Hans Weber

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Papers by Hans Weber

A Magnetostrictive Composite-Fiber Bragg Grating Sensor

Sensors, Aug 30, 2010

This paper presents a light and compact optical fiber Bragg Grating sensor for DC and AC magnetic... more This paper presents a light and compact optical fiber Bragg Grating sensor for DC and AC magnetic field measurements. The fiber is coated by a thick layer of a magnetostrictive composite consisting of particles of Terfenol-D dispersed in a polymeric matrix. Among the different compositions for the coating that were tested, the best magnetostrictive response was obtained using an epoxy resin as binder and a 30% volume fraction of Terfenol-D particles with sizes ranging from 212 to 300 µm. The effect of a compressive preload in the sensor was also investigated. The achieved resolution was 0.4 mT without a preload or 0.3 mT with a compressive pre-stress of 8.6 MPa. The sensor was tested at magnetic fields of up to 750 mT under static conditions. Dynamic measurements were conducted with a magnetic unbalanced four-pole rotor.

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Dynamical Systems and Control

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Study of feasibility in replacing in a centrifugal pump the static wear ring by a floating wear ring

Proceedings of the ... International Congress of Mechanical Engineering, 2015

Primeiramente a Deus, pela saúde e força dada em todos os momentos da minha vida. Aos meus pais, ... more Primeiramente a Deus, pela saúde e força dada em todos os momentos da minha vida. Aos meus pais, e aos meus irmãos e sobrinhos por todo amor, amizade, apoio e confiança nos meus estudos. A minha namorada, pelo amor, companheirismo, incentivo e paciência. A equipe de manutenção de equipamentos dinâmicos da Refinaria Duque de Caxias pelos ensinamentos e apoio concedidos durante o desenvolvimento do trabalho. Ao meu orientador, Professor Hans, por toda sabedoria e pelas valiosas sugestões imprescindíveis para o desenvolvimento deste trabalho. A todos os professores, colegas e funcionários do Programa de Pós-Graduação em Engenharia Mecânica, pelo apoio e amizade. Aos membros da Banca Examinadora, por toda atenção ao lerem minha dissertação e participarem da minha avaliação.

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Stick-Slip Analysis in Drill Strings

This work attempts to model the nonlinear dynamic behavior of torsional stick-slip vibration in r... more This work attempts to model the nonlinear dynamic behavior of torsional stick-slip vibration in rotating systems in interaction with longitudinal vibration. This phenomenon is found in many drilling processes, frequently in oil well drilling, and the vibrations are coupled through the cutting force at the bit. Vibration in this kind of systems is an important cause of premature failure of the components. The longitudinal vibration was analyzed at ICVOP 2002; now the focus will be on torsional vibration, but considering the coupling to the longitudinal vibration. Stick-slip causes a violent torsional vibration due to the long drill pipe and the consequent large amplitudes and it is necessary to understand the dynamic behavior to take care with some operation parameters. To model the stick-slip phenomenon in oil well drilling it is used a slender rotating vertical column, which represents a simplified model of a drill string. For this torsional column, it is considered that the top is rotating with a constant rotary speed and the bottom end is subject to the cutting force. This force represents the effect between rock and bit and is strongly nonlinear. To solve the equation of motion of the model, the one-dimensional space domain is discretized through finite difference, after, the classic Runge-Kutta method is employed to obtain the time response. The numerical simulations show that the behavior of the system depends strongly of the rotation velocity. When represented in state-space the behavior shows a limit cycle that is typical of systems with dry friction. The coupling with the longitudinal vibration occurs under the action of the weight on bit, which consists of a static load perturbed by a dynamic one. The interaction between these two kinds of vibration over the non linear force that connects the bodies is the goal of this work.

format_quoteSystem behavior reveals a strong dependence on rotation velocity, showing limit cycles typical of dry friction in torsional vibrations.format_quote

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An inverse problem via cross-entropy method for calibration of a drill string torsional dynamic model

Proceedings of the 25th International Congress of Mechanical Engineering, 2019

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Copyright

format_quoteThe CE method calibration achieved a Pearson coefficient of 0.9532, indicating a near-perfect match for θ1 and θ2 among three cases analyzed.format_quote

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Development of a Vibroimpact Device for the Resonance Hammer Drilling

Hard rock drilling is still a great challenge for oil companies. One current line of research inv... more Hard rock drilling is still a great challenge for oil companies. One current line of research involves combining the two existing drilling techniques in order to enhance the rate of penetration. This new technique is called Resonance Hammer Drilling. This article proposes the design and development of the first prototype that will operate in resonance, and will be capable of generating considerable dynamic forces. This device will be known as the Resonant Impact Device, or "RIMD". In principle the idea is to build some sort of a "black box", which will be mounted on a vibrating structure with two switches - one calibrating the RIMD resonance frequency and the other acting on the impacts - changing the size of the gap. It is known from previous work that gap size also has influence on the system natural frequency. Therefore there is a relationship between switches. One of the first steps of RIMD design and development is device dimensioning, necessary in order to ...

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Vertical Overhung Rotor Dynamics with Impact

The purpose of this work is to analyze the overhung rotor dynamics considering the contact phenom... more The purpose of this work is to analyze the overhung rotor dynamics considering the contact phenomenon between the disk and an annular ring. The analysis of contact is particularly complex, due to the high nonlinearity of the motion equations. The impact is accounted by a consistent contact model, the Kelvin-Vôigt model. Motion equation for the rotor is encountered employing the Lagrangean method.; These equations are capable of capturing phenomena due to lateral vibration, like: forward whirl, backward whirl, rolling or sliding along the annular ring. Due to the combined parameters and the effect of nonlinearity in the motion equations, the dynamical response is not simple or easily predictable. Numerical simulation is the preferred method of analysis, here it is used the Runge-Kutta Fehlberg method. Simulation results show that under certain conditions, the rotor changes its orbit due to the impacts with the annular ring and after that, it executes backward whirl motion. It is a kind of phenomenon which is considered as the most violent and dangerous in rotating machines. The passing through its critical speed is analyzed when driven by an electric motor (also when the system operates under a constant rotational velocity). In addition in this work, the results obtained with an experimental test rig are used to investigate the whirl phenomenon.

