Strain Analysis of Metals Under Compression Using Shearing Interferometry and Strain Gauges

When a material is subjected to external forces, it undergoes internal mechanical deformations. To measure this type of deformation, mechanical sensors such as load cells, strain gauges, etc., are typically used. These sensors convert mechanical energy into electrical energy, which can then be displayed on electronic displays. Noninvasive methods can be used to measure deformations in materials. These methods use light as a measurement medium. These include non-destructive optical testing (Ronchi test, Foucault test, etc.) and interferometric testing. Among the most commonly used interferometers for strain measurement are shearography configurations, as they are suitable for measuring in-plane or out-of-plane deformations. In the present work, the deformations of four rectangular pieces made of materials used in the automotive and aerospace industries will be analyzed: 6061 aluminum, as well as 304, 1045, and 4041 steels. The analysis will be performed using optical interferometry, using a shearing interferometer, with shear in the direction of the applied compression force, in a Y-shape. In addition, the results will be compared with a Wheatstone bridge arrangement made with four strain gauges, as well as with finite element analysis. Compressive forces of 491 N to 2453 N were applied to each sample, yielding different fringe patterns in the obtained interferograms. When processed to obtain their respective phases, the proposed materials exhibited different elasticity. The interferometric results were compared with those obtained with strain gauges, which were placed on the opposite side of the test objects. Furthermore, the interferometric results reliably reflect the results obtained with the finite element analysis, showing the deformation of the material when the compressive force is applied vertically.