Alexandre Velhinho

Alexandre Velhinho
Universidade NOVA de Lisboa | NOVA · Centre of Materials Research (CENIMAT)

Assistant Professor

About

48
Publications
10,456
Reads
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918
Citations
Citations since 2017
16 Research Items
528 Citations
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
Additional affiliations
March 2004 - present
Universidade NOVA de Lisboa
Position
  • Professor (Assistant)
Description
  • Teaching experience covers Mechanical Properties of Materiais, Composite Materials, Processing Technologies of Metals, Materials Selection for Sustainability.
January 2003 - present
Universidade NOVA de Lisboa
Position
  • Integrated Researcher
November 2001 - December 2003
University of Minho
Position
  • Research Assistant (on secondment from Univ. Nova de Lisboa)

Publications

Publications (48)
Chapter
Tantalum is used in titanium alloy. However, there is still little knowledge about the mechanical proprieties of Ti-Ta alloys. And about their fatigue behavior, no documented information is known. The potential applications of Ti-Ta alloys are medical, naval, aerospace. Data related to the Ti-Ta alloys obtained by additive manufacturing is innovati...
Article
Full-text available
Structural metamaterials presenting negative values of one or more mechanical and thermomechanical indices – namely the Poisson's ratio, the linear compressibility, and the coefficient of thermal expansion – are the promising candidates to the applications in many fields, ranging from precision mechanics to biomedical devices or energy absorption....
Article
Full-text available
A computational environment - in the following called Problem Solving Environment (PSE) - dedicated to the analysis of tomographic images of composite materials is presented. The PSE current version is centered on reinforcement characterization and its main features are: (i) running on a desktop PC equipped with GPGPUs (General Purpose Graphical Pr...
Article
Full-text available
Background: The use of 3D printing of hydrogels as a cell support in bio-printing of cartilage, organs and tissue has attracted much research interest. For cartilage applications, hydrogels as soft materials must show some degree of rigidity, which can be achieved by photo- or chemical polymerization. In this work, we combined chemical and UV lase...
Poster
Shape memory alloys (SMA) present interesting functional characteristics (shape memory effect and superelasticity) that make them quite attractive for a wide range of applications. These functional characteristics are a consequence of phase transformations that take place within well-defined temperature ranges or stress ranges, depending on being t...
Article
Full-text available
This paper reports the application of additive manufacturing technology to fabricate bi-dimensional lightweight composite meshes capable of demonstrating auxetic properties (negative Poisson’s ratio (NPR)) in combination with negative thermal expansion (NTE) behaviour, using as constituent materials polymers that do not exhibit NTE behaviour. To de...
Article
Accumulative Roll Bonding (ARB) was used to fabricate Graphene Oxide-reinforced Al-matrix composites. Graphene Oxide reinforcement was suspended in a stabilized aqueous solution and applied, prior to each ARB cycle, through airgun spraying. Different concentrations (graphene oxide/milipore water) were used and for each concentration, samples produc...
Conference Paper
The sand casting process involves defects inherent to the process itself, such as porosity, blowholes or cavities. These types of defects are usually crack initiators, thus directly influencing the durability of the manufactured parts. For this reason, these defects must be considered at the design stage of the components in order to have a reliabl...
Conference Paper
Full-text available
This work is based on the study of damage causes in a DIN 16MnCr5 steel pair of helical gears. Vickers micro hardness tests were carried out and an in-depth study of two zones of the material in question was studied: hardness analysis of the material composing the gear body and analysis of the hardness of the teeth in the area of head of the tooth...
Conference Paper
In this work we have compared several non-destructive testing (NDT) techniques to evaluate the presence of defects in composite materials fabricated by additive manufacturing. These composite materials had a polymeric matrix and were reinforced by long Ni-Ti, carbon or glass fibres of Ni-Ti, carbon fibres and fibre glass. Four different NDT techniq...
Presentation
Presentation about the Conference Paper ”Additive Manufacturing Based Hybrid Process for Long or Continuous Fibre Reinforced Polymeric Matrix” at CIBEM 2017
Conference Paper
Full-text available
This paper presents an overview of the work under development within FIBR3D PT2020 PAC-funded collaborative project. The FIBR3D project consists in developing a hybrid and integrated process that is combined into a single-step platform for additive and subtractive operations that allows CAD-to-Part production with freeform shapes using long or cont...
Article
Inspired by chitin based hierarchical structures observed in arthropods exoskeleton, this work reports the capturing of chitin nanowhiskers’ chiral nematic order into a chitosan matrix. For this purpose, highly crystalline chitin nanowhiskers (CTNW) with spindle-like morphology and average aspect ratio of 24.9 were produced by acid hydrolysis of ch...
