Special Issue "Multiscale Fatigue Design"

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Mechanical Engineering".

Deadline for manuscript submissions: closed (30 January 2019)

Special Issue Editor

Guest Editor
Prof. Dr. Filippo Berto

Department of Industrial and Mechanical Engineering, Norwegian University of Science and Technology, 7491 Trondheim, Norway
Website | E-Mail
Phone: +4748500574
Interests: fatigue of advanced and traditional materials; fracture mechanics; solid mechanics; structural integrity; additive materials

Special Issue Information

Dear Colleagues,

With the advance of new materials in different engineering fields, and in particular of nano-materials and thin coatings, attention has to be paid to the fracture mechanism at different scale levels. This issue is not easy to deal with because, in small bodies, the high ratio between surface and volume makes the local discontinuities present in the material non negligible.

This Special Issue embraces interdisciplinary work aimed at understanding and deploying mechanisms involved in fatigue damage and failures occurring at all scale levels (from nano to macro), advancing experimental and theoretical failure analyses, modelling of the structural response with respect to both local and global failures, and structural design that accounts for scale and time effects in preventing catastrophic failures of components and structures.

Prof. Dr. Filippo Berto
Guest Editor

Manuscript Submission Information

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Keywords

  • Fatigue
  • Multiaxial loading
  • Fatigue crack growth
  • 3d effects
  • Multiscale approaches
  • Fatigue at nano scale level, local approaches, energy based methods

Published Papers (5 papers)

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Research

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Open AccessArticle Lifetime Assessment and Optimization of a Welded A-Type Frame in a Mining Truck Considering Uncertainties of Material Properties and Structural Geometry and Load
Appl. Sci. 2019, 9(5), 918; https://doi.org/10.3390/app9050918
Received: 19 December 2018 / Revised: 22 February 2019 / Accepted: 26 February 2019 / Published: 4 March 2019
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Abstract
In order to improve the fatigue performance of a welded A-type frame in a heavy off-road mining truck, a novel method was presented to implement lifetime and weight collaborative optimization while considering uncertainties in geometry dimension, material properties, and bearing load. The mechanical [...] Read more.
In order to improve the fatigue performance of a welded A-type frame in a heavy off-road mining truck, a novel method was presented to implement lifetime and weight collaborative optimization while considering uncertainties in geometry dimension, material properties, and bearing load. The mechanical and cyclic material parameters were obtained from experimental work to characterize the base metal and the weldment. The finite element model of a welded A-type frame was constructed to analyze stress distribution and predict fatigue life, the force time histories of which were acquired from multi-body dynamics simulation. The simulated failure position and fatigue life had a good agreement with the actual results. Then, both structural lifetime and weight were considered as optimization objectives. The thickness of main steel plates and elastic and cyclic material parameters were chosen as uncertain design variables as well as main loads at connection locations. The fifty sample points in the light of Latin hypercube sampling method and its responses calculated by finite element analysis were supposed to build the approximation model based on the Kriging approximation method. After its fitting precision was guaranteed, the non-dominated sorting genetic algorithm II (NSGA-II) was utilized to find the optimal solution. Finally, the fatigue life of a welded A-type frame was increased to 2.40 × 105 cycles and its mass was lessened by 8.2%. The optimized results implied that good fatigue performance of this welded A-type frame needs better welding quality, lower running speed for downhill and turning road surface, and thicker front plates. Full article
(This article belongs to the Special Issue Multiscale Fatigue Design)
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Open AccessArticle Cutting Performance and Wear/Damage Characteristics of PCBN Tool in Hard Milling
Appl. Sci. 2019, 9(4), 772; https://doi.org/10.3390/app9040772
Received: 6 January 2019 / Revised: 12 February 2019 / Accepted: 19 February 2019 / Published: 22 February 2019
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Abstract
In the intermittent machining of hardened steel for the die and mold industry, determining how to reduce the wear of PCBN (Polycrystalline Cubic Boron Nitride) tools and improve their machining efficiency and quality is an important subject. This study investigated the intermittent machining [...] Read more.
In the intermittent machining of hardened steel for the die and mold industry, determining how to reduce the wear of PCBN (Polycrystalline Cubic Boron Nitride) tools and improve their machining efficiency and quality is an important subject. This study investigated the intermittent machining of hardened steel (Cr12MoV, 59HRC (Rockwell hardness)) using uncoated PCBN tools to determine the cutting performance (cutting force, chip morphology, surface quality, tool life, cutting temperature) and the wear/damage characteristics of the tools. The results showed that the cutting performance of a PCBN tool was better than that of a cemented carbide tool. The wear mechanism on the PCBN tool flank was diffusion wear, adhesive wear, and oxidation wear. The main failure modes of the PCBN tool in the machining process of hardened steel at low speed were tool micro-chipping, the conchoidal damage of the rake face, and the larger damaged area of the flank face. The main failure modes of the PCBN tool in the machining process of hardened steel at high speed were flank wear and high-rate fatigue damage. Full article
(This article belongs to the Special Issue Multiscale Fatigue Design)
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Open AccessArticle A Comparison of Empirical Procedures for Fatigue Damage Prediction in Instrumented Risers Undergoing Vortex-Induced Vibration
Appl. Sci. 2018, 8(11), 2085; https://doi.org/10.3390/app8112085
Received: 30 September 2018 / Revised: 24 October 2018 / Accepted: 25 October 2018 / Published: 28 October 2018
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Abstract
To gain insight into riser motions and associated fatigue damage due to vortex-induced vibration (VIV), data loggers such as strain sensors and/or accelerometers are sometimes deployed on risers to monitor their motion in different current velocity conditions. Accurate reconstruction of the riser response [...] Read more.
To gain insight into riser motions and associated fatigue damage due to vortex-induced vibration (VIV), data loggers such as strain sensors and/or accelerometers are sometimes deployed on risers to monitor their motion in different current velocity conditions. Accurate reconstruction of the riser response and empirical estimation of fatigue damage rates over the entire riser length using measurements from a limited number of sensors can help in efficient utilization of the costly measurements recorded. Several different empirical procedures are described here for analysis of the VIV response of a long flexible cylinder subjected to uniform and sheared current profiles. The methods include weighted waveform analysis (WWA), proper orthogonal decomposition (POD), modal phase reconstruction (MPR), a modified WWA procedure, and a hybrid method which combines MPR and the modified WWA method. Fatigue damage rates estimated using these different empirical methods are compared and cross-validated against measurements. Detailed formulations for each method are presented and discussed with examples. Results suggest that all the empirical methods, despite different underlying assumptions in each of them, can be employed to estimate fatigue damage rates quite well from limited strain measurements. Full article
(This article belongs to the Special Issue Multiscale Fatigue Design)
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Open AccessArticle Microscopic Elastic and Plastic Inhomogeneous Deformations and Height Changes on the Surface of a Polycrystalline Pure-Titanium Plate Specimen under Cyclic Tension
Appl. Sci. 2018, 8(10), 1907; https://doi.org/10.3390/app8101907
Received: 18 August 2018 / Revised: 7 October 2018 / Accepted: 9 October 2018 / Published: 13 October 2018
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Abstract
A cyclic tensile test was carried out using a plate specimen of commercial pure titanium on a digital holographic microscope stage. Microscopic deformation of the grains was observed, and their height distribution was measured on the specimen surface. Each grain showed nanoscopic movement [...] Read more.
A cyclic tensile test was carried out using a plate specimen of commercial pure titanium on a digital holographic microscope stage. Microscopic deformation of the grains was observed, and their height distribution was measured on the specimen surface. Each grain showed nanoscopic movement up and down, as well as reverse movement corresponding to specimen loading and unloading. We suggest that the different grain-specific changes in height were caused by microscopic inhomogeneities in the material, such as differences in the crystal orientation and geometries of both the surface and subsurface grains. Changes in grain height increased with tensile load, and a strong relationship was found between the height changes that occurred under elastic and plastic conditions. This suggests that microscopic plastic deformation is predictable from microscopic elastic deformation. In order to investigate the plastic deformation of grains in more detail, slip-line angles were measured after the tensile test. We found slip lines with similar angles in neighboring grains, suggesting that the plastic deformation of grains was not independent, but rather was related to that of surrounding grains and influenced by the deformation of subsurface grains. Full article
(This article belongs to the Special Issue Multiscale Fatigue Design)
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Review

