Hammer Activated Measurement System for Submarine Hull Coating Debonding
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Solution Overview
Problem
Current methods for detecting debonding of exterior hull coatings on submarines are prone to inaccuracies, including overdetection and underdetection, and require extensive calibration, making them time-consuming and costly, especially due to the variability in materials and thicknesses of the coatings and hulls.
Innovation Solution
The Hammer Activated Measurement System (HAMSTER) uses a handheld impulse hammer with a force sensor to measure force-versus-time data, normalizing the data to create a universal profile for comparison, eliminating the need for frequency domain analysis and response transducers, allowing for rapid and accurate detection of debonding by calculating the Root Mean Square Difference (RMSD) between measured pulses and the profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual inspection methods (visual inspection and hand-tapping) are used to detect EHC debonding, then the detection process is simple and requires no special equipment, but the detection accuracy is low and prone to both overdetection and underdetection
Solution Approach 1:
The patent replaces manual mechanical inspection (hand-tapping with putty knives) with an automated impact detection system that uses accelerometers and signal processing to detect debonding. The system automatically measures vibration responses to impact forces and analyzes frequency spectra to identify debonded regions, eliminating the need for manual auditory assessment and significantly improving detection accuracy while reducing subjectivity and human error
Solution Approach 2:
The patent introduces an intermediary detection system consisting of accelerometers mounted on the hull that act as mediators between the impact force and the detection process. These sensors capture the vibration responses caused by impacts on the EHC, converting mechanical vibrations into electrical signals that can be analyzed by the control unit to determine the presence of debonding, thus providing an objective and accurate detection method
2Measurement precision
If frequency domain analysis with multiple accelerometers and transfer functions is used to detect debonding, then measurement precision is improved, but device complexity and calibration requirements increase significantly
Solution Approach 1:
The patent extracts and utilizes only the essential frequency information needed for debonding detection by analyzing the frequency spectrum of acceleration signals. Instead of implementing complex multi-accelerometer transfer function analysis, the system focuses on identifying characteristic frequency patterns and peaks that indicate debonding, simplifying the detection algorithm while maintaining high accuracy through targeted frequency domain analysis of single accelerometer signals
Solution Approach 2:
The system performs self-calibration and adaptive learning by automatically establishing baseline frequency characteristics during an initial survey phase. The control unit stores reference frequency data from known good conditions and uses this self-generated reference to detect debonding in subsequent surveys, eliminating the need for manual calibration procedures and reducing operational complexity while maintaining detection precision
3Measurement precision
If extensive calibration procedures are performed to account for material and thickness variability, then measurement precision is improved, but the time required for detection increases significantly
Solution Approach 1:
The patent performs preliminary characterization during an initial survey phase where the system automatically collects and stores baseline frequency data from various hull sections with different EHC materials and thicknesses. This preliminary action creates a library of reference frequency signatures that the system later uses for rapid comparison during operational surveys, eliminating the need for time-consuming calibration procedures before each detection survey while maintaining accuracy across varying conditions
Solution Approach 2:
The system adapts to material and thickness variability by dynamically adjusting detection parameters based on the measured frequency characteristics of each hull section. The control unit automatically modifies analysis thresholds and frequency ranges according to the specific EHC properties detected, allowing the system to maintain high detection accuracy across different materials and thicknesses without requiring manual recalibration for each condition
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
HAMSTER provides high accuracy and rapid detection of bonded or debonded states, reducing user fatigue and survey time, while being adaptable to various substrates and laminate thicknesses, and does not require frequent recalibration or complex equipment.
Implementation Method 1
an impulse hammer with a force sensor attached thereto is swung to impact a region of the laminate
Implementation Method 2
the force sensor measures force-versus-time data upon impact of the impulse hammer
Data Source
AI summary
A device and method are provided for determining whether a laminate is bonded or debonded from its substrate. The device and method provide simple, accurate, rapid, cost-effective, and reliable means for assessing the bonding state of a laminated substrate.