Special Issue "Modern Aerospace Materials"

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: closed (15 April 2019)

Special Issue Editor

Guest Editor
Prof. Dr. Guillermo Requena

Department of Metallic Structures and Hybrid Materials Systems, Institute for Materials Research, German Aerospace Centre, Linder Höhe, 51147, Cologne, Germany
Website | E-Mail
Interests: light alloys; metals for additive manufacturing; three-dimensional material characterization; synchrotron tomography; high energy synchrotron diffraction; aluminum alloys; titanium alloys; magnesium alloys; titanium aluminides; metal matrix composites; phase transformations; relationships microstructure-properties; thermo-mechanical behavior of metals

Special Issue Information

Dear Colleagues,

Aerospace materials are a wide family, characterized by their applications under some of the most demanding mechanical, thermal, and thermo-mechanical service conditions. As such, their development has been accompanying technological breakthroughs along the last two centuries, e.g., the development of damage tolerant lightweight alloys contributed to the massification of civil air transport, superalloys are a must in modern jet engines and high temperature alloys are found in all rocket propulsion systems.

Nowadays, current trends in the frame of the so-called “Industry 4.0 revolution”, as well as strict regulations to decrease the ecological footprint of aircrafts, together with new space travel technologies such as reusable entry vehicles are further pushing the development of metal-based aerospace materials and structures and their corresponding manufacturing methods. This Special Issue is devoted to disseminate scientific and technological efforts in this context and it is, therefore, my pleasure to invite you to submit contributions dealing with the processing and behavior under service-relevant conditions of metal-based aerospace materials.

Prof. Dr. Guillermo Requena
Guest Editor

Manuscript Submission Information

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Keywords

  • high temperature alloys
  • superalloys
  • lightweight alloys
  • fibre metal laminates
  • automatic manufacturing
  • additive manufacturing

Published Papers (6 papers)

