Hundreds of thousands of vibration cycles do not appreciably change an arrow's characteristics

The summary today

The only test dates from 2019, a preprint by a group of engineers who measured arrows by vibrating them with an actuator and deriving stiffness, damping and natural frequency. One arrow per material, carbon, aluminium and cedar, was put through about 600,000 cycles and then measured again. The authors conclude that nothing significant changes and that with a single arrow nothing more can be said. Their tables, however, point the same way throughout: after the cycles the estimated stiffness is higher in every measurement, and outside the range the set of arrows had before, by 52 per cent in the carbon arrow, from 486 to 737 newtons per metre, by 15 per cent in the aluminium one and by 14 and 29 per cent in the two measurements of the cedar arrow, and the natural frequency rises with it, in the carbon arrow from 34.5 to 45.5 hertz. In the aluminium arrow damping halves. On the other hand, the estimated mass of the carbon arrow drops from 10.3 to 9.0 grams, which an intact shaft should not do: part of those differences is noise in the method, and without a control arrow measured twice there is no telling how much. The comparison, moreover, sets the mean of the set before against the single fatigued arrow after. The evidence that exists goes against the claim, but it carries little weight. The five years of use quoted alongside the study is the authors' estimate, ten cycles per shot and thirty shots a day, not a measurement.

Also phrased as: "do arrows wear out"; "carbon arrow fatigue"; "old arrows and spine"; "how long an arrow lasts"; "arrows losing stiffness"

Evidence

• 2019
  Against Equipment tests Published later

  Dynamic identification with a stochastic perturbation actuator: before cycling, Table 3 gives the mean of each set of arrows with the range between maximum and minimum; after about 600,000 cycles, Table 4 gives the value of the single fatigued arrow, one per material. Carbon 500: stiffness from 486.2 newtons per metre (range ± 67.4) to 737.2, frequency from 34.5 to 45.5 hertz; aluminium 2219: stiffness from 1,484.7 (± 29.9) to 1,705.4, frequency from 40.8 to 43.8 hertz, damping ratio from 0.67 to 0.35; cedar 405, measured with the grain in two orientations: stiffness from 891.6 to 1,019.4 and from 967.7 to 1,251.0, frequency from 38.3 to 40.2 and from 37.4 to 41.4 hertz. In every measurement stiffness after cycling is higher, by 14 to 52 per cent, and outside the range the set had before; but the estimated mass also leaves its range, falling from 10.3 to 9.0 grams in the carbon arrow, and no control arrow was measured again without cycling.

  Dynamic Characterization of Arrows through Stochastic Perturbation · Ryan Fish, Youzhi Liang, Kyle Saleeby, Jonathan Spirnak, Mingxiu Sun, Xiang Zhang

• 2019
  Context Equipment tests Published later

  The authors write that the fatigued arrows show no significant change, that slight changes in damping and an increase in stiffness can be seen, and that with one arrow per material no conclusion can be drawn. They estimate that 600,000 cycles equal more than five years of use, counting ten cycles per shot and thirty shots a day: it is their own arithmetic, not a measurement.

  Dynamic Characterization of Arrows through Stochastic Perturbation · Ryan Fish, Youzhi Liang, Kyle Saleeby, Jonathan Spirnak, Mingxiu Sun, Xiang Zhang

Status history

1. 2019 Contradicted The only fatigue test arrives, a preprint on one arrow per material taken to about 600,000 vibration cycles. The authors write that nothing significant changes, but their figures say otherwise: estimated stiffness rises in every measurement, by 14 to 52 per cent, and in the aluminium arrow damping halves. One arrow per material, no statistical test and an estimated mass that changes as well, a sign of a noisy method: the evidence goes against the claim but there is little of it, so contradicted.

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