Conjugate Damper Bidirectional Vibration Damping
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Solution Overview
Problem
Existing vibration and noise reduction systems for aircraft and vehicle structures are inefficient in damping structure-borne vibrations and absorbing acoustic noise, as they either focus on shear deformation in damping layers or require active control systems, leading to varying effectiveness across different frequencies and temperatures.
Innovation Solution
A conjugate damper is introduced, which induces deformation in both directions normal and parallel to the panel surface, utilizing a viscoelastic damping layer and a constraining sheet with perforations, allowing for passive energy dissipation across a wide range of frequencies and temperatures without the need for active control systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If constrained layer damping devices use a viscoelastic foam damping layer to improve the frequency and temperature range for effective damping, then the damping effectiveness is improved, but the device still dissipates energy only to the extent that shear deformation is induced in the damping layer parallel to the structural surface
Solution Approach 1:
The patent introduces a second constraining layer positioned on the opposite side of the damping layer from the first constraining layer, creating bidirectional constraint. This dimensional extension allows the damping layer to experience compression and expansion in the direction normal to the structural surface in addition to shear deformation, enabling energy dissipation in multiple directions and significantly improving damping effectiveness across broader frequency and temperature ranges
2Adaptability or versatility
If separate devices are used to damp structure-borne vibration and to absorb acoustic noise, then vibration damping and noise absorption functions are provided, but the system weight and complexity increase
Solution Approach 1:
The patent combines vibration damping and noise absorption functions into a single integrated device. The damping layer with bidirectional constraining layers simultaneously dampens structure-borne vibrations through viscoelastic deformation and absorbs acoustic noise through the porous structure, eliminating the need for separate vibration damping devices and thermal-acoustic blankets, thereby reducing overall system weight and complexity
Solution Approach 2:
The damping layer is designed to perform multiple functions: it dampens vibrations through shear and compressive deformation, absorbs acoustic noise through its porous structure, and provides thermal insulation. This multi-functionality allows a single device to replace multiple separate systems, reducing weight while maintaining versatility
3Object-affected harmful factors
If a piezoelectric film and active control system are used to expand and contract the foam to produce acoustic waves that cancel acoustic noise, then noise cancellation is achieved, but additional cost, weight, and complexity are introduced from auxiliary control components
Solution Approach 1:
The patent employs passive noise absorption through the porous damping layer structure, which naturally absorbs acoustic energy without requiring active control systems, piezoelectric films, or auxiliary components. The system serves itself by utilizing the inherent viscoelastic and porous properties of the damping material to dissipate both vibrational and acoustic energy, eliminating complexity while maintaining effectiveness
4Reliability
If conventional constrained layer damping devices are used, then vibration damping is provided, but the damping varies significantly with vibration frequency and environmental temperature
Solution Approach 1:
By adding the second constraining layer and enabling compression/expansion deformation in the direction normal to the structural surface, the patent extends the effective operating range of the damping device. This dimensional enhancement allows the viscoelastic damping layer to dissipate energy more consistently across broader frequency and temperature ranges by utilizing additional deformation modes
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 conjugate damper effectively dissipates a higher proportion of vibrational energy, reducing both structure-borne vibrations and acoustic noise transmission, while minimizing weight and complexity, and eliminating the need for separate devices for vibration damping and noise absorption.
Implementation Method 1
a damping layer (120) with a viscoelastic material coupled between the first surface and the constraining sheet
Implementation Method 2
the constraining layer induces shear deformation within the damping layer in directions parallel to the structural surface. The induction of shear deformation in the damping layer correspondingly dissipates a portion of the vibrational energy
Implementation Method 3
The blankets include a material, such as fiberglass or lightweight open-cell foam, that absorbs air-borne noise
Implementation Method 4
damping layer (120) with a viscoelastic material coupled between the first surface and the constraining sheet wherein a porosity of the damping layer varies with a second distance between the constraining sheet and the first surface
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A conjugate damper (100) for a structural panel (50) includes a constraining sheet (102) extending between a first edge (104) and a second edge (106). Each of the first edge (104) and the second edge (106) is at least partially coupled to a first surface (52) of the structural panel (50). The conjugate damper also includes a damping layer (120) coupled between the constraining sheet (102) and the first surface (52) such that, when the structural panel (50) is in a compressively deformed state, a thickness of the damping layer (120) in a direction generally normal to the first surface (52) is decreased relative to a baseline state. The damping layer (120) includes a viscoelastic material.