Conference Paper
Full-text available
Two technological variants of centrifugal casting (CC) are available to fabricate functionally graded particle-reinforced metal composites. While models abound for the commonest variant (radial CC), its alternative (longitudinal CC) has mainly been neglected in that regard. Longitudinal CC is distinguished by the existence of an acceleration ramp,...
Article
Full-text available
The immobilization of Pd on the magnetite surface afforded Nanocat-Fe–Pd using inexpensive precursors and its catalytic role in the Buchwald–Hartwig reaction for arylation of amines and amides was investigated; C–N bond formation was achieved in moderate to excellent yields and the catalyst could be separated and recycled up to five cycles by magne...
Article
Full-text available
Specimens of aluminum-based composites reinforced by silicon carbide nanoparticles (Al/SiCnp) produced by powder metallurgy (PM) were anodized under voltage control in tartaric-sulfuric acid (TSA). In this work, the influence of the amount of SiCnp on the film growth during anodizing was investigated. The current density versus time response and th...
Article
Aluminium–SiC functionally graded composite coatings were produced using a Friction Surfacing multilayering approach. SiC particles with a median size of 118.8, 37.4 and 12.3 lm were packed inside AA6082-T6 aluminium rods and used as consumables. AA2024-T3 plates were used as substrates. By performing successive fully overlapped depositions with in...
Article
Full-text available
A nano-sized Magnesia–Zirconia (nano-MgO–ZrO2) catalyst was prepared by a simple ultradilution coprecipitation method and by using inexpensive precursors. The nano-MgO–ZrO2 was extensively characterized by SIMS together with other analytical techniques such as X-ray diffraction (XRD) and transmission electron microscopy (TEM). The nano-MgO–ZrO2 cat...
Article
Reduction by magnetic nano-Fe(3) O(4) -Ni: A facile, simple and environmentally friendly hydrogen-transfer reaction that takes place over recyclable ferrite-nickel magnetic nanoparticles (Fe(3) O(4) Ni) by using glycerol as hydrogen source allows aromatic amines and alcohols to be synthesized from the precursor nitroarenes and carbonyl compounds.
Article
Full-text available
A facile, simple and environmentally friendly Fe 3 O 4 –cysteine MNP was synthesized without any additive or additional source of linkers. Fe 3 O 4 –cysteine MNPs were successfully used for the synthesis of b-amino carbonyl and hydroquinoline compounds, which were obtained in excellent yields via multicomponent reactions. Magnetic organocatalysts c...
Article
Full-text available
The micro-structural characterization of composite materials uses X-ray tomography to collect information about the internal characteristics of the samples, in order to educate the researcher about their intrinsic properties. The raw tomographic data need to go through several steps of computational processing, starting with the elimination of nois...
Article
An investigation was conducted in order to produce aluminium based functionally graded MMC reinforced by SiC ceramic particles with median size of 118.8, 37.4 and 12.3μm. AA5083 aluminium alloy plates in the H111 and partially annealed conditions were processed. Several strategies for reinforcement were investigated and its influence on the particl...
Article
Full-text available
This study constitutes an effort to assess the relevant issues which should be addressed in order to adapt models currently available in the literature to predict final particle distribution resulting from radial centrifugal casting (CC) of particle-reinforced metal-matrix functionally graded composites (FGM) to the conditions prevailing in longitu...
Article
Full-text available
An investigation was conducted in order to produce aluminium based functionally graded MMC reinforced by SiC ceramic particles with median size of 118.8, 37.4 and 12.3 �m. AA5083 aluminium alloy plates in the H111 and partially annealed conditions were processed. Several strategies for reinforcement were investigated and its influence on the partic...
Article
Full-text available
Syntactic Functionally Graded Metal Matrix Composites (SFGMMC) are a type of composites reinforced by microballoons exhibiting a graded reinforcement distribution. These materials constitute a promising new generation of lightweight structural materials for aerospace, marine and shielding/insulation applications. In this work, A356 alloy reinforced...
Article
Full-text available
Current technology provides means of fabrication of spherical micro-particles, either hollow or compact, for all sorts of engineering materials. Such spherical particles can be further embedded into another material to build-up either random dispersions or close-packed arrays, according to the production route and the degree of anisotropy intended...
Article
Full-text available
Research on the micro-structural characterization of metal-matrix composites uses X-ray computed tomography to collect information about the interior features of the samples, in order to elucidate their exhibited properties. The tomographic raw data needs several steps of computational processing in order to eliminate noise and interference. Our ex...
Article
Full-text available
Syntactic functionally graded metal matrix composites (SFGMMC) are a class of metallic foams in which closed porosity results from the presence of hollow ceramic microspheres (microballoons), whose spatial distribution varies continuously between the inner and the outer section of the part, thus resulting in a continuous variation in properties. In...
