18.9 : 多重载荷下构件的变形

The deformation of a rod with different materials and cross-sections is computed by dividing it into parts, each characterized by individual parameters.

Then, the deformation in each part is calculated, and the total deformation of the member is computed by summing the deformation in each part.

When one end of the rod is fixed, the deformation is equal to the displacement of its free end. But, when both ends of the rod move, the deformation is measured by the relative displacement of one end concerning the other.

Consider an assembly of three elastic bars connected by a rigid pin at point O. If a load is applied at the free end of bar 1, then each bar will deform.

For bars 2 and 3, attached to fixed supports B and C, the common deformation is measured by the displacement of point O.

For bar 1, where both ends move, deformation is measured by the difference between the displacements of points O and A.