Pedro Luiz Côrtes

Bio: Pedro Luiz Côrtes is an academic researcher from Youngstown State University. The author has contributed to research in topics: Ultimate tensile strength & Materials science. The author has an hindex of 15, co-authored 84 publications receiving 981 citations. Previous affiliations of Pedro Luiz Côrtes include Monterrey Institute of Technology and Higher Education & University of Liverpool.

The fracture properties of a fibre–metal laminate based on magnesium alloy

Abstract: A range of fibre–metal laminates (FML) based on a lightweight magnesium alloy have been manufactured and tested. Two types of composite reinforcement have been investigated, a woven carbon fibre reinforced epoxy and a unidirectional glass fibre reinforced polypropylene. Initial tests using the single cantilever beam geometry (SCB) have shown that little or no surface treatment is required to achieve a relatively strong bond between the composite plies and the magnesium alloy. Tests on both types of laminate indicated that increasing the volume fraction of composite, Vc, in the FML resulted in a significant increase in its tensile strength. Similar tests showed that the addition of the woven carbon fibre/epoxy plies did not have any effect on the Young's modulus of the FML whereas increasing the Vc of the glass/polypropylene plies resulted in a continuous decrease in the modulus of these thermoplastic–matrix systems. Fatigue tests on both types of laminate highlighted the positive contribution of the composite plies in the FMLs. Here, the crack growth rates in centre-notched tension specimens were significantly lower in the FMLs than in the plain magnesium alloy system. Low velocity impact tests on the FMLs highlighted their excellent energy-absorbing characteristics relative to two aluminium-based FMLs. The specific perforation energy of the glass fibre/PP laminate was higher than that offered by a similar aluminium alloy FML and significantly higher than that for a glass reinforced epoxy/aluminium FML. Here, extensive delamination and shear fracture in the outer magnesium alloy plies were found to contribute to the energy-absorbing capacity of these laminates.

The Tensile and Fatigue Properties of Carbon Fiber-reinforced PEEK-Titanium Fiber-metal Laminates

Abstract: This paper investigates the tensile and fatigue properties of a novel fiber-metal laminate (FML) based on a titanium alloy and carbon fiber-reinforced poly-ether-ether-ketone (PEEK). Tensile tests on unidirectional unnotched laminates have shown that their mechanical properties follow the predictions offered by a simple law of mixtures approach. Tension-tension fatigue tests on notched unidirectional FMLs have shown that these laminates offer fatigue lives up to fifty times greater than those offered by a notched monolithic titanium alloy. An examination of the failed FMLs highlighted the presence of delamination between the titanium alloy and the fiber-reinforced composite. The experimental evidence suggests that this form of damage is harmful during fatigue loading conditions. It has also been shown that delamination is more widespread in FMLs based on thick composite layers than in laminates containing thin composite layers.

The Impact Properties of High-temperature Fiber-Metal Laminates

Abstract: This study investigates the low and high velocity impact properties of fiber–metal laminates (FMLs) based on carbon fiber-reinforced poly-ether-ether-ketone (CF/PEEK) and glass fiber-reinforced poly-ether-imide (GF/PEI) composites. The aim of this work is to develop a lightweight hybrid material for use in high temperature aerospace applications. Here, low velocity impact tests are undertaken using an instrumented impact tower and high velocity impact tests are conducted using a nitrogen gas gun. Low velocity impact testing has shown that the specific perforation energy of the CF/PEEK-based FMLs is similar to that offered by the CF/PEEK composite. In contrast, the specific perforation energy of the GF/PEI FML system is lower than that of the plain PEI composite. The experimental evidence suggests that the inclusion of strong titanium alloy plies does not improve the perforation resistance of these FMLs. High velocity impact tests resulted in failure processes similar to those observed under low velocity l...