Article
Full-text available
Current technology provides means of fabrication of spherical micro-particles, either hollow or compact, for all engineering materials. Such spherical particles can be further embedded into another material to build-up either random dispersions or close-packed arrays, according to the production route and the degree of anisotropy intended for the u...
Article
Full-text available
This paper provides a brief overview of the possibilities offered by X-ray computed microtomography, and particularly synchrotron radiation X-ray microtomography, regarding metal matrix composite characterization, emphasis being placed in the case of Al-based functionally graded materials. Examples are provided concerning the characterization of th...
Article
Full-text available
In the present paper, work of a preliminary nature pertaining to the development of a simple tool for easy identification of reinforcement clustering in particle-reinforced MMCs is reported. The tool consists of an image processing and analysis routine performed with the aid of a public-domain software. Results obtained were in the form of distribu...
Article
Full-text available
Reliability of functionally graded metal matrix composites (FGMMCs) for automotive components is still dependent on the detailed knowledge of the mechanisms of the microstructural build-up, for instance on the mechanisms leading to the distribution and relative positions of the reinforcing particles. In order to assess the influence of the SiC part...
Article
Full-text available
Reliability of functionally graded metal matrix composites (FGMMCs) for automotive components is still dependent on the detailed knowledge of the mechanisms of the microstructural build-up, for instance on the mechanisms leading to the distribution and relative positions of the reinforcing particles. In order to assess the influence of the SiC part...
Article
Full-text available
The present work reports results obtained from a series of preliminary experiments aiming at complementing the current knowledge about the wear behaviour of centrifugally-cast FGM Al/SiCp composites, through concurrent corrosion processes. Precursor MMC's were prepared by rheocasting, using 118.8 µm SiC particles and an Al-10Si-2.2 Mg alloy. Those...
Conference Paper
Full-text available
The present work reports results obtained from a series of preliminary experiments aiming at complementing the current knowledge about the wear behaviour of centrifugally-cast FGM Al/SiCp composites, through concurrent corrosion processes. Precursor MMC's were prepared by rheocasting, using 118.8 μm SiC particles and an Al-10Si-2.2 Mg alloy. Those...
Article
Full-text available
The concept of functionally graded material (FGM), may be considered as a model particularly interesting to be applied in components for the automotive industry, if reliability and cost can be controlled in an advantageous way. In fact, coupling superior superficial wear resistance with a significant bulk toughness, without compromising important w...
Article
Full-text available
Functionally graded materials (FGM's), particularly in the form of Al-Si metal matrix composites (MMC's) selectively reinforced at the surface with SiC particles, are advanced materials, combining high wear resistance with high bulk toughness or even a thermal barrier at the surface. Centrifugal casting is one of the most effective methods for proc...
Article
The present work refers to an X-ray microtomography experiment aiming at the elucidation of some aspects regarding particle distribution in SiC-particle-reinforced functionally graded aluminium composites.Precursor composites were produced by rheocasting. These were then molten and centrifugally cast to obtain the functionally graded composites. Fr...
Conference Paper
Full-text available
The concept of functionally graded material (FGM), may be considered as a model particularly interesting to be applied in components for the automotive industry, if reliability and cost can be controlled in an advantageous way. In fact, coupling superior superficial wear resistance with a significant bulk toughness, without compromising important w...
Article
Full-text available
Rheocasting, as a semi-solid process, allows the production of aluminium matrix composites at relatively low temperatures (ca. 580ºC), thus favouring a reduced reactivity at the reinforcement-metal matrix interface. When one considers the possibility of further processing (such as any treatment involving remelting, even if partial) of the material,...
Conference Paper
Full-text available
Rheocasting, as a semi-solid process, allows the production of aluminium matrix composites at relatively low temperatures (ca. 580degreesC), thus favouring a reduced reactivity at the reinforcement-metal matrix interface. When one considers the possibility of further processing (such as any treatment involving remelting, even if partial) of the mat...

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Projects

Projects (5)
Project
NiTi wires are subjected to localized heat treatment in order to produce functionally graded wires. These wires are to be used as reinforcements of polymer matrix composites. NiTi wires are characterized using - thermal analysis (DSC) - thermomechanical analysis (TMA) - tensile testing - 3 point bending testing - structural characterization (XRD-SR)