Differential Capacitive Probe for Contact Resistance Measurement
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Solution Overview
Problem
Direct lightning effect tests for aircraft and other structures are resource-intensive and destructive, making it difficult to measure contact resistance in fiber-reinforced materials like carbon fiber reinforced polymers (CFRPs) due to their anisotropic properties and the lack of accessible contact points.
Innovation Solution
A differential capacitive probe is designed to measure contact resistance by generating an electrical current flow through the fiber-reinforced material, using two capacitive pads with equal contact surface areas to isolate the contact resistance from the fiber resistance, allowing for non-destructive and efficient testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct lightning effect testing is used to measure contact resistance in fiber-reinforced materials, then measurement capability is provided, but the testing process becomes resource-intensive and destructive
Solution Approach 1:
The patent replaces the mechanical/electrical direct lightning effect testing system with an optical measurement system. The optical time domain reflectometer (OTDR) uses optical signals to measure contact resistance at fiber interfaces, eliminating the need for complex electrical testing equipment and high-current pulses, thereby reducing resource consumption and avoiding destructive testing.
Solution Approach 2:
The patent introduces an intermediary measurement approach by using optical signals as a mediator to indirectly measure electrical contact resistance. Instead of directly applying electrical current and measuring voltage drop (which requires complex equipment), the system uses optical reflectometry to characterize the interface properties that correlate with contact resistance, simplifying the measurement process.
2Measurement precision
If direct lightning effect testing is used to measure contact resistance in fiber-reinforced materials, then measurement capability is provided, but the testing process becomes destructive requiring inspection and repair
Solution Approach 1:
The patent replaces the mechanical/electrical direct lightning effect testing system with an optical measurement system. The optical time domain reflectometer (OTDR) uses optical signals to measure contact resistance at fiber interfaces, eliminating the need for complex electrical testing equipment and high-current pulses, thereby reducing resource consumption and avoiding destructive testing.
Solution Approach 2:
The patent converts the harmful effect of destructive electrical testing into a beneficial non-destructive optical measurement process. By using optical reflectometry, the system can characterize interface properties and measure contact resistance without causing damage to the fiber-reinforced materials, allowing repeated measurements and preserving the tested components for continued use.
3Measurement precision
If conventional testing methods are used for contact resistance measurement, then measurement is possible, but the complexity of equipment and procedures increases
Solution Approach 1:
The patent replaces the mechanical/electrical direct lightning effect testing system with an optical measurement system. The optical time domain reflectometer (OTDR) uses optical signals to measure contact resistance at fiber interfaces, eliminating the need for complex electrical testing equipment and high-current pulses, thereby reducing resource consumption and avoiding destructive testing.
Solution Approach 2:
The patent introduces an intermediary measurement approach by using optical signals as a mediator to indirectly measure electrical contact resistance. Instead of directly applying electrical current and measuring voltage drop (which requires complex equipment), the system uses optical reflectometry to characterize the interface properties that correlate with contact resistance, simplifying the measurement process.
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 differential capacitive probe effectively isolates contact resistance at fastener interfaces, enabling accurate and non-destructive measurements, which is crucial for ensuring compliance with standards like those set by the Federal Aviation Administration.
Implementation Method 1
generating an electrical current flow through the fiber-reinforced material
Implementation Method 2
first capacitive pad and a second capacitive pad... respective voltage readings from the first capacitive pad and the second capacitive pad
Data Source
Figure 1
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AI summary
A differential capacitive probe for measuring contact resistance, the differential capacitive probe including a frame, an end effector extending from the frame, a first capacitive pad coupled to the frame so as to at least partially circumscribe the end effector, and a second capacitive pad coupled to the frame so as to be radially spaced, relative to the end effector, from the first capacitive pad and to at least partially circumscribe the end effector, wherein a contact surface area of the first capacitive pad is substantially the same as another contact surface of the second capacitive pad.