When a bolt is pulled in tension and eventually fractures, is all the built up strain energy dissipated in the formation of the new surfaces? Does any energy do into accelerating the broken halves of the bolt? Imagine that two plates are bolted together. As the two plates are forced apart, the bolt deforms and eventually yields/fractures. When the fracture occurs, the bolt will be shot out from the joint. I believe that it is the release of the elastic potential energy built up in the plates that is causing the bolt halves to accelerate, and that the energy dissipated in the fracture has no influence on the bolt accelerating. Is this correct? Thinking about it another way: imagine the two plates in the above scenario are infinitely stiff. When they are forces apart so that the bolt fractures, will the bolt move at all? Or will the bolt just break and remain mostly still? (I guess this is assuming the rest of the bolt is infinitely stiff as well; if not there could be built up energy in the deformation of the bolt head that could accelerate the bolt once it breaks) I hope that makes sense!