英语翻译
The shear force V and bending moment M in a beam will usually vary with the distance x defining the location of the cross section at which they occur.When designing a beam ,it is desirable to know the values of V and M at all cross sections of the beam ,and a convenient way to provide this information is by a graph showing how they vary along the axis of the beam..To plot the graph ,we take the abscissa as the position of the cross section ,and we take ordinate as the corresponding value of either the shear force or the bending moment .Such graphs are called shear force and bending moment diagrams.