Giga-Cycle Fatigue Behaviour of Engineering Metallic Alloys
Keywords
Giga-cycle fatigue
Ultrasonic testing
Multiaxial Fatigue
Microstructural defects
Tasks
UHCF behaviour of structural steel and AM alloy under uniaxial loading .
Design and modelling of ultrasonic testing systems for UHCF.
UHCF behaviour of a cast aluminium alloy.
Multiaxial UHCF behaviour of a structural steel.
ULCF data analysis and fatigue modelling.
PTDC/EME-EME/7678/2020
Projeto Financiado por fundos nacionais da Fundação para a Ciência e a Tecnologia, I.P. do Ministério da Ciência, Tecnologia e Ensino Superior
Summary
Today, the fatigue behaviour of engineering metallic alloys for a number of loading cycles surpassing the conventional fatigue limit (10^7) has become a question of major interest. More and more components (ex: modern transportation systems, energy harvesting structures) are subjected to load scenarios of small stress amplitudes that must endure a number of loading cycles up to 10^8 or even beyond, in a range which is either called Giga-Cycle Fatigue (GCF), Ultra-High-Cycle Fatigue (UHCF) or even Very-High-Cycle Fatigue (VHCF). It has been demonstrated for that loading regimes, fatigue cracks may initiate from inclusions inside of the material, instead of the typical surface fatigue cracks. Therefore, the fatigue behaviour in the UHCF regime exhibits extra dependency on material microstructure and extrapolations from high-cycle fatigue to this fatigue regime are questionable. Fatigue limits are often conventionally defined due to limitations in fatigue testing for very long durations, which can lead to unsafe designs.
Fatigue testing in the UHCF regime is then mandatory, but conventional testing equipment cannot provide the answers in an affordable cost and time. The use of high-speed ultrasonic (20kHz) fatigue testing machines has being proposed as a method of evaluating these fatigue characteristics. Nevertheless, this testing procedure also raises many challenges, namely: i) possible frequency effects on both fatigue crack initiation and crack growth; ii) thermal effects due to heating during cycling; iii) the difficulty of defining new testing specimen geometries to comply with constrained real component dimensions; iv) definition of testing procedures to generate multiaxial fatigue test procedures.
The proposed research project aims at performing the UHCF characterization of three metallic alloys resulting from distinct manufacturing processes and, therefore with different typical microstructures, including internal defects. A hot-rolled structural steel (tentatively S355 or S690) used for large structural applications such as bridges and wind towers will be investigated. For this material, there is no limitations as regards the specimen’s geometries, allowing testing using recommended specimens. It is expected to test this material under both constant amplitude and block loading. Also, fatigue notch sensitivity will be investigated using notched specimens. Multiaxial fatigue tests will be also performed. Also, for this material, fatigue tests will performed in conventional machines (low frequency) till 10^6 cycles is order to perceive the equivalence between the two testing procedures.
A light cast metallic alloy will be investigated (tentatively Al-Si cast alloy) which is used for energy efficient transports. In this case the possibly of extracting specimens from real components will be the focus of research. Cast components are typically designed to exhibit thin sections, which hampers the extraction of traditional round specimens. Therefore, for this material, alternative specimens design should be sought after, namely of planar geometry. A new testing procedure will be developed to allow proper ultrasonic fatigue testing using existing equipment with required adaptations. The cast alloy is generally characterized by higher internal defects than hot-rolled materials, which will allow to investigate the effect of different defects density UHCF damage. Finally, a third material (to be selected between Al or steel alloys according availability) produced by additive manufacturing (L-PBF) will be investigated under UHCF regime. It is expected that this material will be the one showing higher internal defects density. The possibility to compare the additive with the conventional counterpart will be investigated as well. For these latter two materials, only uniaxial and constant amplitude loading will be investigated.
Since the UHCF damage is dominated by internal defects, statistical distribution of the internal defects will be evaluated and their relation with fatigue strength will be established. Also, fracture mechanics will be applied to correlate the microstructural defects with the fatigue resistance of the materials attempting to propose models for the UHCF damage.
INSTITUTIONS
Laboratório Associado de Energia, Transportes e Aeronáutica (LAETA)
Associated Laboratory in the fields of Energy, Transportation and Aeronautics, which involves a total of 113 Integrated Post-Doc researchers, 2.8 ISI papers/Researcher, 5 patents awards, 41 FCT projects, and 27 concluded PhD thesis. In the last evaluation performed by the FCT, LAETA was graded as ‘Excellent’.
