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Plastic flow and interfacial bonding behaviors of embedded linear friction welding process:Numerical simulation combined with thermophysical experiment

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Chinese Journal of Aeronautics 2025年第1期38卷 87-98页

作者： Tiejun MA Zhenguo GUO Xiawei YANG Junlong JIN Xi CHEN Jun TAO Wenya LI achilles vairis Liukuan YU State Key Laboratory of Solidification Processing Shaanxi Key Laboratory of Friction Welding TechnologiesNorthwestern Polytechnical UniversityXi'an 710072China Aeronautical Key Laboratory for Welding and Joining Technologies AVIC Manufacturing Technology InstituteBeijing 100024China Mechanical Engineering Department University of West AtticaAthens 12241Greece Mathematic and Physic Department Xianjiaotong-liverpool UniversitySuzhou 215123China

In this study,a new linear friction welding(LFW)process,embedded LFW process,was put forward,which was mainly applied to combination manufacturing of long or overlong loadcarrying titanium alloy structural components in *** interfacial plastic flow behavior and bonding mechanism of this process were investigated by a developed coupling EulerianLagrangian numerical model using software ABAQUS and a novel thermo-physical simulation method with designed embedded hot compression *** addition,the formation mechanism and control method of welding defects caused by uneven plastic flow were *** results reveal that the plastic flow along oscillating direction of this process is even and *** the direction perpendicular to oscillation,thermo-plastic metals mainly flow downward along welding interface under coupling of shear stress and interfacial pressure,resulting in the interfacial plastic zone shown as an inverted“V”*** upward plastic flow in this direction is relatively weak,and only a small amount of flash is extruded from top of ***,the wedge block and welding components at top of joint are always in un-steady friction stage,leading to nonuniform temperature field distribution and un-welded *** to the results of numerical simulation,high oscillating frequency combined with low pressure and small amplitude is considered as appropriate parameter selection scheme to improve the upward interfacial plastic flow at top of joint and suppress the un-welded *** results of thermo-physical simulation illustrate that continuous dynamic recrystallization(CDRX)induces the bonding of interface,accompanying by intense dislocation movement and creation of many low-angle grain *** the interfacial bonding area,grain orientation is random with relatively low texture density(5.0 mud)owing to CDRX.

关键词： Embedded linear friction welding Plastic flow Interfacial bonding behavior Numerical simulation Thermo-physical simulation Temperature field Dynamic recrystallization

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A comparison between friction stir welding, linear friction welding and rotary friction welding

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Advances in Manufacturing 2016年第4期4卷 296-304页

作者： achilles vairis George Papazafeiropoulos Andreas-Marios Tsainis Department of Mechanical Engineering TechnologicalEducation Institute of Crete Heraklion Crete Greece Institute of Structural Analysis and Antiseismic Research National Technical University of Athens Zografou CampusAthens 15780 Greece Faculty of Science Engineering and Computing KingstonUniversity London UK

Three friction welding processes are compared for temperature, stresses and strains, as well as strain rates developed in the early phases of the processes, which are essential in their successful development. These are friction stir welding （FSW）, linear friction welding （LFW） and rotary friction welding （RFW）. Their common characteristic is the use of friction to generate adequate energy and raise temperature locally in order to create favorable conditions for welding at the interface between two parts. Although the mode of movement is different for each one of them, welds are produced through plastic deformation. The Lagrangian and coupled Eulerian-Lagrangian numer- ical models developed have produced results which are in qualitative agreement with experiments and have shed a light on the commonalities of these friction welding processes

关键词： Friction welding (FW) Finite elementanalysis Thermo-mechanical process Ti-6A1-4V

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Multi-scale analyses of phase transformation mechanisms and hardness in linear friction welded Ti17(a+β)/Ti17(β)dissimilar titanium alloy joint

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Chinese Journal of Aeronautics 2024年第1期37卷 312-324页

