What Does
Shearography Mean?
Shearography is an optical measurement technique used to rapidly detect various types of defects on composites and metallic materials. Shearography uses coherent light or sound waves to create a visual representation of the quality of the material for nondestructive testing, strain measurement and vibration analysis. It is commonly used in quality control applications in numerous sectors including aerospace, automotive, marine and power generation.
Shearography is also known as speckle pattern shearing interferometry.
Corrosionpedia Explains Shearography
The basic principle of shearography involves using a camera, or a series of cameras, to record the interferometric properties of a surface. A photo is first taken of the surface in a neutral or unloaded state; this includes various measurements of its roughness and shape.
Next, the material is stressed or excited with a specific type of load, such as heat, vacuum or vibratory excitation. Once loaded, the material reacts, causing the defects to expand accordingly. Another interferometric photo is then taken of the sample in its loaded and deformed state.
The two images are subtracted to create a shearogram that represents the topography of the surface defects. Shearography can be used to detect several types of defects such as delamination, cracks, disbanding, excessive porosity, wrinkling, fluid ingress and more.