Editorial

4 pages, 183 KiB

Open AccessEditorial

Mechanics and Analysis of Advanced Materials and Structures

by Sanichiro Yoshida and Giovanni Pappalettera

Materials 2023, 16(5), 2123; https://doi.org/10.3390/ma16052123 - 06 Mar 2023

Cited by 1 | Viewed by 956

Modern technological development has made the designing and characterization of materials sophisticated [...] Full article

(This article belongs to the Special Issue Mechanics and Analysis of Advanced Materials and Structures)

Research

Jump to: Editorial, Review

12 pages, 667 KiB

Open AccessArticle

Modeling of the Achilles Subtendons and Their Interactions in a Framework of the Absolute Nodal Coordinate Formulation

by Leonid P. Obrezkov, Taija Finni and Marko K. Matikainen

Materials 2022, 15(24), 8906; https://doi.org/10.3390/ma15248906 - 13 Dec 2022

Cited by 4 | Viewed by 1298

Abstract

Experimental results have revealed the sophisticated Achilles tendon (AT) structure, including its material properties and complex geometry. The latter incorporates a twisted design and composite construction consisting of three subtendons. Each of them has a nonstandard cross-section. All these factors make the AT [...] Read more.

Experimental results have revealed the sophisticated Achilles tendon (AT) structure, including its material properties and complex geometry. The latter incorporates a twisted design and composite construction consisting of three subtendons. Each of them has a nonstandard cross-section. All these factors make the AT deformation analysis computationally demanding. Generally, 3D finite solid elements are used to develop models for AT because they can discretize almost any shape, providing reliable results. However, they also require dense discretization in all three dimensions, leading to a high computational cost. One way to reduce degrees of freedom is the utilization of finite beam elements, requiring only line discretization over the length of subtendons. However, using the material models known from continuum mechanics is challenging because these elements do not usually have 3D elasticity in their descriptions. Furthermore, the contact is defined at the beam axis instead of using a more general surface-to-surface formulation. This work studies the continuum beam elements based on the absolute nodal coordinate formulation (ANCF) for AT modeling. ANCF beam elements require discretization only in one direction, making the model less computationally expensive. Recent work demonstrates that these elements can describe various cross-sections and materials models, thus allowing the approximation of AT complexity. In this study, the tendon model is reproduced by the ANCF continuum beam elements using the isotropic incompressible model to present material features. Full article

(This article belongs to the Special Issue Mechanics and Analysis of Advanced Materials and Structures)

► Show Figures

Figure 1

42 pages, 10728 KiB

Open AccessEditor’s ChoiceArticle

On the Stability of Complex Concentrated (CC)/High Entropy (HE) Solid Solutions and the Contamination with Oxygen of Solid Solutions in Refractory Metal Intermetallic Composites (RM(Nb)ICs) and Refractory Complex Concentrated Alloys (RCCAs)

by Panos Tsakiropoulos

Materials 2022, 15(23), 8479; https://doi.org/10.3390/ma15238479 - 28 Nov 2022

Cited by 6 | Viewed by 1397

Abstract

In as-cast (AC) or heat-treated (HT) metallic ultra-high temperature materials often “conventional” and complex-concentrated (CC) or high-entropy (HE) solid solutions (sss) are observed. Refractory metal containing bcc sss also are contaminated with oxygen. This paper studied the stability of CC/HE Nb_ss and [...] Read more.

