Past exam of the MPhil in micro- and nanotechnology enterprise course of the University of Cambridge / 2018 / Paper 2 / Section B / 21B / iii

A Kelvin-Voigt model element places a spring and dashpot in parallel, givingUnder a stress step from a relaxed state,It captures delayed but bounded material creep and eventual strain recovery after unloading, rather than steady terminal flow.

For an ideal strain step,After the loading impulse, the stress remains $G{\gamma }_0$. The model does not produce a gradual stress-relaxation tail at held strain. A real finite-rate ramp replaces the impulse by a finite dashpot stress during loading, but the subsequent held-strain stress is still constant. Thus this model describes material creep retardation but not a solid's genuine time-dependent relaxation toward another finite modulus.