Foocie translation from: http://#110906
1. Introduce
John Sherman broke one of the two straps tied together during a rock climbing, but fortunately there was no accident. So what is the strength of the two straps tied together? BD engineers tied the two straps together to test their strength.
There are three common connection methods for ribbons, as shown in the figure below. It should be noted that the first and second connection methods are essentially the same, but because of the different ways of tying knots, there are different manifestations after stress.
Girth Hitch
Stop Bend
Climbers Hitch
Three different ribbons (11/16" nylon (think cam sling material), 12 mm Black Diamond Dynex, and New 10 mm Black Diamond Dynex) were tested separately.
Part of the flat ribbon for testing
The test consists of three parts: static tension, dynamic tension, and Cyclic
2. test
A) static tension
According to the standard of the new flat belt (22KN as the benchmark, that is, 22KN means 100%)
Girth Hitch Strop Bend Climbers Hitch Comments
11/16 Nylon & 11/16 Nylon 70% 80% 88% Nylon failed
12mm Dynex & 12mm Dynex 70% 85% Not tested
12mm Dynex & 11/16" Nylon 55% 55% Not tested Nylon failed
10mm Dynex & 10mm Dynex 53% 58% 57% Dynex failed
10mm Dynex to 11/16" Nylon 54% 54% 54% Nylon failed
11/16"Nylon to 10mm Dynex 46% 54%(symmetry)54%(symmetry)Nylon failed
8mm Dynex & 8mm Dynex 57% 53% 56% Spectra failed
8mm Dynex to 11/16" Nylon 56% 57%(symmetry)53% Nylon failed
11/16" Nylonto 8mm Dynex 43% 57% 53%(symmetry)Nylon Failed
in conclusion:
The strength of the two ribbons is significantly reduced, in some cases even exceeding 50%; when Nylon and Dynex or Spectra materials are interconnected, all Nylon materials are broken; in general, narrower ribbons mutually Even the strength is lower; under normal circumstances, the strength of the ribbon interconnects of different materials is lower.
B) Impact test
All use Girth Hitch connection, 80kg weight, impact factor is 2. The impact was repeated until the web was broken. A new 11mm power cord was used for each sample. The cord was not changed during the test.
Number of Drops Ultimate Failure Load Comments
11/16 Nylon & 11/16 Nylon 14~14 kN Nylon broke
12mm Dynex & 12mm Dynex >10 ~14 kN Broke 2 ropes
12mm Dynex & 11/16 Nylon >10
>7 ~13 kN
~12 kN Broke 2 ropes
Broke 2 ropes
10mm Dynex & 10mm Dynex 5
4 ~11 kN
~11 kN 10 mm Dynex broke
10 mm Dynex broke
10mm Dynex & 11/16 Nylon 4
3 ~12 kN
~11 kN 10 mm Dynex broke
10 mm Dynex broke
8mm Dynex & 8mm Dynex 2
3 ~10 kN
~11 kN 8 mm Dynex broke
8 mm Dynex broke
8mm Dynex & 11/16 Nylon 2
5
3 ~9.5 kN
~11 kN
~11 kN Nylon broke
8 mm broke
8 mm broke
6mm Dyneema & 6mm Dyneema 2
2 ~9 kN
~9 kN 6 mm broke
6 mm broke
6mm Dyneema & 11/16 Nylon 3
2 ~11 kN
~9 kN 6 mm broke
6 mm broke
in conclusion:
Different types of webbings were connected, and in the dynamic impact, most of the narrow flat webs were broken; in one test, Girth Hitch slipped into Stop Bend and suffered more impact than Girth Hitch; specific Stop Bend Is it better to need more tests than Girth Hitch? There are only two tests done here;
Number of Drops Ultimate Failure Load Comments
10mm Dynex (STROPBEND) 6~13 kN Nylon broke
11/16 Dynex (STROPBEND) 6~12 kN Nylon broke
However, from the current test results, it can be seen that Stop Bend tolerates 50% to 75% more fall than Girth Hitch.
C) Cyclic test
Did not understand what this test is doing. The result is that all have passed the test, but the test environment they can simulate is very low, and it is easy to exceed their test conditions in actual use.
3. in conclusion
First of all, only some tests are not official conclusions; secondly, when you connect two flat belts, do you really think that you really need such a long flat belt? If you must connect, connecting the two straps with the master lock will be much stronger; if you must connect two flat straps, use flat straps of the same material and width, and use a symmetrical knotting method between the flat straps. (Stop Bend or Climbers Hitch).
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