Análise da resposta dinâmica em estrutura esbelta sobre diferentes condições de carregamento através do uso de métodos numéricos

Abstract

Slender structures are commonly found in a number of engineering projects, and these are still a challenge for modern engineering because of its slender design. They provide efficiency in several applications such as mobile towers, power distribution towers, aero generator towers, among others. The use of this type of structure requires its dynamic evaluation, as vibratory modes, response of the structure submitted to harmonic loads, response to random excitation, among other dynamic loads. In this context, this work evaluated some aspects of the dynamic response of a lean bench structure, subjected to free vibration and forced vibration by means of a dc motor with unbalanced mass. Brüel & Kjaer capture hardware accelerometers and vibration signals were measured. Through the treatment of the experimental data obtained, the characterization of the tower and determination of relevant parameters for later calibration of the numerical modeling of the structure was sought. The modeling was performed through ANSYS® software, where a three-dimensional modeling of the structure was elaborated, followed by calibration of the material parameters and contour conditions obtained through the experimental characterization. Making possible the refinement of the numerical model for later modal analysis, transient, harmonic and random vibration. The characterization of the tower, characterization of the DC motor, an adjusted numerical model of the tower, the determination of the first four modal forms and their natural frequencies, the displacement, frequency and phase responses for the harmonic analysis of the structure, implementation Of the experimentally obtained signal of the DC motor fixed in rigid base as basic excitation via PSD for analysis of random vibration, obtaining the response in displacement and in maximum elastic deformation. The analysis in the time domain allowed to observe a possible zone of instability in the operation of the motor for values of electrical voltage of 9 V to 11 V.