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 Page 1 of 2. Messages 1 to 20 | 21 to 36
Author
Busted Carabiner

shortman
6/09/2013
2:01:07 PM


This got posted on Slackchat today. Short line set-up long term. In my mind it shouldn't break.
james
6/09/2013
2:17:11 PM
Don't slack lines have the potential to generate huge forces? Why are you surprised? Its a snap gate & the gate popped open?
mikllaw
6/09/2013
2:20:42 PM
1) slacklines used to be, well, slack. What happened?
2) how wide was the tape in this?

shortman
6/09/2013
2:21:42 PM
Less than 15m line. Granted it had been set-up along time apparently, but really I would be surprised if it saw 1kn, maybe 2kn max. They way the crab snapped trips me out because a bar should bend if no irregular force is applied.
mike3091660
6/09/2013
2:28:18 PM
A slackline which sags .5m in a 15m line for an 80kg slackliner would exceed 5kn, get a bit of a bounce/jump and you would increase the forces beyond what a biner (gate open) would be rated for.
james
6/09/2013
2:30:16 PM
someone bouncing on a slack line is an irregular force, no?

mikl, you meant to ask about width of the webbing not length of the line span? ie if the biner was loaded in the *right* place by skinny or wide tape?
patto
6/09/2013
3:01:57 PM
On 6/09/2013 shortman wrote:
>Less than 15m line. Granted it had been set-up along time apparently, but
>really I would be surprised if it saw 1kn, maybe 2kn max. They way the
>crab snapped trips me out because a bar should bend if no irregular force
>is applied.
HA!

On 6/09/2013 mike3091660 wrote:
>A slackline which sags .5m in a 15m line for an 80kg slackliner would exceed
>5kn, get a bit of a bounce/jump and you would increase the forces beyond
>what a biner (gate open) would be rated for.

My calcs get to ~12kN for a standing 80kg person in the example you posed. Bouncing, you could happily double that.
mike3091660
6/09/2013
3:13:33 PM
Indeed Patto, i was lazy and just threw it in a online slackline calculator, but actually using a calculator and a little trig yields just under 12kn
kieranl
6/09/2013
3:25:45 PM
On 6/09/2013 shortman wrote:
>Less than 15m line. Granted it had been set-up along time apparently, but
>really I would be surprised if it saw 1kn, maybe 2kn max. They way the
>crab snapped trips me out because a bar should bend if no irregular force
>is applied.
It really needs a second shot with the two ends of the break joined but it looks to me like the krab has been bent out of shape a bit. Not quite as much as an old krab of mine that got broken on Richard Delaney's test rig but similar.

Macciza
6/09/2013
3:28:16 PM
Cyclic loading would be the main culprit methinks . . .
Dave_S
6/09/2013
3:50:07 PM
Nah, I really doubt it'd see anywhere near enough cycles for this to be a fatigue (cyclic loading) failure.

E. Wells
6/09/2013
4:23:01 PM
The guy has chalk on his hands and is standing on carpet under artificial light (cheat light) so this was in a gym? biner could have been over edge of wooden box etc?or a bounce creating side load, second bounce schnappsky?

E. Wells
6/09/2013
4:26:50 PM
...and why is a snappy with what? 22kn max doing on any slackline? A basic knowledge of anchors implies the forces on one of those is MEGA. (me no maffs)

shortman
6/09/2013
5:06:34 PM
On 6/09/2013 mike3091660 wrote:
>Indeed Patto, i was lazy and just threw it in a online slackline calculator,
>but actually using a calculator and a little trig yields just under 12kn

You 2 need to get your head outta books.

But, before ya do, figure this one out.

8% line stretch over 12.5 meters, 80kg person, with 15cm sag.

Then do say 20% stretch with 50cm sag, 12.5m, 80kg person.


Eduardo Slabofvic
6/09/2013
5:14:15 PM
On 6/09/2013 shortman wrote:
>>But, before ya do, figure this one out.
>
>8% line stretch over 12.5 meters, 80kg person, with 15cm sag.
>

= go to the shop and buy a decent steel shackle in the first place
gfdonc
6/09/2013
5:47:57 PM
Another possible failure mode is that the krab rotated due to bouncing/slack on the line.

The slackline then pulled it apart across the short axis. That would match the failure line indicated by the photos.

Can't be sure but ..
maelgwn
6/09/2013
6:29:58 PM
Looking at the picture looks like this biner is rated at 15 or 16kN with the gate closed, so if the figures the other guys are quoting are accurate, then not too surprising it broke.
davepalethorpe
6/09/2013
7:51:49 PM
Being that the nose hasn't been bent, I would guess the gate flicked open when it was loaded. If that's the case, not too surprising it broke.
climberman
6/09/2013
11:17:53 PM
On 6/09/2013 shortman wrote:
>On 6/09/2013 mike3091660 wrote:
>>Indeed Patto, i was lazy and just threw it in a online slackline calculator,
>>but actually using a calculator and a little trig yields just under 12kn
>
>You 2 need to get your head outta books.
>
>But, before ya do, figure this one out.
>
>8% line stretch over 12.5 meters, 80kg person, with 15cm sag.
>
>Then do say 20% stretch with 50cm sag, 12.5m, 80kg person.
>
>

have you being eating a lot more pies lately ?

IdratherbeclimbingM9
8/09/2013
9:44:18 PM
On 6/09/2013 shortman wrote:
>
>
>(snip) In my mind it shouldn't break.

... and you recently swapped a couple of them for some slack-line tape, where you told the dude that?
;-)

 Page 1 of 2. Messages 1 to 20 | 21 to 36
There are 36 messages in this topic.

 

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