A Computer Simulation of the Nitinol Thermal Expansion under Fast Varying Working Conditions

We discuss the setup of a simulation on ANSYS to predict the thermal expansion of parts made of Nitinol. A simulation is justified for working conditions in which the part heating is not ho-mogeneous originating a temperature gradient across the part section such that an analytical estimate for the part expansion cannot be calculated. We apply the simulation to the topological optimization of a square section geometry and a bullet geometry for water assisted injection molding. For the topo-logical optimization we consider as parameter the wall thickness and consider both the cases of fast varying temperature and fast varying temperature and pressure.info:eu-repo/semantics/publishedVersio

Numerical Thermal Analysis of a T Jump System Used for Studying Polymer Behaviour

Acknowledgements: The authors would like to acknowledge the financial support from Fundação da Ciência e Tecnologia (Portugal) as part of the UC4EP (Understanding Crystallisation for Enhanced Polymer Properties) at CDRSP PTDC/CTM-POL/7133/2014, UID/Multi/04044/2013, PAMI Nº 022158 and the Fundo Europeu de Desenvolvimento Regional (FEDER), Programa Portugal 2020, through the Programa Operacional Regional do Centro 2020 (CENTRO-01-0145-FEDER-022158). The neutron scattering measurement was performed at the STFC ISIS facilities (United Kingdom).The processing of polymers is highly complex. The study of their crystallisation assumes an important role and needs to be carefully detailed. Scattering experiments can be used to study polymer molecular organisation. However these procedures are still very multifaceted leading to the need for planning all the details in the experiments that are to be performed. This manuscript presents a finite element model developed to study the temperature variation of a T Jump System, which has been used for studying polymer behaviour with the NIMROD instrument at the ISIS Neutron and Muon Source, UK. Results show that the variation across the sample was 2ºC at a maximum temperature of 70ºC and 1ºC at a maximum temperature of 50ºC.info:eu-repo/semantics/publishedVersio

Aerodynamics of a wheelchair sprinter racing at the 100m world record pace by CFD

The aim of this study was to analyze aerodynamics in a racing position of a wheelchair-racing sprinter, at the world record speed. The athlete and wheelchair were scanned at the beginning of the propulsive phase position (hands near the handrims at 12h) for the 3D model acquisition. Numerical simulation was run on Fluent, having as output the pressure, viscosity and total drag force, and respective coefficients of drag at the world record speed in T-52 category. Total drag was 7.56N and coefficient of drag was 1.65. This work helped on getting a deeper insight about the aerodynamic profile of a wheelchair-racing athlete, at a 100m world record speed.info:eu-repo/semantics/publishedVersio

Traffic Vertical Signposting: Materials Characterization and Structural Numerical Simulation

Aknowlegements: This work was supported by the project POCI-01-0247-FEDER-010797from the Agency for Competitiveness and Innovation (IAPMEI). In addition, the authors acknowledge the funding from the project UID/Multi/04044/2013 of the Portuguese Foundation for Science and Technology (FCT) and PAMI - ROTEIRO/0328/2013 (Nº 022158).The existing metallic solutions used for vertical traffic signs are associated with higher costs and environmental issues due to their manufacturing and degradation, when compared with polymeric solutions. Thus, the development of vertical signs considering the injection from polymeric materials in order to overcome problems related with sustainability, maintenance costs, and to achieve higher resistance to corrosion assumes nowadays an important role. The use of ecofriendly and innovative products considering the industrial waste combined with synthetic polymers performing the appropriate mechanical properties, can also be studied to find out new solutions that allow to solve the aforementioned problems. Additionally, these innovative vertical signs can contribute to avoid vandalism events related with theft and graffiti activities. This work presents the prior materials investigation and the structural design of vertical signs that are intended to be produced through polymer injection. Three main steps were considered: i) materials research, ii) materials characterisation through the analysis of polycarbonate resin isolated and in different sets of mixtures with different concentrations through tensile testing and static water contact angle measurements to find the optimal material composition; and iii) structural numerical simulation considering polycarbonate resin and using the current standard EN 12899-1 [1] to compute wind resistance, temporary and permanent deflections. Both experimental and numerical results led to an optimized proposal of the vertical signposting structural design.info:eu-repo/semantics/publishedVersio

