Análise estática, dinâmica e modal de estruturas e mecanismos tensegrity

Orientador: Paulo Roberto Gardel KurkaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia MecânicaResumo: O desenvolvimento de estruturas mais leves, finas, rígidas ou inteligentes é um desafio constante entre engenheiros e cientistas de qualquer área. Sistemas tensegrity, que são formados por corpos rígidos em compressão e cabos em tração, têm perspectiva de serem amplamente aplicados pelas indústrias espacial, civil, mecânica, aeronáutica ou biomédica. O projetista de um tensegrity pode controlar sua rigidez e formato através da mudança de tensão nos cabos, cujos comportamentos são explorados neste trabalho via protótipos e simulações. Um modelo foi sugerido para otimizar massa e volume de uma antena de satélite, o mecanismo tensegrity foi criado para ser lançado num formato colapsado, economizando volume dentro do foguete, e expandido no espaço através da contração de determinados cabos. Em seguida, as tensões dos cabos de um prisma tensegrity foram variadas e a mudança na rigidez foi avaliada por análise modal. Por fim, uma torre tensegrity bidimensional foi submetida a grandes deformações, sua análise estática não linear foi implementada e as frequências naturais das posições deformadas foram calculadas. As três metodologias foram implementadas e, posteriormente, validadas em três experimentos distintos, estes ressaltando os efeitos de cada propriedade em avaliação. O objetivo deste trabalho é propor um procedimento para desenvolver o projeto e construção de uma estrutura tensegrity que englobe as três metodologias: definindo sua expansão a partir de uma configuração colapsada, o controle da rigidez quando estável e a nova posição caso algum esforço provoque grandes deformações. Portanto, além do objetivo prático do primeiro tópico, este trabalho tem como meta fornecer uma documentação geral de soluções relacionadas a estruturas e mecanismos tensegrityAbstract: The development of lighter, thinner, stiffer or smarter structures is a constant challenge among engineers and scientists of all fields. Tensegrity systems, which are formed by rigid bodies under compression and cables under traction, are likely to be largely used by the space, civil, mechanical, aeronautical and biomedical industries. The designer of a tensegrity can control its stiffness and shape by changing the tension in the cables, these behaviours are explored in this work via prototypes and simulations. A model was suggested to optimize mass and volume of a satellite antenna, a tensegrity mechanism was created to be launched in a reduced shape, saving volume in the launcher, and expanded in space by pulling specific tendons. Secondly, the tensions of a tensegrity prism's cables were varied and the change in stiffness was assessed through modal analysis. Finally, a 2D tensegrity tower was put under large deformations, its nonlinear static analysis was implemented and the natural frequencies of the deformed configurations were calculated. All the three methodologies have been implemented and, later, validated through experiments designed to highlight each property of concern. The objective of this work is to propose procedures to develop and build a tensegrity structure that carry those three methodologies: defining its expansion from a compact configuration, its stiffness control once the expansion is finished and its new shape if any load generates large displacements. Thus, beyond the practical end of the first topic, the goal of this work is to provide a general document of solutions related to tensegrity structures and mechanismsMestradoMecanica dos Sólidos e Projeto MecanicoMestre em Engenharia Mecânica132166/2018-6CNP

Theoretical Approaches in Non-Linear Dynamical Systems

From Preface: The 15th International Conference „Dynamical Systems - Theory and Applications” (DSTA 2019, 2-5 December, 2019, Lodz, Poland) gathered a numerous group of outstanding scientists and engineers who deal with widely understood problems of theoretical and applied dynamics. Organization of the conference would not have been possible without great effort of the staff of the Department of Automation, Biomechanics and Mechatronics of the Lodz University of Technology. The patronage over the conference has been taken by the Committee of Mechanics of the Polish Academy of Sciences and Ministry of Science and Higher Education of Poland. It is a great pleasure that our event was attended by over 180 researchers from 35 countries all over the world, who decided to share the results of their research and experience in different fields related to dynamical systems. This year, the DSTA Conference Proceedings were split into two volumes entitled „Theoretical Approaches in Non-Linear Dynamical Systems” and „Applicable Solutions in Non-Linear Dynamical Systems”. In addition, DSTA 2019 resulted in three volumes of Springer Proceedings in Mathematics and Statistics entitled „Control and Stability of Dynamical Systems”, „Mathematical and Numerical Approaches in Dynamical Systems” and „Dynamical Systems in Mechatronics and Life Sciences”. Also, many outstanding papers will be recommended to special issues of renowned scientific journals.Cover design: Kaźmierczak, MarekTechnical editor: Kaźmierczak, Mare

