Effects of wear on static and dynamic failure loads of aluminium-based alloy climbing karabiners

In rock climbing, karabiners are used to arrest falls and consequently must be able to withstand dynamic loads. The current international standard for rating karabiner strength prescribes a quasi-static tensile test, which poorly simulates the dynamic nature of an actual climbing fall. In this study, a new method was developed to measure the dynamic failure loads of climbing karabiners. Both new and heavily worn karabiners were tested open and closed, and results from static and dynamic tests were compared. We found that the dynamic failure loads of closed karabiners were up to 50% lower than the failure loads in static tests, while for open karabiners, the static and dynamic values were similar. The reason for this behaviour is unclear; it is most likely due to the combined effects of different stress concentrations and loading regimes of the two tests. Irrespective of test type, karabiner strength decreased with wear level. Based on our results, we advise frequent inspection of permanently placed karabiners for signs of excessive wear. In addition, testing of climbing karabiners in a dynamic test in addition to the standard static test might be considered when developing new karabiner models.