[ASME ASME 2012 11th Biennial Conference on Engineering Systems Design and Analysis - Nantes, France (Monday 2 July 2012)] Volume 1: Advanced Computational Mechanics; Advanced Simulation-Based Engineering Sciences; Virtual and Augmented Reality; Applied Solid Mechanics and Material Processing; Dynamical Systems and Control - Experimental Analysis of Ring Stiffnesses of Pipes, Made of High Density Polyethylene, due to DIN 16961-2:2010-03 Standard