Rotatable Stiffness Assembly for Precise TMD Frequency Tuning
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Solution Overview
Problem
Tuned Mass Dampers (TMDs) face challenges in achieving precise stiffness adjustments due to manufacturing tolerances and variations in coil springs, leading to delays and additional costs in tuning the natural frequency of structures to reduce vibrations.
Innovation Solution
An adjustable stiffness assembly using rotatable stiffness elements, such as beams with non-circular cross-sections, that can be rotated to vary the total stiffness value in the global direction, allowing for precise tuning of the TMD's stiffness in conjunction with fixed stiffness elements like steel coil springs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If coil springs are used to provide stiffness in the TMD assembly, then the stiffness can be provided with simple structure, but the manufacturing tolerances and variation between spring units cause the resulting stiffness to differ from theoretical values, leading to inability to achieve precise natural frequency requirements
Solution Approach 1:
The patent applies the dynamics principle by making the stiffness element adjustable through rotation. The stiffness element can be rotated to different angular positions to dynamically adjust the stiffness value, transforming a static stiffness system into a dynamic one. This allows precise tuning of the natural frequency by changing the angular position of the stiffness element, thereby achieving manufacturing precision without requiring multiple different spring units.
Solution Approach 2:
The patent applies parameter changes by varying the effective stiffness through rotational adjustment. By changing the angular position of the stiffness element, the effective stiffness parameter is continuously adjustable between minimum and maximum values. This enables precise control of the TMD's natural frequency without being constrained by discrete spring variations, directly addressing the manufacturing precision issue.
2Manufacturing precision
If coil springs with different dimensions are used to adjust stiffness, then the stiffness can be adjusted to match theoretical requirements, but this requires replacing springs and changing spring mount geometry, resulting in delays and additional costs
Solution Approach 1:
The patent applies dynamics by implementing an adjustable stiffness mechanism that can be tuned in-situ without disassembly. The stiffness element's rotational capability allows the system to adapt to different stiffness requirements dynamically, eliminating the time-consuming process of replacing springs and modifying mounting geometry for each adjustment.
Solution Approach 2:
The patent applies preliminary action by designing the stiffness element with built-in adjustability from the outset. Rather than requiring post-manufacturing adjustments through replacement and modification, the system is pre-configured with rotational adjustment capability, allowing immediate tuning without delays.
3Manufacturing precision
If coil springs are replaced iteratively to achieve correct stiffness, then the natural frequency requirement can be approached, but the iterative process results in further delays and additional costs
Solution Approach 1:
The patent applies dynamics by replacing the iterative replacement process with a continuous adjustment mechanism. The rotational capability of the stiffness element allows for smooth, continuous variation of stiffness values, enabling a single adjustment process to achieve the target natural frequency without repeated iterations of replacement and testing.
Solution Approach 2:
The patent applies parameter changes by enabling continuous adjustment of the stiffness parameter through rotation. This eliminates the discrete, stepwise parameter changes required when replacing springs, allowing precise targeting of the desired natural frequency in a single adjustment operation, thereby significantly improving tuning efficiency.
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
Enables precise adjustment of stiffness values to match theoretical requirements, reducing delays and costs by allowing for continuous variation of the stiffness value between minimum and maximum settings, effectively tuning the TMD to resonate with structural vibrations and dissipate energy efficiently.
Implementation Method 1
The first rotatable stiffness element has a minimum stiffness value with respect to forces in a local direction referred to as X, and a maximum stiffness value with respect to forces in another local direction referred to as Y. The first rotatable stiffness element is rotatable relative to the structure mount and the first mass mount to vary the total stiffness value of the complete stiffness assembly with respect to force in the global direction.
Data Source
AI summary
The invention provides an adjustable stiffness assembly for use in conjunction with a fixed stiffness element to elastically connect a structure to a mass. The assembly includes a structure mount, a mass mount, and a rotatable stiffness element. The rotatable stiffness element rotatably engages with the structure mount and the mass mount, and has a minimum stiffness value with respect to forces in a direction a maximum stiffness value with respect to forces in another direction The fixed stiffness element and the adjustable stiffness assembly together provide a complete stiffness assembly having a total stiffness value with respect to force in the global direction for elastically connecting the mass and the structure. The first rotatable stiffness element is rotatable relative to the structure mount and the first mass mount to vary the total stiffness value of the complete stiffness assembly with respect to force in the global direction.