14th Conference on Dynamical Systems Theory and Applications DSTA 2017 ABSTRACTS

From Preface: This is the fourteen time when the conference “Dynamical Systems – Theory and Applications” gathers a numerous group of outstanding scientists and engineers, who deal with widely understood problems of theoretical and applied dynamics. Organization of the conference would not have been possible without a great effort of the staff of the Department of Automation, Biomechanics and Mechatronics. The patronage over the conference has been taken by the Committee of Mechanics of the Polish Academy of Sciences and the Ministry of Science and Higher Education. It is a great pleasure that our invitation has been accepted by so many people, including good colleagues and friends as well as a large group of researchers and scientists, who decided to participate in the conference for the first time. With proud and satisfaction we welcome nearly 250 persons from 38 countries all over the world. They decided to share the results of their research and many years experiences in the discipline of dynamical systems by submitting many very interesting papers. This booklet contains a collection of 375 abstracts, which have gained the acceptance of referees and have been qualified for publication in the conference proceedings [...]

Kinematics and Robot Design IV, KaRD2021

This volume collects the papers published on the special issue “Kinematics and Robot Design IV, KaRD2021” (https://www.mdpi.com/journal/robotics/special_issues/KaRD2021), which is the forth edition of the KaRD special-issue series, hosted by the open-access journal “MDPI Robotics”. KaRD series is an open environment where researchers can present their works and discuss all the topics focused on the many aspects that involve kinematics in the design of robotic/automatic systems. Kinematics is so intimately related to the design of robotic/automatic systems that the admitted topics of the KaRD series practically cover all the subjects normally present in well-established international conferences on “mechanisms and robotics”. KaRD2021, after the peer-review process, accepted 12 papers. The accepted papers cover some theoretical and many design/applicative aspects

Life Sciences Program Tasks and Bibliography for FY 1996

This document includes information on all peer reviewed projects funded by the Office of Life and Microgravity Sciences and Applications, Life Sciences Division during fiscal year 1996. This document will be published annually and made available to scientists in the space life sciences field both as a hard copy and as an interactive Internet web page

Life Sciences Program Tasks and Bibliography

This document includes information on all peer reviewed projects funded by the Office of Life and Microgravity Sciences and Applications, Life Sciences Division during fiscal year 1995. Additionally, this inaugural edition of the Task Book includes information for FY 1994 programs. This document will be published annually and made available to scientists in the space life sciences field both as a hard copy and as an interactive Internet web pag

Proceedings of the ECCOMAS Thematic Conference on Multibody Dynamics 2015

This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: ● Formulations and Numerical Methods ● Efficient Methods and Real-Time Applications ● Flexible Multibody Dynamics ● Contact Dynamics and Constraints ● Multiphysics and Coupled Problems ● Control and Optimization ● Software Development and Computer Technology ● Aerospace and Maritime Applications ● Biomechanics ● Railroad Vehicle Dynamics ● Road Vehicle Dynamics ● Robotics ● Benchmark ProblemsPostprint (published version

Développement d'indicateurs biomécaniques en manutention et leur application dans l'étude des différences entre les sexes lors de levers de charges en hauteur

