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- 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
- Dynamic behavior of 3D printed beamsPublication . Carvalho, André; Ribeiro, AntónioOne of the most widely used 3D printing methods is Fused Deposition Modeling (FDM). This method relies on the deposition of a heated polymeric material filament, that traces the desired geometry of the part to be fabricated. Although geometrically similar, parts manufactured by FDM have a different mechanical behavior than ones manufactured by more conventional machining methods, both in statically and dynamically. Even when comparing parts made by the same material, the results are different. This difference in behavior results mainly from how the material is deposited.
- Characterisation and evaluation of the mechanical behaviour of endodontic-grade NiTi wiresPublication . Pereira, Samuel; Carvalho, André; Reis, Luis; Freitas, Manuel; Montalvao, DiogoWith the introduction of new materials and advances in medical science, the endodontic files have changed since the early days of root canal treatments. In the late days, we have seen an increasing use of Nickel-Titanium (NiTi) alloys. At body temperature, NiTi alloys present a superelastic behaviour, which allows to be more effective in the removal of the tooth pulp tissue, and in the protection of the tooth structure. Anyhow, these NiTi instruments will eventually fracture, usually without any visual signal of degradation. Thus, there is a need of studying these alloys, as they present a high hysteresis cycle and non-linearities in the Elastic domain. Currently, there is no international standard to test NiTi endodontic files, so various authors have attempted to design systems that can test them under fatigue loads, usually based on empirical setups. Following a systematic approach, this work presents the results of rotary fatigue tests for two Alfa Aesar (R) Nitinol wires with different diameters (0.58mm and 0.25mm).The formulation is presented, where the material strength reduction can be quantified from the determination of the strain and the number of cycles until failure, as well numerical FEM simulation to verify the analytical model predictions.
- Characterization and evaluation of the mechanical behaviour of endodontic-grade NiTi wiresPublication . Pereira, Samuel; Carvalho, André; Reis, Luís; Freitas, Manuel; Montalvão, DiogoThe orthodontic files have been used in dentistry since the middle ages and, as so, the shape, material and operation mode have changed since those days. In the late days, we have seen an increasing use of Nickel-Titanium (NiTi) alloys, to the detriment of more conventional alloys. At body temperature, these NiTi alloys present a superelastic behaviour, which allow the file to follow the teeth root in an easier way comparing to conventional alloys and have been reported to be more effective in the removal of the tooth pulp tissue, and in the protection of the tooth structure. Not withs tanding, these NiTi instruments, as all the others being subjected to bending loading, they fracture without any visual signal of degradation. Thereby, there is a need of studying these alloys, as they present a high hysteresis cycle and a high non-linearity in the Elastic Domain. Currently, there is not an international standard for these alloys, so various authors have attempted to design systems that can test NiTi endodontic files under fatigue loads, usually based on empirical setups. Following a systematic approach, this work presents the results of rotary fatigue tests for two Alfa Aesar® Nitinol wires with different diameters (0,58mm and 0,25mm).
- Multibody simulation of the musculoskeletal system of the human handPublication . Carvalho, André; Suleman, AfzalThis paper presents a numerical model of the forward multibody dynamics of the human hand. This model forms the basic foundation in the development of a five-fingered anthropomorphic hand prosthesis. The model is composed of two parts: a model for the rigid-body dynamics of the bone and joint structure of the human hand using the modified articulated-body algorithm for tree structures, and a model to represent the action the muscles tendons present in the hand. The resulting nonlinear model takes as input the actuation of each muscle and outputs the movements of the joints of the hand. This model will be used in the development of a nonlinear controller for the prosthesis and in its testing before being applied into the prosthesis prototype.
- Structural health monitoring suitable for airborne components using the speckle pattern in plastic optical fibersPublication . Reis, Filipe M.; Antunes, Paulo Fernando da Costa; Maia, Nuno Manuel Mendes; Carvalho, André; Sérgio, PauloStructural health monitoring (SHM) is a key factor for the correct operation in large dimension structures. In this paper, we propose and demonstrate the application of a distributed optical sensor, suitable for SHM, based on the evaluation of the speckle pattern at the output of a polymer optical fibers, aiming to evaluate the damage imposed to airborne metallic and composite structures. We propose also several algorithms to analyze the speckle data and access the imposed mechanical perturbation. The maximum sampling frequency of this method is limited by the image acquisition devices, yielding to a value of 15 Hz in our case.
