Effection of Non-Linear Strain Patho on the Onset of Necking for the Metal Sheet Deformed in the 2^nd Qundrant of Major-Minor Strain Plane

A General rule about the effection of non-linear strain on the onset of necking for the metal sheet deformed in the stretch-compressive strain qundramt, which was get from some author's experiments and digital calculations, is proved by a simple mathematical method in this paper. More analysis is made to discuss the way to get larger stretch strain in metal sheet forming processes.