Banca de DEFESA: LENIN LEE HUAMAN VALDIVIA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : LENIN LEE HUAMAN VALDIVIA
DATE: 07/03/2023
TIME: 10:00
LOCAL: CAMPUS DE SANTO ANDRE
TITLE:

STABILITY AND DYNAMIC BEHAVIOR OF A VISCOELASTIC TUBE DISCHARGING FLUID INTERNAL

PAGES: 140
BIG AREA: Engenharias
AREA: Engenharia Mecânica
SUBÁREA: Mecânica dos Sólidos
SPECIALTY: Dinâmica dos Corpos Rígidos, Elásticos e Plásticos
SUMMARY:

In this master's work, the stability and dynamic behavior of a vertically arranged viscoelastic pipe, fixed at the top and free at the bottom end, discharging internal fluid. The system is non-conservative because the flow acts as a source of energy. The tube is seen as a slender structure with small deflections, so the Euler-Bernoulli beam theory is adopted. The viscoelastic material of the tube behaves according to the Kelvin-Voigt internal dissipation model. Here, the paradox of loss of stability due to damping is addressed, a topic of scientific interest. The internal flow is stationary, incompressible, and uniform at constant velocity. The differential equation of motion of the system is obtained by the Newtonian approach, through the dynamic equilibrium of the tube and fluid elements, and it is dimensionless by introducing the dimensionless parameters of mass, fluid velocity, viscoelasticity, and gravity. The equation of motion is discretized by the Galerkin method, assuming as an approximate solution a series of the products of two functions, one spatial and the other temporal, the spatial functions are the modes of vibration free of the cantilever tube, and the temporal functions are harmonics that define the amplitude of vibration of the pipe. The stability analysis is approached through the study of natural frequencies, obtained from the solution of the characteristic equation of the system, which are presented in the Argand diagram where it is possible to identify the regions of instability, the critical velocity, in addition to predict the tube movement type. A critical velocity sensitivity study was conducted by varying the dimensionless parameters that characterize the system. Finally, the dynamic response of the system obtained by the Laplace transform is presented, for specific cases of interest. The results show the stabilizing and destabilizing effect of the viscoelastic material, for velocity above critical flutter instability, and that the viscosity of the external medium to the tube increases the transition time to instability.

COMMITTEE MEMBERS:
Presidente - Interno ao Programa - 1761050 - JUAN PABLO JULCA AVILA
Membro Titular - Examinador(a) Interno ao Programa - 1850088 - REYOLANDO MANOEL LOPES REBELLO DA FONSECA BRASIL
Membro Titular - Examinador(a) Externo à Instituição - FABRICIO CESAR LOBATO DE ALMEIDA
Membro Suplente - Examinador(a) Interno ao Programa - 1604343 - KARL PETER BURR