Predicition of RSS Sealing Performance by Fully Coupled EHL Simulation

The pumping and leakage behavior of radial shaft seals (RSS) has challenged researchers for more than half a century. The main phenomena contributing to reverse pumping have been identified some decades ago, e.g. by Kammüller. However, there is no conclusive proof nor comprehensive model for the exact sealing mechanisms, making it impossible to derive precise guidelines for radial shaft seal design. Thus, the question how to tune and optimize RSS is still open to this day. To change this, Freudenberg has developed its own simulation tool to gain insight in the pumping mechanism and the sealing performance of RSS: FIRS³T – Freudenberg Integrated Radial Shaft Seal Simulation Tool. It includes all steps required to simulate the pumping rate, among which: the Finite Element Analysis of the deformation of the seal, contact mechanics calculations and EHL-modelling of the sealing contact, all the way to the circumferential deformation of the sealing lip roughness in the contact due to the frictional shear stresses. Using this tool, the pump rate of RSS can be simulated accurately and new insights in the sealing mechanism are possible. Furthermore, it will be shown how FST uses this tool to develop new seals with unrivalled functionality.