Introduction

Isolation mounts are used to isolate machine from ground vibrations. Isolators consist of spring damper characteristics and could be active, passive or hybrid in all degrees of freedom. Isolators typically have natural frequency between 1 and 10 Hz. Where active isolators natural frequency is on the order of 1 Hz, Passive air isolators are on the order of 3 Hz and elastomers isolators are on the order of 10 Hz.

As the motion system, which is supported by the isolated machine base, moves its inertial forces are reacted by the machine and the machine starts slow motion in its natural frequency and the entire motion system moves with it. This isolator induced motion is in fact a disturbance that the motion system has to deal with. High performance servo systems with position bandwidth on the order of 40 Hz have no problem dealing with the induced isolator disturbance on the order of less than 10 Hz in their direction of motion. However in the direction perpendicular to the direction of motion the induced isolator vibrations and the structural characteristics of the motion system may result in undesirable errors.

The machine designer therefore needs to estimate the dynamic characteristics of the induced isolator motion in order to design it for minimal disturbance. The design engineer then can design the motion system stiffness to deal with the residual disturbance.

Objectives

The objective of Optinet Isolation is to provide a user friendly, interactive engineering design tool for  3D dynamic analysis of heavy machines oscillating on isolation mounts. The tool will provide the following benefits:

1. Simplified input variables including:

• granite base size

• isolator position

• linear motion profile parameters of 2 positioning systems supported by the granite

2. Simplified Calculations ( by clicking of a button ) including:

• granite mass and 3D moment of inertia

• motion profiles of the 2 positioning systems

• granite 3D linear dynamics ( acceleration, velocity and displacement in X,Y,Z directions )

• granite 3D angular dynamics  ( acceleration, velocity and displacement about X,Y,Z axes)

• isolator 3D reaction forces in XYZ directions

3. Easy multivariable graphical display as a function of time.