Les blessures musculo-squelettiques du membre supérieur représentent un problème de santé publique dans le secteur de la manutention. En plus d’affecter la qualité de vie du travailleur, ces lésions entraînent une perte de temps de travail et une augmentation des coûts de production. Alors que nous avons des évidences épidémiologiques que les femmes manutentionnaires sont plus nombreuses que les hommes à souffrir de douleurs à l’épaule, la littérature fait défaut d’indices biomécaniques qui expliquent l'origine de cette différence. L'objectif général de cette thèse était d'améliorer l'évaluation des techniques de manutention du membre supérieur, avec trois objectifs spécifiques : (1) développer des indices cinématiques, électromyographiques et musculo-squelettiques synthétiques pour évaluer et différencier des techniques de manutention du membre supérieur ; (2) développer un logiciel libre d'analyse biomécanique ; et (3) utiliser les indices et le logiciel développés pour décrire les différences biomécaniques entre des femmes et des hommes manutentionnaires. Nous avons récolté des données de cinématique, d'électromyographie et de force sur 30 femmes et 30 hommes réalisant une tâche de manutention qui consistait à déplacer une boîte de 6 et 12 kg entre la hauteur des hanches et la hauteur des yeux. À partir de ces données, nous avons développé des indicateurs synthétiques : un indicateur cinématique utile pour identifier des techniques de manutention problématiques et plus généralement les fonctions articulaires ; des indicateurs électromyographiques qui permettent d'estimer la quantité d'activation musculaire et la co-contraction musculaire ; et des indicateurs musculo-squelettiques qui permettent d'estimer les contraintes musculaires totales et les contraintes appliquées à l'articulation glénohumérale. Nous avons implémenté ces indicateurs avec pyomeca, notre logiciel libre d'analyse biomécanique. Mis à disposition de la communauté biomécanique, pyomeca supporte des tâches utiles dans le quotidien d'un chercheur biomécanique, mais également des routines biomécaniques plus avancées, axées sur la mécanique du corps rigide et le traitement de signal. Ce dernier se démarque des logiciels biomécaniques existants parce que c'est une solution libre, conviviale, spécialisée et sûre. Nous avons ensuite appliqué les indices synthétiques pour décrire les différences biomécaniques entre les femmes et les hommes participant à notre expérimentation. L'indicateur cinématique a montré que les femmes employaient une technique de manutention moins sécuritaire, avec une plus grande contribution glénohumérale, une faible contribution des membres inférieurs et une boite plus éloignée du tronc. Ces différences de technique se sont répercutées sur les indicateurs électromyographiques et musculo-squelettiques, avec des activations musculaires deux fois plus importantes comparativement aux hommes et une moindre stabilité de l'articulation glénohumérale. Ces différences pourraient contribuer à expliquer la prévalence de blessure du membre supérieur plus élevée chez les femmes manutentionnaires. Cette thèse a donc permis de développer des indicateurs synthétiques et un logiciel libre d'analyse biomécanique qui pourraient permettre aux ergonomes d'évaluer l'exposition aux risques de blessures du membre supérieur pendant une tâche de travail dynamique. Appliqués à une population spécifique, ces indicateurs suggèrent qu'il est crucial d'accorder une attention particulière au sexe pendant l'évaluation d'une tâche de travail au-dessus des épaules.Work-related upper limb musculoskeletal disorders represent a public health challenge in the material handling industry. In addition to affecting the worker's quality of life, these injuries result in lost work time and increased production costs. While we have epidemiological evidence that more female material handlers suffer from shoulder pain than men, the literature is lacking biomechanical indicators that explain the origin of this difference. The general objective of this thesis was to improve the evaluation of upper limb handling techniques, with three specific objectives~: (1) to develop synthetic kinematic, electromyographic and musculoskeletal indicators to evaluate and differentiate upper limb handling techniques~; (2) to develop an open source biomechanical analysis software~; and (3) to use the developed indicators and software to describe the biomechanical differences between female and male workers. We collected kinematics, electromyography and force data on 30 women and 30 men performing a handling task that consisted in lifting a 6 and 12~kg box from hip to eye level. From these data, we developed synthetic indicators~: a kinematic indicator useful to identify poor handling techniques and more generally joint functions~; two electromyographic indicators to quantify the amount of muscle activation and muscle co-contraction~; and two musculoskeletal indicators to estimate total muscle stress and stress applied to the glenohumeral joint. We have implemented these indicators with pyomeca, our open-source biomechanical analysis software. Available to the biomechanical community, pyomeca provide basic operations useful in the daily workflow of a biomechanical researcher, but also more advanced biomechanical routines geared towards rigid body mechanics and signal processing. pyomeca stands from existing biomechanical software because it is an open-source, user-friendly, specialized and secure solution. We then applied our synthetic indicators to describe the biomechanical differences between the women and men participating in our experiment. The kinematic indicator showed that women used a poor handling technique, with a higher glenohumeral contribution, a low contribution from the lower limbs and a box further away from the trunk. These differences in technique affected the electromyographic and musculoskeletal indicators, with twice as much muscle activation compared to men and less glenohumeral stability. These results may contribute to the sex difference in the prevalence of upper limb musculoskeletal disorders. This thesis has enabled the development of biomechanical indicators and an open-source software that could allow ergonomists to assess the upper limb exposure during a dynamic lifting task. Applied to a specific population, these indicators argue for a careful consideration of sex during ergonomics intervention, particularly during overhead work

Life Sciences Program Tasks and Bibliography for FY 1997

This document includes information on all peer reviewed projects funded by the Office of Life and Microgravity Sciences and Applications, Life Sciences Division during fiscal year 1997. This document will be published annually and made available to scientists in the space life sciences field both as a hard copy and as an interactive internet web page