A simple fluid-mechanical model for the prediction of the stress–strain relation of the male urinary bladder

The non-linear, viscoelastic behavior of the male urinary bladder complicates the formulation of suitable stress–strain relations for the quasi-static filling process and the unsteady voiding process. In particular, the voiding process—which, in addition, is affected by contraction of muscles leading to generation of bladder wall tension—makes it difficult to obtain quantitative results. In the present study, a simple model is developed that uses certain urological data from cystometry and uroflowmetry to determine the stress–strain relations of the bladder wall during both filling and voiding.