for some positive A0. This is illustrated in Fig. 1 (a) with t=sd ¼ 8; A0 ¼ 0:35 and the resultant (scaled) shear stress T12ðtÞ=l is
shown in 1(b). The response of the compressible Levinson–Burgess material with s ¼ 1 is shown as the distinct dotted line.
Note that the behaviour of the compressible material with s ¼ 10 (dashed line) is almost indistinguishable from the neo-
Hookean incompressible (solid line) curve. In Fig. 1(c) the experiment is repeated for an imposed ramp shear stress
T12ðtÞ=l given in the form (25) with t=sd ¼ 8; A0 ¼ 0:35. The resultant shear kðtÞ is illustrated in figure (d) for the same three
materials as above, and is computed using expressions (14) and (20). As can be seen, the gross response of the compressible
and incompressible materials is similar, for both prescribed shear and stress, especially as the relaxation ratio s becomes
large.