作者： Zhenguo GUO Tiejun MA Xiawei YANG Ju LI Wenya LI achilles vairis State Key Laboratory of Solidification Processing Shaanxi Key Laboratory of Friction Welding TechnologiesNorthwestern Polytechnical UniversityXi’an 710072China Aeronautical Key Laboratory for Welding and Joining Technologies AVIC Manufacturing Technology InstituteBeijing 100024China Mechanical Engineering Department University of West AtticaAthens 12241Greece

The Ti17(a+β)-Ti17(β)dual alloy-dual property blisk produced using Linear Friction Welding(LFW)is considered as high-performance component in advanced ***,up to now,microstructure evolution and relationship between microstructure and micro mechanical properties of LFWed Ti17(a+β)/Ti17(β)dissimilar joint have not been thoroughly *** this work,complex analyses of the phase transformation mechanisms of the joint are conducted,and phase transformations in individual zones are correlated to their microhardness and *** reveal that a dissolution occurs under high temperatures encountered during LFW,which reduces microhardness of the joint to that of Ti17(a+β)and Ti17(β).In ThermoMechanically Affected Zone of Ti17(a+β)(TMAZ-(a+β))side joint,a large number of nanocrystalline a phases form with different *** microstructure strengthens significantly by fine grains which balances partial softening effect of a dissolution,and increases nanohardness of a phase and microhardness of TMAZ-(a+β).Superlattice metastableβphase precipitates from metastableβin Weld Zone(WZ)during quick cooling following welding,because of short-range diffusion migration of solute atoms,especiallyβstabilizing elements Mo and *** precipitation of the superlattice metastableβphase results in precipitation strengthening,which in turn increases nanohardness of metastableβand microhardness in WZ.

关键词： Linear friction welding Ti17 titanium alloy Phase transformation Microhardness Nanohardness

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The effects of forging pressure and temperature field on residual stresses in linear friction welded Ti6Al4V joints

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Advances in Manufacturing 2016年第4期4卷 314-321页

作者： Ying Fu Wen-Ya Li Xia-Wei Yang Tie-Jun Ma achilles vairis State Key Laboratory of Solidification Processing ShaanxiKey Laboratory of Friction Welding TechnologiesNorthwestern Polytechnical UniversityXi'an 710072 Shaanxi People's Republic of China Department of Mechanical Engineering TEI of Crete71004 Heraklion Crete Greece

Linear friction welding （LFW）, as a solid state joining process, has been developed to manufacture and repair blisks in aeroengines. The residual stresses after welding may greatly influence the performance of the welded components. In this paper, the distribution of residual stresses in Ti6Al4V joints after LFW was inves- tigated with numerical simulations. The effects of applied forging pressure and temperature field at the end of the oscillating stages on the residual stresses within the joints were investigated. The results show that, the residual tensile stresses at the welded interface in the y-direction are the largest, while the largest compressive stresses being present at the flash root in the z-direction. Furthermore, the forging pressure and temperature field at the end of the oscillating stages strongly affect the magnitude of the residual stresses. The larger forging pressure produced lower residual stresses in the weld plane in all three directions （x-, y-, and z-directions）. Larger variance, a, which decides the Gaussian distribution of the temperature field, also yields lower residual stresses. There is good agreement between simulation results and experimental data.

关键词： Linear friction welding (LFW) Modeling Residual stress Forging pressure

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Numerical modeling of linear friction welding： a literature review

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China Welding 2014年第4期23卷 1-7页

作者：李文亚郭嘉马铁军 State Key Laboratory of Solidification Processing Sbaanxi Key Laboratory of Friction Welding Technologies Northwestern Polytechnical University Xi' an 710072.

Linear friction welding （LFW） is a solid state process for joining metals together. While this process was developed originaUy for titanium alloys （e. g. blisks ） , over the past decade a number of materials were found to be weldable with LFW. In this review, the current status of understanding and development of LFW are presented. Particular emphasis has been given to the modeling of the LFW process. Finally, opportunities for further research and development of LFW are identified.

