Repositório Colecção:https://hdl.handle.net/1822/646172024-03-28T13:45:50Z2024-03-28T13:45:50ZStiffness and damping properties of a composite beam designFerreira, M.Peixinho, NunoCarneiro, V.Ribeiro, P.Meireles, José F.Soares, Delfimhttps://hdl.handle.net/1822/902232024-03-28T09:48:54ZTítulo: Stiffness and damping properties of a composite beam design
Autor: Ferreira, M.; Peixinho, Nuno; Carneiro, V.; Ribeiro, P.; Meireles, José F.; Soares, Delfim
Resumo: This work presents a characterization of dynamic mechanical properties of composite beams that were 3D-printed using fused filament fabrication. Two materials were used in the manufacturing process: a flexible material was used as filler of the hollow section (FilaFlex—Polyether-Polyurethane elastomer) while polylactic acid (PLA) polymer was used for the external wall of the beam. The main objective for such material integration is to enhance damping properties without compromising the overall stiffness. Dynamic mechanical analysis (DMA) was used to determine the inherent beam stiffness (storage modulus) and damping (tanδ), to assess the influence of void-filling volume fraction in the dynamic properties and therefore optimize the beam static and dynamic performance. At room temperature, it was shown that the introduction of low contents of flexible filling actually generated an increased in stiffness due to the changes the filament orientation to accommodate the filling material. Regarding the damping performance, it was proved that the introduction of filling enhanced internal friction. It was possible to optimize both stiffness and damping of the beam design by finding the most beneficial combination of these properties.
<b>Tipo</b>: bookPartNumerical simulation of impact behaviour of multi-cell thin-walled structures with configurable thermal trigger designPeixinho, NunoResende, P.https://hdl.handle.net/1822/902192024-03-28T09:38:07ZTítulo: Numerical simulation of impact behaviour of multi-cell thin-walled structures with configurable thermal trigger design
Autor: Peixinho, Nuno; Resende, P.
Resumo: This study presents numerical results for thin-walled octagonal structures subjected to impact loading and analysed for different section and trigger solutions. Triggers are usually considered in crashworthiness applications as geometrical features introduced to promote crash initiation, reduction of peak loads and promotion of efficient energy absorption deformation modes. In this study, the improvement potential of the introduction of thermal triggers is analysed. These are obtained, in concept, through localized heat treatment in selected aluminium alloys wherein a softened region works as trigger area. The main objective of such approach is to absorb impact energy in a progressive and controlled manner with higher efficiency and moderate peak loads. In the present implementation, two different alternatives for section design complimented with geometric and thermal trigger options are analysed. The application is studied recurring to numerical simulation of representative base octagonal geometry and an alternative complex multi-cell section design that is suitable for extrusion manufacturing process. The alternative geometry is allowed for significant improvements in specific absorbed energy. Both geometric and thermal trigger solutions are allowed for reduction in peak loads while maintaining or improving energy absorption parameters.
<b>Tipo</b>: bookPartSimulation strategies for dynamic and static behaviour of composite beamsAlves, Alexandra Manuela Vieira Cruz PintoAlves, S.Peixinho, NunoCarneiro, V. H.Mendonca, Joao PedroRodrigues, O.https://hdl.handle.net/1822/901932024-03-27T17:34:43ZTítulo: Simulation strategies for dynamic and static behaviour of composite beams
Autor: Alves, Alexandra Manuela Vieira Cruz Pinto; Alves, S.; Peixinho, Nuno; Carneiro, V. H.; Mendonca, Joao Pedro; Rodrigues, O.
Resumo: Doors and windows represent a vital role in domestic energy efficiency, and multi-material beams with a thermal break can be fundamental in terms of energetic sustainability. Their static and dynamic structural performance is fundamental to ensure a proper thermal insulation. Two multi-material composite beam topologies were tested in a three-point bending, while one was subjected to an experimental frequency response analysis. FEM models were created for the composite beams, using beam elements (BEAM189) and solid elements (SOLID186) with a shared topology configuration. Their capacity to predict the static and dynamic behaviour of the beams was assessed by comparing the numerical results with the experimental and analytical data. It is shown that the three-point bending behaviour of the physical beam could not be realistically captured by the 1D beam elements model, as their cross section with different components could not be coupled due to the relatively low stiffness of the polymeric components. However, the eigenfrequencies from the beam elements were very close to those measured experimentally, meaning the dynamic modulus at low strain values could keep the beam’s cross section in-plane during the experiment. On the other hand, the 3D solid elements had the opposite outcome, agreeing with the experimental three-point bending test but not with the experimental modal analysis.
