Device for measuring true stress and true strain of sample

A device for measuring true stress and true strain of a sample comprises an upper chuck which is connected with the sample; an extensometer and a clamp type extensometer which are clamped on the sample; a lower chuck which is connected with the sample and a fixed device; a suspension plate which is arranged on the fixed device and is connected with the fixed device through a vertical plate; a screw rod which is arranged between the suspension plate and the fixed device; a motor which is arranged on the fixed device and connected with a first cylindrical gear, wherein the first cylindrical gearis meshed with a second cylindrical gear, the second cylindrical gear is assembled on a lead screw, and a moving device is assembled in the middle section of a lead screw and connected with the clamptype extensometer and a guide groove. The gear drives the screw rod to rotate and a moving device moves up and down; the clamp type extensometer reciprocates up and down in the direction of the guiderail, the sample is necked