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Metallic and Composite Materials and Structures

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Materials Chemistry".

Deadline for manuscript submissions: closed (15 July 2021) | Viewed by 15570

Special Issue Editors


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Guest Editor
Department of Solid Mechanics, Faculty of Civil Engineering and Architecture, Lublin University of Technology, Nadbystrzycka 40 Str., 20-618 Lublin, Poland
Interests: fluid mechanics; finite element analysis; computational fluid dynamics CFD; simulation engineering; thermodynamics; computational fluid mechanics; numerical simulation; turbulence numerical modeling; aerodynamics design engineering; mechanical properties engineering; applied and computational mathematics engineering; optimization engineering drawing; fluid structure interaction; piping; computational analysis; multidisciplinary design; optimization FSI; aeroelasticity patient simulation; FLUENTCFD coding modeling and simulation; thermal engineering; experimental fluid mechanics; turbulence modeling; numerical analysis; convection heat transfer; solid mechanics; civil engineering; finite element methods; ABAQUS mechanical engineering; aerospace; environmental impact assessment; fracture; material characterization; composites elasticity; fracture mechanics; ceramics materials; composite material alginate
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Guest Editor
Department of Mechanics and Strength of Materials, Faculty of Mechanical Engineering, University Politehnica Timisoara, Blvd. M. Viteazu, Nr. 1, 300222 Timisoara, Romania
Interests: composite and cellular materials; mechanical characterisation of materials; mechanics of materials; fracture mechnaics and fatigue; experimental and numerical stress analysis; transport phenomena

Special Issue Information

Dear Colleagues,

Advanced metallic and composite materials and structures are used in different branches of modern engineering practice. Therefore, this issue covers the newest results and trends in modeling, fabrication, testing, and damage detection of metallic and composite materials and structures subjected to different types of loadings.

Advanced multifunctional and classical composite materials including ceramic, metal, polymer or cement matrix composites as well as so-called natural composites applied to the design of modern structural elements require almost perfect assessment of their behavior under complex thermomechanical loadings. Their internal stochastic or homogenized structure depends on the fabrication technology applied in industry or the conditions of their creation in nature. For example, multifunctional materials have a complicated geometry of reinforcement, including nanoparticles or nanofibers, etc., which are strictly related to specific demands of their application in the design of structural elements.

In the space or car industry, the most important applications are thin-walled structures made of different types of metallic alloys, fibrous composites, laminates, and multifunctional composites. The current applications in modern engineering require analysis of structures of various properties, shapes, and sizes, including structural hybrid joints, subjected to different types of loadings: quasistatic, dynamic, cyclic, thermal, impact, penetration, etc.

Advanced metallic and composite materials and structures should satisfy multiple structural functions during operation conditions. Structural functions include mechanical properties like strength, stiffness, damage resistance, fracture toughness, damping, etc. Nonstructural functions include electrical and thermal conductivities, sensing, actuation, energy harvesting, self-healing capability, electromagnetic shielding, etc. 

The aim of this SI is to understand the basic principles of damage initiation and growth, leading to fracture processes in advanced metallic and composite materials and structures. At present, it is widely recognized that important macroscopic properties, like macroscopic stiffness and strength, are governed by processes that occur at one to several scales below the level of observation. A thorough understanding of how these processes influence the reduction of stiffness and strength form the key to the analysis of existing and the design of improved innovative structural composites and elements.

The study of how these various length scales—nano, micro, and meso—can be bridged or taken into account simultaneously in multiscale models is particularly attractive for composite materials and structural elements, since they have a well-defined structure at the above specified levels.

