a The additional spring and dashpot in series with the Voigt model of Fig. 2.14 constitute a standard linear solid (Fig. 2.16). The spring and dashpot in series alone are referred to as a Maxwell model. If a stress (J' is applied at time t = 0 and held constant, sketch the strain-time response expected for a Maxwell model.

b Release the load in part (a) sometime after its application. Sketch strain vs. time following this unloading. c Show that the addition of the strains drawn in (a) and (b) to those schematized in Fig. 2.15 leads to the response illustrated in Fig. 2.17.