:D sounds like quite a problem just in terms of vocabulary and my German is worse than my physics so I won’t suggest posting the German version.
The properties of the tissues is of course not simple and probably not even consistent between different people (maybe consistent enough). I’ve found a lot of information on the elastic/plastic properties of metals but none on penises I guess you could lead the field here.
Like you I start from the position that V-stretches work, the question is how. I think my understanding has improved during the course of this thread but I don’t think we are near a solution yet.
Here’s my best effort at understanding it so far, hopefully in straightforward English.
If we go back to the picture in mcnitro’s pdf it shows basically a U shaped penis with a fulcrum point pressing down in the middle to form the U. Nedd already detailed how a vector is used to calulate tension.
If you take the inner side of the curve of the penis at any point around the fulcrum and draw a tangent out from the fulcrum circle (straight line out from the curve, equal angle on both sides) you can get a direction for a vector and can calculate a tension. If you do the same on the outer edge in the same place on the fulcrum you’d get the same vector and the same tension.
What this is saying is that the tension on the inside of the penis is the same as on the outside. What we are not taking into account though is any tension inherent in the penis simply due to the fact that it is curved. We know from plumped bends that bendind the erect penis causes tension on the outside of the curve and less on the inside of the curve. Thats erect though, with a flaccid penis the inside of the curve will be a lot closer to the outside of the curve but there will still be a tension gradient in any penis cross section around the fulcrum, a larger tension on the outside of the curve.
This is just a complicated way of saying the outside of the curve has to travel a longer length than the inside of the curve and so the outside has to stretch more. So if we are feeling greater tension at the fulcrum it might be because the tension is focused on the outer side of the curve and the tension is less on the inner side of the curve.
The difference in length travelled probably doesn’t have to be that great to have an effect and it won’t be the great.
This seems to make sense but in practise if I do an inverted V-stretch I feel a definate increase in tension on the underside of the penis beyond the fulcrum point. That could be due to the way the penis is deformed over the fulcrum simply being like chenging the direction of the stretch and/or departure points from the fulcrum for the top and the bottom of the penis. I’m a bit fuzzy here.
Beyond the focusing of tension to a particular side of the penis there is also the matter of mechanical advantage. Again When I was doing inverted V-stretches over cans I found that I could find a good position to stretch straight armed leveraging my entire shoulder into the stretch.
I doubt this is anywhere near the whole story.
Thunder's Place: increasing penis size one dick at a time.