TheBitterEnd
Well-known member
More of an idle musing than a serious issue I think (hope) but something I came across at work today got me thinking about fretting fatigue and karabiners. In my experience most cavers used steel maillons up until relatively recently when the trend has been towards alloy karabiners. It seems to me that we are using karabiners in a way that is fundamentally different to their ?normal? use in climbing, perhaps with the exception of their use on fixed ropes on big mountain expeditions. In climbing the krab takes one-off loadings on an occasional basis but in caving we subject them to repeated cyclical loading while in contact with a steel anchor. It seems likely therefore that there will be fretting/galling at the contact point and I guess most krabs will be used in the same orientation each time.
Now with fatigue limits of the order of millions of cycles at caving loads it would take some serious prusiking to get close the failure limit of aluminium alloys but I wonder if fretting fatigue or corrosion could reduce the fatigue limit? I?ve had a bit of search and can?t find any work on this.
A I said I think the FoS is such that a dramatic failure is extremely unlikely but just interested to know if this is something that anyone has investigated.
Now with fatigue limits of the order of millions of cycles at caving loads it would take some serious prusiking to get close the failure limit of aluminium alloys but I wonder if fretting fatigue or corrosion could reduce the fatigue limit? I?ve had a bit of search and can?t find any work on this.
A I said I think the FoS is such that a dramatic failure is extremely unlikely but just interested to know if this is something that anyone has investigated.