In as-cast (AC) or heat-treated (HT) metallic ultra-high temperature materials often “conventional” and complex-concentrated (CC) or high-entropy (HE) solid solutions (sss) are observed. Refractory metal containing bcc sss also are contaminated with oxygen. This paper studied the stability of CC/HE Nb_ss and the contamination with oxygen of Nb_ss in RM(INb)ICs, RM(Nb)ICs/RCCAs and RM(Nb)ICs/RHEAs. “Conventional” and CC/HE Nb_ss were compared. “Conventional” Nb_ss can be Ti-rich only in AC alloys. Ti-rich Nb_ss is not observed in HT alloys. In B containing alloys the Ti-rich Nb_ss is usually CC/HE. The CC/HE Nb_ss is stable in HT alloys with simultaneous addition of Mo, W with Hf, Ge+Sn. The implications for alloy design of correlations between the parameter δ of “conventional” and CC/HE Nb_ss with the B or the Ge+Sn concentration in the Nb_ss and of relationships of other solutes with the B or Ge+Sn content are discussed. The CC/HE Nb_ss has low Δχ, VEC and Ω and high ΔS_mix, |ΔH_mix| and δ parameters, and is formed in alloys that have high entropy of mixing. These parameters are compared with those of single-phase bcc ss HEAs and differences in ΔH_mix, δ, Δχ and Ω, and similarities in ΔS_mix and VEC are discussed. Relationships between the parameters of alloy and “conventional” Nb_ss also apply for CC/HE Nb_ss. The parameters δ_ss and Ω_ss, and VEC_ss and VEC_alloy can differentiate between types of alloying additions and their concentrations and are key regarding the formation or not of CC/HE Nb_ss. After isothermal oxidation at a pest temperature (800 ^oC/100 h) the contaminated with oxygen Nb_ss in the diffusion zone is CC/HE Nb_ss, whereas the Nb_ss in the bulk can be “conventional” Nb_ss or CC/HE Nb_ss. The parameters of “uncontaminated” and contaminated with oxygen sss are linked with linear relationships. There are correlations between the oxygen concentration in contaminated sss in the diffusion zone and the bulk of alloys with the parameters Δχ_Nbss, δ_Nbss and VEC_Nbss, the values of which increase with increasing oxygen concentration in the ss. The effects of contamination with oxygen of the near surface areas of a HT RM(Nb)IC with Al, Cr, Hf, Si, Sn, Ti and V additions and a high vol.% Nb_ss on the hardness and Young’s modulus of the Nb_ss, and contributions to the hardness of the Nb_ss in B free or B containing alloys are discussed. The hardness and Young’s modulus of the bcc ss increased linearly with its oxygen concentration and the change in hardness and Young’s modulus due to contamination increased linearly with [O]^2/3. Full article

(This article belongs to the Special Issue Mechanics and Analysis of Advanced Materials and Structures)

► Show Figures

Figure 1

16 pages, 9164 KiB

Open AccessArticle

Stress Dependence on Relaxation of Deformation Induced by Laser Spot Heating

by Yuma Murata, Tomohiro Sasaki and Sanichiro Yoshida

Materials 2022, 15(18), 6330; https://doi.org/10.3390/ma15186330 - 13 Sep 2022

Cited by 2 | Viewed by 1167

Abstract

This paper deals with a non-destructive analysis of residual stress through the visualization of deformation behaviors induced by a local spot heating. Deformation was applied to the surface of an aluminum alloy with an infrared spot laser. The heating process is non-contact, and [...] Read more.

This paper deals with a non-destructive analysis of residual stress through the visualization of deformation behaviors induced by a local spot heating. Deformation was applied to the surface of an aluminum alloy with an infrared spot laser. The heating process is non-contact, and the applied strain is reversible in the range of room temperature to approximately +10 °C. The specimen was initially pulled up to elastic tensile stress using a tensile test machine under the assumption that the material was subject to the tensile residual stress. The relaxation behaviors of the applied strain under tensile stress conditions were evaluated using contact and non-contact methods, i.e., two strain gauges (the contact method) and a two-dimensional electronic speckle pattern interferometer (non-contact method). The results are discussed based on the stress dependencies of the thermal expansion coefficient and the elasticity of the materials. Full article

(This article belongs to the Special Issue Mechanics and Analysis of Advanced Materials and Structures)

► Show Figures

Figure 1

15 pages, 4154 KiB

Open AccessArticle

Damage Progress Classification in AlSi10Mg SLM Specimens by Convolutional Neural Network and k-Fold Cross Validation

by Claudia Barile, Caterina Casavola, Giovanni Pappalettera and Vimalathithan Paramsamy Kannan

Materials 2022, 15(13), 4428; https://doi.org/10.3390/ma15134428 - 23 Jun 2022

Cited by 7 | Viewed by 1511

Abstract

In this study, the damage evolution stages in testing AlSi10Mg specimens manufactured using Selective Laser Melting (SLM) process are identified using Acoustic Emission (AE) technique and Convolutional Neural Network (CNN). AE signals generated during the testing of AlSi10Mg specimens are recorded and analysed [...] Read more.

