In performing an experimental analysis it is always important to take intoaccount different parameters influencing the results. Boundary conditions inaddition to the specimen size in case of nonlinear materials could be evenmore effective. Hence, a full analysis of these parameters before doing anytest on the real material seems necessary. In this paper, these effects arenumerically analyzed, using ANSYS APDL coding. Samples are cylindricalelastomers becoming ready for a relaxation test in order to get Prony seriesof the material. The influences of friction and applied displacement inaddition to the area-length ratio have been investigated and the optimalvalues in order to do an appropriate relaxation test are proposed.