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- Ankle Foot Orthosis (AFO) stiffness design for mitigation of ankle inversion injuryPublication . Teixeira, D.; Milho, João; Carvalho, M. S.; Loja, AméliaModelling and simulation of human movement has the potential to improve the design of medical devices and rehabilitation process by enabling the identification of cause-effect relationships in individuals suffering from neurological and musculoskeletal issues. The main goal of this work was to provide a simulation-based stiffness design for an Ankle Foot Orthosis (AFO) that can help to mitigate the risk of a sprain by ankle inversion during the landing in freefall which is known to occur for subtalar angles higher than 25 degrees. Computational simulations were performed using human movement models with and without a passive AFO, to access the AFO sensitivity for the translational stiffness that prevents the cuff from translating with respect to the footplate. The Design of Experiments (DoE) methodology was used to access sensitivities between the three principal directions of the AFO stiffness. Results revealed that the ankle inversion angle was less than 25 degrees when increasingly larger values of translational stiffness were used, although a nonlinear behaviour was observed between the three principal directions of the AFO stiffness, for which injury safe design configurations were obtained.
- 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
- A validated railway vehicle interior layout with multibody dummies and finite element seats models for crash analysisPublication . Ambrosio, Jorge; Carvalho, Marta; Milho, João; Escalante, Susana; Martin, RobertoWe propose a methodology for the validation of a numerical model of a railway interior with an inline seating layout arrangement, based on the use of multibody and finite element approaches for the analysis of the passive safety. We model the railway interior layout using a nonlinear finite element model of the passenger seats and all supporting structures. Multibody models of test dummies, appropriate to the identification of the injury mechanisms, are used as measuring tools of the human exposure to injury. The crash scenario model uses a crash pulse, which is the surrogate for the impact of the railway vehicle structure. Being the multibody dummy validated independently by the software vendor and the nonlinear finite element structural models built with detailed data, the validation of the complete layout involves the identification of the uncertain parameters used in the scenario construction and not of the parameters used in the independent models already validated. The interaction between the multibody and finite element is represented via a penalty contact force model, which, together with the dummy positioning data, provides the uncertain parameter set used in the validation process. An experimental test of the inline seating layout, carried with a physical prototype, provides the reference dynamic response for the validation of the numerical model. The injury levels measured with the dummies provide the reference injury criteria values used in the validation process. Following the model validation, we discuss the results obtained for the nominal crash scenario in the framework of the most relevant injury indices for railway passenger passive safety.
- 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.
- Validation of a railway inline seating model for occupants injury biomechanicsPublication . Carvalho, Marta; Martins, Ana Alexandra; Milho, JoãoThis paper presents the validation of a finite element model in LS-DYNA of the interior inline seating layout simulating a frontal rail impact event for which the experimental test results provide the reference for the injury biomechanics of the occupants. The representative layout consists in two rows of seats and its supporting structures modelled with nonlinear finite elements and the crash acceleration pulse that represents the impact of the railway vehicle structure is imposed in the floor of the coach. For the appropriate identification of the injury mechanisms to the occupant associated to the frontal crash analysis is used the Hybrid III 50th percentile Anthropomorphic Testing Device, being the interaction between the occupant model and the structure characterised via penalty contact force models. The validity of the numerical model is discussed to ensure the representativeness of the analysis procedure and to identify the most relevant injury indices of the occupants. In particular, the head injury criterion is the most critical injury index for the inline seating layout, with a relative deviation of 6.2% of the simulation result with respect to the experimental test.
- Railway seat design for injury mitigation in crash scenarioPublication . Carvalho, Marta; Martins, Ana P.; Milho, JoãoA validated framework developed to analyse railway occupant safety is presented here. The inexistence of restraints and the larger distance between contact features for the railway cabin interior decreases the predictability on the kinematics of its occupants. Simulation results are evaluated considering the severity of the injuries, assessed and quantified using the relevant criteria. It was introduced a head padding that conducted to a reduction of the Head Injury Criterion (HIC) but worsening the value of neck-bending moment in extension (NBME). Finally, the multi-objective optimization procedures are applied to achieve a relevant reduction in injuries. With the implementation of a pad with 42 mm thickness and with a reduction of 8.2% of the backseat plate thickness, is obtained a 41% reduction of the HIC but at the cost of an increase of 49% of the NBME index, though this design allows keeping all injury indices below moderate threshold value.
