If a fiber is stretched, abraded on one side, and then gradually relaxed, it will deform into a helix. If the two ends are restrained from rotating during the relaxation, it will form two helical segments of opposite chirality separated by a perversion. Here we investigate the properties of the perversion using a finite-element solution, and show that an excellent approximation to both the shape and the associated strain energy can be obtained using a simple Rayleigh-Ritz approximation. The perversion deviates from the adjacent helices only in a relatively small region, which suggests the possibility of approximating more complex geometries by treating perversions as point defects.

Energetically, perversions are predicted only when they are ‘geometrically necessary’ because of the end restraint against rotation, but this energy differential is small when the fiber is almost straight and additional perversions can be generated by small perturbations. Some of these may approach and annihilate each other in pairs as the fiber is relaxed, but in other cases the additional perversions persist during unloading, despite the increased energy differential.

如果纤维被拉伸，在一侧磨损，然后逐渐松弛，它将变形为螺旋状。如果在松弛过程中限制了两端的旋转，它将形成两个手性相反的螺旋段，并被一个变态隔开。在这里，我们使用有限元解决方案研究了变形的性质，并表明可以使用简单的Rayleigh-Ritz近似获得形状和相关应变能的极佳近似。变形仅在相对较小的区域内偏离相邻的螺旋，这表明通过将变形作为点缺陷来近似更复杂的几何形状的可能性。

从能量上讲，仅由于对旋转的端部限制，仅在“几何上必要”时才预测变形，但是当光纤几乎笔直时，这种能量差异很小，并且通过较小的扰动可以产生其他变形。其中一些可能会在光纤松弛时成对接近并相互消灭，但在其他情况下，尽管能量差异增加，但在卸载过程中还会继续存在其他变形。