Double-Ring Magnet Array Absorber for Suspender Cable Vibration
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Solution Overview
Problem
Large-span suspension bridges face significant challenges in controlling wind-induced vibrations and long-term fatigue damage in suspender cables due to their flexibility and low damping, with existing solutions like tuned mass dampers being prone to fatigue and having limited effectiveness across various frequency bands.
Innovation Solution
A double-ring shaped strong magnet array nonlinear dynamic vibration absorber is introduced, which utilizes adjustable geometric and physical parameters to control linear and nonlinear stiffness, combined with universal wheels and air dampers for effective vibration mitigation, expanding the optimal parameter domain and enhancing robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tuned mass dampers (TMD) are installed on suspender cables, then vibration mitigation effect is improved, but the device is prone to spring fatigue, corrosion and aging problems in long-term service, leading to changes in frequencies and reduced effectiveness
Solution Approach 1:
The patent replaces the traditional mechanical TMD system (springs, masses, dampers) with a magnetic field-based system. Strong magnets are arranged in arrays on both sides of the suspender cable, creating magnetic fields that interact with magnetically susceptible material embedded in the cable. This substitution eliminates mechanical components prone to fatigue and corrosion, achieving reliable long-term vibration control through non-contact magnetic forces.
2Object-affected harmful factors
If TMD are used for vibration control, then vibration response is reduced, but the vibration response of the controlled structure increases under the load of a specific frequency band range
Solution Approach 1:
The patent employs multiple magnet arrays with different magnetic field strengths, orientations, and spacing configurations to create a broadband frequency response. By varying parameters such as magnet strength, array density, and magnetic susceptible material properties, the system effectively mitigates vibrations across a wide frequency range rather than being tuned to a single frequency, thus avoiding the resonance amplification problem of traditional TMD.
3Strength
If separators are installed between cables to avoid hitting, then cable collision is prevented, but the separator has little effect on vibration mitigation in the direction perpendicular to the plane of the double cables
Solution Approach 1:
The magnetic field-based vibration absorber serves multiple functions simultaneously: it provides collision protection between cables while also delivering effective vibration mitigation in all directions including perpendicular to the cable plane. The magnetic field acts on the magnetically susceptible material within the cable regardless of vibration direction, making the device universally effective for multi-directional control without the limitations of mechanical separators.
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 solution significantly reduces vibration displacement and velocity responses, ensuring safe service and extending the life of suspender cables by providing robust, easily tunable, and maintainable vibration control across different cable configurations.
Implementation Method 1
controls the linear and nonlinear stiffness values by changing the geometric and physical parameters of the strong magnet array
Implementation Method 2
uses the friction between the universal wheels and the base of the vibration absorber to dissipate energy
Data Source
AI summary
A double-ring shaped strong magnet array nonlinear dynamic vibration absorber for vibration mitigation of suspender cables and design method thereof, which belongs to the field of structural vibration control. The installation positions and number are designed according to the demand of vibration mitigation, and usually one is installed at the midpoint of the suspender cable. The vibration absorber consists of the inner and outer magnet ring arrays, the additional weights, the universal wheels and a base. It feeds back the control force in the opposite direction of the motion of the suspender cable during the movement, so that the vibration energy of the suspender cable is transferred to the vibration absorber and thus less is returned to the suspender cable, and the energy dissipated through the friction between the universal wheels and the base, adding air dampers and other measures, etc.