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Research

Open AccessArticle Blunt Notch Strength of AA2024 3-3/2-0.4 Fibre Metal Laminate Under Biaxial Tensile Loading
Metals 2019, 9(4), 413; https://doi.org/10.3390/met9040413
Received: 18 March 2019 / Revised: 28 March 2019 / Accepted: 1 April 2019 / Published: 5 April 2019
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Abstract
Fibre metal laminates are utilized in lightweight structures, such as aircraft fuselages, as fibre metal laminates provide outstanding fatigue and damage tolerance capabilities, together with a reduced weight compared to monolithic metallic structures. One critical feature of fuselage structures is their strength reduction [...] Read more.
Fibre metal laminates are utilized in lightweight structures, such as aircraft fuselages, as fibre metal laminates provide outstanding fatigue and damage tolerance capabilities, together with a reduced weight compared to monolithic metallic structures. One critical feature of fuselage structures is their strength reduction that owes to riveting, i.e., a state-of-the-art joining technique in aircrafts. In the present work, the blunt notch strength of fibre-laminate panels with rivet holes is investigated under service-relevant biaxial loading conditions. To this purpose, cruciform specimens with a five-hole pattern were produced. These specimens were tested under various biaxiality ratios and fibre orientations. All tests were supported by three-dimensional digital image correlation to obtain the deformation field in the gauge area. Moreover, the displacement fields obtained during deformation were used in an elasto-plastic finite element model as boundary conditions to determine the maximum strains in the vicinity of the blunt notch holes and thus extend the application of the experimental results. The asymmetric strain fields obtained by digital image correlation reveal the interaction of the fibres with the blunt notch holes. Finally, it is shown that the biaxial loading conditions do not significantly influence the blunt notch strength. Full article
(This article belongs to the Special Issue Modern Aerospace Materials)
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Open AccessArticle Characterization of Local Residual Stress at Blade Surfaces by the V(z) Curve Technique
Metals 2018, 8(8), 651; https://doi.org/10.3390/met8080651
Received: 15 June 2018 / Revised: 16 August 2018 / Accepted: 16 August 2018 / Published: 19 August 2018
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Abstract
The characterization of residual stress in complicated components is a tough issue. The method of Rayleigh surface wave-based V(z) curve is adopted in this work to evaluate the distribution of residual stresses in aeroengine blades. First, the velocity of Rayleigh [...] Read more.
The characterization of residual stress in complicated components is a tough issue. The method of Rayleigh surface wave-based V(z) curve is adopted in this work to evaluate the distribution of residual stresses in aeroengine blades. First, the velocity of Rayleigh surface wave in aeroengine blade was measured by the V(z) curve technique, which can be used to calculate the local residual stress because the change of velocity is thought to be correlated with the contribution from residual stress. Two kinds of plastic-deformed Ti-6Al-4V samples were fabricated by ball-gun shooting to artificially induce distribution of residual stress and then measured by the proposed method. The results indicate that the distribution of the residual stress in both of the samples displays a predictable symmetry. The error of the measured stress is much less than 10% of the yielding stress in Ti-6Al-4V (i.e., about 800 MPa). Finally, the measured residual stresses were verified by X-ray diffraction method, whose results correlate reasonably well with each other. The proposed V(z) curve method and its experimental set-up appear to be a potential in characterizing residual stress at a point-like region, such as in complicated components. Full article
(This article belongs to the Special Issue Modern Aerospace Materials)
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Open AccessArticle B4C Particles Reinforced Al2024 Composites via Mechanical Milling
Metals 2018, 8(8), 647; https://doi.org/10.3390/met8080647
Received: 13 July 2018 / Revised: 3 August 2018 / Accepted: 14 August 2018 / Published: 17 August 2018
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Abstract
The control of a homogeneous distribution of the reinforcing phase in aluminum matrix composites is the main issue during the synthesis of this kind of material. In this work, 2024 aluminum matrix composites reinforced with boron carbide were produced by mechanical milling, using [...] Read more.
The control of a homogeneous distribution of the reinforcing phase in aluminum matrix composites is the main issue during the synthesis of this kind of material. In this work, 2024 aluminum matrix composites reinforced with boron carbide were produced by mechanical milling, using 1 and 2 h of milling. After milling, powdered samples were cold consolidated, sintered and T6 heat treated. The morphology and microstructure of Al2024/B4C composites were investigated by scanning electron microscopy; analysis of X-ray diffraction peaks were used for the calculation of the crystallite size and microstrains by the Williamson–Hall method. The mechanical properties were evaluated by compression and hardness tests. B4C particles were found to be well dispersed into the aluminum matrix as a result of the high-energy milling process. The crystallite size of composites milled for 2 h was lower than those milled for 1 h. The hardness, yield strength and maximum strength were significantly improved in the composites processed for 2 h, in comparison to those processed for 1 h and the monolithic 2024 alloy. Full article
(This article belongs to the Special Issue Modern Aerospace Materials)
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Open AccessArticle An Equivalent Calculation Method for Press-Braking Bending Analysis of Integral Panels
Metals 2018, 8(5), 364; https://doi.org/10.3390/met8050364
Received: 17 April 2018 / Revised: 6 May 2018 / Accepted: 15 May 2018 / Published: 18 May 2018
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Abstract
