Cascade unlooping of a low-pitch helical spring under tension

E. L. Starostin; G. H. M. van der Heijden

doi:10.1016/j.jmps.2009.02.004

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arXiv · 0812.1805

Cascade unlooping of a low-pitch helical spring under tension

E. L. Starostin·G. H. M. van der Heijden

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Abstract

We study the force vs extension behaviour of a helical spring made of a thin torsionally-stiff anisotropic elastic rod. Our focus is on springs of very low helical pitch. For certain parameters of the problem such a spring is found not to unwind when pulled but rather to form hockles that pop-out one by one and lead to a highly non-monotonic force-extension curve. Between abrupt loop pop-outs this curve is well described by the planar elastica whose relevant solutions are classified. Our results may be relevant for tightly coiled nanosprings in future micro- and nano(electro)mechanical devices.

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E. L. Starostin, G. H. M. van der Heijden. 2008-12-09. Cascade unlooping of a low-pitch helical spring under tension. https://doi.org/10.1016/j.jmps.2009.02.004

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