The mechanical response of various combinations of non-linear viscous elements (dashpots) is analysed in this paper. It is assumed that the properties of i-th element can be described by the relation sigma(i) = K(i)xi(i)(mi), where sigma(i) is the stress, xi(i) is the strain rate, K-i and m(i) are constants (0 less than or equal to m(i) less than or equal to 1). Parallel, series and combined combinations are considered. The main object is to find out the potential for various combinations to describe the sigmoidal variation of the flow stress, sigma, with the strain rate, xi, which is a typical feature of superplastic materials. It is found that elements are connected in parallel as well as elements are connected in series are characterised by non-sigmoidal dependency of the net stress sigma on the net strain rate xi. At the same time a mixed combination with two elements in parallel connected with a third one in series is shown to describe the sigmoidal curve with reasonable accuracy.