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A user-friendly yield criterion for metals exhibiting tension-compression asymmetry

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Chinese Journal of Aeronautics 2020年第10期33卷 2602-2609页

作者： Lei CHEN weidong wen Hongjian ZHANG Faculty of Civil Engineering&Mechanics Jiangsu UniversityZhenjiang 212013China College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

The aim of this paper is to model the yielding asymmetry of pressure-insensitive metals,including but not limited to Ni3 Al *** main focuses are put on the flexibility and manipulative *** parameters of theory are kept to a minimum and can be determined by as few tests as *** requirements are fulfilled by constructing a yield function using the second and third-invariants of a linearly transformed stress *** proposed yield criterion has a simple mathematical form and has only seven parameters when used in three-dimensional *** with existing theories,the new yield criterion has much fewer parameters,which makes it very convenient for practical *** coefficients of the criterion are identified by an error minimization *** to a Ni3 Al based intermetallic alloy as well as a Cu-Al-Be shape memory alloy and comparison to other criteria show that the proposed criterion has nearly the same predictive ability and flexibility with other *** proposed yield criterion can estimate the coefficients by using less data,which is a big advantage compared with other similar theories,especially when there is a limited number of experimental data.

关键词： Ni3Al based alloy Plastic anisotropy Plastic deformation Tension-compression asymmetry Yield criterion Yield stress

Fatigue life prediction model of 2.5D woven composites at various temperatures

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Chinese Journal of Aeronautics 2018年第2期31卷 310-329页

作者： Jian SONG weidong wen Haitao CUI College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics Department of Mechanical and Biomedical Engineering City University of Hong Kong

As one of the new structural layout in the family of woven composites, 2.5D Woven Composites（2.5D-WC） have recently attracted an increasing interest owing to its excellent properties, i.e. high specific strength and fatigue resistance, in the aerospace and automobile industry. Indepth understanding of the fatigue behavior of this material at un-ambient temperatures is critical for the engineering applications, especially in aero-engine field. Here, fatigue behavior of 2.5D-WC at different temperatures was numerically investigated based on the unit cell approach. Firstly, the unit cell model of 2.5D-WC was established using ANSYS software. Subsequently, the temperature-dependent fatigue life prediction model was built up. Finally, the fatigue lives alongside the damage evolution processes of 2.5D-WC at ambient temperature（20 ℃） and unambient temperature（180 ℃） were analyzed. The results show that numerical results are in good agreement with the relevant experimental results at 20 and 180 ℃. Fatigue behavior of 2.5D-WC is also sensitive to temperature, which is partially attributed to the mechanical properties of resin and the change of inclination angle of warp yarns. We hope that the proposed fatigue life prediction model and the findings could further promote the engineering application of 2.5D-WC, especially in aero-engine field.

关键词： ANSYS Fatigue behavior Fatigue life prediction model Temperature 2.5D woven composites

Multiaxial fatigue life prediction of composite materials

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Chinese Journal of Aeronautics 2017年第3期30卷 1012-1020页

作者： Jingmeng wenG weidong wen Hongjian ZHANG Jiangsu Province Key Laboratory of Aerospace Power System Nanjing 210016 China State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing 210016 China College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

In order to analyze the stress and strain fields in the fibers and the matrix in composite materials,a fiber-scale unit cell model is established and the corresponding periodical boundary conditions are *** matrix cracking as the failure mode of composite materials,an energy-based fatigue damage parameter and a multiaxial fatigue life prediction method are *** method only needs the material properties of the fibers and the matrix to be *** the relationship between the fatigue damage parameter and the fatigue life under any arbitrary test condition is established,the multiaxial fatigue life under any other load condition can be *** proposed method has been verified using two different kinds of load *** is unidirectional laminates subjected to cyclic off-axis loading,and the other is filament wound composites subjected to cyclic tension-torsion *** fatigue lives predicted using the proposed model are in good agreements with the experimental results for both kinds of load forms.