- Illustrating changes in landscapes of passing opportunities along a set of competitive football matchesPublication . Gómez-Jordana, Luis; Amaro E Silva, Rodrigo; Milho, João; Ric, Angel; Passos, PedroThis study aims to illustrate the landscape of passing opportunities of a football team across a set of competitive matches. To do so positional data of 5 competitive matches was used to create polygons of pass availability. Passes were divided into three types depending on the hypothetical threat they may pose to the opposing defense (penetrative, support, and backwards passes). These categories were used to create three heatmaps per match. Moreover, the mean time of passing opportunities was calculated and compared across matches and for the three categories of passes. Due to the specificity of player’s interactive behavior, results showed heatmaps with a variety of patterns. Specifically the fifth match was very dissimilar to the other four. However, characterizing a football match in terms of passing opportunities with a single heatmap dismisses the variety of dynamics that occur throughout a match. Therefore, three temporal heatmaps over windows of 10 min were presented highlighting on-going dynamical changes in pass availability. Results also display that penetrative passes were available over shorter periods of time than backward passes that were available shorter than support passes. The results highlight the sensibility of the model to different task constrains that emerge within football matches.
- 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.
- Are synergies continuously present in cyclical movements? An example with the basketball dribble taskPublication . Robalo, R.; Diniz, Ana; Milho, João; Pitacas, P.; Passos, P.In human movement, synergies occur when two or more variables co-vary to stabilize a performance goal. The concept of motor redundancy is associated with the existence of several strategies to complete the same task, which enables a movement system to adapt to an ever-changing environment. This feature provides the system with the ability of being flexible enough to produce adaptive movements, but also stable enough to produce acceptable outputs which is a key issue in motor performance. In a kinetic chain of movement, two proximal joints might reciprocally compensate to stabilize an end-effector (i.e., the most distal segment in the limb that interacts with the environment). End-effector variables are 'controlled', and directly linked to performance, whereas the task relevant elements are allowed by the system to have high variability, providing adaptability. In basketball dribbling, we hypothesized that shoulder and elbow variability contributes to stabilize the dribble height as an end-effector performance variable. A specific computational procedure based on the UCM (i.e., Uncontrolled Manifold) notion was used to capture synergies in two groups according to the experience level: amateurs and professionals. Results identified synergy presence during the basketball dribbling, which only occurred when the wrist reached its peak height. The control of the wrist peak height is achieved due to a reciprocal compensation between shoulder and elbow which stabilizes the dribbling height.
- Railway occupant passive safety improvement by optimal designPublication . Carvalho, Marta; Milho, João; Ambrosio, Jorge; Ramos, N.This work presents a systematic approach to the railway occupant passive safety improvement of seating layouts using optimisation methods for the identification of the best design options. The numerical model of this layout is developed using multibody models for the dummies and finite element models for the vehicle interiors, such as seats and any structural part considered as potential target surface during impact being the crash scenario is analysed using the MADYMO code. The objective is the minimisation of the injuries as represented by all relevant injury criteria identified for railway passengers, particularly head and neck, chest and leg. The design variables are seat structural characteristics, easily modified during manufacturing or maintenance without influencing cost. The methodology starts by using a meta-modelling method that supports the definition of a surrogate objective function obtained by fitting a n-dimensional surface to the results of a collection of analysis in which the values of the design variables are varied inside specific domains. A standard deterministic optimisation method is then used to solve the surrogate problem implemented in a Matlab environment. The results show that an optimum design of the interior seating layout is obtained with relevant decreases of the most critical injury criteria.