Papers by DESEJO FILIPESON SOZINANDO
MDPI, 2025
The interaction between thermal fields and mechanical loads in thin-walled cylindrical shells int... more The interaction between thermal fields and mechanical loads in thin-walled cylindrical shells introduces complex dynamic behaviors relevant to aerospace and mechanical engineering applications. This study investigates the axial stress wave propagation in a circular cylindrical shell subjected to combined thermal gradients and time-dependent harmonic compression. A semi-analytical model based on Donnell-Mushtari-Vlasov (DMV) shells theory is developed to derive the governing equations, incorporating elastic, inertial, and thermal expansion effects. Modal solutions are obtained to evaluate displacement and stress distributions across varying thermal and mechanical excitation conditions. Empirical Mode Decomposition (EMD) and Instantaneous Frequency (IF) analysis are employed to extract time-frequency characteristics of the dynamic response. Complementary Finite Element Analysis (FEA) is conducted to assess modal deformations, stress wave amplification, and the influence of thermal softening on resonance frequencies. Results reveal that increasing thermal gradients leads to significant reductions in natural frequencies and amplifies stress responses at critical excitation frequencies. The combination of analytical and numerical approaches captures the coupled thermomechanical effects on shell dynamics, providing an understanding of resonance amplification, modal energy distribution, and thermal-induced stiffness variation under axial harmonic excitation across thin-walled cylindrical structures.
MDPI, 2025
A concentric double-flange butterfly valve (DN-500, PN-10) was analyzed to examine its dynamic be... more A concentric double-flange butterfly valve (DN-500, PN-10) was analyzed to examine its dynamic behavior and internal fluid flow across multiple opening angles. Finite Element Analysis (FEA) was employed to determine natural frequencies, mode shapes, and effective mass participation factors (EMPFs) for valve positions at 30 • , 60 • , and 90 •. The valve geometry was discretized using a curvature-based mesh with linear elastic isotropic properties for 1023 carbon steel. Lower-order vibration modes produced global deformations primarily along the valve disk, while higher-order modes showed localized displacement near the shaft-bearing interface, indicating coupled torsional and translational dynamics. The highest EMPF in the X-direction occurred at 1153.1 Hz with 0.2631 kg, while the Y-direction showed moderate contributions peaking at 0.1239 kg at 392.06 Hz. The Z-direction demonstrated lower influence, with a maximum EMPF of 0.1218 kg. Modes 3 and 4 were critical for potential resonance zones due to significant mass contributions and directional sensitivity. Computational Fluid Dynamics (CFD) simulation analyzed flow behavior, pressure drops, and turbulence under varying valve openings. At a lower opening angle, significant flow separation, recirculation zones, and high turbulence were observed. At 90 • , the flow became more streamlined, resulting in a reduction in pressure losses and stabilizing velocity profiles.
11th South African Conference on Computational and Applied Mechanics (SACAM 2018), 2018
The interactions between rotor-stator submerged in incompressible fluid flows are strong nonlinea... more The interactions between rotor-stator submerged in incompressible fluid flows are strong nonlinear phenomena that have wide applications in scientific and engineering disciplines. This paper presents vibration analysis of a vertical oscillating rotor-rub system interacted in incompressible flow regimes. The governing equation of the coupled lateral and torsional vibrations of a rotor-rub system and the inviscid fluid forces action are firstly established based on Energy Principle and Euler method for the incompressible fluid. The unsteady 5-Degree-of-Freedom system of rotorstator-fluid motion is simulated by means of an appropriate solver. In the analysis it was found througth the severity of the fault detected that the presence of inviscid fluid gives strong softening and fluctuating interferences components in the response when the rotating system is involved in rotor-stator contact. Further, the responses displayed a generally softening nonlinearity on torsional deflection of the rotor. The results reveal that, the inviscid fluid had a significant attenuation on the orbit of the shaft in comparison to a standard orbit of the rotor. The obtained results indicate that the fluid-rotor interaction considerably reduce the dynamic vibration response of the faulted rotor system.
Journal of Engineering
Sectionalized gate valves can reduce the volume of product released in the event of a buried pipe... more Sectionalized gate valves can reduce the volume of product released in the event of a buried pipeline failure or rupture. The risk of pipeline failure is a constant and common occurrence, and many factors can lead to pipeline incidents. In this paper, the free undamped vibration of the pipeline, sectionalized gate valve structure, and the dynamics of the fluid passing through the system are investigated. First and foremost, a modal analysis based on finite element analysis (FEA) is introduced as a fundamental linear dynamics analysis to provide insight into how a pipeline sectionalized gate valve structure may respond to different types of dynamic loading. Secondly, an implicit numerical analysis using computational fluid dynamics (CFD) is employed to describe physical quantities such as the flow velocity profiles at different stream positions and pressure fields at different points in a control volume. Through modal analysis, the effective mass factor shows the mass involved in eac...
