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11 pages, 9399 KiB

Open AccessArticle

Functionally Graded AISI 316L and AISI H13 Manufactured by L-DED for Die and Mould Applications

by Marta Ostolaza, Jon Iñaki Arrizubieta, Aitzol Lamikiz and Magdalena Cortina

Appl. Sci. 2021, 11(2), 771; https://doi.org/10.3390/app11020771 - 15 Jan 2021

Cited by 17 | Viewed by 2881

Tooling in the die and mould industry is subjected to high-wear and high-temperature environments, which often leads to the premature failure of this high-added-value tooling. When severe damage occurs, an alternative to replacing the whole component consists of the repair by laser-directed energy [...] Read more.

Tooling in the die and mould industry is subjected to high-wear and high-temperature environments, which often leads to the premature failure of this high-added-value tooling. When severe damage occurs, an alternative to replacing the whole component consists of the repair by laser-directed energy deposition (L-DED). For that end, intermediate layers are commonly employed as buffer material, where introducing a functionally graded material (FGM) might be beneficial to avoid material incompatibilities and improve the overall performance of the tooling. In the present work, an FGM composed of gradient AISI 316L to AISI H13 has been manufactured, and its microstructure and hardness analysed. Firstly, cracking owing to the formation of brittle intermediate phases has been detected. Secondly, an increase of the hardness and a decrease of the corrosion resistance has been observed when transitioning from AISI 316L to AISI H13. Thirdly, despite the FGM composition evolving linearly, nonlinear material properties such as hardness and corrosion have been observed, which are conditioned by the microstructure formed during the L‑DED process and the nonlinear influence of the composition of steel on such properties. Consequently, nonlinear compositional gradients are recommended if linear mechanical properties are to be obtained in the case of steel FGMs. Full article

(This article belongs to the Special Issue Functionally Graded Materials)

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13 pages, 1767 KiB

Open AccessArticle

Optimization of Metal–Ceramic Functionally Graded Plates Using the Simulated Annealing Algorithm

by Victor Franco Correia, José S. Moita, Filipa Moleiro and Cristóvão M. Mota Soares

Appl. Sci. 2021, 11(2), 729; https://doi.org/10.3390/app11020729 - 13 Jan 2021

Cited by 12 | Viewed by 1893

Abstract

This work involves the design optimization of metal–ceramic through the thickness of functionally graded material (FGM) plates subjected to thermomechanical loadings. Constrained optimization was performed for minimum mass and minimum material cost of the FGM plates. The design process of FGM plate structures [...] Read more.

This work involves the design optimization of metal–ceramic through the thickness of functionally graded material (FGM) plates subjected to thermomechanical loadings. Constrained optimization was performed for minimum mass and minimum material cost of the FGM plates. The design process of FGM plate structures requires a good choice of metal and ceramic materials and the adequate definition of the components volume fractions through the thickness direction in order to accomplish a certain structural behavior, while optimizing the material costs and/or the plate mass. Here, the optimization problems are solved with the simulated annealing (SA) algorithm, not requiring the calculation of the derivatives of the objective or constraint functions. Constrained single objective optimization cases are studied, and validated with alternative solutions, considering the p-index and the FGM plate thickness as design variables. New optimization cases, involving additionally the metal and ceramic materials as design variables, are presented both for benchmark purposes and to demonstrate the suitability of the SA algorithm to solve those optimization problems. Full article

(This article belongs to the Special Issue Functionally Graded Materials)

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25 pages, 4433 KiB

Open AccessFeature PaperArticle

Thermal Buckling and Free Vibration Analysis of Functionally Graded Plate Resting on an Elastic Foundation According to High Order Shear Deformation Theory Based on New Shape Function

by Aleksandar Radaković, Dragan Čukanović, Gordana Bogdanović, Milan Blagojević, Blaža Stojanović, Danilo Dragović and Nazim Manić

Appl. Sci. 2020, 10(12), 4190; https://doi.org/10.3390/app10124190 - 18 Jun 2020

Cited by 6 | Viewed by 2487

Abstract

Functionally graded square and rectangular plates of different thicknesses placed on the elastic foundation modeled according to the Winkler-Pasternak theory have been studied. The thermal and mechanical characteristics, apart from Poisson’s ratio, are considered to continuously differ through the thickness of the studied [...] Read more.