INEGI - Instituto de Ciência e Inovação em Engenharia Mecânica e Engenharia Industrial
The INEGI - Institute of Science and Innovation in Mechanical and Industrial Engineering from the University of Porto is an industry-oriented RTO with research activity in the areas of new technologies for advanced production processes, experimental mechanics, applied mechanics, energy, new materials, biomechanics, and the development of new products and systems. INEGI has more than 100 associate members, and a workforce of about 250 people, including more than 120 PhD researchers, being the largest research group in the Mechanical Engineering in Portugal. INEGI’s research infrastructure includes a broad set of well-equipped laboratories and an extensive engineering tools base for supporting its R&D activity as well as the production of industrial or commercial prototypes. INEGI is actively participating in several national and international expert panels, consulting committees, groups and societies, sectorial industry clusters (automotive, aeronautics, tooling, additive manufacturing, sea economy, health and energy). The figures related to INEGI’s scientific production in 2019 resume the performance of the FCT R&D unit LAETA.
Instituto de Engenharia Mecânica (IDMEC)
IDMEC (https://www.idmec.tecnico.ulisboa.pt/) is a private non-profit association of science, technology and training of Instituto Superior Técnico (IST), of the University of Lisbon. The activity of IDMEC is oriented towards five key strategic objectives; (i) to promote R&D actions, (ii) to promote technology transfer, (iii) to develop advanced training programmes, (iv) to evaluate and audit new entrepreneurial processes and (v) to develop integrated management programmes in energetic, logistic and technical areas. The activity of IDMEC is mainly focused on mechanical engineering and its structure is organized in five Centers: Mechanical Design; Intelligent Systems; Manufacturing and Industrial Management; Energy and Fluid Mechanics; Aerospace Science and Technology, supported by well-equipped laboratories that play a significant role in national and international R&D in different areas of mechanical engineering. IDMEC is one of the units of the research institution LAETA - Associated Laboratory for Energy, Transports and Aeronautics.
Ultrasonic Fatigue Testing System
Why test in ultrasonic frequencies?
With the ultrasonic fatigue testing system,with the frequency 20 kHz, fatigue tests in the Very-High-Cycle-Fatigue (VHCF) range can be performed time- and cost-efficiently.
Results can be obtained after 10 minutes, for fatigue behaviour and the fatigue strength at 107 cycles and after 6 days will be reach at 1010 cycles, this number of cycles, in a conventional system, would take one year to complete.
Human resources financed by the project
Filipe G.A. Silva (Post-Doctoral Contract)
Felipe Fiorentin (PhD Scholarship)
Orlando Oliveira (BII);
David Peliteiro (BII)
Tomás Brito (BII)
José Henrique Costa Lopes (BII)
Master's student participation
Michael Ascenção Gouveia
Master's thesis title: Giga-cycle Fatigue Behaviour of the Structural Steel S690 URL: https://hdl.handle.net/10216/143741
Ricardo Vieira Lobo
Master's thesis title: Development of an Ultrasonic Frequency Equipment for Fatigue Testing URL: https://hdl.handle.net/10216/144559
Orlando Miguel Gonçalves de Oliveira
Master's thesis title: Development of human-machine interface for ultrasonic fatigue testing machine URL: https://hdl.handle.net/10216/145566
David Peliteiro
Master's thesis title: Giga-Cycle Fatigue Behavior of high pressure die-casting aluminum alloys URL: https://hdl.handle.net/10216/153495
Tomás Moutinho de Azevedo Brito
Master's thesis title: Comportamento à fadiga de ligas de alumínio no regime supercíclico de extrema longa duração URL:
José Henrique Costa Lopes
Master's thesis title:
Awards
VESTAS Prize awarded to student Michael Ascenção Gouveia in the academic year 2021/22 for the dissertation presented in the Master in Mechanical Engineering, entitled “Giga-cycle Fatigue Behavior of the Structural Steel S690”
PhD's student participation
Felipe Klein Fiorentin
PhD's thesis title: High-Cycle and Ultra-High Cycle Fatigue Behaviour of Directed Energy Deposited Inconel 625 URL: https://hdl.handle.net/10216/149204
Vitor Gomes
PhD's thesis title: A Methodology for Fatigue Performance Analysis of Leaf Springs Suspensions in Freight Wagons URL: https://hdl.handle.net/10216/155893
Rita Dantas
PhD's thesis title: Fatigue behaviour of S690 structural steel for ocean systems applications URL:
News
Numerical Modeling specimens to obtained a resonant frequency of 20kHz.
