Tuned Mass Damper Vibration Isolation for Precision Pointing

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Solution Overview

Problem

Precision pointing systems, such as those carrying telescopes, face structural vibrations due to mechanical components like reaction wheel assemblies, leading to performance degradation and fatigue, and existing vibration isolation methods using elastomer pads are ineffective as they creep unpredictably and cause electromagnetic interference.

Innovation Solution

A vibration isolation apparatus featuring a main spring with tuned mass dampers coupled equidistantly between its ends to reduce axial surge mode resonance by at least 50% within a predetermined frequency range, using fluid-filled bellows and a temperature compensator to maintain damping and prevent overheating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If elastomer pads are used to attenuate resonance, then vibration damping is improved, but electrical and thermal conduction are blocked causing electromagnetic interference and overheating

Engineering Contradiction:

Improvevibration dampingVSAvoidelectromagnetic interference

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces insulating elastomer pads with a metallic tuned mass damper system that provides both vibration damping and electrical/thermal conduction. The mounting structure and mass are designed to conduct electricity and heat while utilizing inertial forces for resonance attenuation, thereby eliminating electromagnetic interference and overheating issues.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Strength

If the main spring is used to provide axial stiffness, then structural support is provided, but the spring resonates at certain frequencies interfering with vibration damping capability

Engineering Contradiction:

Improveaxial stiffnessVSAvoidvibration damping capability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent converts the harmful resonance of the main spring into a beneficial effect by attaching a tuned mass damper. The damper's natural frequency is tuned to match the spring's resonant frequency, causing the inertial forces generated by the oscillating mass to counteract and reduce the spring's resonance amplitude, thereby improving overall vibration damping capability.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent utilizes mechanical vibration principles by introducing a tuned mass damper that oscillates at the same frequency as the main spring's resonance. The out-of-phase motion of the damper mass creates inertial forces that actively cancel the resonant vibrations of the spring, reducing the overall vibration amplitude without compromising axial stiffness.

Inventive Principle:

Principle #18Mechanical vibration

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution significantly improves damping capabilities, reduces resonance, and prevents premature wear of the spring, providing enhanced structural integrity and thermal management without unpredictable creep or electromagnetic interference.

Implementation Method 1

The first tuned mass damper is coupled to the main spring at a first axial position located substantially equidistantly between the main spring first end and the main spring second end and is configured to reduce the first axial surge mode magnitude at least 50% when the main spring is vibrated within the predetermined frequency range

Methodology Applied

Scientific EffectTuned mass damper: Tuned Mass Damper

Implementation Method 2

The main spring has a first end and a second end and is configured to resonate when vibrated within a predetermined frequency range with a first axial surge mode having a magnitude

Methodology Applied

Scientific EffectResonance: Resonance

Implementation Method 3

A flange extends radially from a midsection of the piston and has a top surface that is coupled to a first sealed bellows and a bottom surface that is coupled to a second sealed bellows. Each of the bellows has a chamber that is filled with fluid. Thus, when the piston moves axially through the shaft, fluid flows from one of the bellows chambers to the other

Methodology Applied

Scientific EffectFluid flow:

Implementation Method 4

The shaft and piston are disposed within the main spring, which provides axial stiffness to the isolation strut in general

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 5

A temperature compensator is coupled to the bellows and is configured to maintain a constant volume of the fluid-filled bellows chambers

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS8002094B2Vibration isolation apparatus and methods of manufacture

Publication Date: 2011.08.23 HONEYWELL INTERNATIONAL INC

AI summary

A vibration isolation apparatus is provided that includes a main spring and a tuned mass damper. The main spring has a first end and a second end, and is configured to resonate when vibrated within a predetermined frequency range with a first axial surge mode having a magnitude. The tuned mass damper is coupled to the main spring at a first axial position located substantially equidistantly between the main spring first end and the main spring second end and is configured to reduce the first axial surge mode magnitude at least 50% when the main spring is vibrated within the predetermined frequency range. Methods of manufacturing the vibration isolation apparatus are also provided.