In this study, the damage evolution stages in testing AlSi10Mg specimens manufactured using Selective Laser Melting (SLM) process are identified using Acoustic Emission (AE) technique and Convolutional Neural Network (CNN). AE signals generated during the testing of AlSi10Mg specimens are recorded and analysed to identify their time-frequency features in three different damage evolution stages: elastic stage, plastic stage, and fracture stage. Continuous Wavelet Transform (CWT) spectrograms are used for the processing of the AE signals. The AE signals from each of these stages are then used for training a CNN based on SqueezeNet. Moreover, k-fold cross validation is implemented while training the modified SqueezeNet to improve the classification efficiency of the network. The trained network shows promising results in classifying the AE signals from different damage evolution stages. Full article

(This article belongs to the Special Issue Mechanics and Analysis of Advanced Materials and Structures)

► Show Figures

Figure 1

15 pages, 3378 KiB

Open AccessArticle

Application of Digital Image Correlation in Space and Frequency Domains to Deformation Analysis of Polymer Film

by Caroline Kopfler, Sanichiro Yoshida and Anup Ghimire

Materials 2022, 15(5), 1842; https://doi.org/10.3390/ma15051842 - 01 Mar 2022

Cited by 3 | Viewed by 1336

Abstract

Using speckle patterns formed by an expanded and collimated He-Ne laser beam, we apply DIC (Digital Image Correlation) methods to estimate the deformation of LLDPE (linear low-density polyethylene) film. The laser beam was transmitted through the film specimen while a tensile machine applied [...] Read more.

Using speckle patterns formed by an expanded and collimated He-Ne laser beam, we apply DIC (Digital Image Correlation) methods to estimate the deformation of LLDPE (linear low-density polyethylene) film. The laser beam was transmitted through the film specimen while a tensile machine applied a load to the specimen vertically. The transmitted laser light was projected on a screen, and the resultant image was captured by a digital camera. The captured image was analyzed both in space and frequency domains. For the space-domain analysis, the random speckle pattern was used to register the local displacement due to the deformation. For the frequency-domain analysis, the diffraction-like pattern, due to the horizontally-running, periodic groove-like structure of the film was used to characterize the overall deformation along vertical columns of analysis. It has been found that when the deformation is small and uniform, the conventional space domain analysis is applicable to the entire film specimen. However, once the deformation loses the spatial uniformity, the space-domain analysis falls short if applied to the entire specimen. The application of DIC to local (windowed) regions is still useful but time consuming. In the non-uniform situation, the frequency-domain analysis is found capable of revealing average deformation along each column of analysis. Full article

(This article belongs to the Special Issue Mechanics and Analysis of Advanced Materials and Structures)

► Show Figures

Figure 1

18 pages, 13549 KiB

Open AccessArticle

Analytical Approach and Numerical Simulation of Reinforced Concrete Beams Strengthened with Different FRCM Systems

by Luis Mercedes, Christian Escrig, Ernest Bernat-Masó and Lluís Gil

Materials 2021, 14(8), 1857; https://doi.org/10.3390/ma14081857 - 08 Apr 2021

Cited by 10 | Viewed by 1848

Abstract

Fabric-reinforced cementitious matrices (FRCMs) are a novel composite material for strengthening structures. Fabric contributes to tying cross-sections under tensile stress. The complexity of the interfaces between the fabric and the matrix does not allow having a simple and accurate model that enables practitioners [...] Read more.

