PSI - Issue 5

Pedro J. Sousa et al. / Procedia Structural Integrity 5 (2017) 1253–1259 Pedro J. Sousa et al. / Structural Integrity Procedia 00 (2017) 000 – 000

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Fig. 6. Shape differences between the unloaded (reference) and loaded (deformed) states. The values are in the range [-3.5, 0.2].

The shape-matching scheme that was used only considers deformations from the matched region towards the tip. This means that the actual differences in shape are bigger than the calculated ones. Nevertheless, it allows the comparison of the actual shapes, disregarding any rigid body rotations and translations.

4. Conclusion and future work

The presented work was a successful first step towards deformation monitoring of rotating targets up to 1200 rpm. It was possible to acquire images with enough quality for the application of Digital Image Correlation. As such, shape acquisition and displacement measurement was performed, matching the expected results. The Digital Image Correlation procedure used in VIC-3D is very sensitive to differences between the acquired images, which resulted in difficulties, since the Photron FASTCAM SA4 is currently giving lower quality images than the SA3. This quality difference is not present while in live mode, however the images have lower contrast and a blueish tint when acquired. Some workarounds are currently being considered for future works in order to reduce or eliminate this quality loss. In parallel, in order to improve the robustness of the system, a new approach to DIC is currently being developed in INEGI in order to replace VIC-3D in the future. Currently planned future work in this area involve the use of additional lighting and faster shutter speeds or of high power strobes in order to solve the problem of motion blur. In parallel, the problem of the depth-of-field should also be solvable with additional lighting, increasing the usable depth-of-field by closing the aperture of the cameras.

Acknowledgements

The authors gratefully acknowledge the funding of Project NORTE-01-0145-FEDER-000022 - SciTech - Science and Technology for Competitive and Sustainable Industries, co-financed by Programa Operacional Regional do Norte (NORTE2020) through Fundo Europeu de Desenvolvimento Regional (FEDER).

References

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