Loading...
10 results
Search Results
Now showing 1 - 10 of 10
- Kinematics of a classical ballet base movement using a kinetic sensorPublication . Barbosa, Inês; Milho, João; Lourenço, Inês; Mota, Ana; Nascimento, Vanda Maria dos Santos; Carvalho, Alda; Carvalho, André; Portal, RicardoDance is an art form considered a language since it can sometimes reflect a population’s culture or even a celebration that accompanies humanity from its earliest times and which requires from performers a high physical and emotional dexterity. It is expected that the dancer performs rigorous and repetitive technical movements that often lead to painful injuries, resulting in 56% of classical ballet dancers will suffer from some type of musculoskeletal injury. Due to this high number of injuries, it is essential to study and analyse base movements for this type of dance in order to prevent injuries and to optimize the dancer's choreography and productivity. These movements are precedents of more complex movements. In this work, the study of a base dance movement, the Echappé Sauté, using biomechanical techniques is carried out to study the kinematics of the movement. For the data collection, three dancers voluntarily participated and the movements were capture using a 2nd Generation Kinect camera that allows the capture of 3D movement. The biomechanical analysis was performed using the IpiSoft software and a manual procedure was used to perform a 2D biomechanical analysis based on the assumption that the dance movements for this study occur only in one plane. The results were compared to show the adequacy of the use of the Kinetic sensor for 3D dance movement analysis. 7
- Mechanical behaviour of corrugated laminatesPublication . Pinheiro, D. J. G.; Loja, Amélia; Barbosa, Inês; Milho, JoãoThe present research work intends to perform a wide set of structural analyses upon corrugated composite laminated panels and based on these analyses, to assess their mechanical response in correspondence to the constructive solutions, which may range from the composite materials selection to the geometrical features and other modelling parameters. To improve the mechanical performance of those panels one may consider enhancing their geometrical characteristics, their corrugation shape configuration and the materials used to build them. In this latter case, when considering materials selection, laminated composites may also constitute an important alternative. In any case it is considered necessary to assess the impact that each of these parameters may have in the static and in the free vibration behaviour of the structures, in a comprehensive and detailed way. To achieve the main objective of this research work, a comprehensive and diversified set of case studies is considered in order to characterize the influence that each of the modelling, material and geometrical parameters and characteristics may have in the mechanical response of a corrugated panel. This study allowed concluding that for the wide set of design parameters considered, the fibre orientation and corrugation parameters are the ones responsible for the majority of the significantly improved performances.
- Análise biomecânica de movimento de ballet usando um sensor KineticPublication . Lourenço, Inês; Barbosa, Inês; Milho, João; Mota, Ana; Nascimento, Vanda; Carvalho, Alda; Carvalho, André; Portal, RicardoA dança é uma forma de arte considerada como uma forma de linguagem uma vez que pode refletir por vezes uma cultura de uma população ou até uma celebração que acompanha a humanidade desde os seus mais remotos tempos [1] e que requer do bailarino uma destreza física e emocional exigente. Dentro das capacidades físicas, é esperado do bailarino movimentos técnicos realizados de forma rigorosa e repetitiva que levam muitas vezes a lesões dolorosas para os mesmos, admitindo-se que 56% das bailarinas praticantes de Ballet clássico irão sofrer de algum tipo de lesão musculoesquelética [2].
- Characterization of a dance movement using a Kinetic cameraPublication . Barbosa, Inês; Milho, João; Lourenço, Inês M.; Mota, Ana; Nascimento, Vanda S.; Carvalho, André; Portal, Ricardo; Carvalho, AldaDance is an art form considered as a form of language since it can sometimes reflect a culture of a population or even a celebration that accompanies humanity from its earliest times and which requires of the dancer a high physical and emotional dexterity. However, it is expected that the dancer performs rigorous and repetitive technical movements that often lead to painful injuries. Due to the high number of injuries, it is essential to study and analyze base movements for this type of dance in order to prevent injuries and to optimize the dancer's choreography and productivity. These movements are precedents of more complex movements. In this work, the study of a basic jump, the Grand Jete, using biomechanical techniques is carried out by finding the kinematics of the movement. For the data collection, three dancers (2 females and 1 male) voluntarily participated and the movements were capture using a 2nd Generation Kinect camera that allows the capture of 3D movement. The biomechanical analysis was performed for the movement recorded and the results were presented to show the adequacy of the methodology proposed. By using this methodology, the aim is to characterize the movement and to be able to promote a better understanding of everything involved in the performance of the movement with the performers and teachers.
- Design of a laminated composite multi-cel structure subjected to torsionPublication . Barbosa, Inês; Loja, AméliaLaminate composite multi-cell structures have to support both axial and shear stresses when sustaining variable twist. Thus the properties and design of the laminate may not be the most adequate at all cross-sections to support the torsion imposed on the cells. In this work, the effect of some material and geometric parameters on the optimal mechanical behaviour of a multi-cell composite laminate structure is studied when torsion is present. A particle swarm optimization technique is used to maximize the multi-cell structure torsion constant that can be used to obtain the angle of twist of the composite laminate profile.
