Fluid-Filled Frequency-Tunable Mass Damper
mechanical and fluid systems
Fluid-Filled Frequency-Tunable Mass Damper (MFS-TOPS-91)
Includes an adjustable mechanism for altering frequency of mitigation
Overview
Innovators at the Marshall Space Flight Center (MSFC) have developed a fluids-based tunable mass damper system that allows for significant distribution of loads while also providing a simple mechanism that allows for the capability to change its frequency of mitigation with negligible impact on the damper system. For existing fluid filled pipes, ducts, ballast tanks, etc., the fluid can now be leveraged to provide vibration mitigation. This new technology enables structural engineers to set and change the fundamental mitigation attributes of the mass damper system with little to no modification of the fluid container.
The Technology
NASA MSFC’s Fluid-Filled Frequency-Tunable Mass Damper (FTMD) technology implements a fluid-based mitigation system where the working mass is all or a portion of the fluid mass that is contained within the geometric configuration of either a channel, pipe, tube, duct and/or similar type structure. A compressible mechanism attached at one end of the geometric configuration structure enables minor adjustments that can produce large effects on the frequency and/or response attributes of the mitigation system.
Existing fluid-based technologies like Tuned Liquid Dampers (TLD) and Tuned Liquid Column Dampers (TLCD) rely upon the geometry of a container to establish mitigation frequency and internal fluid loss mechanisms to set the fundamental mitigation attributes. The FTMD offers an innovative replacement since the frequency of mitigation and mitigation attributes are established by the compressible mechanism at the end of the container. This allows for simple alterations of the compressible mechanism to make frequency adjustments with relative ease and quickness.
FTMDs were recently successfully installed on a building in Brooklyn, NYC as a replacement for a metallic TMD, and on a semi-submersible marine-based wind turbine in Maine.
The FTMD technology is available for non-exclusive licensing and partially-exclusive licensing (outside of building construction over 300 feet).
.jpg "text")
.jpg "FTMD has been successfully incorporated into a semi-submersible wind turbine platform, and may be able to dampen potentially harmful shaking in a variety of other structures.")
Benefits
- Offers a simple compressible mechanism for changing mitigation frequency in a damping system that does not require a modification of the fluid tank geometry
- Enables small adjustments to frequency (+/- 10%) and large adjustments to frequency (2x - 3x) that can be done at will
- Minimizes size, weight, and cost in view of competing technologies
- Can be applied to numerous applications with different requirements for fundamental mitigation attributes
- Can utilize existing fluid filled reservoirs and or simple configurations of added reservoirs
Applications
- Structural: Installations on large civil structures to mitigate flexing or bending modes (e.g., stacks, towers bridges, pools for spent nuclear fuel, etc.)
- Oil and gas: Offshore oil rigs, above-ground storage tanks
- Municipal: Water tanks/towers
- Marine: Installations on numerous maritime architectures such as submersible, semisubmersible and surface platforms to mitigate pitch, heave and/or roll
- Alternative to Tuned Liquid Dampers (TLD), Tuned Liquid Column Dampers (TLCD), Tuned Mass Absorbers, Tuned Mass Dampers (TMD), Harmonic Absorbers, or Seismic Dampers while providing enhanced packaging, performance and installation advantages
Technology Details
mechanical and fluid systems
MFS-TOPS-91
MFS-33613-1-CIP
Rocket Technology Stops Shaking in Its Tracks. https://spinoff.nasa.gov/Spinoff2017/ps_2.html
|
Tags:
|
Similar Results
Self-Tuning Compact Vibration Damper
Structural vibrations frequently need to be damped to prevent damage to a structure or payload. To accomplish this, a standard linear damper or elastomeric-suspended masses are used. The problem associated with a linear damper is the space required for its construction. For example, if the damper's piston is capable of three inches of movement in either direction, the connecting shaft and cylinder each need to be six inches long. Assuming infinitesimally thin walls, connections, and piston head, the linear damper is at least 12 inches long to achieve +/3 inches of movement. Typical components require 18+ inches of linear space. Further, tuning this type of damper typically involves fluid changes, which can be tedious and messy. Masses suspended by elastomeric connections enable even less range of motion than linear dampers.