关键词： Fatigue damage parameter Finite element analysis Life prediction Multiaxial fatigue Periodical boundary condition

Multiaxial fatigue life prediction of composite laminates

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Chinese Journal of Aeronautics 2021年第12期34卷 227-237页

作者： Jingmeng wenG Tong MENG weidong wen Shaodong wenG Xi'an Aerospace Propulsion Institute Xi'an 710100China Academy of Space Electronic Information Technology Xi'an 710100China College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China School of Mechcmo-Electronic Engineering Xidian UniversityXi'an 710071China

A study of composite laminates under tension–torsion biaxial loading is *** focus is placed on fatigue lives of composite laminates under different tension–torsion biaxial fatigue loading paths.A macro-meso model used to predict multiaxial fatigue life of composite laminates is also presented in this ***,a macro-scale 3 D RVE corresponding to composite laminates is established to determine strain components in the material principal direction of each layer for each biaxial stress ***,a meso-scale 3 D RVE corresponding to each layer with fibers distributed randomly is established,with progressive damage prediction method,biaxial strength of composite laminates can be predicted,and the final failure layer can be ***,select any one of fatigue loading path at which the final failure of composite laminates is fiber failure(matrix failure)to establish the reference curve for fiber(matrix).Finally,with reference curve,fatigue life of composite laminates under any biaxial loading path can be *** numerical results show good agreements with experimental data.

关键词： Composite laminates Fatigue damage parameter Life prediction Multiaxial fatigue Multiaxial strength

Strength Prediction of Cruciform Specimen Under Biaxial Loading

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Transactions of Nanjing University of Aeronautics and Astronautics 2017年第3期34卷 286-295页

作者： weng Jingmeng wen weidong Xu Ying Jiangsu Province Key Laboratory of Aerospace Power System State Key Laboratory of Mechanics and Control of Mechanical StructuresNanjing University of Aeronautics and Astronautics

In order to achieve a better understanding of failure behavior of cruciform specimen under different biaxial loading conditions,a three-dimensional finite element model is established with solid and interface *** stress criterion,two Hashin-type criteria and the new proposed criteria are used to predict the strength of plain woven textile composites when biaxial loading ratio equals *** with experimental data,only the new proposed criteria can reach reasonable *** applicability of the new proposed criteria is also verified by predicting the tensile and compressive strength of cruciform specimen under different biaxial loading ***,the introduction of interface element makes it more intuitive to recognize delamination *** shape of the predicted delamination failure region in the interface layer is similar to that of the failure region in neighboring entity layers,but the area of delamination failure region is a little larger.

关键词： woven compressive tensile intuitive verified recognize specimen Prediction neighboring loaded

Damage Initiation and Propagation in Composites Subjected to Low-Velocity Impact:Experimental Results,3D Dynamic Damage Model,and FEM Simulations

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Transactions of Nanjing University of Aeronautics and Astronautics 2019年第3期36卷 488-499页

作者： JIA wenbin wen weidong FANG Lei Jiangsu Province Key Laboratory of Aerospace Power System College of Energy and Power EngineeringNanjing University of Aeronautics and Astronautics

A three-dimensional dynamic damage model that fits both small and large damage sizes is developed to predict impact damage initiation and propagation for each lamina of T300-carbon/epoxy ***,13 specimens of the same lamination sequence are subjected to three different impact energies(10 J,15 J,and 20 J).After the impact,the laminates are inspected by the naked eye to observe the damage in the outer layers,and subsequently X-rayed to detect the inner ***,the stress analysis of laminates subjected to impact loading is presented,based on the Hertz contact law and virtual displacement *** on the analysis results,a three-dimensional dynamic damage model is proposed,including the Hou failure criteria and Camanho stiffness degradation model,to predict the impact damage shape and *** numerical predictions of the damage shape and area show a relatively reasonable agreement with the ***,the impact damage initiation and propagation for each lamina are investigated using this damage model,and the results improve the understanding of the impact process.