Mathematical and Computational Applications
Diagnosis of faults in a rotor system operating in a fluid is a complex task in the field of rota... more Diagnosis of faults in a rotor system operating in a fluid is a complex task in the field of rotating machinery. In an ideal scenario, a forced shutdown due to rotor-stator contact failure would necessitate the replacement of the rotor or stator. However, factors such as time constraints, economic considerations, and the aging of infrastructure make it imprudent to abruptly shut down machinery that can still be safe to operate. The purpose of this paper is to present an experimental study that validates the theoretical results of the dynamic behavior and friction detection using the wavelet synchrosqueezing transformation (WSST) method for recurrent rotor-stator contacts in a fluid environment, as presented in a previous study. The investigation focused on the analysis of whirl orbits, shaft deflection, and fluctuation frequency during passage through critical speeds. The WSST method was used to decompose the dynamic responses of the rotor in the supercritical speed zone into severa...
Applied Sciences
The current study aims to study the drill string–casing system operating in an inviscid fluid und... more The current study aims to study the drill string–casing system operating in an inviscid fluid under imbalanced and rubbing damage types. The Navier–Stokes equations were linearized to establish the hydrodynamic forces surrounding the drill string and resulted in a five-dimensional system of nonlinear differential equations. To ensure the accurate acquisition of friction characteristics in a fluid medium, a nonlinear wavelet synchronized transform (NWSST) technique was enhanced based on the denoised wavelet hard thresholding algorithm to extract the features of the rubbing system. The developed model was verified through various test conditions, and the extracted data tests show that the frictional impact proves sufficient to modify the dynamic behavior of the drill string throughout the energy concentration with a slight shift above and below the resonant frequency. It was shown by simulation that the vibration of the submerged drill string system potentially enhanced highly undesir...
Flow Balance and Pressure Drop of Pumping Station System During Routine Maintenance Activities
2022 IEEE 13th International Conference on Mechanical and Intelligent Manufacturing Technologies (ICMIMT)
International Journal of Rotating Machinery, 2020
Mechanical failures of a complex machine such as rotor widely used in severe conditions often req... more Mechanical failures of a complex machine such as rotor widely used in severe conditions often require specialized knowledge, technical expertise, and imagination to prevent its rupture. In this paper, a model for analyzing excitation of a coupled lateral-torsional vibrations of a shaft system in an inviscid fluid is proposed. The model considers the recurrent contact of the vibrating shaft to a fixed stator. The simplified mathematical model of the rotor-stator system is established based on the energy principle. The dynamic characteristics of the fluid-rotor system are studied, and the features of rub-impact are extracted numerically and validated experimentally under the effects of the unbalance and the hydrodynamic forces. The main contribution of this article is in extraction and identification of the rub features in an inviscid medium which proved to be complex by the obstruction of the fluid and required the use of appropriate signal processing tools. The results through a syn...
Dynamic Analysis of Vertical Rotor Mass-Visco Fluid System Enhancing Subsequent Rub
2021 IEEE 12th International Conference on Mechanical and Intelligent Manufacturing Technologies (ICMIMT), 2021
Taking into account the coupling effect of a viscous fluid and a vertical rotor in permanent cont... more Taking into account the coupling effect of a viscous fluid and a vertical rotor in permanent contact with a fixed stator has proven to be a complex and challenging task in fault diagnosis. In this paper, an isotropic vertical rotor-stator model that take into account the longitudinal, lateral and torsional vibrations in a viscous fluid is analyzed. Fluid resistance forces established based on the 2D model of Navier-Stokes equations are fed into the rotor-stator system resulting in a highly nonlinear fluid-vertical rotor system. Based on the complexity of the governing equations obtained, it was necessary to perform the Wavelet Synchrosqueezed Transform (WST) to extract the rubbing fault in a fluid medium and its oscillating modes. The analysis demonstrated through the time-frequency spectrum that the combined unbalance and rub is the leading cause of parametric resonance. The effect of the viscous fluid around the rotor-stator surface contact point generates viscous drag resistance forces and reduces the fluctuation of the rotor’s oscillating frequencies.
Vibroengineering PROCEDIA
Two-dimensional linearized Navier-Stokes equations have been used to model the inviscid fluid for... more Two-dimensional linearized Navier-Stokes equations have been used to model the inviscid fluid forces acting on a vertical rotor-cylindrical stator system partially immersed in an inviscid incompressible fluid. The response of the fluid-stator-system subjected to subsequent fault feature extraction. The influences of parameters of the fluid system, among them, fluid density, and mass ratio on the unstable contact zones are analyzed. It is shown that for an effective prediction of rub-impact in a submerged rotor system, the influence of the fluid mass on the stability of the system is an important dynamic factor. It is revealed, that the fluid forces increase the amplitude of vibration, while the frequency of oscillation is reduced, phenomena that stabilise the isotropic vertical rotor-stator system.
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Papers by DESEJO FILIPESON SOZINANDO