# US 2019/0168892 A1 · Nondestructive Inspection Techniques for Rotorcraft Composites

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- Number: US 2019/0168892 A1
- Document ID: US20190168892A1
- Status: Published application
- Kind: A1
- Application number: 16/204,995
- Filed: 2018-11-29
- Published: 2019-06-06
- Earliest claimed: 2012-07-19
- Assignees: Bell Helicopter Textron Inc.
- Applicants: Bell Helicopter Textron Inc.
- Inventors: Jeffrey P. Nissen; Edward Hohman; Robert J. Barry
- Web page: https://patentgrep.com/patent/US20190168892A1

## CPC

- B64F 5/60: Testing or inspecting aircraft components or systems
- G01N 21/3581: using far infrared light; using Terahertz radiation
- G01N 21/8806: {Specially adapted optical and illumination features}
- G01N 21/95: characterised by the material or shape of the object to be examined (G01N21/89 - G01N21/91, G01N21/94 take precedence)
- G06T 5/90: Dynamic range modification of images or parts thereof
- G06T 7/0004: {Industrial image inspection}
- G06T 7/13: Edge detection
- H04N 23/23: from thermal infrared radiation
- B64C 2001/0072: {from composite materials}
- G01N 2021/8472: {Investigation of composite materials}
- G06T 2207/10048: Infrared image
- G06T 2207/10152: Varying illumination
- Y02T 50/40: Weight reduction
- B64F: GROUND OR AIRCRAFT-CARRIER-DECK INSTALLATIONS SPECIALLY ADAPTED FOR USE IN CONNECTION WITH AIRCRAFT; DESIGNING, MANUFACTURING, ASSEMBLING, CLEANING, MAINTAINING OR REPAIRING AIRCRAFT, NOT OTHERWISE PROVIDED FOR; HANDLING, TRANSPORTING, TESTING OR INSPECTING AIRCRAFT COMPONENTS, NOT OTHERWISE PROVIDED FOR
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- B64C: AEROPLANES; HELICOPTERS
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

A field deployable infrared imaging (FDIR) system and method for inspecting a composite component comprises a hand-held long-wave IR camera to capture a thermal image of the composite component, wherein the camera has an adjustable temperature control that captures an image with a 10 degree working range, a frame capture rate of at least 1 second for a length of time of not less than 90 seconds; and a processor for post-processing the thermal image using a second order derivative algorithm wherein the post-processed thermal image shows the defect better than the captured infrared image, and detects the one or more defects in the composite component.

## Claims

### Claim 1

A method for detecting defects in a composite component of an aircraft comprising:
subjecting the composite component to infrared radiation;
using a hand-held, long-wavelength IR camera to capture a thermal image of the composite component, wherein the camera has an adjustable temperature control, captures an image having a 10 degree working range, a frame capture rate of at least 1 second (minimum) for a length of time of not less than 90 seconds, wherein the image is detected within a predetermined amount of time from a start of a temperature change; and
post-processing the thermal image using a second order derivative algorithm wherein the post-processed thermal image shows more detail of defects than the captured infrared image, and detects the one or more defects in the composite component.

### Claim 2 (depends on 1)

The method of claim 1, further comprising a user interface coupled to the processing system and configured to process the captured infrared image on a pixel-by-pixel basis and produce a processed image, wherein the processed image shows more detail of defects than the captured infrared image.

### Claim 3 (depends on 2)

The method of claim 2, wherein the processing system is configured to enhance the contrast of the captured infrared image using at least one of a first order derivative algorithm and a second order derivative algorithm.

### Claim 4 (depends on 2)

The method of claim 2, further comprising input and output devices coupled to the processing system and configured to communicate with an external device to transfer the captured infrared image, the processed image, or both.

### Claim 5 (depends on 2)

The method of claim 2, further comprising an environmental sensor coupled to the processing system and configured to detect an environmental factor and associate the environmental factor with the captured infrared image.

### Claim 6 (depends on 2)

The method of claim 2, further comprising location position sensing devices coupled to the processing system and configured to provide location based data.

### Claim 7 (depends on 1)

The method of claim 1, further comprising an emitter configured to emit infrared radiation onto the composite component at a first wavelength range, wherein the infrared camera captures images at a second wavelength range, and wherein the first wavelength range is different from the second wavelength range.

### Claim 8 (depends on 7)

The method of claim 7, wherein the first wavelength range comprises a wavelength from about 800 nanometers to about 2,500 nanometers.