关键词： composites impact three-dimensional dynamic damage model impact damage initiation and propagation

Vibration Fatigue Probabilistic Life Prediction Model and Method for Blade

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Transactions of Nanjing University of Aeronautics and Astronautics 2018年第3期35卷 494-506页

作者： Lou Guokang wen weidong Wu Fuxian Zhang Hongjian College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics

Vibration fatigue is one of the main failure modes of *** vibration fatigue life of blade is scattered caused by manufacture error,material property dispersion and external excitation randomness.A new vibration fatigue probabilistic life prediction model(VFPLPM)and a prediction method are proposed in this ***,as one-dimensional volumetric method(ODVM)only considers the principle calculation direction,a three-dimensional space vector volumetric method(TSVVM)is proposed to improve fatigue life prediction accuracy for actual threedimensional engineering ***,based on the two volumetric methods(ODVM and TSVVM),the material C-P-S-N fatigue curve model(CFCM)and the maximum entropy quantile function model(MEQFM),VFPLPM is established to predict the vibration fatigue probabilistic life of *** VFPLPM is combined with maximum stress method(MSM),ODVM and TSVVM to estimate vibration fatigue probabilistic life of blade simulator by finite element simulation,and is verified by vibration fatigue *** results show that all of the three methods can predict the vibration fatigue probabilistic life of blade simulator *** &TSVVM method has the highest computational accuracy for considering stress gradient effect not only in the principle calculation direction but also in other space vector directions.

关键词： vibration fatigue probabilistic life prediction C-P-S-N fatigue curve volumetric method maximum entropy quantile function

An Elasticity Model Considering Grain Boundaries and Tensile Orientations for Directionally Solidified Superalloys

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Transactions of Nanjing University of Aeronautics and Astronautics 2019年第4期36卷 652-662页

作者： XIAO Jianfeng ZHANG Hongjian wen weidong CUI Haitao Aero-engine Thermal Environment and Structure Key Laboratory of Ministry of Industry and Information Technology Jiangsu Province Key Laboratory of Aerospace Power SystemState Key Laboratory of Mechanics and Control of Mechanical StructuresCollege of Energy & Power EngineeringNanjing University of Aeronautics and AstronauticsNanjing 210016P.R.China

In order to investigate the elastic properties of directionally solidified(DS)superalloys,an elasticity model called boundaries elastic model(GBE model),considering grain boundaries and tensile orientations,is proposed in this *** assumptions are adopted in the GBE model:(1)The displacement of grains,which moves along the perpendicular direction,is restricted by the grain boundaries;(2)Grain boundaries influence region(GBIR)is formed around the grain *** on the single crystal(SC)calculation method of elastic properties,the GBE model can well predict macroscopic equivalent elastic modulus(Young’s modulus)of DS superalloys under different tensile orientations *** demonstrate the correctness of the GBE model,3D finite element simulation is adopted and tensile experiments on a Ni3Al?base DS superalloy(IC10)along five tensile orientations are carried ***,the grain boundaries are observed by light microscopy and transmission electron microscope(TEM).Therefore,the GBE model is proved to be feasible by comparing the simulated results with the experiments.

关键词： directionally solidified superalloys single crystal Young’s modulus grain boundaries

Yield anisotropy and tension/compression asymmetry of a Ni_3 Al based intermetallic alloy

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Chinese Journal of Aeronautics 2013年第3期26卷 801-806页

作者： Chen Lei wen weidong Cui Haitao Zhang Hongjian Xu Ying College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics

In order to investigate the yielding behavior of the newly developed Ni 3 Al-based intermetallic alloy IC10, yield stresses have been measured in tension and compression with different orientations. The specimens were cut from a sheet with different angles inclined from the solidification direction. The inclined angles were taken to be 0 , 22.5 , 45 , 67.5 and 90 . All experiments were conducted at room temperature except for orientation 0 , whose deformation temperatures ranged from 298 to 1273 K. Experimental results show that the yield strength of alloy IC10 has the anomalous behavior which has been observed for other Ll 2 -long-range ordered intermetallic alloys, but it is less pronounced. The abnormalities show the following characteristics：（i） the yield strength increases as the temperature is raised below the peak temperature, （ii） yield strength anisotropy, （iii） tension/compression asymmetry. Compared to Ni 3 Al single crystals, the polycrystalline exhibits some different yielding behaviors which may be due to the high volume fraction of c phase.

关键词： Alloy IC10 Critical resolved shear stress (CRSS) Intermetallics Ni 3 Al-based superalloy Plastic anisotropy t/c Asymmetry