Nonlocal Acoustic Black Hole Metastructure for Low-Frequency Vibration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current passive vibration attenuation systems, particularly those using Acoustic Black Holes (ABH), face limitations in attenuating low-frequency vibrations due to the intrinsic dependence on spatial periodicity and unit cell dimensions, restricting their performance in the low-frequency regime.
Innovation Solution
A nonlocal acoustic black hole metastructure system is introduced, comprising a load bearing layer, a non-load bearing layer, and a rigid beam connector, which provides a nonlocal connection to transfer energy and utilize viscoelastic damping for broadband low-frequency vibration attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If periodic arrangements of ABHs are used to attenuate vibrations, then mid and high-frequency attenuation is improved, but low-frequency attenuation performance deteriorates due to spatial constraints on unit cell dimensions
Solution Approach 1:
The patent transitions from traditional two-dimensional periodic ABH arrangements to a three-dimensional hierarchical structure with multiple layers (load-bearing layer, non-load-bearing layer, intermediate layer) connected by rigid beam connectors. This dimensional expansion enables simultaneous achievement of low-frequency attenuation (through out-of-plane bending modes in the non-load-bearing layer) and mid-high frequency attenuation (through in-plane vibrations in the load-bearing layer), overcoming the spatial periodicity limitations of planar designs.
Solution Approach 2:
The patent divides the vibration attenuation system into functionally distinct segments: a load-bearing layer for structural support and high-frequency attenuation, a non-load-bearing layer for low-frequency attenuation through flexible deformation, and intermediate layers with rigid beam connectors for energy transfer. This segmentation allows each layer to specialize in specific frequency ranges while working cooperatively to achieve broadband attenuation across the entire spectrum.
2Reliability
If the diameter of ABH is increased to reduce cut-on frequency, then low-frequency attenuation is improved, but device complexity and manufacturing constraints are worsened
Solution Approach 1:
The patent applies local quality by creating regions with different mechanical properties: the non-load-bearing layer is designed with lower stiffness and density to enable large deformations at low frequencies, while the load-bearing layer maintains higher stiffness for structural integrity and high-frequency attenuation. The rigid beam connectors provide localized stiff connections for energy transfer. This spatial variation in material properties allows low-frequency attenuation without requiring large overall dimensions.
Solution Approach 2:
The patent implements a nested hierarchical structure where the non-load-bearing layer with ABH features is embedded within or coupled to the load-bearing layer, which itself is part of a multi-layered composite structure. This nesting enables small-scale ABH features to achieve low-frequency attenuation through the compliant non-load-bearing layer, while the overall compact structure avoids the need for large diameters that would otherwise be required.
3Reliability
If passive systems are used for vibration attenuation, then system simplicity and reliability are improved, but adaptability to different operating conditions deteriorates
Solution Approach 1:
The patent employs a composite metastructure combining materials and structures with different mechanical characteristics: rigid load-bearing layers, compliant non-load-bearing layers with ABH features, and stiff intermediate connectors. This composite architecture enables passive adaptation to different frequency ranges through the inherent multi-scale vibration modes of the structure, achieving broadband attenuation without active control while maintaining mechanical robustness.
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 system effectively extends the operating range of ABH metastructures to achieve significant broadband and low-frequency vibration attenuation, reducing the steady-state response amplitude by up to 40% and shifting the first frequency bandgap from 170 Hz to approximately 2 Hz, enhancing structural dynamics applications.
Implementation Method 1
The rigid beam connector couples the load bearing layer to the non-load bearing layer. The coupling of the non-load bearing layer to the load bearing layer through the use of the rigid beam connector may provide a nonlocal connection to transfer energy from the load bearing layer to the non-load bearing layer.
Implementation Method 2
A nonlocal acoustic black hole metastructure system is introduced, comprising a load bearing layer, a non-load bearing layer, and a rigid beam connector, which provides a nonlocal connection to transfer energy and utilize viscoelastic damping for broadband low-frequency vibration attenuation.
Data Source
AI summary
The vibration attenuation system includes a load bearing layer, a non-load bearing layer, and a rigid beam connector. The load bearing layer has a first density and a first stiffness. The non-load bearing layer has a second density and a second stiffness. The second density is lower than the first density. The rigid beam connector has a third density and a third stiffness. The rigid beam connector couples the load bearing layer to the non-load bearing layer. The coupling of the non-load bearing layer to the load bearing layer is enabled through the use of the rigid beam connector which provides a nonlocal connection to transfer energy from the load bearing layer to the non-load bearing layer.