- Towards damage quantification caused by drilling in fibre composite laminatesPublication . Alves, M. S. F.; Barbosa, Inês; Bragança, Ivo; Loja, AméliaDrilling operations are a very frequent need when one needs to connect diferente components in a structure, regardless the nature of the materials involved. When these components are total or partially made of composite materials, this manufacturing operation requires a particular care, as the heterogeneous character of composites makes them especially prone to delamination or fibre pulling-out. These undesirable situations, not only contribute to reduce the stiffness/strength of the material in the drilled region neighbourhood, but they may even lead to a subsequent damage propagation and failure. It is therefore important to improve drilling processes efficiency from the damage minimization perspective. To this purpose, the characterization of the drilling parameters influence in a cross-relation to the composite material characterization may be a relevant contribution. With the present work, one intends to present preliminary results associated to the experimental procedure that will enable the characterization of the influence of drilling parameters and of material and geometrical specimen parameters on the drilling affected areas. The information acquisition of the affected areas is carried out through thermographic digital images. A set of illustrative cases is presented and preliminar conclusions are drawn.
- A study on the static behavior of functionally graded I-shaped beamsPublication . LOJA, M.A.R.; Carvalho, André; Barbosa, InêsFunctionally graded materials are well-known for their ability to minimize abrupt stress transitions that are typical of laminated composites, as well as for being very suitable to operate in adverse high-temperature environments. They can act as thermal barriers if a proper selection of the constituent materials is considered. These materials and structures have attracted the attention of many researchers; however, previous research efforts have been focused on the systematic study of rectangular-shaped cross-section profiles. The use of beams characterized by other cross-sections, which are commonly used in metallic construction, may benefit from the continuous, smooth materials mixture that is typically found within functionally graded composites. Hence, this work aims to investigate the behavior of symmetrical, I-shaped, cross-section beams made from these advanced composites by performing a set of parametric analyses. These beams are modeled after solid finite elements to be able to describe the materials mixture evolution through the beam thickness with greater detail. Thick and moderately thick beams are submitted to static loading while considering different boundary conditions, and their linear static behavior is analyzed. As expected, the stress profiles are highly influenced by the materials' mixture profiles. Significant shear stress was found in the I-shaped cross sections.
- Towards damage quantification caused by drilling in fibre composite laminatesPublication . Alves, M. S. F.; Barbosa, Inês; Bragança, Ivo; Loja, AméliaDrilling operations are a very frequent need when one needs to connect diferente components in a structure, regardless the nature of the materials involved. When these components are total or partially made of composite materials, this manufacturing operation requires a particular care, as the heterogeneous character of composites makes them especially prone to delamination or fibre pulling-out. These undesirable situations, not only contribute to reduce the stiffness/strength of the material in the drilled region neighbourhood, but they may even lead to a subsequent damage propagation and failure. It is therefore important to improve drilling processes efficiency from the damage minimization perspective. To this purpose, the characterization of the drilling parameters influence in a cross-relation to the composite material characterization may be a relevant contribution. With the present work, one intends to present preliminary results associated to the experimental procedure that will enable the characterization of the influence of drilling parameters and of material and geometrical specimen parameters on the drilling affected areas. The information acquisition of the affected areas is carried out through thermographic digital images. A set of illustrative cases is presented and preliminar conclusions are drawn.
- An assessment of thermally influenced and delamination-induced regions by composites drillingPublication . Loja, Amélia; Alves, M. S. F.; Bragança, Ivo; Rosa, R. S. B.; Barbosa, Inês; Barbosa, JoaquimThe connection among different structural components may be promoted by several means. Among these, if one considers mechanical connections, it becomes often necessary to drill the components. When these structures are total or partially made of composite materials, this drilling operation imposes a particular care, due to its heterogeneous character highly prone to delamination or fibre pulling-out. Under these circumstances, not only will the stiffness and strength of the material be reduced in the drilled region neighbourhood, but ultimately a more worrying situation may arise if specific conditions exist to enable propagation and subsequent failure. It is therefore important to improve the drilling processes efficiency from the damage minimization perspective. To this purpose, the characterization of the drilling parameters influence in a cross-relation to measurable resulting effects may be a relevant contribution. With the present work, one intends to characterize how different drilling parameters may affect the surrounding region, either from an induced damage quantification perspective as well as from a thermally affected area characterization. The information acquisition of the affected areas was carried out both through scans and thermographic digital videos and images. A set of illustrative cases is presented to support the conclusions.
- Identification of contact properties of the foot in the stance phase of walkingPublication . Barbosa, InêsIn the study of biped walking, when using forward dynamics analysis, the description of the contact between the feet and the ground is of fundamental importance. The aim of this work is to build a foot model that is capable of describe the foot-ground contact during the stance phase in a simulation. Hyper ellipsoids are used as the contact elements between the foot and the ground and an optimization procedure is used to identify the material and geometric properties of the ellipsoids for the model to simulate human walking. The optimal problem is the minimization of a function relating the predicted ground reaction forces with the forces measured experimentally for a given trial and their application points. Several optimization methods were tested. In the end, a combination of a genetic algorithm and the Sequential Quadratic Programming method was used. There is a good correlation between the solution obtained by the model and experimental data acquired. The model presented is able to simulate the same task as the one captured experimentally and reliable enough to be used in a biomechanical model of the human locomotor system.