Optical Non-Destructive Testing (NDT)

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Optical Non-Destructive Testing (NDT)
Real-time electronic holography Speckle Shearing
Interferometry (Shearography)

• Full-field optical technique
• Capable of detecting surface and sub-surface
  defects in components
• In real-time
• In situ
• In service
• Over a wide area
• Through coatings- without surface preparation

Pseudo-coloured output
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Optical NDT
Schematic of a portable shearography system
Optical system containing laser and imaging optics
PC and monitor
Component under test
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Optical NDT
AOS Products

• Robust field portable optical systems
• Customised mounting arrangements for optical
  systems
• User friendly software
• Customised loading mechanisms

AOS Services

• Research and Development
• Design Manufacture of Optical Systems and
  Mounting Units
• Inspection Services

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Optical NDT
Shearography

• Based on the capture and processing of images of
  a test component illuminated by laser light
• Image taken before and after the component is
  subjected to a deformation. The deformation may
  be the result of, for example
• Internal pressure modification
• Mechnaical loading
• Localised heating
• Difference image provide strain profile
  information

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Optical NDT
Defect detection using shearography

• Difference image reveals
• Normal Deformations of component
• Abnormal deformations of the component induced by
  defects
• Defect are detected through the observation of
  fringe distortion/concentrations
• The size and location of a defect are directly
  related to the size and location of the fringe
  anomaly
• The nature of the defect may be determined from
  the signature of the fringe anomaly

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Optical NDT
Schematic of a shearography system
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Optical NDT
NDT using shearography

• Essentially becomes the development of a
  practical means of loading the component that
  can reveal the defects
• Loading methods widely used include
• Mechanical Strain measurement and crack
  detection in homogenous and composite materials
• Thermal Delamination and impact damage in
  composite materials
• Vacuum General purpose for composites
• Internal Pressurisation General purpose for
  pressure vessels and piping
• Acoustic Resonant frequencies and modal
  characteristics analysis

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Optical NDT
Fitness for Purpose information using
shearography

• By imposing loading similar to that experienced
  by the component in service, only those defects
  that serve to reduce the strength/performance of
  the component can be detected
• Information aboutcriticality of the defect is
  obtained
• Cosmetic defects can be ignored

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Optical NDT
Benefits

• Reduce inspection time and costs
• whole component inspection viable
• real-time, in-situ, in service inspections of
  components
• surface preparation requirements eliminated
• Produce real-time data during inspection
• permanent computer based records
• Fitness for purpose information
• Identify significant defects

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Optical NDT
Applications

• Gas Petrochemical
• Pressure vesssels and piping (homogeneous and
  composites)
• Automotive
• engine components, body panels, dash boards
• Aerospace
• Composite panels, turbineblades, tyres
• Marine
• Boat body panels, pressure vessels

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Examples of Applications
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Thank you
S.C.Murray 2004