Fabric-reinforced cementitious matrices (FRCMs) are a novel composite material for strengthening structures. Fabric contributes to tying cross-sections under tensile stress. The complexity of the interfaces between the fabric and the matrix does not allow having a simple and accurate model that enables practitioners to perform feasible calculations. This work developed an analytical approach and a numerical simulation based on the reduction of FRCMs’ strength capabilities under tensile stress states. The concept of effective strength was estimated for different types of fabrics (basalt, carbon, glass, poly p-phenylene benzobisoxazole (PBO), and steel) from experimental evidence. The proposed models calculate the ultimate bending moment for reinforced concrete (RC) structures strengthened with FRCMs. The numerical models performed simulations that reproduced the moment–deflection curves of the different tested beams. Steel fabric showed the highest contribution to strength (78%), while PBO performed the worst (6%). Basalt and carbon showed irregular contributions. Full article

(This article belongs to the Special Issue Mechanics and Analysis of Advanced Materials and Structures)

► Show Figures

Figure 1

22 pages, 12722 KiB

Open AccessArticle

Dynamic ESPI Evaluation of Deformation and Fracture Mechanism of 7075 Aluminum Alloy

by Shun Takahashi, Sanichiro Yoshida, Tomohiro Sasaki and Tyler Hughes

Materials 2021, 14(6), 1530; https://doi.org/10.3390/ma14061530 - 20 Mar 2021

Cited by 4 | Viewed by 2289

Abstract

The deformation and fracture mechanism in 7075 aluminum alloy is discussed based on a field theoretical approach. A pair of peak-aged and overaged plate specimens are prepared under the respective precipitation conditions, and their plastic deformation behaviors are visualized with two-dimensional electronic speckle [...] Read more.

The deformation and fracture mechanism in 7075 aluminum alloy is discussed based on a field theoretical approach. A pair of peak-aged and overaged plate specimens are prepared under the respective precipitation conditions, and their plastic deformation behaviors are visualized with two-dimensional electronic speckle pattern interferometry (ESPI). The in-plane velocity field caused by monotonic tensile loading is monitored continuously via the contour analysis method of ESPI. In the plastic regime, the peak-aged specimen exhibits a macroscopically uniform deformation behavior, while the annealed specimen exhibits non-uniform deformation characterized by a localized shear band. The occurrence of the shear band is explained by the transition of the material’s elastic resistive mechanism from the longitudinal force dominant to shear force dominant mode. The shear force is interpreted as the frictional force that drives mobile dislocations along the shear band. The dynamic behavior of the shear band is explained as representing the motion of a solitary wave. The observed decrease in the solitary wave’s velocity is accounted for by the change in the acoustic impedance with the advancement of plastic deformation. Full article

(This article belongs to the Special Issue Mechanics and Analysis of Advanced Materials and Structures)

► Show Figures

Figure 1

18 pages, 2994 KiB

Open AccessArticle

Absolute Measurement of Material Nonlinear Parameters Using Noncontact Air-Coupled Reception

by Hyunjo Jeong, Sungjong Cho, Shuzeng Zhang and Xiongbing Li

Materials 2021, 14(2), 244; https://doi.org/10.3390/ma14020244 - 06 Jan 2021

Cited by 1 | Viewed by 1449

Abstract

Nonlinear ultrasound is often employed to assess microdamage or nonlinear elastic properties of a material, and the nonlinear parameter is commonly used to quantify damage sate and material properties. Among the various factors that influence the measurement of nonlinear parameters, maintaining a constant [...] Read more.

Nonlinear ultrasound is often employed to assess microdamage or nonlinear elastic properties of a material, and the nonlinear parameter is commonly used to quantify damage sate and material properties. Among the various factors that influence the measurement of nonlinear parameters, maintaining a constant contact pressure between the receiver and specimen is important for repeatability of the measurement. The use of an air-coupled transducer may be considered to replace the contact receiver. In this paper, a method of measuring the relative and absolute nonlinear parameters of materials is described using an air-coupled transducer as a receiver. The diffraction and attenuation corrections are newly derived from an acoustic model for a two-layer medium and the nonlinear parameter formula with all corrections is defined. Then, we show that the ratio of the relative nonlinear parameter of the target sample to the reference sample is equal to that of the absolute nonlinear parameter, and this equivalence is confirmed by measurements on three systems of aluminum samples. The proposed method allows the absolute measurement of the nonlinear parameter ratio or the nonlinear parameter without calibration of the air-coupled receiver and removes restrictions on the selection of reference samples. Full article