Prof. Tomasz Sadowski
Prof. Liviu Marsavina
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Metallic and composite materials
  • Multifunctional materials
  • Novel fabrication technologies for composites and structures
  • Classical and thin-walled structures
  • Application of classical and novel experimental techniques
  • Assessment of damage and fracture processes
  • Multiscale modeling, including molecular dynamics, FEM, XFEM, and peridynamics
  • Quasistatic, dynamic, cyclic, thermal, impact, penetration loadings

Published Papers (6 papers)

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Research

22 pages, 11265 KiB  
Article
Technological and Strength Aspects of Layers Made of Different Powders Laminated on a Polymer Matrix Composite Substrate
by Przemysław Golewski and Tomasz Sadowski
Molecules 2022, 27(4), 1168; https://doi.org/10.3390/molecules27041168 - 09 Feb 2022
Cited by 5 | Viewed by 1286
Abstract
This study presents a description of the new technology for producing external or internal layers made of different powders mixed with epoxy resin, which can perform various functions as a protection against impact, erosion, or elevated temperatures as well as provide interlayers during [...] Read more.
This study presents a description of the new technology for producing external or internal layers made of different powders mixed with epoxy resin, which can perform various functions as a protection against impact, erosion, or elevated temperatures as well as provide interlayers during the manufacturing of a ceramic protective barrier by air plasma spraying (APS) on the PMC substrate made of carbon–epoxy. Six types of powders (copper, quartz sand, Al2O3, aluminum, crystalline silica, and microballoon) were used to manufacture (120 °C) different kinds of protective layers (PLs), perfectly joined with the PMCs, in one single autoclave process. The two-layered specimens (2 × 25 × 110 mm) were subjected to a three-point bending (3-PB) displacement-controlled deformation process to determine the critical values of deformations at which the PLs can work safely without being cracked or delaminated. The tests were performed up to the final failure, observing various damage and cracking phenomena. Finally, the numerical simulations were carried out using the representative volume element (RVE) model of the most efforted central parts of the samples to determine the effect of powder grain diameter and resin content on the elastic properties and damage growth of the newly proposed multifunctional PLs. The stress concentrations and damage processes, including cracking and delamination, were analyzed in the whole two-layered system. The best result, in terms of strength during 3-PB testing, was achieved with the PL made of aluminum powder. Full article
(This article belongs to the Special Issue Metallic and Composite Materials and Structures)
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15 pages, 3593 KiB  
Article
Efficient Use of Carbon Fibers as Heating Elements for Curing of Epoxy Matrix Composites
by Lykourgos C. Kontaxis, Ioannis E. Chontzoglou and George C. Papanicolaou
Molecules 2021, 26(16), 5095; https://doi.org/10.3390/molecules26165095 - 23 Aug 2021
Cited by 2 | Viewed by 2515
Abstract
The aim of this study is to achieve a fully cured thermoset matrix that is heated by a direct electric current passing through the reinforcement fibers i.e., the Joule heating effect. Two types of fibers were used as heating elements for curing the [...] Read more.
The aim of this study is to achieve a fully cured thermoset matrix that is heated by a direct electric current passing through the reinforcement fibers i.e., the Joule heating effect. Two types of fibers were used as heating elements for curing the epoxy resins. Kanthal resistance fibers were used as reference heating elements and subsequently, they were replaced by a Torayca Carbon Tow of the same radius. The specimens were cured by the heat produced by a direct electric current passing through the fibers and achieving temperatures of 50 °C and 70 °C. Specimens cured in a conventional oven were also manufactured, to compare the resistance heating method to the conventional one. Next, all specimens were mechanically characterized in a quasi-static three-point bending mode of loading and experimental results were compared to derive useful conclusions concerning the applicability of the technique to polymer/composite materials mass production. Finally, a preliminary economical study concerning power consumption needed for the application of both the traditional oven curing and the carbon fibers heating elements use for the manufacturing of the same amounts of materials is presented, showing a maximum financial benefit that can be achieved, on the order of 68%. Full article
