Study of elastomeric membranes for vibration dampers in non-stationary conditions

The present work describes the study carried out to characterize the constitutive and operating behavior of a rubber membrane; the application under examination consists of a air-oil separator for dampers of helicopter rotor blades. The main requirements are that the membrane must be mounted inside the main tube through a manual reversal movement, must withstand a differential pressure of 3 bar in exercise and 7.5 bar in the acceptance test, without tearing and respecting the dimensions allowable within the damper, and it must ensure a tight seal. Moreover, the membrane will be subjected to cycles of elongation and shortening due to the operation of a piston which, by means of a suitable contrast spring, allows the consumption and charging of the oil in the damper. The study was conducted using FEM simulations that take into account large displacements and the hyperelastic, viscoelastic and pseudo-elastic characteristics of the rubber material, in order to simulate the global behavior of the membrane starting from the very first loading cycles and for a given time duration. © The Society for Experimental Mechanics, Inc. 2014.