Press-braking bending is widely applied in the manufacture of aircraft integral panels because of the advantages of strong adaptability to different contours, simplicity of bending tools, short manufacturing time and low process cost. However, a simulation of bending process requires long-time calculation and [...] Read more.
Press-braking bending is widely applied in the manufacture of aircraft integral panels because of the advantages of strong adaptability to different contours, simplicity of bending tools, short manufacturing time and low process cost. However, a simulation of bending process requires long-time calculation and consumes extensive computational resources. Considering the factors that the original model (ORM) of an integral panel is large and the press-braking bending is used only for the local area of integral panels with heavy thickness in practice, an equivalent calculation method for press-braking bending analysis of integral panels is proposed. The local bending area of an integral panel is simplified to a model of plate in this method. An exponential strengthening model is used to derive the equations of stress, strain and forming radius of the ORM and its simplified model (SPM). Meanwhile, the equivalent parameters of the SPM are determined and deduced based on three principles: that the material begin to be yielded simultaneously, the ultimate stress of the ORM is the same as that of the SPM at the same punch displacement, and the forming radii of neutral surfaces of the ORM and the SPM are identical after springback. The distribution of the stress and strain determined by finite element (FE) simulations are compared, and the FE simulations indicate that the contour curve of the SPM is in fairly good agreement with the profile of the ORM under the same bending process parameters, and the maximum difference is 13.17%. The computational efficiency is increased by more than 48%. Therefore, the proposed approach is quite suitable for industrial applications to improve the bending quality and efficiency of integral panels. Full article
(This article belongs to the Special Issue Modern Aerospace Materials)
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Open AccessArticle Microstructure and Properties of Friction Stir Welded 2219 Aluminum Alloy under Heat Treatment and Electromagnetic Forming Process
Metals 2018, 8(5), 305; https://doi.org/10.3390/met8050305
Received: 25 March 2018 / Revised: 21 April 2018 / Accepted: 21 April 2018 / Published: 28 April 2018
Cited by 2 | PDF Full-text (3992 KB) | HTML Full-text | XML Full-text
Abstract
Among available processing technologies of heat-treatable aluminum alloys such as the 2219 aluminum alloy, the use of both friction stir welding (FSW) as joining technology and electromagnetic forming (EMF) for plastic formation technology have obvious advantages and successful applications. Therefore, significant potential exists [...] Read more.
Among available processing technologies of heat-treatable aluminum alloys such as the 2219 aluminum alloy, the use of both friction stir welding (FSW) as joining technology and electromagnetic forming (EMF) for plastic formation technology have obvious advantages and successful applications. Therefore, significant potential exists for these processing technologies, both of which can be used on the 2219 aluminum alloy, to manufacture large-scale, thin-wall parts in the astronautic industry. The microstructure and mechanical properties of 2219 aluminum alloy under a process which compounded FSW, heat treatment, and EMF were investigated by means of a tensile test as well as via both an optical microscope (OM) and scanning electron microscope (SEM). The results show that the reduction of strength, which was caused during the FSW process, can be recovered effectively. This can be accomplished by a post-welding heat treatment composed of solid solution and aging. However, ductility was still reduced after heat treatment. Under the processing technology composed of FSW, heat treatment, and EMF, the forming limit of the 2219 aluminum alloy decreased distinctly due to the poor ductility of the welding joint. A ribbon pattern was found on the fractured surface of welded 2219 aluminum alloy after EMF treatment, which was formed due to the banded structure caused by the FSW process. Because of the effects of induced eddy current in the EMF process, the material fractured, forming a unique structure which manifested as a molten surface appearance under SEM observation. Full article
(This article belongs to the Special Issue Modern Aerospace Materials)
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Open AccessArticle Electromagnetic Forming Rules of a Stiffened Panel with Grid Ribs
Metals 2017, 7(12), 559; https://doi.org/10.3390/met7120559
Received: 11 October 2017 / Revised: 15 November 2017 / Accepted: 7 December 2017 / Published: 12 December 2017
Cited by 1 | PDF Full-text (10888 KB) | HTML Full-text | XML Full-text
Abstract
Electromagnetic forming (EMF), a technology with advantages of contact-free force and high energy density, generally aims at forming parts by using a fixed coil and one-time discharge. In this study, multi-stage EMF is introduced to form a panel with stiffened grid ribs. The [...] Read more.
Electromagnetic forming (EMF), a technology with advantages of contact-free force and high energy density, generally aims at forming parts by using a fixed coil and one-time discharge. In this study, multi-stage EMF is introduced to form a panel with stiffened grid ribs. The forming rules of the stiffened panel is revealed via analyzing the distribution and evolution of the simulated stress and strain in the ribs and web, where the grid-rib panels were decomposed as the flat panel and two panels with uni-directional ribs (ribs only in X direction or Y direction). It is shown that the forming depth is mainly attributed to the forces on the web, although electromagnetic force is applied on both the ribs and the web, especially, large force on the ribs. The ribs are subjected to uniaxial stress parallel to their directions, and the web is subjected to plane stress in the deformation region. Furthermore, the change of the uniaxial stress characteristic in the X-direction ribs is influenced by the electromagnetic force, reverse bend and inertial effect. The plastic deformation mainly occurs in the Y-direction ribs of the deformation region under a three-direction strain state. Full article
(This article belongs to the Special Issue Modern Aerospace Materials)
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