Functionally graded square and rectangular plates of different thicknesses placed on the elastic foundation modeled according to the Winkler-Pasternak theory have been studied. The thermal and mechanical characteristics, apart from Poisson’s ratio, are considered to continuously differ through the thickness of the studied material as stated in a power-law distribution. A mathematical model of functionally graded plate which include interaction with elastic foundation is defined. The equilibrium and stability equations are derived using high order shear deformation theory that comprises various kinds of shape function and the von Karman nonlinearity. A new analytically integrable shape function has been introduced. Hamilton’s principle has been applied with the purpose of acquiring the equations of motion. An analytical method for identifying both natural frequencies and critical buckling temperature for cases of linear and nonlinear temperature change through the plate thickness has been established. In order to verify the derived theoretical results on numerical examples, an original program code has been implemented within software MATLAB. Critical buckling temperature and natural frequencies findings are shown below. Previous scientific research and papers confirms that presented both the theoretical formulation and the numerical results are accurate. The comparison has been made between newly established findings based on introduced shape function and the old findings that include 13 different shape functions available in previously published articles. The final part of the research provides analysis and conclusions related to the impact of the power-law index, foundation stiffness, and temperature gradient on critical buckling temperature and natural frequencies of the functionally graded plates. Full article

(This article belongs to the Special Issue Functionally Graded Materials)

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15 pages, 4523 KiB

Open AccessArticle

Experimental Analysis of Welded Rods with a Functionally Graded Material Approach

by Ayse Nihan Basmaci, Seckin Filiz and Mümin Şahin

Appl. Sci. 2020, 10(11), 3908; https://doi.org/10.3390/app10113908 - 05 Jun 2020

Cited by 7 | Viewed by 2920

Abstract

In recent years, with the development of welding methods, using these methods in manufacturing industry and in advanced engineering has become more popular. In this study, mechanical properties of rods obtained by friction welding and electric arc welding are compared. Hence, three specimens [...] Read more.

In recent years, with the development of welding methods, using these methods in manufacturing industry and in advanced engineering has become more popular. In this study, mechanical properties of rods obtained by friction welding and electric arc welding are compared. Hence, three specimens with different material properties are manufactured, two of which are welded by friction welding and one of which is welded by electric arc welding. These three specimens are adapted to the ASTM E8-04 standard with the help of a universal lathe. Moreover, the tensile stress values and the elasticity modulus of all these specimens are obtained as a result of tensile tests. Accordingly, the effects of the type of welding and material properties used in manufacturing on the mechanical behavior of the specimens are examined. In addition, specimens taken from the cracked surfaces of the pieces broken from the specimens as a result of the tensile test are examined with SEM (scanning electron microscopy). These examinations reveal the microstructure of the specimens. The elemental distribution data obtained as a result of examinations with SEM and the mechanical property data obtained as a result of tensile tests support each other. Furthermore, effects of a heat affected zone (HAZ) on the mechanical properties of the rod are investigated as a functionally graded material. Full article

(This article belongs to the Special Issue Functionally Graded Materials)

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16 pages, 3453 KiB

Open AccessArticle

Out-of-Plane Bending of Functionally Graded Thin Plates with a Circular Hole

by Quanquan Yang, He Cao, Youcheng Tang and Bo Yang

Appl. Sci. 2020, 10(7), 2231; https://doi.org/10.3390/app10072231 - 25 Mar 2020

Cited by 6 | Viewed by 3332

Abstract

The out-of-plane bending problems of functionally graded thin plates with a circular hole are studied for two-dimensional deformations. The thin plates have arbitrary variations of elastic properties along the radial direction. The general solutions of the stresses and moments are presented for the [...] Read more.

The out-of-plane bending problems of functionally graded thin plates with a circular hole are studied for two-dimensional deformations. The thin plates have arbitrary variations of elastic properties along the radial direction. The general solutions of the stresses and moments are presented for the plates subjected to remote bending moments based on the theory of complex variable functions. Two different cases—a whole functionally graded plate with a circular hole and a functionally graded ring reinforced in a homogeneous perforated plate—are considered by numerical examples. The influence of parameters like Young’s modulus and Poisson’s ratio, function types of these elastic properties, and width of the reinforcing ring on the moments around the hole is presented. It is shown that the moment concentration, caused by the geometric discontinuity of the hole in the traditional homogeneous plate, can be well relieved or even eliminated by careful selection of the above parameters. The results for some special cases are compared with previous literatures and are found in good agreement. Full article

(This article belongs to the Special Issue Functionally Graded Materials)

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22 pages, 8827 KiB

Open AccessFeature PaperArticle

Thermoelastic Analysis of Functionally Graded Cylindrical Panels with Piezoelectric Layers

by Yasin Heydarpour, Parviz Malekzadeh, Rossana Dimitri and Francesco Tornabene

Appl. Sci. 2020, 10(4), 1397; https://doi.org/10.3390/app10041397 - 19 Feb 2020

Cited by 26 | Viewed by 3578

Abstract

We propose a coupled thermoelastic approach based on the Lord-Shulman (L-S) and Maxwell’s formulations to study the wave propagation in functionally graded (FG) cylindrical panels with piezoelectric layers under a thermal shock loading. The material properties of the FG core layer feature a [...] Read more.

