Tuned Mass Damper With Nonlinear Spring For Broadband Vibration Control
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Solution Overview
Problem
Current tuned mass damper systems are limited by their responsive nature, which makes them dependent on frequency and amplitude, leading to nonlinearity and narrowband frequency sensitivity, requiring precise tuning and energy transfer to mitigate vibrations effectively.
Innovation Solution
The introduction of a resistance-to-motion controlled coupling mechanism that alters the primary system response by dictating the allowable phase of participation between masses, eliminating the need for energy dissipation and frequency tuning, and providing constant or varying resistance to achieve desired modal gain characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a standard tuned mass damper uses responsive damping with velocity or displacement dependence, then energy dissipation occurs at resonance, but the system exhibits significant nonlinearity and frequency sensitivity, limiting effectiveness to a narrow frequency range
Solution Approach 1:
The patent changes the damping parameter from velocity-dependent (C2) to displacement-dependent through the use of a nonlinear spring element. This allows the system to maintain constant energy dissipation across varying frequencies by adjusting the spring stiffness based on displacement magnitude rather than relying on velocity-proportional damping forces.
Solution Approach 2:
The invention introduces a dynamically adjustable spring element whose stiffness changes with displacement magnitude. This dynamic parameter adjustment enables the TMD to adapt to different vibration amplitudes and frequencies, expanding the effective frequency range beyond what fixed-parameter systems can achieve.
2Loss of energy
If a TMD is tuned to a specific structural frequency for optimal performance, then energy dissipation is maximized at that frequency, but the system becomes highly sensitive to frequency variations and performs poorly outside the tuned range
Solution Approach 1:
The patent employs a nonlinear spring element that changes its stiffness parameter based on displacement magnitude. This allows the TMD to maintain effective energy dissipation across a broader frequency spectrum by automatically adjusting its natural frequency in response to varying vibration conditions, reducing sensitivity to precise frequency tuning.
Solution Approach 2:
The system is designed with a pre-configured nonlinear spring characteristic that anticipates varying vibration amplitudes. The spring's progressive stiffness provides preliminary adaptation to different operating conditions, ensuring reliable performance across frequency variations without requiring active control or retuning.
3Reliability
If a TMD relies on resonant response of the mitigating mass for energy dissipation, then the system can effectively mitigate vibrations, but it requires precise frequency matching and has limited effectiveness at small or large vibration amplitudes due to nonlinear damping characteristics
Solution Approach 1:
The patent replaces velocity-proportional damping with displacement-proportional restoring force through a nonlinear spring. This parameter change ensures that the mitigation force scales appropriately with vibration amplitude, providing consistent effectiveness across small, medium, and large amplitude conditions without the limitations of linear damping mechanisms.
Solution Approach 2:
The nonlinear spring element provides dynamic adaptation to varying vibration amplitudes. As displacement magnitude changes, the spring stiffness automatically adjusts to maintain optimal mitigation force, enabling the TMD to remain effective across a wide range of vibration amplitudes without requiring amplitude-specific tuning.
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 approach results in a vibration mitigation system that performs consistently across various amplitudes and frequencies, outperforming traditional TMD designs by maintaining effective vibration attenuation without the need for precise frequency matching or energy transfer.
Implementation Method 1
a resistance-to-motion controlled coupling mechanism that replaces prior art C2 dampers
Data Source
AI summary
A tuned mass system has a bulk mass acted upon by an excitation amplitude and a reaction mass coupled to the bulk mass. A resistance-to-motion controlled coupling mechanism associated with the reaction mass is configured to proportionally modulate independent of excitation force such that the relative phase of the bulk mass and the reaction mass is substantially constant throughout an extended range of excitation amplitude. The resistance-to-motion controlled coupling mechanism is a Variable Aperture Reciprocating Reed (VARR) Valve in one embodiment, and operates as a passive mechanism. In other embodiments, active resistance-to-motion controlled coupling mechanisms are employed.