Horizontal-motion vibration isolator using bent flexures
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Solution Overview
Problem
Existing horizontal-motion vibration isolators are limited by their height and sensitivity to payload changes, making it difficult to achieve low frequency isolation while maintaining high isolation performance and compact geometry.
Innovation Solution
The use of bent or curved flexures with high vertical stiffness and low horizontal stiffness, loaded in shear to approach the point of elastic instability, combined with pre-compressed springs or spring-like elements to adjust stiffness and reduce natural frequency, allows for a compact horizontal-motion isolator with improved payload range and reduced sensitivity to payload changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional vibration isolators (pendulums, inverted pendulums, springs, rubber bellows) are used to achieve low frequency isolation, then isolation performance is improved, but the device height increases and/or sensitivity to payload changes increases
Solution Approach 1:
The isolator is divided into distinct functional elements: pre-compressed springs providing vertical support and negative stiffness beam-columns providing horizontal isolation. This segmentation allows each element to be optimized independently, achieving low frequency isolation without requiring the large heights of traditional pendulum-based systems.
Solution Approach 2:
The invention transitions from single-degree-of-freedom isolators to a two-degree-of-freedom system that independently handles vertical and horizontal motions. The pre-compressed springs manage vertical loads while the beam-columns provide horizontal isolation, allowing compact vertical dimensions while maintaining effective horizontal isolation performance.
2Reliability
If traditional vibration isolators are used to achieve low frequency isolation, then isolation performance is improved, but sensitivity to payload changes increases
Solution Approach 1:
The system parameters are carefully selected so that the natural frequency of the isolation system is much lower than the operating frequency range. This parameter selection makes the isolator less sensitive to payload variations, as the isolation effectiveness depends on the frequency ratio rather than precise matching to payload mass.
Solution Approach 2:
Instead of designing the isolator to match the payload mass (traditional approach), the invention inverts the approach by designing the isolator to operate effectively across a wide range of masses through low natural frequency design. The beam-column geometry is optimized for horizontal stiffness characteristics that are less sensitive to vertical load variations.
3Length of stationary object
If pre-compressed springs and negative stiffness beam-columns are used, then compact geometry is achieved, but device complexity increases
Solution Approach 1:
The negative stiffness beam-columns are designed as slender, flexible elements that derive their functionality from geometric nonlinearity rather than complex mechanisms. These thin-walled structural elements provide the required negative stiffness through their buckling behavior, achieving compact dimensions without requiring elaborate mechanical structures.
Solution Approach 2:
The pre-compressed springs act as intermediary elements that decouple the vertical support function from the horizontal isolation function. This allows the beam-columns to be optimized for horizontal stiffness without being constrained by vertical load requirements, simplifying the overall structural design while achieving compact geometry.
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
This configuration enables a more compact horizontal-motion vibration isolator with low vertical height and low horizontal natural frequencies, maintaining high isolation performance and allowing for bi-directional or omni-directional isolation capabilities.
Implementation Method 1
bent or curved flexures with high vertical stiffness and low horizontal stiffness, loaded in shear to approach the point of elastic instability
Implementation Method 2
pre-compressed springs or spring-like elements to adjust stiffness and reduce natural frequency
Implementation Method 3
Horizontal-motion vibration isolator... to effectively reduce the transmission of horizontal vibrations between the object and the base
Data Source
AI summary
A horizontal-motion vibration isolator utilizes a plurality of bent flexures to support an object to be isolated from horizontal motion. Each bent flexure includes a fixed end coupled to a base and a floating end which is cantilevered and coupled to the object being isolated. The arrangement of bent flexures allows the vertical height of the isolator to be reduced without compromising vibration isolation performance. Compressed springs or spring-like elements can be added to bear some of the weight of the object being isolated thus increasing the payload capacity of the isolator.