We propose a coupled thermoelastic approach based on the Lord-Shulman (L-S) and Maxwell’s formulations to study the wave propagation in functionally graded (FG) cylindrical panels with piezoelectric layers under a thermal shock loading. The material properties of the FG core layer feature a graded distribution throughout the thickness and vary according to a simple power law. A layerwise differential quadrature method (LW-DQM) is combined with a non-uniform rational B-spline (NURBS) multi-step time integration scheme to discretize the governing equations both in the spatial and time domains. The compatibility conditions of the physical quantities are enforced at the interfaces to describe their structural behavior in a closed form. A validation and comparative analysis with the available literature, together with a convergence study, show the efficiency and stability of the proposed method to handle thermoelastic problems. Numerical applications are herein performed systematically to check for the sensitivity of the thermoelastic response to the material graded index, piezoelectric layer thickness, external electrical voltage, opening angle, and shock thermal loading, which would be very helpful for practical engineering applications. Full article

(This article belongs to the Special Issue Functionally Graded Materials)

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16 pages, 2589 KiB

Open AccessArticle

Improved Packing Model for Functionally Graded Sand-Fines Mixtures—Incorporation of Fines Cohesive Packing Behavior

by Ammar El-Husseiny

Appl. Sci. 2020, 10(2), 562; https://doi.org/10.3390/app10020562 - 13 Jan 2020

Cited by 10 | Viewed by 3058

Abstract

Binary soil mixture, containing large silica particles (sand) mixed with variable content of very fine silt or clay, is an example of a functionally graded material that is important for several science and engineering applications. Predicting the porosity (or void ratio), which is [...] Read more.

Binary soil mixture, containing large silica particles (sand) mixed with variable content of very fine silt or clay, is an example of a functionally graded material that is important for several science and engineering applications. Predicting the porosity (or void ratio), which is a fundamental quantity that affects other physical properties, of such material as function of fines (clay or silt) fraction can be significant for sediment research and material design optimization. Existing analytical models for porosity prediction work well for binary mixed soils containing multi-sized non-cohesive particles with no clay, while such models frequently underestimate the porosity of sand-clay mixtures. This study aims to present an analytical model that accurately predicts the porosity of mixed granular materials or soils containing sand and very fine silt or clay (cohesive particles). It is demonstrated that accounting for the cohesive nature of very fine particles, which exists due to the effect of inter-particle forces, is a major missing aspect in existing packing models for mixed soils. Consequently, a previously developed linear packing model is modified so that it accounts for fines cohesive packing in sand-fines mixtures. The model prediction is validated using various experimental published data sets for the porosity of sand-fines mixtures. Improvement in the prediction of permeability and maximum packing dry density when incorporating cohesive packing behavior is discussed. The current model also provides important insights on the conditions under which, the lowest permeability and maximum packing state are expected. Full article

(This article belongs to the Special Issue Functionally Graded Materials)

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Review

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41 pages, 4673 KiB

Open AccessFeature PaperReview

Review of Functionally Graded Thermal Sprayed Coatings

by Leszek Łatka, Lech Pawłowski, Marcin Winnicki, Pawel Sokołowski, Aleksandra Małachowska and Stefan Kozerski

Appl. Sci. 2020, 10(15), 5153; https://doi.org/10.3390/app10155153 - 27 Jul 2020

Cited by 68 | Viewed by 8386

Abstract

The paper briefly describes major thermal spray techniques used to spray functionally graded coatings such as atmospheric plasma spraying, high velocity oxy-fuel spraying, suspension and solution precursor plasma spraying, and finally low and high pressure cold gas spray method. The examples of combined [...] Read more.

The paper briefly describes major thermal spray techniques used to spray functionally graded coatings such as atmospheric plasma spraying, high velocity oxy-fuel spraying, suspension and solution precursor plasma spraying, and finally low and high pressure cold gas spray method. The examples of combined spray processes as well as some examples of post spray treatment including laser and high temperature treatments or mechanical one, are described. Then, the solid and liquid feedstocks used to spray and their properties are shortly discussed. The reviewed properties of functional coatings include: (i) mechanical (adhesion, toughness, hardness); (ii) physical (porosity, thermal conductivity and diffusivity, thermal expansion, photo-catalytic activity), and; (iii) bioactivity and simulated body fluid (SBF) corrosion. These properties are useful in present applications of functionally graded coatings as thermal barriers, the bioactive coatings in prostheses, photo-catalytic coatings in water treatment, coatings used in printing industry (anilox and corona rolls). Finally, some of the future possible fields of functional thermal sprayed coatings applications are discussed, e.g., to coat polymer substrates or to use the cheap technology of low pressure cold gas spray method instead of expensive technology of vacuum plasma spraying to obtain bond coatings. Full article

(This article belongs to the Special Issue Functionally Graded Materials)

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