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Chinese Journal of Aeronautics 2019年第9期32卷 2199-2210页

作者： Aoshuang WAN junjiang xiong School of Transportation Science and Engineering Beihang University

This paper attempts to investigate the effects of stress ratio and high temperature on the HCF(high-cycle-fatigue) and VHCF(very-high-cycle-fatigue) behaviors of nickel-based wrought superalloy GH3617 M. Fatigue tests over the full HCF and VHCF regimes were conducted on superalloy GH3617 M subjected to constant-amplitude loading at five stress ratios of -1, -0.5, 0,0.4, and 0.8 in environments of 20 °C and 700 °C temperatures. From experimental observation and fractographic analysis, fatigue mechanisms were deduced to reveal the synergistic interaction between high temperature and stress ratio on the HCF and VHCF behaviors of superalloy GH3617 M. A phenomenological model was crafted from available fatigue design knowledge to evaluate the synergistic interaction, and a good correlation between predictions and experiments has been achieved.

关键词： High cycle fatigue High-temperature Nickel-based superalloy Stress ratio Very high cycle fatigue

Progressive damage behaviors of woven composite laminates subjected to LVI, TAI and CAI

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Chinese Journal of Aeronautics 2020年第10期33卷 2807-2823页

作者： Zhengqiang CHENG junjiang xiong School of Transportation Science and Engineering Beihang UniversityBeijing 100083China

This paper seeks to deal with progressive damage behaviors of woven composite laminates subjected to low-velocity impact(LVI),tension-after-impact(TAI)and compression-afterimpact(CAI).The LVI,TAI and CAI tests were conducted on woven carbon fibre lamina3238 A/CF3052 and woven glass fibre lamina 3238 A/EW250 F,and the time-dependent LVI contact force and deflection curves,static TAI and CAI load versus displacement curves were determined and discussed.A modified progressive damage model was presented for explicit dynamic LVI and implicit static TAI and CAI analysis by using basic material properties and geometrical dimensions,and progressive damage LVI,TAI and CAI behaviors of woven composite laminates were simulated,demonstrating a good correlation between simulations and experiments.

关键词： Compression after impact Low velocity impact Progressive damage Tension after impact Woven composite laminates

Static Pull and Push Bending Properties of RTM-made TWF Composite Tee-joints

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Chinese Journal of Aeronautics 2012年第2期25卷 198-207页

作者： LUO Chuyang xiong junjiang School of Transportation Science and Engineering Beihang University Beijing 100191 China China Airborne Missile Academy Luoyang 471009 China

This paper deals with static pull and push bending tests on two-dimensional （2D） orthogonal EW220/5284 twill weave fabric （TWF） composite tee-joints processed with the resin transfer moulding （RTM） technique. Static pull and push bending properties are determined and failure initiation mechanism is deduced from experimental observations. The experiments show that the failure initiation load, on average, is greater for push bending than for pull bending, whereas the scatter is smaller for push bending than for pull bending. The failure mode of RTM-made tee-joints in pull bending tests can be reckoned to be characteristic of debonding of resin matrix at the interface between the triangular resin-rich zone and the curved web of tee-joint until complete separation of the curved web from the bottom plate. In contrast, as distinct from the products subject to pull bending loading, the RTM tee-joints in push bending tests experience matrix cracking and fibre fracture from outer layers to inner layers of the bottom plate until catastrophic collapse resulting from the bending. Three-dimensional finite element （FE） models are presented to simulate the load transfer path and failure initiation mechanism of RTM-made TWF composite tee-joint based on the maximum stress criterion. Good correlation between experimental and numerical results is achieved.

关键词： fabrics mechanical properties finite element analysis resin transfer moulding tee-joint

Temperature effect on buckling properties of ultra-thin-walled lenticular collapsible composite tube subjected to axial compression

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Chinese Journal of Aeronautics 2014年第5期27卷 1312-1317页

作者： Bai Jiangbo xiong junjiang School of Transportation Science and Engineering Beihang University

