Swift and inverse Swift effect in alumina fiber reinforced aluminum wires Original Research Article

The change in length during torsion is examined (i.e. the Swift effect) of an aluminum wire reinforced with 45% continuous Nextel®610 alumina fibers at ambient temperature, and also its rotation under applied tensile stress after pre-twisting (i.e. the inverse Swift effect). The wire is shown to shorten when twisted away from its initial configuration in which all fibers are parallel. The shortening is proportional to the square of the twisting angle over a large range of angles. Reversal of the shear from a given pre-twist elongates the wire again, up to its initial length when zero cumulated twist is reached. In the inverse Swift experiment the wire increasingly untwists as the external load is increased. Analytical models for both Swift and inverse Swift behavior of the wire are presented, and are shown to be in good agreement with the experiments.