Explanation on Equation F.1 and Equation F.2 in Annex F of GB/T 228.1-2010

The general equation for crosshead separation rate was derived through the tensile testing theoretical model built in this paper. In the linear elastic deformation phase, the exact function relation between the strain rate and testing machine system stiffness could be got through the general equation. And in the yield plastic deformation phase, the approximate accurate function relation between the strain rate and testing machine system stiffness could be got through theoretical analysis and reasonably approximate treatment according to the general equation. It is exact for equation F. 1 and F. 2 in Annex F of GB/T 228.1-2010 used in linear elastic deformation phase. On the other hand, it is approximately accurate for equation F. 1 and F. 2 used in yield plastic deformation phase. The approximate accurate equation in theory is not wrong equation.