This paper seeks to outline the temperature effect on the buckling properties of ultra-thin-walled lenticular collapsible composite tube（LCCT） subjected to axial *** buckling tests of the LCCT specimens subjected to axial compression were carried out on INSTRON-500 N servo-hydraulic machine in dry state and at the temperatures of 25 C, 100 C and 80 C. The load–displacement curves and buckling initiation loads were measured and the buckling initiation mechanism was discussed from experimental observations. Experiments show that the buckling initiation load, on average, is only about 2.2% greater at the low temperature of 80 C than at the room temperature of 25 C due to the material hardening, demonstrating an insignificant increase in the buckling initiation load, whereas it is about 19.5% lower at the high temperature of 100 C than at the room temperature owing to the material softening, implying a significant decrease in the buckling initiation load. The failure mode of the LCCT in axial compression tests at three different temperatures can be reckoned to be characteristic of the buckling initiation and propagation around the central region until rupture. The finite element（FE） model is presented to simulate the buckling initiation mechanism based on the eigenvalue-based methodology. Good correlation between experimental and numerical results is achieved.

关键词： Axial compression Buckling Composite Finite element analysis Lenticular collapsible tube

Analytical Solution for Predicting In-plane Elastic Shear Properties of 2D Orthogonal PWF Composites

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Chinese Journal of Aeronautics 2012年第4期25卷 575-583页

作者： CHENG Xu xiong junjiang BAI Jiangbo School of Transportation Science and Engineering Beihang UniversityBeijing 100191China

This paper proposes a new analytical solution to predict the shear modulus of a two-dimensional（2D） plain weave fabric（PWF） composite accounting for the interaction of orthogonal interlacing strands with coupled shear deformation modes including not only relative bending but also torsion,*** two orthogonal yarns in a micromechanical unit cell are idealized as curved beams with a path depicted by using sinusoidal shape *** internal forces and macroscopic deformations carried by the yarn families,together with macroscopic shear modulus of PWFs are derived by means of a strain energy approach founded on *** sets of experimental data pertinent to three kinds of 2D orthogonal PWF composites have been implemented to validate the new *** calculations from the new model are also compared with those by using two models in the earlier *** is shown that the experimental results correlate well with predictions from the new model.

关键词： textile composites mechanical properties shear modulus properties plain weave fabric

Tear Resistance of Orthogonal Kevlar-PWF-reinforced TPU Film

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Chinese Journal of Aeronautics 2011年第1期24卷 113-118页

作者： BAI Jiangbo xiong junjiang CHENG Xu School of Transportation Science and Engineering Beijing University of Aeronautics and Astronautics Beijing 100191 China

This work seeks to investigate the notch sensitivity and fracture behaviour of orthogonal Kevlar-plain woven fabric （PWF）-reinforced thermoplastic polyurethanes （TPU） film applied to high altitude balloon. Four types of specimens are implemented to measure notched strength and fracture toughness by conducting static tension and tear tests on an MTS system respectively. The damage and failure mechanisms are discussed and the results for notched strength and tear resistance are evaluated and compared with each other. From the experiments, it is found that the notch sensitivity of the film increases with the increase in the size of the hole, but the notch sensitivity and the stress concentration of the notch are insignificant and there is a decrease of only about 4%-10% in tensile strength for the notched specimens with different hole sizes in diameter compared with the unnotched specimen. In contrast, the tear resistance containing a central slit with only 1 mm length is about half of tensile strength of the unnotched film, which implies that the tear resistance exists an significant notch sensitivity. The results of this study provide an insight into notch sensitivity and fracture behaviour of the Kevlar-PWF-reinforced TPU film and constitute a fundamental basis for the design of high altitude balloon.

关键词： fracture toughness notched strength thermoplastic polyurethanes film Kevlar fabric tear resistance

Material parameter modeling and solution technique using birth–death element for notched metallic panel repaired with bonded composite patch

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Chinese Journal of Aeronautics 2014年第2期27卷 445-452页

作者： Tong Lei Li Shiqiu xiong junjiang School of Transportation Science and Engineering Beihang University

This paper seeks to outline a novel three-layer model and a new birth-dteath element solution technique to evaluate static strength of notched metallic panel repaired with bonded com- posite patch and to optimize material parameters. The higher order 3D, 8-node isotropic solid ele- ment and 8-node anisotropic layered solid element with three degrees of freedom per node are respectively implemented to model substrate panel, adhesive layer and composite patch to establish three-layer model of repaired panel. The new solving technique based on birth-death element is developed to allow solution of the stress pattern of repaired panel for identifying failure mode. The new model and its solution are used to model failure mode and residual strength of repaired panel, and the obtained results have a good agreement with the experimental findings. Finally, the influences of material parameter of adhesive layer and composite patch on the residual strength of repaired panel are investigated for optimizing material properties to meet operational and envi- ronmental constraints.

