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Special Issue "Selected Papers from XIX International Colloquium on Mechanical Fatigue of Metals—ICMFM 19"

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: 31 July 2019

Special Issue Editors

Guest Editor
Dr. Abílio M.P. De Jesus

Department of Mechanical Engineering, University of Porto, 4200-456 Porto, Portugal
Website 1 | Website 2 | E-Mail
Interests: fatigue and fracture of materials and structures; ultra to high-cycle fatigue behaviours; probabilistic methods in fatigue and fracture; structural integrity; manufacturing processes and relation with fatigue behaviour; materials constitutive models identification; material cutting processes; additive manufacturing
Guest Editor
Dr. José A.F.O. Correia

INEGI, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal
Website | E-Mail
Interests: pressure vessels; fatigue; probabilistic fatigue modelling; cyclic plasticity; failure mechanisms; structural integrity; life prediction; probabilistic damage tolerance
Guest Editor
Assoc. Prof. Dr. Shun-Peng Zhu

Center for System Reliability & Safety, University of Electronic Science and Technology of China, Chengdu 611731, China
Website | E-Mail
Interests: probabilistic physics of failure modeling; damage accumulation; reliability and risk analysis; life prediction; uncertainty quantification; Bayesian inference; probability-based design; degradation modeling and analysis; structural reliability; prognostics and health management; structural health monitoring; gas/steam turbine technologies
Guest Editor
Prof. Dr. Xiancheng Zhang

Key Laboratory of Pressure Systems and Safety, Ministry of Education, East China University of Science and Technology, Shanghai 200237, China
Website | E-Mail
Interests: multi-physics damage modeling; high temperature fatigue; fatigue-creep interaction; life design and prediction; structural integrity; damage tolerance
Guest Editor
Prof. Dr. Dianyin Hu

School of Energy and Power Engineering, Beihang University, Beijing 100083, China
Website 1 | Website 2 | E-Mail
Interests: fatigue; fracture mechanics; design; life prediction; polycrystal materials; probability-based design; advanced testing

Special Issue Information

Dear Colleagues,

Fatigue damage represents one of the most important types of damage to which structural materials are subjected to in normal industrial services, which can finally result in a sudden and unexpected abrupt fracture. Since metal alloys are still the most used materials in designing a majority of components and structures able to carry the highest service loads, the study of the different aspects of metals fatigue attracts the permanent attention of scientists, engineers and designers.

The first International Colloquium on Mechanical Fatigue of Metals (ICMFM) was organized in Brno, Czech Republic in 1968. Afterwards, regular Colloquia on Mechanical Fatigue of Metals started in 1972 also in Brno and were originally limited to participants form the countries of the former “Eastern Block”. They continued until the 12th Colloquium in 1994 (Miskolc, Hungary) every two years. After a break twelve years long, the Colloquia restarted in 2006 (Ternopil, Ukraine), followed by the ones in 2008 (Varna, Bulgaria), 2010 (Opole, Poland), 2012 (Brno, Czech Republic), 2014 (Verbania, Italy), until the last one, which was organized in 2016 in Gijón (Asturias), Spain, with the aim of opening the Colloquium to participants from all countries interested in the subject of fatigue of metallic materials.

The XIX International Colloquium on Mechanical Fatigue of Metals (ICMFM XIX) will be organized in 5­–7 September 2018, at the Faculty of Engineering of the University of Porto, in Porto City, located at seaside in the northwest region of Portugal. This International Colloquium is intended to facilitate and encourage the exchange of knowledge and experiences among the different communities involved in both basic and applied research in this field, the fatigue of metals, looking at the problem of fatigue from a multiscale perspective, and exploring analytical and numerical simulative approaches, without losing the applications perspectives.

The limits of current generation materials are continuously reached according to the frontier of hostile environments, whether in the aerospace, nuclear or petro chemistry industry, or in the design of gas turbines where efficiency of energy production and transformation demands increased temperatures and pressures. At the same time, increase the reliability and performance, in particular by the control and understanding of early failures is one key point for the future materials. Moreover, increasing of material lifetimes in service and the extension of recycling time are expected. Accordingly, continued improvements on “materials by design” have been possible through accurate modeling of failure mechanisms by introducing advanced theoretical and simulation approaches/tools. Based on this, researches on failure mechanisms can provide assurance for new materials at the design stage and ensure the integrity in the construction at the fabrication phase. Specifically, material failure in hostile environments occurs under multi-sources of variability, resulting from load environments, material properties, geometry variations within tolerances, and other uncontrolled variations. Thus, advanced methods and applications for theoretical, numerical, and experimental contributions that address these issues on failure mechanism modeling and simulation of materials are desired and expected.

