Moreover, despite Darwin's widely accepted interpretation of coiled tendrils as soft springs, their mechanical behavior remains unknown. Our experiments on cucumber tendrils demonstrate that tendril coiling occurs via asymmetric contraction of an internal fiber ribbon of specialized cells. Under tension, both extracted fiber ribbons and old tendrils exhibit twistless overwinding rather than unwinding, with an initially soft response followed by strong strain-stiffening at large extensions. We explain this behavior using physical models of prestrained rubber strips, geometric arguments, and mathematical models of elastic filaments. Collectively, our study illuminates the origin of tendril coiling, quantifies Darwin's original proposal, and suggests designs for biomimetic twistless springs with tunable mechanical responses.