Capacitive Probe for Polymer Hose Aging Detection
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Solution Overview
Problem
Current non-destructive testing methods are ineffective for measuring degradation in polymer cylindrical objects like aircraft fuel lines and hoses, leading to unnecessary replacements and high maintenance costs, as existing techniques have not been successfully applied to tubes or hoses with polymer inner walls.
Innovation Solution
A non-destructive testing apparatus and method using a capacitive probe with a tuned resonant circuit and analyzer to detect changes in dielectric properties by capacitively coupling with the polymer material, generating an electric field, and analyzing resonance changes indicative of aging characteristics, allowing for the determination of remaining useful life without damaging the components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If scheduled maintenance replacement is implemented, then safety is ensured, but components are needlessly replaced and maintenance costs increase
Solution Approach 1:
The patent changes the parameter from time-based replacement to condition-based replacement by measuring dielectric properties. The system monitors changes in dielectric constant and loss tangent as parameters that indicate degradation, allowing replacement only when these parameters exceed thresholds, thus avoiding unnecessary replacements while ensuring safety.
Solution Approach 2:
The patent replaces mechanical destruction (cutting and laboratory testing) with electrical field-based nondestructive measurement. The capacitive probe uses electrical fields to measure dielectric properties internally, substituting physical destruction with field-based sensing to determine component health.
2Measurement precision
If components are extracted and tested in laboratory, then degradation is measured, but components are destroyed and must be replaced
Solution Approach 1:
The patent enables the component to be tested in its installed position without removal. The capacitive probe engages with the component in-situ, allowing the component to serve both its functional purpose and its testing purpose simultaneously, eliminating the need for extraction and destruction.
Solution Approach 2:
The patent replaces mechanical extraction and physical testing with electrical field-based nondestructive testing. The capacitive probe uses electrical fields to measure dielectric properties without physical contact that would damage the component, preserving it for continued service.
3Reliability
If replacement maintenance is performed, then safe operation is ensured, but aircraft downtime increases
Solution Approach 1:
The patent performs preliminary assessment of component condition through nondestructive dielectric measurement before failure occurs. By monitoring degradation trends in advance, the system allows planning of maintenance during scheduled downtime rather than causing unscheduled downtime from unexpected failures.
Solution Approach 2:
The patent changes the maintenance trigger from fixed time intervals to variable condition thresholds. By monitoring dielectric parameters and replacing only when degradation exceeds acceptable levels, the system minimizes unnecessary downtime while ensuring safety.
4Reliability
If dielectric spectroscopy is applied to polymer materials, then nondestructive inspection is achieved, but the technique has not been successfully used on tubes or hoses with polymer inner walls
Solution Approach 1:
The patent introduces an electrolyte solution as an intermediary medium between the capacitive probe and the polymer inner wall. The electrolyte enhances the electrical field penetration and coupling with the polymer material, enabling effective dielectric measurement through the polymer wall that would otherwise be difficult or impossible to achieve.
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 non-destructive assessment of polymer cylindrical objects' aging characteristics, reducing maintenance costs and downtime by accurately determining when components need replacement based on measured dielectric property changes, rather than adhering to scheduled maintenance.
Implementation Method 1
Nondestructive testing techniques employing dielectric spectroscopy and dielectric loss as a measure of polymer aging
Implementation Method 2
capacitively coupling a tuned resonant circuit with the part by placing the circuit in physical contact with the part
Implementation Method 3
a source of electrical energy... a probe for engaging an inner surface of the cylindrical object, the probe bearing capacitor circuitry that will generate an electric field to penetrate the surface of the object
Implementation Method 4
a tuned resonant circuit that includes a first variable inductor for tuning the circuit... changes in the resonance of the circuit are indicative of changes of the dielectric constant in the part
Data Source
AI summary
Apparatus for non-destructively testing a polymeric cylindrical object to measure aging characteristics includes a source of electrical energy, a monitoring device, a probe for engaging an inner surface of the cylindrical object, and a conductor connecting at least the source of electrical energy and the probe, the probe comprising contact portions having object engaging surfaces including capacitor circuitry thereon. The probe further includes a nose portion having recesses disposed about the circumference within which the contact portions are housed, the nose portion being engagable with an inner surface of the cylindrical object and the object engaging surfaces being movable between a first position in which the object engaging surfaces are housed entirely within recesses and a second position in which the object engaging surfaces are deployed away from the nose portion.