Digitalização e correlação da imagem obtida pela técnica da fotoelasticidade com as tensões em materiais submetidos a esforços em regime elástico

Abstract

The photoelasticity technique uses light polarizing filters positioned downstream and upstream of a material with photoelastic properties to visualize a fringe pattern correlated with stress. Therefore, it is an experimental technique for observing stress in components subjected to loads. The Applied Mechanics Laboratory LabMEC/UFG has a photoelasticity bench, also known as a polariscope, which was developed as part of Guimarães' (2024) undergraduate thesis entitled "DESIGN OF A DIDACTIC BENCH FOR THE APPLICATION OF THE PHOTOELASTICITY TECHNIQUE". In addition to the design, that work resulted in the construction of the polariscope, with qualitative comparisons of stress in thin plates with different geometric features against numerical models obtained using Autodesk Inventor. However, at the end of the study, suggestions were presented for future work: [1] improving the plane polariscope by converting it into a circular one; [2] instrumenting the material under stress using strain gauges; [3] instrumenting and exploring other load application modes, such as bending, torsion, shear, and axial loading; and [4] digitizing the photoelasticity image and correlating it with theoretical stress models. Furthermore, the present project will also contribute to the research project "Development of Didactic-Experimental Support Apparatuses for Mechanical Engineering," in which the polariscope bench will support courses in the Mechanical Systems Design area through experimental stress analysis practices. In addition, image digitization and correlation with known models represent innovation and technology in experimental stress studies. Finally, the present project aims to improve the LabMEC/UFG polariscope and contribute to the didactic-experimental support apparatuses of the research project. As a result, the instrumentation of the bench proved satisfactory for the controlled application of loads and for obtaining photoelastic fringe patterns. The comparison between the optical arrangements indicated a significant improvement with the use of the circular polariscope, which provided better definition of the fringe contours, sharper chromatic transitions, and less visual interference compared to the plane polariscope. It is concluded that the adaptation of the system, associated with digital image processing, increased the reliability of the bench as a didactic-experimental tool for stress analysis.