Fracture properties of a fiber-metal laminates based on magnesium alloy

Abstract: Fiber-metal laminates (FMLs) are high performance laminated structures based on stacked arrangements of composite material and aluminum alloy. Currently, a glass fiber reinforced epoxy/aluminum alloy FML (GLARE) is being considered for use in the manufacture of the upper fuselage of the A380 Airbus aircraft [1]. Previous work on FMLs has shown that they combine the excellent durability and machinability common to many metals with the superior fatigue and fracture properties offered by many fiber-reinforced composites [2–4]. Krishnakumar [2] tested a Kevlar fiber FML (ARALL) and showed that its ultimate tensile strength is considerably greater than that of a conventional aluminum alloy. Vogelsang [3] conducted tension-tension fatigue tests on a number of FML systems as well as a plain aluminum alloy and showed that crack growth rates in the former were significantly less than those in the plain aluminum alloy. Several workers have investigated the impact response of aerospace-grade fiber-metal laminates [5, 6]. Vlot et al. [5] conducted low and high velocity impact tests on a GLARE system, a plain aluminum alloy and a carbon fiber reinforced thermoplastic. Their results showed that the FML offered the highest damage threshold energy of all the systems considered. The aim of the present work is to investigate the fracture properties of a novel fiber-metal laminate based on a lightweight magnesium alloy and a carbon fiber reinforced plastic. Magnesium alloys offer a number of advantages over many metals including their low density (thirty percent lower than an aluminum alloy), their superior corrosion resistance and their excellent electromagnetic shielding ability. Currently, magnesium alloys are being used in the automotive industry in the manufacture of transmission casings and in the aerospace industry for the manufacture of gearboxes and other lightweight components. The fiber-metal laminates examined in this study were based on 0.5 mm thick magnesium alloy sheets (AZ31 alloy from Advance Metals International Ltd.) and a woven carbon fiber reinforced toughened epoxy (Stesapreg EP121-C15-53 from Stesalit Ltd, Switzerland). The composite and metal plies were placed in a picture frame mold with dimensions 240 × 200 mm and cured for 4 h at 125 ◦C. All of the laminates tested in this research project were based on a 2/1 configuration (two magnesium alloy skins either side of a carbon fiber reinforced epoxy core). Table I summarizes the stacking configurations investigated in this study. The composite volume fraction within the FMLs was varied by increasing the number of composite plies between the two outermost magnesium alloy skins from two to eight. The tensile properties of the FMLs and the magnesium alloy were evaluated using 20 mm wide rectangular samples at a crosshead displacement rate of 2 mm/min. The initial strain history in each sample was recorded using a clip-on extensometer fixed to the specimen edge. The extensometer was incapable of measuring large strains. In such cases, the crosshead displacement was normalized by the length of the working section to yield a nominal strain (this was only undertaken when a complete stress-strain curve was required). The energy-absorbing properties of the fiber-metal laminates were evaluated through a series of single edge notch bend (SENB) tests on specimens with dimensions 100 × 18 mm × thickness. Prior to testing, a 9 mm long pre-crack was introduced at the mid-span. The precrack was sharpened by swiping a sharp razor blade along the tip of the stress concentration. The SENB specimens were positioned on two simple supports positioned 72 mm apart and loaded at a crosshead displacement rate of 5 mm/min. The work of fracture was then determined by dividing the area (energy) under the load-displacement curve by the cross-sectional area of the fractured ligament. Fig. 1 shows typical stress-strain (nominal) curves for the three FMLs and the plain magnesium alloy. The stress-strain curve for the plain magnesium alloy indicates that although its tensile strength is below that of the FMLs, it does exhibit quite a high degree of ductilty beyond the elastic limit. The stress-strain curves for all of the FMLs exhibited an almost linear response up to maximum stress at which point the composite layers fractured in a brittle manner. An examination

Additive Manufacturing Processes: Selective Laser Melting, Electron Beam Melting and Binder Jetting-Selection Guidelines.

Abstract: Additive manufacturing (AM), also known as 3D printing or rapid prototyping, is gaining increasing attention due to its ability to produce parts with added functionality and increased complexities in geometrical design, on top of the fact that it is theoretically possible to produce any shape without limitations. However, most of the research on additive manufacturing techniques are focused on the development of materials/process parameters/products design with different additive manufacturing processes such as selective laser melting, electron beam melting, or binder jetting. However, we do not have any guidelines that discuss the selection of the most suitable additive manufacturing process, depending on the material to be processed, the complexity of the parts to be produced, or the design considerations. Considering the very fact that no reports deal with this process selection, the present manuscript aims to discuss the different selection criteria that are to be considered, in order to select the best AM process (binder jetting/selective laser melting/electron beam melting) for fabricating a specific component with a defined set of material properties.

Review of the mechanical properties of carbon nanofiber/polymer composites

Abstract: In this paper, the mechanical properties of vapor grown carbon nanofiber (VGCNF)/polymer composites are reviewed. The paper starts with the structural and intrinsic mechanical properties of VGCNFs. Then the major factors (filler dispersion and distribution, filler aspect ratio, adhesion and interface between filler and polymer matrix) affecting the mechanical properties of VGCNF/polymer composites are presented. After that, VGCNF/polymer composite mechanical properties are discussed in terms of nanofibers dispersion and alignment, adhesion between the nanofiber and polymer matrix, and other factors. The influence of processing methods and processing conditions on the properties of VGCNF/polymer composite is also considered. At the end, the possible future challenges for VGCNF and VGCNF/polymer composites are highlighted.