- Developments on finite element methods for medical image supported diagnosticsPublication . Almeida, Ana; Barbosa, Joaquim; Carvalho, André; Loja, Amélia; Portal, Ricardo; Rodrigues, José Alberto; Vieira, Lina OliveiraVariational image-processing models offer high-quality processing capabilities for imaging. They have been widely developed and used in the last two decades, enriching the fields of mathematics as well as information science. Mathematically, several tools are needed: energy optimization, regularization, partial differential equations, level set functions, and numerical algorithms. For this work we consider a second-order variational model for solving medical image problems. The aim is to obtain as far as possible fine features of the initial image and identify medical pathologies. The approach consists of constructing a regularized functional and to locally analyse the obtained solution. Some parameters selection is performed at the discrete level in the framework of the finite element method. We present several numerical simulations to test the efficiency of the proposed approach.
- Determination of the rotary fatigue life of NiTi alloy wiresPublication . Carvalho, André; Montalvao, Diogo; Freitas, Manuel; Reis, Luís; Fonte, M.Nickel-Titanium (NiTi) alloys with superelastic properties have been increasingly introduced as a substitute to more conventional alloys, such as stainless steel, in a variety of applications. In Dentistry, NiTi alloys are used in tools such as Endodontic rotary files, allowing the file to follow teeth root canals more easily than their stainless steel counterparts. Nevertheless, during surgery, the file is subjected to cyclic bending loading, since it is rotating while being deformed inside the curved canals and is prone to fracture due to fatigue, without showing any visible signals of degradation. Following a systematic approach, this work presents the results of rotary fatigue tests for several NiTi wires from different manufacturers (Memry and Euroflex). The formulation is presented, where the material strength reduction can be quantified from the determination of the strain and the number of cycles until failure. Experimental tests as well as numerical Finite Element Analysis (FEA) simulations are presented to better understand the fatigue fracture mechanisms present in NiTi alloys, showing that there is good agreement between the predicted strains (difficult to measure in such small wires) and the cycles to failure.
- Rotary fatigue life of NiTi alloy wires and FEA modelling of fatigue damagePublication . Montalvão, Diogo; Carvalho, André; Freitas, Manuel; Reis, LuísNickel-Titanium (NiTi) alloys with superelastic properties have been increasingly introduced as a substitute to more conventional alloys. For example, NiTi alloys used in Dentistry, such as in Endodontic rotary files, possess superelastic properties that allow for the file to follow teeth root canals more easily than their stainless-steel counterparts. Nevertheless, during surgery, the file is subjected to cyclic bending loading, since it is spinning while being deformed inside the curved canal. Therefore, these instruments are prone to fracture due to fatigue, without showing any visible signals of degradation. This problem brought new challenges on how new instruments should be tested, as NiTi alloys are highly non-linear. However, most existing test setups ignore the fracture mechanics involved in the fatigue phenomenon. In this work, the results of rotary fatigue tests for NiTi wires from different manufacturers is presented. The formulation is described, where the material strength reduction can be quantified from the determination of the strain and the number of cycles until failure. Experimental tests as well as numerical Finite Element Analysis (FEA) simulations are presented to better understand the fatigue fracture mechanisms present in NiTi alloys, showing that there is good agreement between the predicted strains (difficult to measure in such small wires) and the cycles to failure. One characteristic is that these alloys exhibit a large hysteresis in the elastic domain if loaded up to the mixture of austenitic and martensitic phases (also known as B19’ martensite) and then unloaded. Rotating bending fatigue tests of NiTi wires show that, when loaded up to the B19’ martensite, the number of cycles to failure decrease with the applied strain.
- Rotary fatigue testing machine to determine the fatigue life of NiTi alloy Wwres and endondontic filesPublication . Carvalho, André; Freitas, Manuel; Reis, Luís; Montalvao, Diogo; Fonte, M.Endodontic rotary file instruments used to treat root canals in dentistry suffered breakthrough transformations in recent years when stainless steel was replaced by Nickel-Titanium (NiTi). NiTi alloys used in Endodontics possess superelastic properties at body temperature (37C) that bring many advantages on the overall performance of the root-canal treatment. They can follow curved root canals more easily than stainless steel instruments and have been reported to be more effective in the removal of the inflamed pulp tissue and protection of the tooth structure. However, these instruments eventually fracture under cyclic bending loading due to fatigue, without any visible signals of degradation to the practitioner. This problem brought new challenges on how new instruments should be tested, as NiTi alloys are highly non-linear and present a large hysteresis cycle in the Elastic domain. Current existing standards are only available for Stainless Steel testing. Thus, many authors have attempted to design systems that can test NiTi endodontic files under fatigue loads. However, no approach has been universally adopted by the community yet, as in most cases they are based on empirical set ups. Following a more systematic approach, this work presents the results of rotary fatigue tests for several NiTi wires from different manufacturers (MemryTM and EuroflexTM). The tests were done on a versatile fully automatic rotary bending testing machine. The formulation is also presented, where the material strength reduction can be quantified from the determination of the strain and the number of cycles until failure.