Abstract

We correct two serious errors made by Robson and Sethian (Am.J.Phys 60 p.1111, 1992).  These authors have ignored the well established methods of Newtonian stress analysis, and then they erroneously claimed that the Newtonian stresses did not exist.  Secondly, the misrepresented railgun recoil and wire fragmentation experiments by wrongly asserting that the observed effects had been caused by metal heating.  Robson and Sethian were not aware that the thermo-mechanical wire fracture mechanism had already been disproved by experiment.  They also ignored a large body of the metallurgical literature which deals with the annealing of metals.