Multibody dynamics: Modeling component flexibility with fixed, free, loaded, constraint, and residual modes

The assumed-modes method in multibody dynamics allows the elastic deformation of each component in the system to be approximated by a sum of products of spatial and temporal functions commonly known as modes and modal coordinates respectively. The choice of component modes used to model articulating and non-articulating flexible multibody systems is examined. Attention is directed toward three classical Component Mode Synthesis (CMS) methods whereby component normal modes are generated by treating the component interface (I/F) as either fixed, free, or loaded with mass and stiffness contributions from the remaining components. The fixed and free I/F normal modes are augmented by static shape functions termed constraint and residual modes respectively. A mode selection procedure is outlined whereby component modes are selected from the Craig-Bampton (fixed I/F plus constraint), MacNeal-Rubin (free I/F plus residual), or Benfield-Hruda (loaded I/F) mode sets in accordance with a modal ordering scheme derived from balance realization theory. The success of the approach is judged by comparing the actuator-to-sensor frequency response of the reduced order system with that of the full order system over the frequency range of interest. A finite element model of the Galileo spacecraft serves as an example in demonstrating the effectiveness of the proposed mode selection method

A component modes projection and assembly model reduction methodology for articulated, multi-flexible body structures

A two-stage model reduction methodology, combining the classical Component Mode Synthesis (CMS) method and the newly developed Enhanced Projection and Assembly (EP&A) method, is proposed in this research. The first stage of this methodology, called the COmponent Modes Projection and Assembly model REduction (COMPARE) method, involves the generation of CMS mode sets, such as the MacNeal-Rubin mode sets. These mode sets are then used to reduce the order of each component model in the Rayleigh-Ritz sense. The resultant component models are then combined to generate reduced-order system models at various system configurations. A composite mode set which retains important system modes at all system configurations is then selected from these reduced-order system models. In the second stage, the EP&A model reduction method is employed to reduce further the order of the system model generated in the first stage. The effectiveness of the COMPARE methodology has been successfully demonstrated on a high-order, finite-element model of the cruise-configured Galileo spacecraft

Line contact force model under elastohydrodynamic lubrication applied to radial roller bearings

Orientadores: Katia Lucchesi Cavalca Dedini, Fábio Nonato de PaulaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia MecânicaResumo: Esse trabalho tem como objetivo propor um novo modelo de força de contato de linha sujeito à lubrificação elastohidrodinâmica (EHD) e sua aplicação a mancais de rolamento. O modelo reduzido de força de contato EHD em função de parâmetros de rigidez e amortecimento tem como principal vantagem inserir os efeitos do filme de óleo nos sistemas de forma a tornar mais realístico o modelo estudado. No que diz respeito ao rolamento, o contato entre os elementos do mancal afeta significativamente seu equilíbrio de forças e no seu comportamento dinâmico, consequentemente, a resposta do sistema rotativo no qual está inserido. O sistema de equações EHD foi solucionado numericamente usando métodos multiníveis tanto para o contato de linha infinito quanto finito. O modelo proposto de força de contato é baseado nos termos de força restitutiva e força dissipativa. A força restitutiva do contato de linha EHD é calculada por meio de uma relação explícita de força-deslocamento e dois parâmetros independentes (rigidez e uma constante de separação de superfícies). O termo de força dissipativo do contato é baseado em um amortecimento linear viscoso, o qual é estimado usando o princípio da conservação da energia para o problema em regime transiente. A partir dos parâmetros do modelo reduzido de força do contato, obtêm-se as forças do mancal de rolamento radial. Foram objeto de estudo dois modelos comerciais de rolamento: mancal com elementos de agulha e mancal com rolos cilíndricos. A validação do modelo foi feita em uma bancada de testes experimentais de dinâmica de rotores. Foi feito um estudo das respostas, numérica e experimental, no domínio da frequência por meio de função de resposta em frequência (FRF). No domínio do tempo, foram monitoradas as órbitas nos sensores de posição e foi feita a comparação entre as transformadas discretas de Fourier (DFTs) das amplitudes dos deslocamentos teórico e experimentalAbstract: This work aims to propose a new line contact force model under elastohydrodynamic (EHD) lubrication and its application to rolling bearings. The reduced model of EHD contact force in function of stiffness and damping parameters has the main advantage of inserting the effects of the oil film into systems in order to make the model more realistic. As far as bearing are concerned, the contact between the bearing elements significantly affects its force equilibrium and its dynamic behavior and, consequently, the response of the rotating system in which it is inserted. The system of EHD equations was numerically solved using multilevel methods for both infinite and finite line contact. The proposed model of contact force is based on the terms of restitutive force and dissipative force. The restitutive force of the EHD line contact is calculated by an explicit force-displacement relationship and two independent parameters (stiffness and a surface separation constant). The dissipative contact force term is based on a linear viscous damping, which is estimated using the principle of conservation of energy for the transient problem. From the parameters of the reduced model of the contact force, the forces of the rolling radial bearing are obtained. Two commercial bearing models were studied: needle rolling element bearing and cylindrical roller bearing. The validation of the model was evaluated in experimental test bench of rotor dynamics. A numerical and experimental study of the frequency domain using frequency response function (FRF) was evaluated. In the time domain, the orbits of the proximity sensors were monitored and the discrete Fourier transforms (DFTs) of the amplitudes of the theoretical and experimental displacements were comparedDoutoradoMecânica dos Sólidos e Projeto MecânicoDoutora em Engenharia Mecânica33003017CAPE