When the specimen start to oscillate with the resonant frequency, he doesn’t need to receive more inputs to keep on the oscillation.
We can see in the video the movement in the edges were the strass tensions are zero and the displacement is maximum.
The small section that defines the symmetrical plane of the specimen, presents a zero displacement, but a large stress amplitude value.
In this section the specimen is subjected to compression and traction during the cycle.
These stress fluctuations are responsible for the crack propagation and heat generation.
Numerical Modeling the system buster, waveguide and specimens to obtained a resonant frequency of 20kHz for all de system.
Stress analysis
Displacement analysis
Embrittlement of steel at low temperatures (S690, in liquid nitrogen)
These tests carried out at resonant frequency systems, and in this case at super sonic frequencies, have the characteristic that, normally, the crack does not propagate until the total rupture of the resistant section. since the section reduction changes the stiffness and therefore the resonance frequency of the system.
After carrying out the fatigue test, to visualize the fracture surface, it is necessary to fracture the remaining resistant section. To avoid contamination of the fatigue fracture surface, due to the deformations caused by the fracture of the remaining section, the sample temperature is reduced to cryogenic temperatures, immersing it in liquid nitrogen.
After a few minutes, the samples will be in a state of embrittlement due to the reduction in temperature, making it possible to break the samples with small efforts and without plastic deformation and the consequent risk of contamination of the fatigue fracture surface.
Crack growth in thin specimens tested at 20kHz, (Al6082-T6 alloy).
Published Articles
1) A Predictive Methodology for Temperature, Heat Generation and Transfer in Gigacycle Fatigue Testing, Felipe Klein Fiorentin, Luis Reis, Grzegorz Lesiuk, Ana Reis and Abílio de Jesus. Metals 2023, 13(3), 492;
https://doi.org/10.3390/met13030492
2) Very high cycle fatigue behaviour of S690 structural steel, Rita Dantas, Michael Gouveia, Filipe G.A. Silva, Felipe Fiorentin, Abílio de Jesus, José Correia, Grzegorz Lesiuk, Procedia Structural Integrity,Volume 42,2022,Pages 1676-1683,
https://doi.org/10.1016/j.prostr.2022.12.211
3) Notch effect in very high-cycle fatigue behaviour of a structural steel, Rita Dantas, Michael Gouveia, Filipe G.A. Silva, Felipe Fiorentin, Abílio de Jesus, José Correia, Grzegorz Lesiuk, International Journal of Fatigue, Volume 177, December 2023, 107925,
https://doi.org/10.1016/j.ijfatigue.2023.107925
4) Fatigue Assessment of Inconel 625 Produced by Directed Energy Deposition from Miniaturized Specimens, Klein Fiorentin, Felipe, Duarte Maciel, Jorge Gil, Miguel Figueiredo, Filippo Berto, and Abílio de Jesus, Metals 12 (1) 156, January 2022 .
https://doi.org/10.3390/met12010156
5) Very high cycle fatigue under tension/torsion loading of mold low alloy steel, Pedro R. da Costa, Luís Reis, Manuel Freitas, Fatigue Fract Eng Mater Struct. 2022;1‐14, https://doi.org/10.1111/ffe.13907
6) Crack path and fracture surface analysis of ultrasonic fatigue testing under multiaxial loadings, Luís Reis, Pedro R. Da Costa, Ricardo Pereira, Diogo Montalvão, Manuel Freitas, Engineering Failure Analysis 142 (2022) 106785, https://doi.org/10.1016/j.engfailanal.2022.106785
7) AISI P20 steel under VHCF testing conditions, Pedro R. da Costa, Luís Reis, Manuel Freitas, Procedia Structural Integrity,Volume 42,2022,Pages 1560-1566,
https://doi.org/10.1016/j.prostr.2022.12.197
8) Improving the understanding of how biaxiality ratios correlate on cruciform fatigue test specimens for VHCF ultrasonic fatigue testing, Diogo Montalvão, Kadir Hekim, Pedro Costa, Luís Reis, Manuel Freitas, Procedia Structural Integrity,Volume 42,2022,Pages 1215-1522, https://doi.org/10.1016/j.prostr.2022.12.155
Missions to share knowledge
1) ICMFM XX WROCLAW, 15.09 – 17.09.2021
AN ANALYTICAL PREDICTION METHODOLOGY FOR HEAT GENERATION AND TRANSFER IN GIGACYCLE FATIGUE TESTING.