This Special Issue selects excellent papers from ICMFM 19 that are related to materials development. Potential topics include, but are not limited to:

  • Environmental assisted fatigue
  • Multi damage/degradation
  • Multi-scale modeling and simulation
  • Micromechanics of fracture
  • Material defects evolution
  • Interactions of extreme environments
  • Microstructure-based modeling and simulation
  • Fracture in extreme environments
  • Probabilistic Physics of Failure modeling and simulation
  • Advanced testing and simulation
  • Life prediction and extension
  • Stochastic degradation modeling and analysis
  • Ultra-low, low-, high- and giga-cycle fatigue
  • Fatigue in biomaterials
  • Cyclic plasticity and internal structure

Prof. Dr. Abílio M.P. De Jesus
Dr. José A.F.O. Correia
Assoc. Prof. Dr. Shun-Peng Zhu
Prof. Dr. Xiancheng Zhang
Prof. Dr. Dianyin Hu
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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. Materials 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 1800 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

  • Wind/gas/steam turbine technologies
  • Power plant technologies
  • Failure mechanisms
  • Damage/degradation
  • Probabilistic Physics of Failure
  • Advanced testing and statistics

Published Papers (6 papers)

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Research

Open AccessArticle
PSO-BP Neural Network-Based Strain Prediction of Wind Turbine Blades
Materials 2019, 12(12), 1889; https://doi.org/10.3390/ma12121889
Received: 30 April 2019 / Revised: 6 June 2019 / Accepted: 6 June 2019 / Published: 12 June 2019
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Abstract
The full-scale static testing of wind turbine blades is an effective means to verify the accuracy and rationality of the blade design, and it is an indispensable part in the blade certification process. In the full-scale static experiments, the strain of the wind [...] Read more.
The full-scale static testing of wind turbine blades is an effective means to verify the accuracy and rationality of the blade design, and it is an indispensable part in the blade certification process. In the full-scale static experiments, the strain of the wind turbine blade is related to the applied loads, loading positions, stiffness, deflection, and other factors. At present, researches focus on the analysis of blade failure causes, blade load-bearing capacity, and parameter measurement methods in addition to the correlation analysis between the strain and the applied loads primarily. However, they neglect the loading positions and blade displacements. The correlation among the strain and applied loads, loading positions, displacements, etc. is nonlinear; besides that, the number of design variables is numerous, and thus the calculation and prediction of the blade strain are quite complicated and difficult using traditional numerical methods. Moreover, in full-scale static testing, the number of measuring points and strain gauges are limited, so the test data have insufficient significance to the calibration of the blade design. This paper has performed a study on the new strain prediction method by introducing intelligent algorithms. Back propagation neural network (BPNN) improved by Particle Swarm Optimization (PSO) has significant advantages in dealing with non-linear fitting and multi-input parameters. Models based on BPNN improved by PSO (PSO-BPNN) have better robustness and accuracy. Based on the advantages of the neural network in dealing with complex problems, a strain-predictive PSO-BPNN model for full-scale static experiment of a certain wind turbine blade was established. In addition, the strain values for the unmeasured points were predicted. The accuracy of the PSO-BPNN prediction model was verified by comparing with the BPNN model and the simulation test. Both the applicability and usability of strain-predictive neural network models were verified by comparing the prediction results with simulation outcomes. The comparison results show that PSO-BPNN can be utilized to predict the strain of unmeasured points of wind turbine blades during static testing, and this provides more data for characteristic structural parameters calculation. Full article
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Open AccessArticle
Reliability-Based Low Fatigue Life Analysis of Turbine Blisk with Generalized Regression Extreme Neural Network Method
Materials 2019, 12(9), 1545; https://doi.org/10.3390/ma12091545
Received: 23 March 2019 / Revised: 6 May 2019 / Accepted: 8 May 2019 / Published: 10 May 2019
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Abstract
Turbine blisk low cycle fatigue (LCF) is affected by various factors such as heat load, structural load, operation parameters and material parameters; it seriously influences the reliability and performance of the blisk and aeroengine. To study the influence of thermal-structural coupling on the [...] Read more.