关键词： linear friction welding finite element modeling process optimization

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Impact of travel speed on the microstructure and mechanical properties of adjustable-gap bobbin-tool friction stir welded Al–Mg joints

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International Journal of Minerals,Metallurgy and Materials 2021年第4期28卷 710-717页

作者： Dong Wu Wen-ya Li Yan-jun Gao Jun Yang Quan Wen Nektarios Vidakis Achillefs vairis State Key Laboratory of Solidification Processing Shaanxi Key Laboratory of Friction Travel TechnologiesNorthwestern Polytechnical UniversityXi'an 710072China Capital Aerospace Machinery Company Beijing 100076China Department of Mechanical Engineering Hellenic Mediterranean UniversityHeraklionCrete 71004Greece

The butt welds of 4-mm thick 5A06 aluminum alloy plates were produced by adjustable-gap bobbin-tool friction stir travel with travel speeds of 200, 300, and 400 mm/min in this *** microstructure was studied using optical microscopy and electron backscatter diffraction(EBSD).Tensile tests and microhardness measurements were performed to identify the effect of the travel speed on the joint mechanical *** joints were obtained at 200 mm/min while voids were present at different positions of the joints as the travel speed *** EBSD results show that the grain size, high angle grain boundaries, and density of geometrically necessary dislocations in different regions of the joint vary depending on the recovery and recrystallization *** attention was given to the relationship between the local microstructure and mechanical *** measurements show that the average hardness of the stir zone(SZ) was greater than that of the base material, which was only affected slightly by the travel *** tensile strength of the joint decreased with increasing travel speed and the maximal strength efficiency reached 99%.

关键词： friction stir welding bobbin-tool aluminum alloy microstructure mechanical properties adjustable-gap

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Dielectric Permittivity of Rigid Rapeseed Oil Polyol Polyurethane Biofoams and Petrochemical Foams at Low Frequencies

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Journal of Renewable Materials 2020年第9期8卷 1151-1170页

作者： Ilze Beverte vairis Shtrauss Aldis Kalpinsh Uldis Lomanovskis Ugis Cabulis Irina Sevastyanova Sergejs Gaidukovs Institute for Mechanics of Materials University of LatviaRigaLV-1006Latvia Latvian State Institute of Wood Chemistry RigaLV-1006Latvia Faculty of Materials Science and Applied Chemistry Institute of Polymer MaterialsInstitute of Applied ChemistryRiga Technical UniversityRigaLV-048Latvia

Early investigations of dielectric permittivity of rigid polyurethane foams at low frequencies were made on petrochemical-origin foams,mainly by means of parallel plate *** the present investigation biopolyol was synthesized from Latvia-grown rapeseeds’oil by the transesterification method with triethanolamine,in an environmentally friendly process,without emission of harmful substances,at temperatures 175℃±5℃.Rigid,closed-cell rapeseed oil polyol polyurethane biofoams and petrochemical foams were made ensuring content of the renewable rapeseed oil polyol in ready foams 27 wt.%–29 wt.%.Dielectric permittivity of the polyurethane foams and the underlying monolithic petrochemical-origin polyurethane and biopolyurethane was measured with a non-destructive dielectric spectrometer equipped with a capacitive sensor of one-side access type at 16 discrete frequencies distributed geometrically over the band 10 Hz,…,330 *** value of the gaseous phase in the closed-cells was estimated to beεg≈1.001 that corresponds to the values,characteristic for the most of *** permittivity of petrochemical polyurethane foams and the mentioned biofoams was compared with permittivity of polyurethane foams from industrial producers Sika JSC and General Plastics Manufacturing *** foams of the developed formulation exhibit competitive,low dielectric permittivity,not exceeding that of the foams from industrial producers:petrochemical foams up to 550 kg/m^(3) and the mentioned biofoams,comprising the renewable rapeseed oil polyol,up to densities 230–250 kg/m^(3).Considering petrochemical-origin polyurethane foams as a heterogeneous media“Polymer—gaseous phase”,the applicability of the rule of mixture and Maxwell–Garnett equation to model mathematically the dependence of effective dielectric permittivity on the volume fraction of phases was showed.