Measuring in-situ X-ray scattering of natural rubber biaxial deformation: A new equipment for polymer studies

This research is supported by national funds through the FCT (Portuguese Foundation for Science and Technology)/MCTES (PIDDAC) under the projects UIDB/04044/2020, UIDP/04044/2020, Associate Laboratory ARISE LA/P/0112/2020 and PAMI—ROTEIRO/0328/2013 (Nº 022158) and UID/Multi/04044/2013.Understanding biaxial deformation is essential for a more realistic evaluation of rubber elasticity compared to the more usual uniaxial deformation. To study crystallisation occurring during biaxial deformation of natural rubber films, a new simple equipment has been designed and assembled. The equipment, mounted in the beamline of ALBA synchrotron light source facility, allowed the in-situ measurement of X-ray scattering of natural rubber during biaxial deformation. This work provides, for the first time, quantitative information on crystallisation during biaxial extension.info:eu-repo/semantics/publishedVersio

Chromatic reintegration of historical mortars with lime-based pozzolanic consolidant products

The consolidation process of old renders with loss of cohesion is nowadays performed usually with inorganic compatible products, such as calcium or barium hydroxide or ethyl silicate. The use of organic consolidants as acrylic or vinilic resins is discouraged due to its physico-chemical incompatibility with the original lime-based renders; these organic products work as adhesive in the original substrate, while inorganic consolidants contribute to recover the cohesion loss improving the binder amount and guarantying better durability and full ompatibility. The restoration intervention on historic mortars, including consolidation, often causes aesthetic heterogeneity and prejudices, sometimes dramatically, the global legibility of the architectonic surface. The aesthetic function can be restored by chromatic reintegration, through several techniques, with resource to overpaints, for instance based on calcium hydroxide, pigments and silicates. In this study several consolidant lime-based products were produced and characterized. Pigments were added to the products, in order to achieve chromatic reintegration properties as well as consolidation. The consolidant products consist in aqueous dispersion of calcium hydroxide, a pozzolanic additive (metakaolin or diatomite) and mineral pigments, namely a yellow earth pigment and a synthetic red pigment. The incorporation of a pozzolanic material was made to improve the mechanical strength and durability of the binder. The consolidant products were applied on mortar specimen with a simulated cohesion loss, through a reduced binder quantity and an optimization of the aggregate grain size. Specimens were subjected to different storage conditions (50 and 95% RH), to verify the influence of curing conditions. Physicomechanical and microstructural characterization was performed on the treated mortar specimens to verify the consolidant treatment efficacy. Consolidant treatments show intesting results, and their efficacy vary depending on the pozolanic addition; pigments do not influence that much the consolidation efficiency.Architectural Engineering + TechnologyArchitecture and The Built Environmen

Personalized reusable face masks with smart nano-assisted destruction of pathogens for COVID-19. A visionary road

The Coronavirus disease 2019 (COVID-19) emergency has demonstrated that the utilization of face masks plays a critical role in limiting the outbreak. Healthcare professionals utilize masks all day long without replacing them very frequently, thus representing a source of cross-infection for patients and themselves. Nanotechnology is a powerful tool with the capability to produce nanomaterials with unique physicochemical and antipathogen properties. Here, how to realize non-disposable and highly comfortable respirators with light-triggered self-disinfection ability by bridging bioactive nanofiber properties and stimuli-responsive nanomaterials is outlined. The visionary road highlighted in this Concept is based on the possibility of developing a new generation of masks based on multifunctional membranes where the presence of nanoclusters and plasmonic nanoparticles arranged in a hierarchical structure enables the realization of a chemically driven and on-demand antipathogen activities. Multilayer electrospun membranes have the ability to dissipate humidity present within the mask, enhancing the wearability and usability. The photothermal disinfected membrane is the core of these 3D printed and reusable masks with moisture pump capability. Personalized face masks with smart nano-assisted destruction of pathogens will bring enormous advantages to the entire global community, especially for front-line personnel, and will open up great opportunities for innovative medical applications