Turbine blisk low cycle fatigue (LCF) is affected by various factors such as heat load, structural load, operation parameters and material parameters; it seriously influences the reliability and performance of the blisk and aeroengine. To study the influence of thermal-structural coupling on the reliability of blisk LCF life, the generalized regression extreme neural network (GRENN) method was proposed by integrating the basic thoughts of generalized regression neural network (GRNN) and the extreme response surface method (ERSM). The mathematical model of the developed GRENN method was first established in respect of the LCF life model and the ERSM model. The method and procedure for reliability and sensitivity analysis based on the GRENN model were discussed. Next, the reliability and sensitivity analyses of blisk LCF life were performed utilizing the GRENN method under a thermal-structural interaction by regarding the randomness of gas temperature, rotation speed, material parameters, LCF performance parameters and the minimum fatigue life point of the objective of study. The analytical results reveal that the reliability degree was 0.99848 and the fatigue life is 9419 cycles for blisk LCF life when the allowable value is 6000 cycles so that the blisk has some life margin relative to 4500 cycles in the deterministic analysis. In comparison with ERSM, the computing time and precision of the proposed GRENN under 10,000 simulations is 1.311 s and 99.95%. This is improved by 15.18% in computational efficiency and 1.39% in accuracy, respectively. Moreover, high efficiency and high precision of the developed GRENN become more obvious with the increasing number of simulations. In light of the sensitivity analysis, the fatigue ductility index and temperature are the key factors of determining blisk LCF life because their effect probabilities reach 41% and 26%, respectively. Material density, rotor speed, the fatigue ductility coefficient, the fatigue strength coefficient and the fatigue ductility index are also significant parameters for LCF life. Poisson’s ratio and elastic modulus of materials have little effect. The efforts of this paper validate the feasibility and validity of GRENN in the reliability analysis of blisk LCF life and give the influence degrees of various random parameters on blisk LCF life, which are promising to provide useful insights for the probabilistic optimization of turbine blisk LCF life. Full article
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Open AccessArticle
Application of a New, Energy-Based ΔS* Crack Driving Force for Fatigue Crack Growth Rate Description
Materials 2019, 12(3), 518; https://doi.org/10.3390/ma12030518
Received: 31 December 2018 / Revised: 4 February 2019 / Accepted: 7 February 2019 / Published: 9 February 2019
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Abstract
This paper presents the problem of the description of fatigue cracking development in metallic constructional materials. Fatigue crack growth models (mostly empirical) are usually constructed using a stress intensity factor ΔK in linear-elastic fracture mechanics. Contrary to the kinetic fatigue fracture diagrams [...] Read more.
This paper presents the problem of the description of fatigue cracking development in metallic constructional materials. Fatigue crack growth models (mostly empirical) are usually constructed using a stress intensity factor ΔK in linear-elastic fracture mechanics. Contrary to the kinetic fatigue fracture diagrams (KFFDs) based on stress intensity factor K, new energy KFFDs show no sensitivity to mean stress effect expressed by the stress ratio R. However, in the literature there is a lack of analytical description and interpretation of this parameter in order to promote this approach in engineering practice. Therefore, based on a dimensional analysis approach, ΔH is replaced by elastic-plastic fracture mechanics parameter—the ΔJ-integral range. In this case, the invariance from stress is not clear. Hence, the main goal of this paper is the application of the new averaged (geometrically) strain energy density parameter ΔS* based on the relationship of the maximal value of J integral and its range ΔJ. The usefulness and invariance of this parameter have been confirmed for three different metallic materials, 10HNAP, 18G2A, and 19th century puddle iron from the Eiffel bridge. Full article
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Open AccessArticle
First-Principles Study on the Adsorption and Dissociation of Impurities on Copper Current Collector in Electrolyte for Lithium-Ion Batteries
Materials 2018, 11(7), 1256; https://doi.org/10.3390/ma11071256
Received: 11 June 2018 / Revised: 10 July 2018 / Accepted: 19 July 2018 / Published: 21 July 2018
Cited by 1 | PDF Full-text (3692 KB) | HTML Full-text | XML Full-text
Abstract
The copper current collector is an important component for lithium-ion batteries and its stability in electrolyte impacts their performance. The decomposition of LiPF6 in the electrolyte of lithium-ion batteries produces the reactive PF6, which reacts with the residual water and [...] Read more.
