Evaluation of Reactions of Multi-Supported Hydrostatic Slide through Finite Element Analysis

Hydrostatic slides are used on many machines with multiple hydrostatic supports. These supports are provided on top and bottom faces of the slide to take load in both upward and downward directions. Similar supports are given in the other guiding plane. In order to design the pocket sizes for these hydrostatic bearings, the expected reaction load at these points is required. When there are only three simple supports in a particular direction, and when the load passes through the base of these supports, these reactions cannot be obtained directly from the equilibrium equations. When there are more than three supports, one has to obtain reactions through Finite element analysis. Though FEA is the answer to find reactions with multi supports, it Is not straightforward, because the present slide arrangement of hydrostatic bearings is such that they can support in +Z and/or -Z directions along with similar support in one other direction X or Y). But in FEM analysis such partial directional constraints (i.e constrained in only +Z direction or only -Z direction) cannot be given. This leads to different trials in getting the required reactions. As there are no established methods to solve such problem, an attempt is made in this paper to find a solution to such problems. Different approaches are also given to solve such problems.