Hi everyone,
Passionate about kitesurfing, I am currently studying, during an engineering internship, a safety system for the practice of this sport. Video here: https://www.youtube.com/watch?v=88sWcpgPH6E
More photos here: http://www.fksa.org/gallery3/var/resizes/Florida/Admin-File/album346/alb... and here:http://www.southwaleskitesurfing.co.uk/wp-content/uploads/2012/09/cabrin...
The contact is held by pressure and a small rubber band. I tried to model the problem very simply: http://hpics.li/fafde54
I don't know if you see how it works compared to the photos. In fact the problem is not so easy to model because on top of that, we draw the black part (on my model). This implies pressure on the green part exerted by the blue part. So in addition to friction, there is also pressure that is exerted. How do you get that pressure? I don't know... I just know that it pulls on the black part in the vertical direction with an intensity of 200N... How can I model it in Solidworks? I was thinking of using Solidworks Motion? (I already have all the parts modeled in .step format, I just have to do the assembly)
So I would like to know the force needed to push the green part about 2 cm so that the metal part comes out taking into account all these details!
thank you very much for your help,
Hoping you understand my problem!
I start again my answer which has just disappeared instead of being published.
Once you have exceeded your 200N release force, the red ring is free and "rubs" a little.
Your elastic doesn't correspond to a torsion spring to lock the paddle in the red ring? otherwise I don't see where he is
Thank you for your answer! In fact, the 200N applied does not mean that the system will be triggered on the contrary! I'm looking for the necessary force to push the red part in order to release the small metal part and therefore free the system as you can see on the video.
The 200 N are there to put ourselves in a slightly more real situation because when using this system we have a constant pull in this direction (the fact of being hooked to the harness). The only problem is that it pulls on the metal part that presses on the red part and therefore exerts pressure on it. Maybe it has no influence on the trigger force but I don't think so.
As for the elastic, here are some pictures. For the moment at the limit I think we can forget it (I will model it by a spring).
http://hpics.li/0d58553
http://hpics.li/e9a3095
http://hpics.li/ca7fa0f
For me your elastic is just to keep the palette attached to the red ring when you drop. And so conversely, the red ring does not move away from the palette.
So the release force comes from the elastic + friction of the paddle on the ring.
Your pallet tends to open due to the pull of the fixed lines towards its axis of rotation (a little off-center). Your red ring is opposed to the opening of the palette. the whole is balanced.
And otherwise to model your elastic, you fix 2 springs between the top of the red ring (where the elastics come out) and the hole or the elastic passes on the support of the pallet.
After if you have the system in your hands, you can always test the stiffness of your elastic, and compare it to the release force.
And what does the Afnor NFS 52-503 standard say about trigger forces?
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That's exactly it! Thank you very much! You wouldn't practice kitesurfing by chance because you use terms like dump and you know the ;) standard!
I'm going to test the elastic stiffness indeed. On the other hand, to model all this and know the trigger force I wanted to do it with Solidworks Motion. Spring easily modelable but for the frictional force of the paddle how can I do it?
I did a small study by hand (see attachment) to know the force both due to pressure and to friction, what do you think? So I must surely be able to enter on Solidworks Motion this force (on the other hand it is angle dependent)...
nsupport.pdf
Hello
I think we can add friction (but I'll have to check).
On the other hand, to know the coefficient of friction when there is water and sand... Finally you can always model it with the red palette/ring coef.
Otherwise you start for a constant tension in the lines, this gives you a constant value on the pallet. Then you change this value for each case study. (e.g. study for 100kg, 200kg...)
Yes, I just wanted to put the red paddle/ring friction coeff for the moment. On the other hand, I don't understand. My load would be fixed at 250 kg, that's why on the diagram I put 2500 N. The frame (lines) will be fixed. But I don't know how to model my force that I calculated by hand with Solidworks, especially since it varies depending on the angle. So the more I push the red ring, the more the palette goes down (the angle varies) until the palette comes out completely... You know what I mean?
EDIT: Finally the more I advance, the more I say to myself do I really need to model it with Solidworks?? A manual solution may be possible, right? See the attachment for the modeling of the problem. I was thinking of using the PFS and for the springs, it gives me an unknown L. On the other hand, since I have access to the system I can directly measure L as soon as the pallet comes out of the red part, right? What do you think? I don't think I'll take into account the effect of the pivot link in A because after all my pin part is blocked and doesn't rotate (only problem if I do this is that I can isolate only the handle part... whereas if I take into account the pivot, I can isolate the pin piece and then the handle piece and there it works!
EDIT1: I just did a test by isolating the pin and then the handle! It seems to be working! Just the appearance of this L...
modelization2.jpg
