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Shoelace Study Untangles a Knotty¹ Problem 鞋带易结也易解

You’re strolling down the street or maybe hauling that load of laundry down a flight of stairs when all of a sudden. [sound fx] Your laces come undone². If you’ve ever pondered what precipitates³ this pedestrian wardrobe malfunction⁴, you might want to tie your shoes and beat a path to the Proceedings⁵ of the Royal Society A.

你在街上散步,也或许是在搬一大堆的衣服,突然……!!你的鞋带松了!如果你从未想过这种行人衣柜出的故障，或许你会绑好鞋带，开辟一条路去《英国皇家学会学报》。

In that journal, researchers have trotted⁶ out data that show that a combination of whipping and stomping⁷ forces is what causes laces to unravel⁸ without warning.

在这本杂志上，研究人员已经分析了数据，这些数据显示，甩来甩去以及跺脚这些结合的因素会导致鞋带毫无警告的松动。

The investigators⁹ noted¹⁰ that shoelace knots frequently fail when people are walking. But not when they are, say, sitting on the edge of a table and swinging their legs. Laces also stay tight when marching in place with no forward motion.

调查人员注意到，当人们在行走的时候，鞋带结经常松动。但是当他们坐在桌子的边缘，左右摆动双腿的时候却不会呢!当没有向前运动的时候，鞋带是不会松动的。

That led the gumshoes to suspect that stepping and swinging somehow work together to foil footwear security. But how? To untangle this knotty problem, the researchers made a slo-mo video of a student running on a treadmill¹¹, thus recording¹² the literal steps that lead to catastrophic knot failure.

这导致行业们怀疑，踏步以及摇摆会阻止鞋子的安全性。但是是怎样的呢?为了解开这个棘手的问题，研究人员做了一个慢动作的视频，视频是关于学生在跑步机上跑步，因为这就记录了导致打结失败的一步步。

Here’s what they slowly saw: When the foot strikes the ground, the force of that impact causes the knot at the center of the lace to deform¹³ and stretch. And when the foot swings forward, the ends of the shoelace fly forward. That whipping motion pulls the knot open a bit more, which allows the free end of the lace to slip through a tiny bit. With each cycle of impact and whip, the free end slides a little more, until enough of it has come through that the knot finally unravels¹⁴.

这是他们所慢慢看到的：当脚着地的时候，这种冲击力会使得鞋带结中心的变形、拉伸。当脚步向前的时候，鞋带也会向前飞。这就甩动的动作会导致鞋带结被再打开一点，进而导致鞋自由的一端在滑耸动一点。伴随一次次的冲击以及甩动，自由的一端变得一点点松动，最终从打的结中滑落出来。

The researchers confirmed that some knots are stronger than others. The granny knot that most of us use on our shoes is fairly weak and prone¹⁵ to failure, perhaps because the knot winds up twisted when pulled tight. A square knot, on the other hand, held up well in the treadmill test. To get that knot to buckle¹⁶, the researchers had to attach weights to the free end to aid in the tugging¹⁷ of those whipping tips.

研究人员证实,有些结比较坚固。我们大多数人在鞋子上打的松8字结相当薄弱,容易滑落。也许是因为当我们拉紧的时候，这个结变形。而另一方面，方结，在跑步机上的测试则结果良好。为了得到这个结扣，研究人员必须在鞋带自由端增加一定的质量。

The researchers did not determine whether different types of laces are more likely to produce ties that bind¹⁸. So though this initial study has made great strides in our understanding of shoelace mechanics, we still have a long way to go before this research is all tied up.

研究人员不能决定是否不同类型的鞋带会造成这种捆绑的。尽管最初的研究，让我们在理解鞋带的机理上取得了巨大的进展，但是，在研究全部结束之前，我们还有很长的路要走。