### Claim 9 (depends on 8)

The method of claim 8, wherein a change in temperature of an aircraft is caused by: moving the aircraft our of a hanger and into sunlight, out of the sunlight and into a hanger, by forced air, by removing thermal blankets, or other exposure to a change in temperature that affects a large area of the aircraft.

### Claim 10 (depends on 8)

The method of claim 8, wherein a large area thermal image of a temperature-soaked aircraft, or part thereof, is captured within 60 seconds of being introduced to delta temperature difference.

### Claim 11 (depends on 8)

The method of claim 8, wherein the second wavelength range comprises a wavelength from about 1,000 nanometers to about 2,000, 5,000 nanometers, or 12,000 nanometers.

### Claim 12 (depends on 1)

The method of claim 1, wherein the defect is a structure of an aircraft made of fiber reinforced composite materials of low thermal conductivity and the area of detection is a sub-structure, or a fiber reinforced composite materials of low thermal conductivity located on a metallic sub-structure, and the processed image shows integrity and location on the aircraft.

### Claim 13 (depends on 1)

The method of claim 1, wherein the long wave IR camera is a receiver of available thermal excitation sunlight, ambient, or forced air resulting in a minimum delta of 10 degrees Fahrenheit over a structure having a homogeneous temperature.

### Claim 14 (depends on 1)

The method of claim 1, wherein the composite component is located on an aircraft.

### Claim 15 (depends on 1)

The method of claim 1, further comprising using a low cost, a long-wave camera having integrated processor, environmental sensor, I/O devices and a user interface.

### Claim 16 (depends on 1)

The method of claim 1, further comprising moving an aircraft into sunlight, into shade, or to a location with a change in environmental temperature prior to capturing the image.

### Claim 17 (depends on 1)

The method of claim 1, further comprising capturing the image within 30, 60, 90, or 120 seconds from the change in environmental temperature.

### Claim 18

An apparatus, comprising:
a hand-held long-wave IR camera to capture a thermal image of the composite component, wherein the camera has an adjustable temperature control that captures an image with a 10 degree working range, a frame capture rate of at least 1 second for a length of time of not less than 90 seconds;
a processing system coupled to the camera, wherein the processing system is configured to process the captured infrared image on a pixel-by-pixel basis and determine whether a defect exists within the composite component; and
a user interface coupled to the processing system and configured to process the captured infrared image on a pixel-by-pixel basis and produce a processed image, wherein the processed image shows the defect better than the captured infrared image.

### Claim 19 (depends on 18)

The apparatus of claim 18, wherein the processing system is configured to enhance the contrast of the captured infrared image using a second order derivative algorithm.

### Claim 20 (depends on 18)

The apparatus of claim 18, further comprising an emitter configured to emit infrared radiation at a wavelength between about 800 nanometers and about 2,500 nanometers onto the composite component.

### Claim 21 (depends on 18)

The apparatus of claim 18, wherein the emitter is configured to emit infrared radiation comprising an intensity of at least about 200 watts per meter squared (W/m2).

### Claim 22 (depends on 18)

The apparatus of claim 18, wherein the composite component is located on an aircraft.

### Claim 23

An apparatus operable to detect defects in a composite component of an aircraft comprising:
a hand-held long-wave IR camera to capture a thermal image of the composite component, wherein the camera has an adjustable temperature control that captures an image with a 10 degree working range, a frame capture rate of at least 1 second for a length of time of not less than 90 seconds; and
a processor for post-processing the thermal image using a second order derivative algorithm wherein the post-processed thermal image shows the defect better than the captured infrared image, and detects the one or more defects in the composite component.

### Claim 24 (depends on 23)

The apparatus of claim 23, wherein the infrared radiation comprises a first wavelength between about 800 nanometers and about 2,500 nanometers and an intensity of at least about 200 watts per meter squared (W/m2), and wherein the capturing the thermal image comprises capturing the thermal image at a first wavelength of at least one of: a range of about 1,000 to about 2,000 nanometers; a range of about 3,000 to about 5,000 nanometers; and a range of about 8,000 to about 12,000 nanometers.

### Claim 25 (depends on 23)

The apparatus of claim 23, wherein a high emissive black coating is applied to the composite component prior to subjecting the composite component to infrared radiation.

### Claim 26 (depends on 23)

The apparatus of claim 23, wherein the thermal image of the composite component occurs at an offset angle of at least about 10 degrees from the infrared radiation.