关键词： Birth-death elementBonding Bonding repair Composite patch Residual strength Three-layer model

Analytical Solutions for Predicting Tensile and Shear Moduli of Triaxial Weave Fabric Composites

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Acta Mechanica Solida Sinica 2016年第1期29卷 59-77页

作者： Jiangbo Bai junjiang xiong Meng Liu Ziyu Man School of Transportation Science and Engineering Beihang University Beijing 100083 China

Novel micromechanical curved beam models were presented for predicting the ten- sile and shear moduli of triaxial weave fabric （TWF） composites by considering the interactions between the triaxial yarns of 0° and ±60° The triaxial yarns in micromechanieal representative unit cell （RUC） were idealized as curved beams with a path depicted using the sinusoidal shape functions, and the tensile and shear moduli of TWF composites were derived by means of the strain energy approach founded on micromechanics. In order to validate the new models, the predictions were compared with the experimental data from literature. It was shown that the predictions from the new model agree well with the experimental results. Using these models, the tensile and shear properties of TWF composites could be predicted based only on the properties of basic woven fabric.

关键词： triaxial weave fabric (TWF) composite elastic properties tension modulus shearmodulus

Static mechanical properties of hybrid RTM-made composite Ⅰ-and Ⅱ-beams under three-point flexure

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Chinese Journal of Aeronautics 2015年第3期28卷 903-913页

作者： Fu Yu xiong junjiang Luo Chuyang Yun Xinyao School of Transportation Science and Engineering Beihang University

Abstract This paper deals with three-point flexure tests on hybrid I- and II-beams, made out of multi-layer carbon fiber/epoxy resin （including twill woven fabric CF3031/5284 and unidirectional cord fabric U3160/5284） reinforced composites, processed using the RTM （resin transfer molding） technique. Static bending properties were determined and failure initiation mechanism was deduced from experimental observations. Failure mode of the tested hybrid RTM-made I-beams can be reckoned to be characteristic of the delamination from the cutout edge within the web and the debonding propagation along the interface between the inverted triangular resin-rich zone and the adjacent curved web until local buckling within the curved webs around the conjunction fillet region. In contrast, as distinct from hybrid RTM I-beams subjected to three-point bending loading, hybrid RTM-made H-beams in three-point flexure tests experienced the resin debonding in the inverted triangular resin-rich zones and the debonding propagation along the interface between the inverted triangular resin-rich zone and the adjacent curved web until complete separation of the curved web from the flange. Progressive damage models （PDMs） were presented to predict fail- ure loads and process of hybrid RTM-made I- and N-beams under three-point flexure. Good cor- relation was achieved between experimental and numerical results.

关键词： Beam Composites Experiment Fabric Molding Simulation

Testing and evaluation for fatigue crack propagation of Ti-6Al-4V/ELI and 7050-T7452 alloys at high temperatures

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Chinese Journal of Aeronautics 2018年第6期31卷 1388-1398页

作者： Yuntao ZHU junjiang xiong Zhiyang LV Yanguang ZHAO School of Transportation Science and Engineering Beihang University Beijing 100083 China AECC Beijing Institute of Aeronautical Materials Beijing 100095 China

This paper seeks to evaluate crack propagation properties and residual lives of metallic alloys subjected to fatigue loading at room and high temperatures. Fatigue crack growth tests were performed on Ti-6Al-4V/ELI and 7050-T7452 subjected to constant-amplitude and actual randomspectra loading at room temperature of about 25 ℃ and at high temperatures of 250 ℃ and 150 ℃ to determine their crack growth properties and residual lives. The damage mode and mechanisms at high temperature were compared with those at room temperature on the basis of the results of fractographic analysis. Temperature-dependent residual lives under actual random-spectra load history were evaluated based on a modified accumulation damage rule accounting for the load *** correlation was achieved between the predictions and actual experiments, demonstrating the practical and effective use of the proposed method.

关键词： Crack growth Fatigue High temperature Metallic alloy Residual fife