Destructive Testing: Webbing Termination Methods
Today I ran through a quick test involving different webbing termination methods and I figured I would share the results. I explored five termination options: a webbing locker*, a carabiner line locker**, a bartack-sewn loop, an abnormal-stitch pattern and an overhand knot. The sewn loops were created with 4mm x 0.5mm bar tacks using size 92 nylon thread (about 15 lbf MBS).
The webbing I used was some generic, 1Â flat nylon webbing which did not turn out to be nearly as strong as I expected.
Anyway, the photos!
The samples, from left to rightÂabnormal stitching pattern, sewn loop and webbing lockers:
Carabiner line-locker testing:
In short, it seems as if this webbing is not overly influenced by termination methods, aside from knots. I suspect the main reason why different termination options are not influencing the webbing more than a few percent is because the webbing has a very high elongation relative to the webbing used in climbing and slacklining (nylon, polyester, polyethylene, Vectran, ect).
I was especially surprised to see that the abnormal stitching pattern did not influence the strength compared to the standard bar tack stitching pattern. I choose the pattern I used in the Âabnormal stitching patternÂ test because it distributes the load very inefficiently amongst the fivers, which would normally result in premature failure. However, the webbing elongation was so high that it did not matter either way. The following photo clearly illustrates how the abnormal stitch pattern causes circular uneven loading of the webbingÂs fibers:
Last, I do not believe the results of this test can speak beyond the scope of the exact webbing I tested, and therefore I am going to repeat the test later with 1Â climbspec. As I know someone is going to ask, I did not start with 1" climbspec is because it fails at around 4,500 lbf in a webbing locker and I do not have any extra webbing lockers to spare for destructive testing, so I choose to use a webbing with a low failure strength.
What was your stitch count? That is did you use the same number of stitches in each type of bar tack?