Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Distributive type parameters
Reexamination Certificate
2002-01-14
2004-01-06
Le, N. (Department: 2858)
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Distributive type parameters
C324S643000
Reexamination Certificate
active
06674292
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention is generally directed to corrosion, mold and/or moisture detection and, more particularly, the present invention is related to systems and methods for carrying out corrosion, mold and/or moisture detection utilizing microwave energy. The present invention employs microwave energy to non-destructively characterizes the dielectric properties of materials so as to be able make a determination of any presence or absence of byproducts of corrosion, mold and/or moisture, and can also enable assessment as to the bonding quality of paint onto metallic surfaces.
BACKGROUND
Corrosion of aluminum and steel is a complex situation when considering its effect and impact on military, commercial and industrial vessels and equipment. The U.S. Navy, for example, operates its aviation assets in extreme environments, which can result in staggering annual costs associated with corrosion remediation and repair. Like the federal aircraft fleet, the commercial aircraft numbers are staggering when viewed as a single market. Both military and commercial aviation operators are currently testing vinyl appliqué as an alternative to paint. One of the criticisms of appliqué in corrosive environments is the relative difficulty of inspecting for corrosion through the film-like material.
There is no known nondestructive evaluation (NDE) tool currently available that can detect corrosion under paints and appliqués. What is currently needed are corrosion detection systems and methods that do not require some removal of the paint or appliqué system in order to effectively and accurate accomplish detection of corrosion, especially with complex, high-demand systems such as military aircraft.
The present inventors herein disclose microwave-based corrosion detection systems and methods useful for nondestructive evaluation of targets. The present technology can consider the interaction between incident microwave radiation and the dielectric materials on the surface of the inspected item, including corrosion products, paints, and appliques, to detect the presence of corrosion. The ability of any corrosion detection system to sense corrosion in its earliest stages in aircraft applications, for example, is an important benefit of an NDE system. The savings available by using a condition-based maintenance approach to coating maintenance, for example, is potentially large.
BRIEF SUMMARY OF THE INVENTION
In accordance with the present Nondestructive evaluation (NDE) systems and methods, corrosion, mold and/or moisture can be detected under outlayers of structures, such as surfaces associated with vehicles or buildings. For example, moisture and/or corrosion under paint and appliques found on military and commercial aircraft can be detected using the microwave energy as described herein. Furthermore, moisture, mold and/or corrosion can be found within sublayers, underlayers and/or covered areas associated with materials, walls, ceilings, floors and/or any other structures known in the building construction industry, using microwave energy as disclosed herein. For purposes of the following disclosure, “corrosion” can be interpreted to include mold and moisture and other foreign matter not intended to be associated with a given target. Corrosion can also include improperly applied or defective materials (e.g., poorly-bonded paint-to-target surface). This condition would ultimately lead to increased susceptibility to moisture ingress and corrosion if undetected and/or repaired. Furthermore, for purposes of the following disclosure, the term “target” can be interpreted to refer surfaces, materials, and/or systems of vessels (e.g., boats, airplanes, land-based vehicles) and buildings.
In accordance with one aspect of the present invention, microwave corrosion detector (MCD) technology enables NDE/assessment through the interaction of microwaves and dielectrics such as paints, appliqués, sublayers and corrosion associated with evaluated targets. The present invention assesses the difference between incident and reflected (backscattered) microwave signals against a target to determine the presence of, or damages caused by, corrosion within a target or a targeted area associated with a target. It should be appreciated that word “corrosion” as referred to throughout the disclosure is intended to mean both corrosion and induced by corrosion.
In accordance with another aspect of the present invention, a method for non-destructively characterizing the dielectric properties of materials associated with a target is provided. The method can direct primary microwave energy from a microwave source towards a target; receive secondary microwave energy signals (backscatter) returned from the target; analyze secondary microwave energy signals; and characterize dielectric properties of materials associated with said target based on the analysis of the secondary microwave signals.
In accordance with another aspect of the present invention, a system for non-destructively characterizing the dielectric properties of materials associated with a target is provided. The system can include a microwave energy source, means for directing primary microwave energy towards a target, a receiver for receiving and measuring secondary microwave energy, a microprocessor programmed for analyzing the secondary microwave energy, and means for providing results of microprocessor analysis.
In accordance with another aspect of the present invention, a portable, hand-held system is provided for carrying out MCD inspections. The system can easily detect corrosion for maintenance or monitoring purposes.
In accordance with another aspect of the present invention, a system can non-destructively characterize the dielectric properties of materials so as to be able to determine presence or absence of byproducts of corrosion, as well as the quality of bonding of paint to metallic surfaces.
In accordance with another aspect of the present invention, a system can detect corrosion under painted aircraft surfaces without the need to strip the paint.
In accordance with another aspect of the present invention, a system can detect corrosion under painted surfaces such as petrochemical storage tanks without the need to strip the paint.
In accordance with another aspect of the present invention, a system can detect corrosion under aircraft surfaces covered with vinyl films and appliqués without the need to remove the films or appliqués (e.g., NDE).
In accordance with another aspect of the present invention, a system can detect corrosion around fastener heads on aircraft surfaces without the need to remove paint or appliqué films that would otherwise obscure the corroded areas from visual or optical inspection.
In accordance with another aspect of the present invention, an evaluator can discriminate between paint that has properly bonded to metallic surfaces and that which has not.
In accordance with another aspect of the present invention, a system can detect the presence of moisture in composite aircraft structures such as fuel tanks, radomes and control surfaces.
In accordance with another aspect of the present invention, a system can non-destructively detect the presence of moisture in building materials such as wood and gypsum wallboard.
REFERENCES:
patent: 5508203 (1996-04-01), Fuller et al.
patent: 5514970 (1996-05-01), Marshall
patent: 6198293 (2001-03-01), Woskov et al.
patent: 6411105 (2002-06-01), Liu
Bray Alan V.
Cuevas Alfonso
Dube Victor
Schmidt Gary R.
Le N.
Lopez Kermit D.
Nguyen Vincent Q.
Ortiz Luis M.
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