关键词： Polyurethane foams rapeseed oil polyol biofoams dielectric permittivity capacitive sensor one-side access low frequencies

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On the double-side probeless friction stir spot welding of AA2198 Al-Li alloy

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Journal of Materials Science & Technology 2019年第5期35卷 784-789页

作者： Q.Chu W.Y.Li H.L.Hou X.W.Yang A.vairis C.Wang W.B.Wang State Key Laboratory of Solidification Processing Shaanxi Key Laboratory of Friction Welding Technologies Northwestern Polytechnical University Xi'an 710072 China Beijing Aeronautical Manufacturing Technology Research Institute Beijing 100024 China Mechanical Engineering Department TEI of Crete HeraklionCrete71004 Greece

Double-side probeless friction stir spot welding (DP-FSSW) of AA2198 alloy was conducted to investigate the microstructure and mechanical properties. Compared with common single-side probeless friction stir spot welding (P-FSSW), the plastic strain during DP-FSSW is nearly symmetrical with respect to the bondline to suppress the extension of hook defect, which is detrimental to the joint mechanical strength. With DP-FSSW, a fully metallurgically bonded region has formed due to severe plastic deformation at high temperatures. Tensile/shear tests show that the joint strength could exceed 8 kN, which is comparable to P-FSSW and refill FSSW, and all fractures happen in a shear failure mode as cracks extend along the in terface of two sheets. The microhard ness profile exhibits a uniform distribution along the thick ness direction, in which the hook defect shows the lowest value.

关键词： Friction stir welding Double-side Al-Li alloy Microstructure Mechanical property

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Microstructure and mechanical optimization of probeless friction stir spot welded joint of an Al-Li alloy

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Journal of Materials Science & Technology 2018年第10期34卷 1739-1746页

作者： Q. Chu W.Y. Li X.W. Yang J.J. Shen A. vairis W.Y. Feng W.B. Wang State Key Laboratory of Solidification Processing Shaanxi Key Laboratory of Friction Welding Technologies Northwestern Polytechnical University Xi'an710072 China Helmholtz-Zentrum Geesthacht Institute of Materials Research Materials Mechanics Geesthacht 21502 Germany Mechanical Engineering Department TEl of Crete Heraklion Crete 71004 Greece China PSW Center Beijing 100024 China

In this work, a third generation AI-Li alloy has been successfully spot welded with probeless friction stir spot welding （P-FSSW）, which is a variant of conventional friction stir welding. The Box-Behnken exper-imental design in response surface methodology （RSM） was applied to optimize the P-FSSW parameters to attain maximum tensile/shear strength of the spot joints. Results show that an optimal failure load of 7.83 kN was obtained under a dwell time of 7.2 s, rotation speed of 950 rpm and plunge rate of 30 mm/rain. Sufficient dwell time is essential for heat conduction, material flow and expansion of the stir zone to form a sound joint. Two fracture modes were observed, which were significantly affected by hook defect. In addition to mechanical testing, electron backscattering diffraction （EBSD） and differential scanning calorimetry （DSC） were used for microstructure evolution and property analysis. The precipitation of GP zone and AI3Li as well as the ultrafine grains were responsible for the high microhardness in the stir zone.

关键词： Probeless friction stir spot welding Precipitation Mechanical property Fracture mechanism

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Subset Multiple Correspondence Analysis as a Tool for Visualizing Affiliation Networks

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Journal of Data Analysis and Information Processing 2016年第2期4卷 81-89页

作者： achilles Dramalidis Angelos Markos School of Education Democritus University of Thrace Alexandroupolis Greece

In this paper we investigate the potential of Subset Multiple Correspondence Analysis (s-MCA), a variant of MCA, to visually explore two-mode networks. We discuss how s-MCA can be useful to focus the analysis on interesting subsets of events in an affiliation network while preserving the properties of the analysis of the complete network. This unique characteristic of the method is also particularly relevant to address the problem of missing data, where it can be used to partial out their influence and reveal the more substantive relational patterns. Similar to ordinary MCA, s- MCA can also alleviate the problem of overcrowded visualizations and can effectively identify associations between observed relational patterns and exogenous variables. All of these properties are illustrated on a student course-taking affiliation network.

关键词： Affiliation Networks Two-Mode Networks Subset Correspondence Analysis

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