Arthur Mereles

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.