Construção de polariscópio linear para ensaio de tensão em vigas com geometrias bioinspiradas

Abstract

The work employs photoelasticity in the analysis of strain variations in mechanical components through the construction of a transmission plane polariscope. The technique consists of using a polarized light that passes through transparent elements (acrylic) subjected to deformation, resulting in the multi-color variation of the fringe spectrum related to the intensity of tension to which the piece is subjected. The polariscope and the specimens were modeled beforehand in 3D software, proceeding with their construction in carbon steel and acrylic sheets, respectively, described in the chapter Materials and Methods. Flexion tests were carried out with a centered bi-supported load, in curved models A and B, with holes in elliptical formats based on mappings of the ellipses of a real bone structure, observing in a comparative way the distribution of fringes along their structures and the directions of the main tensions. The C model (smooth surface and without holes), as it is a part used in the work by Melo (2019), was used only to calibrate the polariscope. The revised model of the polariscope proved to be effective for obtaining, through images, the variations of deformation through the specimens. Two cross sections were chosen to decompose the fringes. In the analysis, it was observed that Section 1 of model A has a stress concentration coefficient 19.1% lower compared to Section 1 of model B, and Section 2 of A presented 15.75% lower than Section 2 of B. The models showed balanced stress distributions, with stress-strain variation extending along the same longitudinal directions. Regarding the search for sustainability in the use of materials, the design of bioinspired projects with "leaked" materials can contribute to the decrease in the amount of material from one model to the other (C with 0.019Kg±0.001 and A with 0.018Kg ± 0.001) as well as their δ_avg values, indicate more economically viable solutions in cases of mechanical projects with low stress concentration requirements, conservation of admissible design stresses and weight reduction.