Marcus Varanis

Instrumentation for mechanical vibrations analysis in the time domain and frequency domain using the Arduino platform

In this paper, we use the Arduino platform together with sensors as accelerometer, gyroscope and ultrasound, to measure vibrations in mechanical systems. The main objective is to assemble a signals acquisition system easy to handle, of low cost and good accuracy for teaching purposes. It is also used the Python language and its numerical libraries for signal processing. This paper proposes the study of vibrations of a beam, which is measured by position, velocity and acceleration. An experimental setup was implemented. The results obtained are compared with analytical models and computer simulations using finite elements. The results are in agreement with the literature.

The influence of the wavelet filter in the parameters extraction for signal classification: An experimental study.

This paper treats the influence of the wavelet filters on the parameter extraction for signal classification. Therefore, a database with vibration signal failures of an induction motor in stationary case was utilized. The classification is done by techniques based on the wavelet packet transform and dimension reduction, using the principal component analysis (PCA). Different wavelet filters with different supports are used for comparison. The use of signals from a validated experimental bench shows that the results of the classification model has a high precision.

Rubbing Effect Analysis in a Continuous Rotor Model

One of the most important malfunction that can cause severe damage in rotating machines is the contact between fixed and rotating parts. The most common sources for rubbing is mass unbalance and instabilities due to fluid-rotor interaction. In this way, this paper presents a continuous rotor model for rubbing applications considering transverse shear, rotatory inertia, and gyroscopic moments. The contribution of it is to present a model to be applied in cases where these effects are not negligible. It is shown that for low slenderness ratio the model is equivalent to the commonly used Euler-Bernoulli continuous model. The normal and friction contact forces between the rotor and the stator are modeled using the Hertz contact theory, which is a nonlinear contact model, and the Coulomb friction model, respectively. In addition, the response of the rotor under impact was studied in the frequency domain using Wavelet Techniques for detection and characterization of rubbing phenomenon.

Mathematical model of a vehicle crash: A case study

Case studies are very useful when it comes to students’ education. They show to them the issues that are faced by the mechanical engineers and what the students should do to resolve those issues during their professional career. In that sense, this paper presents a case study that can be presented in undergraduate and graduate courses where a vehicle crash collision is modeled by a spring-mass-damper system. The spring of the system will be considered to have a nonlinear force–deflection characteristic. The model proposed in this paper allows one to obtain the parameters of the system, and then compare them with the ones obtained experimentally to test the suitability of the model with the vehicle crash. The responses of the system will be obtained by numerical approximation by using the Runge–Kutta algorithm.

Extração de parâmetros para classificação de falhas em motores elétricos utilizando banco de filtros daubechies

Motores eletricos sao componentes de grande importância na maioria dos equipamentos de plantas industriais. As diversas falhas que ocorrem nas maquinas de inducao podem gerar consequencias severas no processo industrial. Os principais problemas estao relacionados a elevacao dos custos de producao, piora nas condicoes do processo e de seguranca e, sobretudo piora na qualidade do produto final. Muitas destas falhas mostram-se progressivas. Neste trabalho, apresenta-se uma contribuicao ao estudo da Implementacao de Tecnicas de Processamento de Sinais Baseadas na Transformada Wavelet com uso de filtros Daubechies, obtidos a partir de sinais de vibracao.