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Open AccessReview Cracking and Toughening Mechanisms in Nanoscale Metallic Multilayer Films: A Brief Review
Appl. Sci. 2018, 8(10), 1821; https://doi.org/10.3390/app8101821
Received: 5 September 2018 / Revised: 18 September 2018 / Accepted: 25 September 2018 / Published: 4 October 2018
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Abstract
Nanoscale metallic multilayer films (NMMFs) have captured scientific interests on their mechanical responses. Compared with the properties of monolithic films, multilayers possess unique high strength as the individual layer thickness reduces to the nanoscale, which is benefited from the plentiful hetero-interfaces. However, NMMFs [...] Read more.
Nanoscale metallic multilayer films (NMMFs) have captured scientific interests on their mechanical responses. Compared with the properties of monolithic films, multilayers possess unique high strength as the individual layer thickness reduces to the nanoscale, which is benefited from the plentiful hetero-interfaces. However, NMMFs always exhibit a low fracture toughness and ductility, which seriously hinders their practical applications. While there have been reviews on the strengthening and deformation mechanisms of microlaminate, rapid developments in nanotechnology have brought an urgent requirement for an overview focused on the cracking and toughening mechanisms in nanoscale metallic multilayers. This article provides an extensive review on the structure, standard methodology and fracture mechanisms of NMMFs. A number of issues about the crack-related properties of NMMFs have been displayed, such as fracture toughness, wear resistance, adhesion energy, and plastic instability. Taken together, it is hoped that this review will achieve the following two purposes: (1) introducing the size-dependent cracking and toughness performance in NMMFs; and (2) offer a better understanding of the role interfaces displayed in toughening mechanisms. Finally, we list a few questions we concerned, which may shed light on further development. Full article
(This article belongs to the Special Issue Multiscale Fatigue Design)
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