DEVELOPMENT OF MULTIFUNCTIONAL STRUCTURES FOR MEASURING TEMPERATURE, STRAIN, ANGLE, AND VIBRATION FREQUENCIES USING ADDITIVE MANUFACTURING TECHNIQUES
Nome: ROBERTSON WESLEY MONTEIRO PIRES JUNIOR
Data de publicação: 17/04/2024
Orientador:
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| ARNALDO GOMES LEAL JUNIOR | Orientador |
Banca:
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| ARNALDO GOMES LEAL JUNIOR | Orientador |
Resumo: This Master’s Thesis presented the development of different multifunctional structures embedded with fiber Bragg gratings (FBGs). Additive manufacturing techniques were used to manufacture these structures. A manufacturing method that became popular mainly with the advent of fused filament manufacturing (FFF) printers. The manufactured multifunctional structures consist of an artificial tendon capable of monitoring deformation parameters, temperature, and curvature angle; a temperature sensor capable of measuring it in different environments; and a frequency meter in the form of a cantilever beam. The artificial tendon was manufactured by pouring polyurethane resin (PU) into a mold made with polylactic acid (PLA) filament so that the resin coated the FBGs. The temperature sensor was manufactured with light-cured resin and the FBG was embedded in an aperture in the structure. Two accelerometers were manufactured by FFF using nylon filaments and 17-4 PH, which is stainless steel but in the form of a filament aggregated with polymeric particles. The materials used to manufacture the structures were characterized by static and dynamic mechanical tests. In static tests, it was noted that Young’s modulus (E) increases as a function of the increase in the cross-section of the specimen, which was modified by varying the infill and wall thickness of the body. However, the mechanical resistance of the optical fiber predominated over these constructive characteristics after embedding in the test specimens. This impact is more noticeable in the results of the fiber embedded in PU since the test specimen E with the fiber embedded is almost 10 times greater than that with raw PU. In dynamic tests, the amorphous polymer chains of nylon embedded with fiber cause the material to present different E during its transition to the rubbery plateau, which is only reached from 60 , while 17-4 PH shows no difference notable in E when the vibration frequency varies. The artificial tendon was characterized for strain showing different sensitivities between the FBGs positioned in the center and close to the tendon wall. Furthermore, the tendon presented an average sensitivity of 9.06 pm/ for characterization between 0 and 30 and a root mean square error of 3.25º when the curvature angle varied from 0º to 90º. The temperature sensor had reduced sensitivity, making it necessary to use a new design for this structure. Finally, the 17-4 PH accelerometer cantilever showed sensitivity to the variation in vibration amplitude (which ranged from 0.5 V to 2.0 V) of 1.79 pm/V when vibrated at a frequency of 10 Hz and 3.61 pm/V for 100 Hz. Therefore, in future works, the intention is to apply the multifunctional structures developed, with the artificial tendon being used in the actuation of robotic parts, and the accelerometers in predictive vibration analysis, for example.
