Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
SIMULTANEOUS SHEAROGRAPHY WITH THREE SHEARING DIRECTING USING A MULTI-OPENING MASK
Submission Author:
Tainara Pedrosa de Lima , PB , Brazil
Co-Authors:
Tainara Pedrosa de Lima, Thiago Wilvert, Luan de Campos Corrêa, Estiven Sánchez Barrera, ARMANDO ALBERTAZZI JR
Presenter: Tainara Pedrosa de Lima
doi://10.26678/ABCM.COBEM2021.COB2021-0747
Abstract
Shearography is a non-destructive technique that utilizes optical principles to obtain information from the measurand. The deformation of the analyzed surface is identified through the techniques of interferometry based on laser, in addition to a series of image treatments. To exemplify, one of the configurations most used in shearography is a set composed of a beam splitter, secondary lens, a movable mirror, a tilting mirror, a camera, and also a laser. Aiming the simplification of the measuring system and the usage of fewer components to its formation, it was presented a measuring device with simultaneous shearography without using secondary lenses and prisms. The device uses a main lens to form the image and a mask with three apertures to produce the lateral shears in three directions. The combination of apertures adopted allows the passage of a small fraction of the light generated by the source due to the reduced size of the holes. The light source employed was a powerful laser manufactured by COBALT, providing enough power to illuminate the test samples and generate the carrier fringes. In simultaneous shearography , just one image is captured before and after the application of the load, which are processed with the phase spatial measurement method using the Fourier transformation. After the removal of the phase leap, the fringe of interference can be visualized. Three different strategies of excitation were adopted to validate the device via simultaneous measurement: 1) mechanical load with the help of micrometer screw to induce a known displacement in the circular test sample, 2) thermal load in cylindrical test sample with a composite material coating, 3) mechanical loading through the application of internal pressure in the cylindrical test sample. The performed experiments validated the prototype presented in this work, Shearography images were obtained which exhibited the famous butterfly pattern in three distinct directions, showing the already known defects present in the test sample. The arrangement exhibited the following advantages: robustness and less laboratory costs. However, it had the following limitations: high sensibility and images with noise. Therefore, it is a promising method with potential use for applications that require a quick set up and accepts noise to a certain level.
Keywords
speckle interferometry, multiple apertures, in-field optical measurement, spatial carrier
