摘要
Most solid materials behave elastically, but the real solids rarely behave exactly according to the elastic Hook’s law. It is often found that the solid deformations are time dependent. This behavior is studied in rheology. The authors have introduced a rheological model, the Maxwell model, describing the materials with the behavior of a Newtonian liquid, and now the authors introduce another rheological model, the Kelvin model, describing the materials with the behavior of a viscoelastic solid.