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Biomechanics Model and Artificial Control Design of Upright Standing in Humans

Modelagem matematica, simulação e controle artificial da postura em seres humanos

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Numerical and experimental investigations of the nonlinear dynamics and chaos in non-smooth systems

Journal of Sound and Vibration, Mar 1, 2007

Nature is full of non-smooth nonlinearities that are usually related to either friction phenomena... more Nature is full of non-smooth nonlinearities that are usually related to either friction phenomena or the discontinuous characteristics of intermittent contacts. In general, non-smooth characteristics cause difficulties in the modeling and simulation of natural systems. A smoothed switch model is used in this contribution in order to analyze non-smooth systems. The procedure is shown to be an effective method of dealing with this kind of system, and has advantages in numerical implementation. As an application of the general formulation, a single-degree of freedom oscillator with discontinuous support is analyzed. An experimental apparatus is developed in order to verify the capability of the mathematical formulation and the numerical procedure used to describe the system general behavior. This apparatus is instrumented to obtain all system state variables, making it possible to compare experimental results with those obtained through numerical simulations. The system's dynamical behavior shows a rich response that includes dynamical jumps, bifurcations and chaos. Different aspects related to nonlinear dynamics are carried out showing that numerical simulations are in close agreement with experimental data.

format_quoteThe oscillator's stiffness was identified as 8.47 N/m, facilitating accurate modeling of the non-smooth system's behavior in subsequent analysis.format_quote

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Elastic and Plastic Collision Comparison Using Finite Element Method

The prevision of post-impact conditions and the behavior of the bodies during the impact have bee... more The prevision of post-impact conditions and the behavior of the bodies during the impact have been object of several collision models. The formulation from Hertz's theory is generally used dated from the 19<sup>th</sup> century. These models consider the repulsive force as proportional to the deformation of the bodies under contact and may consider it proportional to the rate of deformation. The objective of the present work is to analyze the behavior of the bodies during impact using the Finite Element Method (FEM) with elastic and plastic material models. The main parameters to evaluate are, the contact force, the time of contact and the deformation of the bodies. An advantage of using the FEM approach is the possibility to apply a plastic deformation to the model according to the material definition: there will be used Johnson–Cook plasticity model whose parameters are obtained through empirical tests of real materials. This model allows analyzing the permanent de...

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Influence of unbalance levels on nonlinear dynamics of a rotor-backup rolling bearing system

Journal of Sound and Vibration, 2017

 Users may download and print one copy of any publication from the public portal for the purpose... more  Users may download and print one copy of any publication from the public portal for the purpose of private study or research.  You may not further distribute the material or use it for any profit-making activity or commercial gain  You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

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Devellopment of an App for Choosing Skin Expanders

Proceedings of the 23rd ABCM International Congress of Mechanical Engineering, 2015

Development of a Robotic Walk Assistant Device for Elderly and Handicapped People

Proceedings of the 23rd ABCM International Congress of Mechanical Engineering, 2015

Numerical and experimental endentation analysis of plane hyperelastic membranes

Proceedings of the 23rd ABCM International Congress of Mechanical Engineering, 2015

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Torsional Friction-Induced Vibrations in Slender Rotating Structures

Advances in Mechanism and Machine Science, 2019

Due to the drill-string slenderness, torsional vibration is present in most drilling routines, ev... more Due to the drill-string slenderness, torsional vibration is present in most drilling routines, eventually reaching the stick-slip phenomenon. This torsional vibration results from the nonlinear interaction between drill-bits and rocks. Despite the complexity of the bit-rock interaction, the relationship between torque and bit velocity is often treated as dry friction in a slender system. This contribution utilizes data from a test rig that was designed to offer similar dynamic properties as a drill-string and has a special device to introduce friction disturbing the rotating motion. This test rig is modeled as an actuated torsional pendulum and is used to model numerical approaches for the investigation of the experimental friction. We propose a friction model based on experimental data, and analyze the hysteretic characteristic observed. The experimental results are used to identify the proposed model parameters. Lastly, we compare experimental and numerical results.

Aparelho medidor de pressão interna: desenvolvimento de aparelho que meça a pressão intraexpansor de pele

Foram desenvolvidos e construidos dois aparelhos medidores de pressao interna portatil, com a cap... more Foram desenvolvidos e construidos dois aparelhos medidores de pressao interna portatil, com a capacidade de registro de dados, para aplicacoes na medicina, com a finalidade de auxiliar o medico clinico na aquisicao de dados para um posterior estudo do decaimento das pressoes em infusoes e implantes subcutâneas ao longo do tempo. A exemplo disso as infiltracoes em expansores de pele, e o acompanhamento de implantes mamarios

Aparelho Infusor De Líquido Em Expansor Subcutâneo

Finite axisymmetric deformations of an initially stressed fluid-filled cylindrical membrane

International Journal of Solids and Structures, Mar 1, 2001

This paper investigates the large deformations of an extended fluid-filled cylindrical membrane. ... more This paper investigates the large deformations of an extended fluid-filled cylindrical membrane. The static case and the behaviour of the membrane rotating at a constant angular velocity are both considered. A detailed experimental analysis was carried out involving different geometries, and initial axial forces and the influence of the axial force and the fluid volume were investigated. An apparatus was

New biaxial test method for the characterization of hyperelastic rubber-like materials

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