The NASA invention is a compact and self-tunable structural vibration damper. The damper includes a rigid base with a slider mass for linear movement. Springs coupled to the mass compress in response to the linear movement along either of two opposing directions. A rack-and-pinion gear coupled to the mass converts the linear movement to a corresponding rotational movement. A rotary damper coupled to the converter damps the rotational movement. To achieve +/- 3 inches of movement, this design requires slightly more than six inches of space.
Compact Vibration Damper
Structural vibrations frequently need to be damped to prevent damage to a structure. To accomplish this, a standard linear damper or elastomeric-suspended masses are used. The problem associated with a linear damper is the space required for its construction. For example, if the damper's piston is capable of three inches of movement in either direction, the connecting shaft and cylinder each need to be six inches long. Assuming infinitesimally thin walls, connections, and piston head, the linear damper is at least 12 inches long to achieve +/-3 inches of movement. Typical components require 18+ inches of linear space. Further, tuning this type of damper typically involves fluid changes, which can be tedious and messy. Masses suspended by elastomeric connections enable even less range of motion than linear dampers.
The NASA invention is for a compact and easily tunable structural vibration damper. The damper includes a rigid base with a slider mass for linear movement. Springs coupled to the mass compress in response to the linear movement along either of two opposing directions. A rack-and-pinion gear coupled to the mass converts the linear movement to a corresponding rotational movement. A rotary damper coupled to the converter damps the rotational movement. To achieve +/- 3 inches of movement, this design requires slightly more than six inches of space.
Tension Element Vibration Damping
NASAs Tension Element Vibration Damping technology presents a novel method of managing the dynamic behavior of structures by capturing the vibrational displacement of the structure via a connecting link and using this motion to drive a resistive element. The resistive element then provides a force feedback that manages the dynamic behavior of the total system or structure. The damping force feedback can be a tensile or compressive force, or both. Purely tensile force has advantages for packaging and connection alignment flexibility while combined tensile/compression forces have the advantage of providing damping over a complete vibratory cycle.
This innovation can be readily applied to existing structures and incorporated into any given design as the connecting element is easily affixed to displacing points within the structure and the resistive element to be located in available space or a convenient location. The resistive element can be supplied by any one of either hydraulic, pneumatic or magnetic forces. As such the innovation can provide a wide range of damping forces, a linear damping function and/or an extended dynamic range of attenuation, providing broad flexibility in configuration size and functional applicability.
NASA-built prototypes have been shown to be highly effective on a 170-foot long wind turbine blade in test beds at the University of Maine.
Ocean Platform Motion Control
The NASA innovation leverages existing ballast fluid of a maritime structure to proactively mitigate undesirable resonant response characteristics of the platform or vessel. Essentially, this innovation couples water ballast as a functional working mass to the dynamic motion of a floating structure in order to provide passive motion management of the primary structure.
The system can be implemented pre-design or post manufacture. The systems are simple and are easily manufactured, transported, and implemented onto a primary structure.
The NASA technology has been designed (patents applied for) for a range of platform designs and can be further customized depending on the final application requirements. Prototypes have been built and tested in a wind-wave tank test bed at the University of Maine.
Fluid Structure Coupling Technology
FSC is a passive technology that can operate in different modes to control vibration:
Harmonic absorber mode: The fluid can be leveraged to act like a classic harmonic absorber to control low-frequency vibrations. This mode leverages already existing system mass to decouple a structural resonance from a discrete frequency forcing function or to provide a highly damped dead zone for responses across a frequency range.
Shell mode: The FSC device can couple itself into the shell mode and act as an additional spring in a series, making the entire system appear dynamically softer and reducing the frequency of the shell mode. This ability to control the mode without having to make changes to the primary structure enables the primary structure to retain its load-carrying capability.
Tuned mass damper mode: A small modification to a geometric feature allows the device to act like an optimized, classic tuned mass damper.