(This article belongs to the Special Issue Metallic and Composite Materials and Structures)
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13 pages, 32606 KiB  
Article
Effect of Molybdenum (Mo) Addition on Phase Composition, Microstructure, and Mechanical Properties of Pre-Alloyed Ti6Al4V Using Spark Plasma Sintering Technique
by Murugesan Rajadurai, Ayyapparaj Muthuchamy, A. Raja Annamalai, Dinesh K. Agrawal and Chun-Ping Jen
Molecules 2021, 26(10), 2894; https://doi.org/10.3390/molecules26102894 - 13 May 2021
Cited by 6 | Viewed by 2160
Abstract
The effect of molybdenum additions on the phases, microstructures, and mechanical properties of pre-alloyed Ti6Al4V was studied through the spark plasma sintering technique. Ti6Al4V-xMo (where x = 0, 2, 4, 6 wt.% of Mo) alloys were developed, and the sintered compacts were characterized [...] Read more.
The effect of molybdenum additions on the phases, microstructures, and mechanical properties of pre-alloyed Ti6Al4V was studied through the spark plasma sintering technique. Ti6Al4V-xMo (where x = 0, 2, 4, 6 wt.% of Mo) alloys were developed, and the sintered compacts were characterized in terms of their phase composition, microstructure, and mechanical properties. The results show that the equiaxed primary alpha and Widmänstatten (alpha + beta) microstructure in pre-alloyed Ti6Al4V is transformed into a duplex and globular model with the increasing content of Mo from 0 to 6%. The changing pattern of the microstructure of the sample strongly influences the properties of the material. The solid solution hardening element such as Mo enhances mechanical properties such as yield strength, ultimate tensile strength, ductility, and hardness compared with the pre-alloyed Ti6Al4V alloy. Full article
(This article belongs to the Special Issue Metallic and Composite Materials and Structures)
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13 pages, 18178 KiB  
Article
Molecular Dynamics Simulation of High-Temperature Creep Behavior of Nickel Polycrystalline Nanopillars
by Xiang Xu, Peter Binkele, Wolfgang Verestek and Siegfried Schmauder
Molecules 2021, 26(9), 2606; https://doi.org/10.3390/molecules26092606 - 29 Apr 2021
Viewed by 2398
Abstract
As Nickel (Ni) is the base of important Ni-based superalloys for high-temperature applications, it is important to determine the creep behavior of its nano-polycrystals. The nano-tensile properties and creep behavior of nickel polycrystalline nanopillars are investigated employing molecular dynamics simulations under different temperatures, [...] Read more.
As Nickel (Ni) is the base of important Ni-based superalloys for high-temperature applications, it is important to determine the creep behavior of its nano-polycrystals. The nano-tensile properties and creep behavior of nickel polycrystalline nanopillars are investigated employing molecular dynamics simulations under different temperatures, stresses, and grain sizes. The mechanisms behind the creep behavior are analyzed in detail by calculating the stress exponents, grain boundary exponents, and activation energies. The novel results in this work are summarized in a deformation mechanism map and are in good agreement with Ashby’s experimental results for pure Ni. Through the deformation diagram, dislocation creep dominates the creep process when applying a high stress, while grain boundary sliding prevails at lower stress levels. These two mechanisms could also be coupled together for a low-stress but a high-temperature creep simulation. In this work, the dislocation creep is clearly observed and discussed in detail. Through analyzing the activation energies, vacancy diffusion begins to play an important role in enhancing the grain boundary creep in the creep process when the temperature is above 1000 K. Full article
(This article belongs to the Special Issue Metallic and Composite Materials and Structures)
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16 pages, 28011 KiB  
Article
A Novel Approach by Spark Plasma Sintering to the Improvement of Mechanical Properties of Titanium Carbonitride-Reinforced Alumina Ceramics