(This article belongs to the Special Issue Mechanics and Analysis of Advanced Materials and Structures)

► Show Figures

Figure 1

18 pages, 4765 KiB

Open AccessArticle

Criticality Hidden in Acoustic Emissions and in Changing Electrical Resistance during Fracture of Rocks and Cement-Based Materials

by Gianni Niccolini, Stelios M. Potirakis, Giuseppe Lacidogna and Oscar Borla

Materials 2020, 13(24), 5608; https://doi.org/10.3390/ma13245608 - 09 Dec 2020

Cited by 18 | Viewed by 1713

Abstract

Acoustic emissions (AE) due to microcracking in solid materials permit the monitoring of fracture processes and the study of failure dynamics. As an alternative method of integrity assessment, measurements of electrical resistance can be used as well. In the literature, however, many studies [...] Read more.

Acoustic emissions (AE) due to microcracking in solid materials permit the monitoring of fracture processes and the study of failure dynamics. As an alternative method of integrity assessment, measurements of electrical resistance can be used as well. In the literature, however, many studies connect the notion of criticality with AE originating from the fracture, but not with the changes in the electrical properties of materials. In order to further investigate the possible critical behavior of fracture processes in rocks and cement-based materials, we apply natural time (NT) analysis to the time series of AE and resistance measurements, recorded during fracture experiments on cement mortar (CM) and Luserna stone (LS) specimens. The NT analysis indicates that criticality in terms of electrical resistance changes systematically precedes AE criticality for all investigated specimens. The observed greater unpredictability of the CM fracture behavior with respect to LS could be ascribed to the different degree of material homogeneity, since LS (heterogeneous material) expectedly offers more abundant and more easily identifiable fracture precursors than CM (homogenous material). Non-uniqueness of the critical point by varying the detection threshold of cracking events is apparently due to finite size effects which introduce deviations from the self-similarity. Full article

(This article belongs to the Special Issue Mechanics and Analysis of Advanced Materials and Structures)

► Show Figures

Figure 1

19 pages, 6151 KiB

Open AccessArticle

Optimal Design of Annular Phased Array Transducers for Material Nonlinearity Determination in Pulse–Echo Ultrasonic Testing

by Sungjong Cho, Hyunjo Jeong and Ik Keun Park

Materials 2020, 13(23), 5565; https://doi.org/10.3390/ma13235565 - 06 Dec 2020

Cited by 3 | Viewed by 4077

Abstract

Nonlinear ultrasound has been proven to be a useful nondestructive testing tool for micro-damage inspection of materials and structures operating in harsh environment. When measuring the nonlinear second harmonic wave in a solid specimen in the pulse–echo (PE) testing mode, the stress-free boundary [...] Read more.

Nonlinear ultrasound has been proven to be a useful nondestructive testing tool for micro-damage inspection of materials and structures operating in harsh environment. When measuring the nonlinear second harmonic wave in a solid specimen in the pulse–echo (PE) testing mode, the stress-free boundary characteristics brings the received second harmonic component close to zero. Therefore, the PE method has never been employed to measure the so-called “nonlinear parameter (β)”, which is used to quantify the degree of micro-damage. When there are stress-free boundaries, a focused beam is known to improve the PE reception of the second harmonic wave, so phased-array (PA) transducers can be used to generate the focused beam. For the practical application of PE nonlinear ultrasonic testing, however, it is necessary to develop a new type of PA transducer that is completely different from conventional ones. In this paper, we propose a new annular PA transducer capable of measuring β with improved second harmonic reception in the PE mode. Basically, the annular PA transducer (APAT) consists of four external ring transmitters and an internal disk receiver at the center. The focused beam properties of the transducers are analyzed using a nonlinear sound beam model which incorporates the effects of beam diffraction, material attenuation, and boundary reflection. The optimal design of the APAT is performed in terms of the maximum second harmonic reception and the total correction close to one, and the results are presented in detail. Full article

