Optical Non-Destructive Testing (NDT)

1. 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

2. Optical NDT Schematic of a portable shearography system Optical system containing laser and imaging optics PC and monitor Component under test

3. 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

4. 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

5. 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

6. Optical NDT Schematic of a shearography system

7. 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

8. 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 about”criticality” of the defect is obtained • “Cosmetic “ defects can be ignored

9. 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

10. 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

11. Examples of Applications

17. Thank you S.C.Murray 2004