by Magdalena Szutkowska, Marcin Podsiadło, Tomasz Sadowski, Paweł Figiel, Marek Boniecki, Daniel Pietras and Tomasz Polczyk
Molecules 2021, 26(5), 1344; https://doi.org/10.3390/molecules26051344 - 03 Mar 2021
Cited by 9 | Viewed by 1894
Abstract
Ti(C,N)-reinforced alumina-zirconia composites with different ratios of C to N in titanium carbonitride solid solutions, such as Ti(C0.3,N0.7) (C:N = 30:70) and Ti(C0.5,N0.5) (C:N = 50:50), were tested to improve their mechanical properties. Spark plasma [...] Read more.
Ti(C,N)-reinforced alumina-zirconia composites with different ratios of C to N in titanium carbonitride solid solutions, such as Ti(C0.3,N0.7) (C:N = 30:70) and Ti(C0.5,N0.5) (C:N = 50:50), were tested to improve their mechanical properties. Spark plasma sintering (SPS) with temperatures ranging from 1600 °C to 1675 °C and pressureless sintering (PS) with a higher temperature of 1720 °C were used to compare results. The following mechanical and physical properties were determined: Vickers hardness, Young’s modulus, apparent density, wear resistance, and fracture toughness. A composite with the addition of Ti(C0.5,N0.5)n nanopowder exhibited the highest Vickers hardness of over 19.0 GPa, and its fracture toughness was at 5.0 Mpa·m1/2. A composite with the Ti(C0.3,N0.7) phase was found to have lower values of Vickers hardness (by about 10%), friction coefficient, and specific wear rate of disc (Wsd) compared to the composite with the addition of Ti(C0.5,N0.5). The Vickers hardness values slightly decreased (from 5% to 10%) with increasing sintering temperature. The mechanical properties of the samples sintered using PS were lower than those of the samples that were spark plasma sintered. This research on alumina–zirconia composites with different ratios of C to N in titanium carbonitride solid solution Ti(C,N), sintered using an unconventional SPS method, reveals the effect of C/N ratios on improving mechanical properties of tested composites. X-ray analysis of the phase composition and an observation of the microstructure was carried out. Full article
(This article belongs to the Special Issue Metallic and Composite Materials and Structures)
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26 pages, 5075 KiB  
Article
A Novel Hybrid Model Based on a Feedforward Neural Network and One Step Secant Algorithm for Prediction of Load-Bearing Capacity of Rectangular Concrete-Filled Steel Tube Columns
by Quang Hung Nguyen, Hai-Bang Ly, Van Quan Tran, Thuy-Anh Nguyen, Viet-Hung Phan, Tien-Thinh Le and Binh Thai Pham
Molecules 2020, 25(15), 3486; https://doi.org/10.3390/molecules25153486 - 31 Jul 2020
Cited by 28 | Viewed by 4193
Abstract
In this study, a novel hybrid surrogate machine learning model based on a feedforward neural network (FNN) and one step secant algorithm (OSS) was developed to predict the load-bearing capacity of concrete-filled steel tube columns (CFST), whereas the OSS was used to optimize [...] Read more.
In this study, a novel hybrid surrogate machine learning model based on a feedforward neural network (FNN) and one step secant algorithm (OSS) was developed to predict the load-bearing capacity of concrete-filled steel tube columns (CFST), whereas the OSS was used to optimize the weights and bias of the FNN for developing a hybrid model (FNN-OSS). For achieving this goal, an experimental database containing 422 instances was firstly gathered from the literature and used to develop the FNN-OSS algorithm. The input variables in the database contained the geometrical characteristics of CFST columns, and the mechanical properties of two CFST constituent materials, i.e., steel and concrete. Thereafter, the selection of the appropriate parameters of FNN-OSS was performed and evaluated by common statistical measurements, for instance, the coefficient of determination (R2), root mean square error (RMSE), and mean absolute error (MAE). In the next step, the prediction capability of the best FNN-OSS structure was evaluated in both global and local analyses, showing an excellent agreement between actual and predicted values of the load-bearing capacity. Finally, an in-depth investigation of the performance and limitations of FNN-OSS was conducted from a structural engineering point of view. The results confirmed the effectiveness of the FNN-OSS as a robust algorithm for the prediction of the CFST load-bearing capacity. Full article
(This article belongs to the Special Issue Metallic and Composite Materials and Structures)
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