<b>Tipo</b>: bookPartEnergy performance of a service building: Comparison between EnergyPlus and RevitSilva, João Pedro VasconcelosBrás, JoséNoversa, RicardoRodrigues, Nelson José OliveiraMartins, Luís BarreirosTeixeira, J. CarlosTeixeira, S. F. C. F.https://hdl.handle.net/1822/720392022-03-31T11:04:03ZTítulo: Energy performance of a service building: Comparison between EnergyPlus and Revit
Autor: Silva, João Pedro Vasconcelos; Brás, José; Noversa, Ricardo; Rodrigues, Nelson José Oliveira; Martins, Luís Barreiros; Teixeira, J. Carlos; Teixeira, S. F. C. F.
Resumo: Currently, the energy consumption study in buildings is very important, since it is one of the sectors of activity where there is great potential to improve energy efficiency. On the market, there are several simulation software, and the aim of this work consists in conducting a comparison between two dynamic simulation software, EnergyPlus, and Revit, with respect to the results obtained of thermal loads and annual energy consumption of a service building.
In the simulation using EnergyPlus, an annual energy consumption of 442 MWh was obtained, that compares with 533 MWh when using Revit. Concerning the thermal loads in the sales area of the hypermarket, the simulation results for the thermal loads were the following: 761 kW for heating and 79 kW for cooling, versus 924 kW for heating and 86 kW for cooling when using the EnergyPlus and the Revit software, respectively. This discrepancy between the values obtained could be due to the limited selection of climatic files in Revit as well as the different definitions of the HVAC systems.
<b>Tipo</b>: conferencePaperThermal simulation of a supermarket cold zone with integrated assessment of human thermal comfortNoversa, RicardoSilva, João Pedro VasconcelosRodrigues, Nelson José OliveiraMartins, Luís BarreirosTeixeira, J. CarlosTeixeira, S. F. C. F.https://hdl.handle.net/1822/720362022-03-31T10:52:27ZTítulo: Thermal simulation of a supermarket cold zone with integrated assessment of human thermal comfort
Autor: Noversa, Ricardo; Silva, João Pedro Vasconcelos; Rodrigues, Nelson José Oliveira; Martins, Luís Barreiros; Teixeira, J. Carlos; Teixeira, S. F. C. F.
Resumo: This work seeks to analyze the thermal comfort of the occupants in a large building of Commerce and Services, integrating measures of assessment and energy efficiency promotion. The building is still in the construction phase and at its conclusion, will correspond to a supermarket located in the Central region of Portugal. For the evaluation of thermal comfort, Fanger’s methodology was used, where the Predicted Mean Vote (PMV) and Predicted Percentage of Dissatisfied (PPD) were calculated based on a detailed analysis of the environmental variables. These are essential to obtain, namely, mean air velocity, mean radiant temperature, mean air temperature and relative humidity. The other crucial variables are the metabolic rate and the thermal clothing resistance. The simulations necessary for the thermal comfort assessment were performed in ANSYS Fluent, in order to minimize the energy consumption in the cold thermal zone of the building, the sales area with frozen and chilled food, by means of reducing the inflow of air, without compromising thermal Comfort. The final results showed that the reduction of the amount of air to be inflated did not compromise the thermal comfort of the occupants. The Computational Fluid Dynamics (CFD) methodology allowed the creation of comfort maps, albeit for a single zone due to computational limitations. According to the results, the most comfortable zone was located right below the air insufflation with the summer being a more comfortable season. In winter, the main problem detected was the cold located near the floor.
<b>Tipo</b>: conferencePaper