New method to create a vascular arteriovenous fistula in the arm with an endoscopic technique

AbstractWe describe a new technique in which the basilic vein is transposed subcutaneously with endoscopic surgery to create a vascular access in the arm. The vein was harvested with the Endoscopic Vascular Surgery System (Olympus Co, Tokyo, Japan). We could harvest a vessel about 25 cm long with endoscopy. After vessel transposition, an arteriovenous fistula was created in the usual manner. In all 10 patients, we created an effective blood access as scheduled before surgery. We could use the arteriovenous fistula 6 days after surgery and get blood flow in all cases. (J Vasc Surg 2002;36:635-8.

¿Y es uno o son dos?: El levantamiento del velo societario en el arbitraje

El levantamiento del velo societario es uno de los temas más interesantes y complejos dentro del derecho civil, el derecho de sociedades y el arbitraje. En particular, para el arbitraje, el levantamiento del velo societario permite al tribunal arbitral verificar su propia competencia sobre las partes. Esta teoría de incorporación, sin embargo, es compleja debido a que muchas instituciones legales básicas se ven enfrentadas: la relatividad de los contratos, la personalidad jurídica, la responsabilidad limitada de los accionistas y la existencia de consentimiento de acudir al arbitraje. Esta tesis tiene como objetivo analizar la casuística del arbitraje en torno a la aplicación de la figura y los principios internacionales que se han construido a partir de ella, para proponer: (i) una fórmula que uniformice la interpretación de los requisitos necesarios para el levantamiento del velo societario hacia una solución integral en el proceso y (ii) respuestas a las interrogantes pendientes sobre la aplicación del levantamiento del velo societario en el arbitraje. Para ello se analizan, entre otros, tres aspectos relevantes a la figura: (i) los requisitos y estándares para aplicar el levantamiento del velo societario, (ii) la interpretación del consentimiento al convenio arbitral; y, (iii) la ley aplicable al levantamiento del velo.The lifting of the corporate veil is one of the most interesting and complex issues in civil law, corporate law and arbitration. Particularly for arbitration, the lifting of the corporate veil allows the arbitral tribunal to verify its own jurisdiction over the parties. This theory of incorporation, however, is complex because many basic legal institutions are confronted: the relativity of contracts, legal personality, the limited liability of shareholders and the existence of consent to arbitration. This thesis aims to examine the casuistry of arbitration in relation to the application of the figure and the international principles that have been built on it, in order to propose: (i) a formula that standardizes the interpretation of the necessary requirements for the lifting of the corporate veil towards an integral solution in the process and (ii) answers to pending questions on the lifting of the corporate veil in arbitration. For this purpose, three aspects relevant to the figure are analyzed, among others: (i) the requirements and standards to lift the corporate veil, (ii) the interpretation of the consent to the arbitration agreement; and, (iii) the law applicable to the lifting of the veil

Influence de la configuration des hélices sur la résistance à l'arrachement de pieux hélicoïdaux

The uplift capacity of multi-helix anchors usually depends on the helical blades configuration (including the number\ud and the diameter) and the soil characteristics. An evaluation of those parameters is based on the results obtained from two different\ud experimental programs. The first experiments were performed in centrifuge on dry Fontainebleau sand. For the second testing\ud program, tension load tests were carried out in field at São Carlos in Brazil in a tropical soil. The geometrical effect (cylindrical or\ud tapered helices) is also presented.La capacité portante en traction des pieux hélicoïdaux dépend de la configuration des hélices (dont le nombre et le\ud diamètre) et des propriétés du sol. Deux programmes expérimentaux permettent d’éclaircir l’influence relative de ces paramètres.\ud L’un est réalisé sur modèles réduits centrifugés dans du sable sec de Fontainebleau, l’autre est mis en oeuvre in situ sur un site test à\ud Sao Carlos au Brésil, constitué de sols tropicaux. L’effet de la géométrie (hélices inscrites dans un cylindre ou dans un cône) est\ud présenté.FAPESP - Proc 2010/19039-

