Multi-Resonant Cantilever Beam Tuning for Bridge Energy Harvesting
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Solution Overview
Problem
Energy harvesting systems based on infrastructure vibrations face challenges such as high costs and the need for customization due to varying vibration frequencies across different bridges, limiting their economic feasibility and efficiency.
Innovation Solution
An automated design method for cantilever beams in energy harvesting systems that matches resonant frequencies with dominating acceleration frequencies of the host structure, using accelerometers, Fast Fourier Transform, and simulation tools to optimize parameters like length, width, mass distribution, and piezoelectric element placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If traditional vibration-based energy harvesting designs use multiple single-beam cantilevers to capture different frequencies, then energy harvesting capability is improved, but system cost increases significantly
Solution Approach 1:
The patent employs a single cantilever beam that can capture multiple vibration frequencies simultaneously through multiple degrees of freedom. The cantilever beam is designed with multiple masses at different positions, allowing it to resonate at multiple frequencies corresponding to different traffic loading conditions, thereby replacing the need for multiple separate single-beam cantilevers while reducing system cost and complexity
Solution Approach 2:
The cantilever beam is segmented into multiple functional sections with different masses positioned at specific locations along the beam. Each mass-cantilever combination creates a specific resonant frequency, enabling the single beam to function as multiple frequency-specific harvesters would, thus achieving multi-frequency capture without the cost of multiple complete systems
2Power
If energy harvesting systems are customized for each specific bridge's vibration frequencies, then energy harvesting efficiency is improved, but implementation time and cost increase
Solution Approach 1:
The patent performs preliminary measurement of the bridge's vibration frequencies using accelerometers and Fast Fourier Transform analysis before deploying the energy harvesting system. Based on these measured frequencies, the cantilever beam parameters (masses, lengths, positions) are pre-calculated and pre-configured to match the specific bridge's characteristics, ensuring optimal energy harvesting efficiency from the start of deployment
Solution Approach 2:
The system allows for adjustment of cantilever beam parameters including mass values, mass positions, beam length, and beam width to match the specific vibration frequencies of different bridges. By changing these physical parameters, the system can be optimized for each bridge's unique frequency characteristics, achieving high efficiency without requiring complete system redesign
3Power
If cantilever beam parameters are optimized to match resonant frequencies with dominating acceleration frequencies, then energy output is improved, but design complexity increases
Solution Approach 1:
The patent uses a feedback approach where accelerometers mounted on the bridge continuously monitor vibration frequencies, and this data is processed through Fast Fourier Transform to identify dominating acceleration frequencies. These measured frequencies feed back into the design process to determine the optimal cantilever beam parameters, ensuring the system is tuned to the actual operating conditions of the specific bridge
Solution Approach 2:
The system exploits mechanical vibration and resonance principles by designing the cantilever beam with specific natural frequencies that match the dominating acceleration frequencies of the bridge. When the bridge vibrates under traffic loading, the cantilever beam resonates at these matched frequencies, maximizing the mechanical energy available for conversion to electrical energy by the piezoelectric elements
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
This approach enables efficient energy harvesting from infrastructure vibrations by optimizing cantilever beam parameters, significantly improving energy output and reducing costs through customized designs that match the specific vibration frequencies of each bridge.
Implementation Method 1
a plurality of piezoelectric elements coupled to the cantilever beam
Implementation Method 2
determining values of the plurality of parameters that result in a match between resonant frequencies of the cantilever beam and the dominating acceleration frequencies of the host structure
Data Source
AI summary
A computer-implemented method of automated design for a vibration-based energy harvesting system for a host structure includes receiving acceleration signals obtained from one or more accelerometers attached to the host structure, determining dominating acceleration frequencies of the host structure from the received acceleration signals, determining a degree-of-freedom number of a cantilever beam based on the number of dominating acceleration frequencies of the host structure, simulating vibration of the cantilever beam across a plurality of parameters, determining values of the plurality of parameters that result in a match between resonant frequencies of the cantilever beam and the dominating acceleration frequencies of the host structure, and outputting a proposed design of the cantilever beam including the values of the plurality of parameters.