2) EM2022-1st INTERNATIONAL CONFERENCE ON ENGINEERING MANUFACTURE, 05.05 – 06.05.2022
High-cycle and ultra-high cycle behaviour of directed energy deposition Inconel 625 super alloy
3) 5th Meeting of the Young Researchers of LAETA, 05.05 – 06.05.2022
FATIGUE BEHAVIOUR OF INCONEL 625 PRODUCED BY DIRECTED ENERGY DEPOSITION
4) 5th Iberian Conference of Structural Integrity, 30.03 – 01.04.2022
High-Cycle and Ultra-High Cycle Fatigue Behaviour of 51CrV4 High Strength Steel
5) 5th Iberian Conference of Structural Integrity 30.03 – 01.04.2022
Fatigue Crack Growth Rate (FCGR) analysis in additively manufactured IN625 alloy
6) 23rd European Conference on Fracture, 27.06 –01.07.2022.
Very high cycle fatigue behaviour of S690 structural steel, https://doi.org/10.1016/j.prostr.2022.12.211
https://www.youtube.com/watch?v=0cizjN9J05w
7) 2nd International Symposium on Risk Analysis and Safety of Complex Structures and Components, 02.04 -04.04.2023
Frequency effect in fatigue behaviour of a structural steel and a spring steel https://web.fe.up.pt/~iras/wp-content/uploads/2023/03/Programme-IRAS-2023_corrected-3.pdf
8) International Conference on Structural Integrity, 28 .08 – 01 .09, 2023 "An analysis of notch sensitivity in the VHCF fatigue regime of S690 steel” https://www.icsi.pt/files/abstracts2023/128.pdf
9) The third European Conference on the Structural Integrity of Additively Manufactured Materials, September 4-6, 2023 “New specimen design for ultrasonic fatigue testing of Al6082-T6 plates” https://www.esiam.site
10) The third European Conference on the Structural Integrity of Additively Manufactured Materials Porto, Portugal, September 4-6, 20, High-Cycle Fatigue Assessment of Inconel 625 Miniaturized and Standard Specimens Produced by Directed2, https://www.esiam.site
11) The third European Conference on the Structural Integrity of Additively Manufactured Materials Porto, Portugal, September 4-6, 20, Striation Marks and Fatigue Crack Growth Ratio Relation in MAMed Nickel Superalloy Inconel 625", https://www.esiam.site
12) The 5th International Conference on Structural Integrity 28th August – 1st September 2023 Funchal, Madeira, Tension/Torsion UFT for Different Axial/Shear Stress Ratios, https://www.icsi.pt
13) 13th International Fatigue Congress is held in Hiroshima, 2023, Different Axial/Shear Stress Ratios under Tension/Torsion UFT, https://fatigue2022.org
14) 13th International Fatigue Congress is held in Hiroshima, November 6th to 10th,2023, Crack Initiation and Propagation of Cruciform Specimens in Ultrasonic Fatigue Testing, https://fatigue2022.org
15) 13th International Fatigue Congress is held in Hiroshima, November 6th to 10th,2023, An approach to evaluate fatigue behaviour of notched specimens in VHCF, https://fatigue2022.org
16) Portuguese Conference on Fracture, 1-2 February, 2024. Politécnico de Setúbal Portugal, Notch sensitivity of a structural steel under VHCF, https://www.pcfracture.pt
17) Portuguese Conference on Fracture, 1-2 February, 2024. Politécnico de Setúbal Portugal, New specimen design for ultrasonic fatigue testing for thin flat specimens, https://www.pcfracture.pt
18) Portuguese Conference on Fracture, 1-2 February, 2024. Politécnico de Setúbal Portugal, Methods for ultrasonic fatigue component frequency modulation: From the ultrasonic setup to uniaxial and multiaxial specimens, https://www.pcfracture.pt