(This article belongs to the Special Issue Mechanics and Analysis of Advanced Materials and Structures)

► Show Figures

Figure 1

20 pages, 1868 KiB

Open AccessArticle

Analytical Solutions Based on Fourier Cosine Series for the Free Vibrations of Functionally Graded Material Rectangular Mindlin Plates

by Chiung-Shiann Huang and S. H. Huang

Materials 2020, 13(17), 3820; https://doi.org/10.3390/ma13173820 - 29 Aug 2020

Cited by 12 | Viewed by 1878

Abstract

This study aimed to develop series analytical solutions based on the Mindlin plate theory for the free vibrations of functionally graded material (FGM) rectangular plates. The material properties of FGM rectangular plates are assumed to vary along their thickness, and the volume [...] Read more.

This study aimed to develop series analytical solutions based on the Mindlin plate theory for the free vibrations of functionally graded material (FGM) rectangular plates. The material properties of FGM rectangular plates are assumed to vary along their thickness, and the volume fractions of the plate constituents are defined by a simple power-law function. The series solutions consist of the Fourier cosine series and auxiliary functions of polynomials. The series solutions were established by satisfying governing equations and boundary conditions in the expanded space of the Fourier cosine series. The proposed solutions were validated through comprehensive convergence studies on the first six vibration frequencies of square plates under four combinations of boundary conditions and through comparison of the obtained convergent results with those in the literature. The convergence studies indicated that the solutions obtained for different modes could converge from the upper or lower bounds to the exact values or in an oscillatory manner. The present solutions were further employed to determine the first six vibration frequencies of FGM rectangular plates with various aspect ratios, thickness-to-width ratios, distributions of material properties and combinations of boundary conditions. Full article

(This article belongs to the Special Issue Mechanics and Analysis of Advanced Materials and Structures)

► Show Figures

Figure 1

Review

Jump to: Editorial, Research

25 pages, 4847 KiB

Open AccessReview

Organic Anode Materials for Lithium-Ion Batteries: Recent Progress and Challenges

by Alexander A. Pavlovskii, Konstantin Pushnitsa, Alexandra Kosenko, Pavel Novikov and Anatoliy A. Popovich

Materials 2023, 16(1), 177; https://doi.org/10.3390/ma16010177 - 25 Dec 2022

Cited by 10 | Viewed by 2501

Abstract

In the search for novel anode materials for lithium-ion batteries (LIBs), organic electrode materials have recently attracted substantial attention and seem to be the next preferred candidates for use as high-performance anode materials in rechargeable LIBs due to their low cost, high theoretical [...] Read more.

In the search for novel anode materials for lithium-ion batteries (LIBs), organic electrode materials have recently attracted substantial attention and seem to be the next preferred candidates for use as high-performance anode materials in rechargeable LIBs due to their low cost, high theoretical capacity, structural diversity, environmental friendliness, and facile synthesis. Up to now, the electrochemical properties of numerous organic compounds with different functional groups (carbonyl, azo, sulfur, imine, etc.) have been thoroughly explored as anode materials for LIBs, dividing organic anode materials into four main classes: organic carbonyl compounds, covalent organic frameworks (COFs), metal-organic frameworks (MOFs), and organic compounds with nitrogen-containing groups. In this review, an overview of the recent progress in organic anodes is provided. The electrochemical performances of different organic anode materials are compared, revealing the advantages and disadvantages of each class of organic materials in both research and commercial applications. Afterward, the practical applications of some organic anode materials in full cells of LIBs are provided. Finally, some techniques to address significant issues, such as poor electronic conductivity, low discharge voltage, and undesired dissolution of active organic anode material into typical organic electrolytes, are discussed. This paper will guide the study of more efficient organic compounds that can be employed as high-performance anode materials in LIBs. Full article

(This article belongs to the Special Issue Mechanics and Analysis of Advanced Materials and Structures)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Mechanics and Analysis of Advanced Materials and Structures

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Published Papers (13 papers)

Editorial

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI