Structural Health Monitoring System Using Frequency Filters
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Solution Overview
Problem
Structural health monitoring systems face challenges in integrating active and passive components due to high voltage excitation signals damaging sensitive passive system circuitry, requiring bulky and expensive high-voltage switches for isolation.
Innovation Solution
Implementing high-pass filters in the active system and low-pass filters in the passive system to attenuate high-frequency interrogating signals, allowing both systems to operate connected to the same transducers without the need for switches, reducing complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-voltage switches are used to isolate the passive system from active system signals, then the passive system is protected from damage, but the device complexity and cost increase significantly
Solution Approach 1:
The harmful high-frequency signal component is extracted and removed from the signal path using a low-pass filter, allowing the passive system to operate without requiring complex switching isolation mechanisms. The filter extracts only the damaging frequency components while allowing useful low-frequency signals to pass through.
Solution Approach 2:
The signal characteristics are changed by frequency filtering - converting the high-frequency interrogation signals into a form that the passive system can handle. The low-pass filter changes the frequency parameter of the signals, allowing them to coexist in the same electrical environment without damage.
2Reliability
If high-voltage switches are placed between transducers and passive system, then signal isolation is achieved, but the system becomes bulky and expensive
Solution Approach 1:
The mechanical/electrical switching system is replaced with a passive electronic filtering system. Instead of using active high-voltage switches that require control logic and power, a simple low-pass filter circuit is used to achieve the same isolation effect passively, reducing cost and complexity.
3Ease of operation
If custom software is written to operate the switches, then precise control is achieved, but development time and expense increase
Solution Approach 1:
The filtering system is self-regulating and requires no external control software. The low-pass filter automatically performs the signal isolation function based on its inherent electrical properties, eliminating the need for custom control programming while maintaining precise signal separation.
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
Enables efficient and cost-effective operation of active and passive components within the same structural health monitoring system, protecting the passive system from high voltage signals while allowing for effective damage detection and monitoring.
Implementation Method 1
a signal filter operable to receive the interrogation signals from the signal transmitter, to attenuate the received interrogation signals at the first frequency, and to substantially pass received signals at a second frequency that is different from the first frequency
Data Source
AI summary
A structural health monitoring (SHM) system that protects its active and passive components with filter circuits, instead of switches. The active module of the SHM system utilizes a high pass filter, and the passive module of the SHM system utilizes a low pass filter. The active module transmits its interrogating, or excitation, signals at relatively high frequencies that are filtered out by the low pass filter of the passive module, preventing the passive module from sustaining any damage due to the high voltage excitation signals. Meanwhile, the high frequency interrogating signals are passed to the active module's circuitry by its high pass filter, where they can be analyzed accordingly.