Carbon Nanotube Sensor Array for Micro-Crack Detection
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Solution Overview
Problem
Conventional ultrasonic inspection systems are unable to detect micro-sized and nano-sized cracks, sub-surface closed cracks, and residual stress, and are not well-suited for in situ testing of thin films and coatings due to limitations in sensor technology and frequency range.
Innovation Solution
An apparatus and method using a sensor array comprising carbon nanotubes to generate electrical signals in response to high-frequency acoustic shockwaves, allowing for the detection of structural integrity and generation of 2-dimensional images of material conditions, including cracks and residual stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ultrasonic transducers are used for inspection, then the inspection system can operate at frequencies between 20 kHz and 10 MHz, but the system cannot detect micro-sized and nano-sized cracks, sub-surface closed cracks, and residual stress
Solution Approach 1:
The patent changes the frequency parameter from conventional ultrasonic ranges (20 kHz - 10 MHz) to super high-frequency ranges (>10 MHz, specifically 20-100 GHz). This parameter change enables the detection of micro-sized and nano-sized cracks, sub-surface closed cracks, and residual stress that are invisible to conventional ultrasonic systems. The nanotube sensors are specifically designed to operate at these elevated frequencies.
Solution Approach 2:
The patent replaces conventional mechanical ultrasonic transducers with nanotube-based sensors that utilize quantum mechanical effects (phonon absorption and electron transport). This substitution enables detection at super high frequencies that mechanical transducers cannot achieve, while also providing enhanced sensitivity to minute structural defects and residual stresses.
2Adaptability or versatility
If conventional ultrasonic inspection systems are used, then the system can perform non-destructive testing, but the system cannot adequately inspect thin films and coatings or perform in situ testing
Solution Approach 1:
The patent employs nanotube sensors that can be fabricated as thin films or flexible structures, enabling direct application to thin film and coating inspections. The nanoscale dimensions of the sensors allow them to conform to and detect defects in thin structures without requiring substantial access or disassembly, making in situ testing feasible.
3Measurement precision
If conventional strength testing procedures are used, then the material strength can be determined, but the material is destroyed or permanently deformed
Solution Approach 1:
The patent replaces destructive mechanical loading tests with non-destructive super high-frequency ultrasonic inspection. By using nanotube sensors to detect acoustic emissions, wave propagation changes, and resonance characteristics at frequencies >10 MHz, the system can assess material strength and detect defects without applying loads that would cause permanent deformation or failure.
4Measurement precision
If conventional ultrasonic transducers are used, then the system can perform inspection, but the sensors are too large to detect micro-sized and nano-sized cracks
Solution Approach 1:
The patent changes the operational frequency parameter to super high frequencies (>10 MHz), which allows the use of nanoscale sensors instead of large conventional transducers. At these elevated frequencies, the wavelength becomes comparable to micro and nano defect dimensions, enabling detection with sensors that are orders of magnitude smaller than conventional ultrasonic transducers.
Solution Approach 2:
The patent utilizes carbon nanotube composite structures that combine the mechanical properties needed for high-frequency operation with nanoscale dimensions. These composite nanotube sensors provide both the sensitivity required for detecting minute defects and the small size necessary for micro and nano-scale inspection applications.
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 the detection of micro-sized and nano-sized anomalies, sub-surface defects, and residual stress, providing a non-destructive, in situ inspection capability for structural integrity assessment.
Implementation Method 1
The plurality of nanotubes are configured to generate electrical signals when acted upon by an acoustic shockwave propagating through the part
Implementation Method 2
acoustic shockwave propagating through the part
Implementation Method 3
The electrical signals are proportional to an intensity of the acoustic shockwave
Data Source
AI summary
Disclosed herein is an apparatus for inspecting structural integrity of a part. The apparatus includes a body and at least one sensor. The body is movable relative to the part. The at least one sensor is coupled to the body and includes a plurality of nanotubes configured to generate electrical signals when acted upon by an acoustic shockwave propagating through the part. The electrical signals are proportional to an intensity of the acoustic shockwave.