¿Uno o dos sombreros?: lineamientos para una regulación del double-hatting en arbitrajes de inversión

The phenomenon of double-hatting, that is, the exercise of multiple roles by professionals in the field of arbitration, can have a significant impact on the necessary qualities of independence and impartiality that every arbitrator must have. The regulation of this phenomenon brings back to the table the recurrent discussion on conflicts of interest derived from the inevitable interaction in the group of professionals involved in investment arbitration. The inclusion of articles expressly addressing this phenomenon in recent international treaties and the discussion that has been held about its express regulation in the "Draft Code of Conduct for adjudicators in investor-state dispute settlement" prepared by the ICSID and UNCITRAL Secretariats, leads us to propose some guidelines for such regulation.El fenómeno del double-hatting; esto es, el ejercicio de múltiples roles por parte de los profesionales vinculados al arbitraje, puede tener un importante impacto en las necesarias cualidades de independencia e imparcialidad que todo árbitro debe tener. La regulación de este fenómeno vuelve a poner sobre la mesa la recurrente discusión sobre los conflictos de interés derivados de la inevitable interacción en el grupo de profesionales que se dedican a arbitrajes de inversión. La inclusión de artículos que abordan expresamente este fenómeno en recientes tratados internacionales y la discusión que se viene sosteniendo por su expresa regulación en el "Proyecto de Código de Conducta para adjudicadores en solución de controversias inversionista-Estado" preparado por las Secretarías del CIADI y UNCITRAL, nos lleva a proponer algunos lineamientos para dicha regulación

Construção e validação de instrumento para avaliação da assistência ao comportamento suicida

OBJECTIVE: To develop and validate an instrument for evaluating primary health care professionals’ assistance to people with suicidal behavior. METHODS: This was a methodological study, which began with a literature review, followed by the elaboration of an instrument. In its first version, the instrument had 34 items, divided into four domains: “professional characterization,” “professional perception ” “professional knowledge/abilities,” and “organization of the care network.” Contents were validated using the Delphi method. Semantic analysis was performed by college-educated primary health care professionals in greater and lesser strata of ability. For internal consistency analysis, Cronbach’s alpha coefficient was calculated. The study was conducted between January and December 2017. RESULTS: After four Delphi rounds, the instrument was successfully validated. In its final form, it is comprised of 50 items, divided into five domains: “professional characterization,” “professional sensibility,” “professional experience,” “professional knowledge/abilities,” and “organization of the care network.” Questions belonging to the last four domains have answers on a five-point Likert scale. In the semantic analysis, 93.6% of the evaluations were “good” and “very good.” The instrument’s general Cronbach alpha was 0.90. CONCLUSIONS: The final version of the instrument was able to fulfill its objectives. It is useful as a support for epidemiological research and planning of health actions. The evaluation of professional approaches to suicidal behavior is crucial for the organization of suicide assistance services in primary health care, and for the integration of services provided by different care unitsOBJETIVO: Desenvolver e validar um instrumento para avaliação da assistência às pessoas com comportamento suicida por profissionais da atenção primária à saúde. MÉTODOS: Estudo metodológico iniciado com revisão de literatura e construção de um instrumento que, em sua primeira versão, continha 34 itens divididos em quatro domínios: “identificação profissional”, “percepção profissional”, “conhecimento/habilidade profissional” e “organização da rede de atenção”. O conteúdo foi validado pela técnica Delphi. A análise semântica foi realizada por profissionais de nível superior de maior e menor habilidades da atenção primária à saúde. Para a análise da consistência interna, foi calculado o coeficiente alfa de Cronbach. O estudo foi realizado entre janeiro e dezembro de 2017. RESULTADOS: Após quatro rodadas Delphi, o instrumento foi validado com 50 itens, divididos em cinco domínios: “identificação profissional”, “percepção profissional”, “experiência profissional”, “conhecimento/habilidade profissional” e “organização da rede de atenção”. Os últimos quatro domínios foram inseridos em escala Likert de cinco pontos. A análise semântica apresentou 93,6% de avaliações “bom” e “muito bom”. O alfa de Cronbach geral do instrumento foi de 0,90. CONCLUSÕES: O instrumento final mostrou-se capaz de avaliar o que se propõe. Pode auxiliar em pesquisas epidemiológicas e no planejamento de ações. A avaliação da abordagem profissional ao comportamento suicida é crucial para a organização dos serviços na atenção primária à saúde e para a integração dos diferentes pontos assistenciais de atenção