Acoustic Black Hole Structural Damper with Active Control
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Solution Overview
Problem
Existing structural dampers using acoustic black holes face limitations in achieving effective low-frequency attenuation due to practical constraints and manufacturing limitations, leading to reduced damping performance, especially in broader applications.
Innovation Solution
Incorporating a controller and actuator system with sensors to dynamically control the actuating force applied to an acoustic black hole, enhancing its low-frequency performance and allowing for broader application in structural damping, including the use of various types of acoustic black holes with different thickness profiles and dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tip of the ABH reduces to zero thickness to achieve ideal acoustic black hole effect, then wave reflection is eliminated and attenuation is maximized, but structural requirements and manufacturing limitations cannot be met
Solution Approach 1:
The patent applies parameter changes by modifying the thickness profile parameters (power law exponent, taper length, tip thickness) of the acoustic black hole structure to achieve optimal damping performance while satisfying manufacturing constraints. The controller dynamically adjusts these parameters to maintain effectiveness across different operating conditions.
Solution Approach 2:
The patent implements dynamics by using a controller and actuator system to dynamically adjust the ABH parameters in real-time, allowing the structure to adapt to varying frequency ranges and loading conditions, thereby maintaining optimal damping performance without requiring a perfect zero-thickness tip.
2Loss of energy
If shunted PZT transducers are used for vibration energy harvesting, then electrical energy dissipation is achieved, but overall damping is limited and only higher frequencies are attenuated
Solution Approach 1:
The patent replaces the passive electrical dissipation mechanism of shunted PZT with an active control system using sensors, controllers, and actuators. This substitution enables mechanical energy to be converted into controlled actuating forces that can effectively damp vibrations across a broader frequency range, including low frequencies where passive electrical dissipation is ineffective.
3Reliability
If a controlled actuator system is added to improve low-frequency performance, then damping effectiveness is enhanced, but device complexity increases
Solution Approach 1:
The patent applies self-service by implementing a feedback control system where the structure's own vibration response (detected by sensors) is used to automatically adjust the actuator output, eliminating the need for external complex control systems or manual intervention. The system serves itself by using its own dynamic characteristics as the control input.
Solution Approach 2:
The patent achieves universality by designing a control system that can handle multiple vibration modes, frequency ranges, and loading conditions with a single integrated sensor-actuator-controller configuration, making the ABH structure universally applicable to various damping applications without requiring multiple specialized systems.
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 controlled actuation system significantly improves the low-frequency damping performance of acoustic black holes, enabling their use in a wider range of applications and reducing resonances, while potentially reducing the size and strength requirements of the actuator.
Implementation Method 1
The acoustic black hole effect is typically achieved by introducing a power law taper into a beam or plate that changes the thickness over a set distance. This change in thickness profile causes the flexural waves propagating along the direction of the ABH to decrease in wave speed.
Implementation Method 2
a controller configured to control the actuator in dependence on a signal from the at least one sensor so as to provide structural damping of a primary structure
Data Source
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AI summary
A structural damper (2) having an acoustic black hole (5), at least one sensor (7), a damper structure (4), an actuator (8) configured to apply an actuating force to the damper structure (4) and a controller (H) configured to control the actuator in dependence on a signal from the at least one sensor so as to provide structural damping of a primary structure (3).