NONDESTRUCTIVE INSPECTION OF COMPOSITE STRUCTURES

Presented by:-Rohit Goyal14MMT0068

• Composite materials are widely used in a number of industrial sectors from aviation, space, to boat building, automotive, and sports goods.

• The various forms of composite materials, with their advantages of light weight, design flexibility, and high specific stiffness and specific strength, are widely used as structural materials in the aviation, space, marine automobile, and sports industries.

• composites is a crucial component in critical structures on airplanes, space vehicles, and boats

AIRCRAFT ANALYSIS:

• Nondestructive testing is used extensively during the manufacturing ,in-service of aircraft.

AIRCRAFT ANALYSIS:

• Carbon graphic composite materials are now being used in the latest generation of commercial aircraft such as the Boeing 787 and the Airbus A350

• Classical inspection methods such as the tap-hammer or ultrasound are still widely used for the inspection of composite structures on aircraft

Limitation• Dependency of the inspection results on the experience of the

inspector

• Do not allow for the scanning of large areas in an economically

efficient manner.

Active thermography

• Active thermography is a non-destructive inspection systems are used to verify the Structural integrity of composite materials.

• active thermography enables large-area measurements to be performed and results presented as images that can be easily interpreted.

• active inspection systems are relatively easy to operate and do not necessarily require an experienced inspector to perform.

• a single measurement can cover an area of from a few millimeters to several square meters

Active Thermography

What is active thermography?

•Active thermography system is an automated image scanning unit designed to detect defects in advanced composite structures designed and built for high performance aircraft.

How it works?

•Based on inducing a heat flow in the part to be inspected

•The propagation of the heat flow inside the object directly affects the temporal behavior of the surface temperature

•By imaging the object with an infrared camera, captured data can be analsed to show the internal structure of the part and any defects

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• Automation AT system consists of a measuring head and a tablet computer.

• measuring head contains an IR Smart Eye 320 GEV infrared Ethernet camera with integrated control electronics and a halogen lamp heat source with integrated power electronics.

• these components are mounted on a frame that contains three legs with vacuum-driven suction cups .suction cups are used for fixing the measuring head to the surface of the object to be inspected

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Benefits•required inspection can be done in a series of tests by personnel without a NDT background.

•Detection of hidden defects like cracks, disbondings or delaminations in metal or plastic materials

•No system calibration required

•Inspect most parts in minimum time.

•the complete side of an A320 rudder could be checked in 2.5 hours.

Laser Ultrasonic Systems

• Laser ultrasonic non-destructive inspection systems are used to verify the structural integrity of composite materials

•  Laser Ultrasound (LUS) is a method to generate and detect ultrasonic signals remotely with the aid of lasers, without requiring direct physical contact between probe and samples

• What is LaserUT®?

• LaserUT® system is an automated ultrasonic scanning unit designed to detect defects in advanced composite structures designed and built for high performance aircraft.

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How it Works?• LaserUT® uses pulse-echo ultrasound and requires only single-sided access to a structure.

• Laser beams that generate and detect ultrasound are scanned across the testing surface.

•Ultrasound generation works by a mechanism called thermo-elastic expansion

•In this process, a pulse generation laser is directed at the surface of the material under test.

•The beam is absorbed into a shallow volume of the material

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• The rapid absorption of the pulse laser energy creates a localized heating, which results in expansion of the materials, inducing a stress wave.

• This stress wave is also an ultrasonic wave

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• The ultrasonic signal is detected using another pulsed laser whose wavelength is scattered from the surface of the material .

• The light scattered off the surface is collected and inserted into an interferometer to “strip off” the ultrasonic signal

• Once the signal is “stripped off” by the interferometer, it is sent to silicon detectors that convert the light signals to electrical signals

• The signal from each detection point on the surface of the part is collected by a computer, filtered, processed, stored, and displayed.

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Block Diagram of LaserUT® System

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• Completed LaserUT® scans of composite skins are displayed in the User Interface

LaserUT® Scan of a Typical Composite Showing A, B, and C-Scan Images

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Benefits•Significantly reduces setup time (typically 5 minutes or less)

•No special tooling or fixtures required for each part

•Minimal training requirements - results are operator invariant

•No system calibration required

•No special foundation required

• Requires no couplant of any kind .

•No direct contact between probe and surface

•Scan surface of complex shaped parts at speeds on the order of ten-times faster than conventional ultrasonic systems.

References• David K. Hsu, "Nondestructive Evaluation of Damage in

Composite Structures," Proceedings of the 21st Technical Conference of the American Society for Composites, September 17-20, 2006, Dearborn, Michigan, pp. 1-14.

• A. Pasztor, “Older Airbus Jets Get High-Tech Rudder Check,” Wall Street Journal, December 19, 2006. p.41 F. Fiorino, “Rudder Alert”, Aviation Week and Space Technology, April 3, 2006, p.41

• NTSB website http://www.ntsb.gov/AA587/default.html

• J. S. Sandhu, H. Wang, M. M. Sonpatki, and W. J. Popek, “Real time full field ultrasonic inspection of composites using acoustography,” NDE and Health Monitoring of Aerospace Materials and Composites II, edited by A. L. Gyekenyesi and P. J. Shull, Proc. SPIE, Vol. 5046, 00-104 (2003).

• M. Lasser and G. Harrison, “High speed high resolution ultrasound imaging system for composite inspection,” 29th International SAMPE Conference, 1997.

Thanks

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