Technology Overview
Shearwin is a specialized software tool for automatic and manual controlled operating and recording of (speckle) interferometry.
The work-flow kernel of Shearwin records the user operations. Its recall and re-do options of any operation sequences offers facilities to control individual research set ups as well as automatic solutions for industry problems. Remote controlled gain and shearing are features in conjunction with the sensors.
Typical applications are in-plane and out-of-plane strain and deformation measurements, vibration analysis and non destructive testing.
The Shearwin software supports the Matrox Meteor frame grabber series for b/w and color cameras of different producers. Operating systems are Windows 2000, NT and XP.
Application Example: Non-destructive Testing
Non-destructive testing is the common use of shearography. The defects become visible on measuring their inhomogeneous deformation gradients. Depending on the spatial distribution of deformation the defect or the structure itself can be characterized. The example belows shows a non-destructive testing of a rotor. The measurements show a dis-bond (left), a crack (right) and a structural transition (center).
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The high sensitivity of shearography calls for small loads. Commonly-used loading principles are:
- variation of pressure for tubes and tanks,
- vacuum chambers and heat applied by flash lights and
- dynamic excitation, which is a proprietary technique.
Solution Features
Automatic project and work-flow management: each operation step of your measurement or image operation is recorded and can be repeated with recall and redo functions or manipulated parameters.
Exposure of speckle interferograms in different acquisition techniques. This is for example the 3x3 or 4x4 phase step techniques, as well as the real time and the time average technique with renewed reference frame.
Automatic measuring routines for in-plane and out-of-plane holography as well as in-plane and out-of plane shearography. In combination with the strainograph or/and the laser-diode units or liquid crystal shutters there is the option to extend the hardware to automated 3D deformation and strain analysis system.
Shearwin offers various standard filter-types and special filters adapted to discontinuities of phase maps using State of the Art sin/cos-transformation. A new feature of Shearwin is the Fast Fourier Transformation (FFT) of interferograms including FFT Filtering and FFT evaluation of the interference phase. An outstanding function of Shearwin is the automatic sign correction after FFT phase evaluation.
Shearwin proposes an easy handling tool for masking your images by circles rectangles and polygons as well as inverting these functions to cut parts of the image which contain any irregularities and the parts of interest.
Shearwin contains a standard demodulation or unwrapping algorithm that removes the phase steps and converts the filtered phase map into a continuous plot.
If your phase map is filtered and demodulated there is the choice of automatic evaluation by the parameters such like the wave length of the used light source that have been saved in the image property sheets during the measurements.
For presentation or analysis of your results Shearwin offers tools such as 2-D or 3-D plots. If you want to include your results into other documents, you have the choice of common input and output image formats (bmp, tiff, jpg, ...) as well as the compatibility for numerical exchanges to Math-Lab, Excel and other software.
The software includes a self-calibration function for the piezo-drive that adapts automatically to the phase shift steps to your Laser wave length. Automatic shearing adjustment and control is performed with the shear control unit with or without DMS feedback controlled piezomechanical stabilization in the nanometer range. This can be also applied to stabilization of position sensitive arrangements.