SUMMARY

The reduction or elimination of leakage of hydraulic fluid from fluid power systems is considered a fundamental prerequisite for the expanded use of fluid power. There is also a need to reduce seal friction to both reduce energy dissipation and eliminate control problems. These seals are developed through empirical means at the present time, since the fundamental physics of seal operation has been unclear.
The proposed research develops numerical models for analyzing reciprocating hydraulic rod seals with various rod surfaces. They consist of coupled fluid mechanics, contact mechanics and deformation analyses. For seals with a smooth rod and a plunge-ground rod, the model combines a 1-D finite volume Reynolds Equation solver with 2-D axisymmetric finite element deformation and static contact mechanics analyses, and a Greenwood-Williamson dynamic contact mechanics analysis. Leakage and friction results with the plunge-ground rod are compared with those with the smooth rod. For seals with a micro-patterned rod, the model consists of a 2-D finite volume Reynolds Equation solver, 3-D finite element deformation and static contact mechanics analyses, and a Greenwood-Williamson dynamic contact mechanics analysis. A unique approach is used in the 3-D finite element analyses to reduce the number of required elements to a manageable level. Simulations with different micro-pattern geometries will be performed to analyze the fundamental mechanism of surface pattern influence on seal operation and determine the optimum engineered micro-pattern design to reduce seal friction while maintaining minimal net leakage.