The copper current collector is an important component for lithium-ion batteries and its stability in electrolyte impacts their performance. The decomposition of LiPF6 in the electrolyte of lithium-ion batteries produces the reactive PF6, which reacts with the residual water and generates HF. In this paper, the adsorption and dissociation of H2O, HF, and PF5 on the Cu(111) surface were studied using a first-principles method based on the density functional theory. The stable configurations of HF, H2O, and PF5 adsorbed on Cu(111) and the geometric parameters of the admolecules were confirmed after structure optimization. The results showed that PF5 can promote the dissociation reaction of HF. Meanwhile, PF5 also promoted the physical adsorption of H2O on the Cu(111) surface. The CuF2 molecule was identified by determining the bond length and the bond angle of the reaction product. The energy barriers of HF dissociation on clean and O-atom-preadsorbed Cu(111) surfaces revealed that the preadsorbed O atom can promote the dissociation of HF significantly. Full article
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Open AccessArticle
Surface Nanocrystallization and Amorphization of Dual-Phase TC11 Titanium Alloys under Laser Induced Ultrahigh Strain-Rate Plastic Deformation
Materials 2018, 11(4), 563; https://doi.org/10.3390/ma11040563
Received: 7 March 2018 / Revised: 27 March 2018 / Accepted: 3 April 2018 / Published: 6 April 2018
Cited by 2 | PDF Full-text (2931 KB) | HTML Full-text | XML Full-text
Abstract
As an innovative surface technology for ultrahigh strain-rate plastic deformation, laser shock peening (LSP) was applied to the dual-phase TC11 titanium alloy to fabricate an amorphous and nanocrystalline surface layer at room temperature. X-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy [...] Read more.
As an innovative surface technology for ultrahigh strain-rate plastic deformation, laser shock peening (LSP) was applied to the dual-phase TC11 titanium alloy to fabricate an amorphous and nanocrystalline surface layer at room temperature. X-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy (HRTEM) were used to investigate the microstructural evolution, and the deformation mechanism was discussed. The results showed that a surface nanostructured surface layer was synthesized after LSP treatment with adequate laser parameters. Simultaneously, the behavior of dislocations was also studied for different laser parameters. The rapid slipping, accumulation, annihilation, and rearrangement of dislocations under the laser-induced shock waves contributed greatly to the surface nanocrystallization. In addition, a 10 nm-thick amorphous structure layer was found through HRTEM in the top surface and the formation mechanism was attributed to the local temperature rising to the melting point, followed by its subsequent fast cooling. Full article
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Open AccessArticle
Indentation Behavior and Mechanical Properties of Tungsten/Chromium co-Doped Bismuth Titanate Ceramics Sintered at Different Temperatures
Materials 2018, 11(4), 503; https://doi.org/10.3390/ma11040503
Received: 26 February 2018 / Revised: 22 March 2018 / Accepted: 22 March 2018 / Published: 27 March 2018
Cited by 2 | PDF Full-text (32816 KB) | HTML Full-text | XML Full-text
Abstract
A sort of tungsten/chromium(W/Cr) co-doped bismuth titanate (BIT) ceramics (Bi4Ti2.95W0.05O12.05 + 0.2 wt % Cr2O3, abbreviate to BTWC) are ordinarily sintered between 1050 and 1150 °C, and the indentation behavior and mechanical [...] Read more.
A sort of tungsten/chromium(W/Cr) co-doped bismuth titanate (BIT) ceramics (Bi4Ti2.95W0.05O12.05 + 0.2 wt % Cr2O3, abbreviate to BTWC) are ordinarily sintered between 1050 and 1150 °C, and the indentation behavior and mechanical properties of ceramics sintered at different temperatures have been investigated by both nanoindentation and microindentation technology. Firstly, more or less Bi2Ti2O7 grains as the second phase were found in BTWC ceramics, and the grain size of ceramics increased with increase of sintering temperatures. A nanoindentation test for BTWC ceramics reveals that the testing hardness of ceramics decreased with increase of sintering temperatures, which could be explained by the Hall–Petch equation, and the true hardness could be calculated according to the pressure-state-response (PSR) model considering the indentation size effect, where the value of hardness depends on the magnitude of load. While, under the application of microsized Vickers, the sample sintered at a lower temperature (1050 °C) gained four linearly propagating cracks, however, they were observed to shorten in the sample sintered at a higher temperature (1125 °C). Moreover, both the crack deflection and the crack branching existed in the latter. The hardness and the fracture toughness of BTWC ceramics presented a contrary variational tendency with increase of sintering temperatures. A high sintering tends to get a lower hardness and a higher fracture toughness, which could be attributed to the easier plastic deformation and the stronger crack inhibition of coarse grains, respectively, as well as the toughening effect coming from the second phase. Full article
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