n.fav wrote:I don't really understand what is "welding", I post what I think it is but I may be wrong.
Those two photos are good ones to use to talk about welding
The one on the left does use metal bars holding each other up in some odd way. The two pieces are just touching each other - they aren't connected or overlapping. This is a technique known as 'resting on', and is different from welding, because the pieces aren't 'stuck' together
The key aspect of welding is that the two pieces being 'welded' together actually have to cross over each other, or intersect. in the picture on the right, the rubber in the middle is being held up by the node at the bottom, and in turn it's endpoints are holding the end rubber bit in place.
Both of these techniques rely on the fact that endpoints of materials can't pass through other materials (in the same 'plane')