A shearography camera is used to measuring the surface displacement of a pressure vessel during the application of a small pressure load well below its operating pressure.
NASA WSTF
Shearography provide fast, accurate, real-time information about internal material discontinuities and inconsistencies on large and small surfaces. This portable, non-contacting method can detect extremely small, defect induced deformations in surface profiles indicating a hidden flaw or stress point such as
- Impact and heat damage
- Disbonds, unbonds, and delamination
- Core damage
- Foreign Objects and Debris
- Epoxy Matrix Deficiency or Excess
- Near Surface Cracks
- Fluid Ingress
- Loose Fiber Tows
A shearography camera records two images of a test article’s surface. The first image captures the surface of the test article in a neutral state. The second images captures the surface under a load or stress typically in the form of heat, cold, pressure, vacuum, vibration or electromagnetic energy. Comparison of the images quickly identifies variations between both images revealing underlying issues.
Dangerous subsurface defects, like the impact damage to this spherical composite pressure vessel, often evade visual detection (L). These are clearly identified via shearography (R).
NASA WSTF