I checked it , it happened the way you said it would. I also tried to tie the particles using some form of spring joints from the engine with a little work around, and it had the same effect ( tendency to move in one direction). I'm beginning to believe that it could be due to the fact that the springs are made uneven ( n particles tied to m particles and no spring between the n or the m particles for stability).

I checked it , it happened the way you said it would.

Ok, so far so good.

I also tried to tie the particles using some form of spring joints from the engine with a little work around, and it had the same effect ( tendency to move in one direction).
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What is this engine, you are using? What little workaround? It seems the problem is somewhere inside this "black box".

I'm beginning to believe that it could be due to the fact that the springs are made uneven ( n particles tied to m particles and no spring between the n or the m particles for stability).
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If all the physics is set up right, then this should not be a problem. It seems like you are violating Newton's laws of motion. Does all particles have the same mass? Is your engine based on force or impulse?

I would strongly recommend you to code all physics yourself and not rely on ready-made physics engines. If you don't know exactly how they work, debugging can be near-impossible as in this case. And again; I'd gladly share some code samples showing exactly how to make soft bodies without relying on external libs and engines.

Cheers,
Mike

I'm sorry for the late reply

What is this engine, you are using?

It's physX 2.8.1 ( because it still has soft bodies).

I would strongly recommend you to code all physics yourself and not rely on ready-made physics engines.

I would if I could understand it all, but sadly at this time it's too late for me to do that. however I would really appreciate it if you could offer some samples on soft bodies. Perhaps I will find my mistake by understanding it .
Thank-you for your helpful posts, it helped solve a couple of my problems.