为研究鸟撞飞机典型结构过程中鸟体姿态对鸟撞损伤的影响规律,以某型水陆两栖飞机-机翼前缘这一典型结构为研究对象,通过光滑粒子流体动力学(Smoothed Particle Hydrodynamics,SPH)耦合有限元法(Finite Element Method,FEM)建立鸟撞数...为研究鸟撞飞机典型结构过程中鸟体姿态对鸟撞损伤的影响规律,以某型水陆两栖飞机-机翼前缘这一典型结构为研究对象,通过光滑粒子流体动力学(Smoothed Particle Hydrodynamics,SPH)耦合有限元法(Finite Element Method,FEM)建立鸟撞数值模型,并通过鸟撞试验验证计算模型的准确性。最后,以试验修正后的机翼前缘数值模型为依托,研究分析鸟体俯仰和偏航12种撞击姿态下机翼前缘的损伤变形情况和冲击响应规律。结果表明,仿真分析和试验结果通过一致性验证;蒙皮凹坑和凹陷范围随鸟体姿态角增大而增大,鸟体剩余能量随之降低;俯仰角增大,前缘结构吸收的能量更多,蒙皮高应力区增大,结构更易破坏。因此对于鸟撞威胁影响更大的重要飞机结构的抗鸟撞安全评估应计入鸟体姿态的影响。研究结果可在飞机抗鸟撞设计与适航评估方面提供重要参考。展开更多
In this work, the transient free surface of con- tainer filling with non-linear constitutive equation＇s fluids is numerically investigated by the smoothed particle hydrody- namics （SPH） method. Specifically, the fi...In this work, the transient free surface of con- tainer filling with non-linear constitutive equation＇s fluids is numerically investigated by the smoothed particle hydrody- namics （SPH） method. Specifically, the filling process of a square container is considered for non-linear polymer fluids based on the Cross model. The validity of the presented SPH is first verified by solving the Newtonian fluid and Oldroyd- B fluid jet. Various phenomena in the filling process are shown, including the jet buckling, jet thinning, splashing or spluttering, steady filling. Moreover, a new phenomenon of vortex whirling is more evidently observed for the Cross model fluid compared with the Newtonian fluid case.展开更多
Creation of arbitrary features with high resolution is critically important in the fabrication of nano-optoelectronic devices.Here,sub-50 nm surface structuring is achieved directly on Sb2S3 thin films via microsphere...Creation of arbitrary features with high resolution is critically important in the fabrication of nano-optoelectronic devices.Here,sub-50 nm surface structuring is achieved directly on Sb2S3 thin films via microsphere femtosecond laser irradi-ation in far field.By varying laser fluence and scanning speed,nano-feature sizes can be flexibly tuned.Such small patterns are attributed to the co-effect of microsphere focusing,two-photons absorption,top threshold effect,and high-repetition-rate femtosecond laser-induced incubation effect.The minimum feature size can be reduced down to~30 nm(λ/26)by manipulating film thickness.The fitting analysis between the ablation width and depth predicts that the feature size can be down to~15 nm at the film thickness of~10 nm.A nano-grating is fabricated,which demonstrates desirable beam diffraction performance.This nano-scale resolution would be highly attractive for next-generation laser nano-lithography in far field and in ambient air.展开更多
A mathematical model of CE reaction schemes under first or pseudo-first order conditions with different diffusion coefficients at a spherical electrode under non-steady-state conditions is described. The model is base...A mathematical model of CE reaction schemes under first or pseudo-first order conditions with different diffusion coefficients at a spherical electrode under non-steady-state conditions is described. The model is based on non-stationary diffusion equation containing a non-linear reaction term. This paper presents the complex numerical method (Homotopy perturbation method) to solve the system of non-linear differential equation that describes the homogeneous processes coupled to electrode reaction. In this paper the approximate analytical expressions of the non-steady-state concentrations and current at spherical electrodes for homogeneous reactions mechanisms are derived for all values of the reaction diffusion parameters. These approximate results are compared with the available analytical results and are found to be in good agreement.展开更多
文摘为研究鸟撞飞机典型结构过程中鸟体姿态对鸟撞损伤的影响规律,以某型水陆两栖飞机-机翼前缘这一典型结构为研究对象,通过光滑粒子流体动力学(Smoothed Particle Hydrodynamics,SPH)耦合有限元法(Finite Element Method,FEM)建立鸟撞数值模型,并通过鸟撞试验验证计算模型的准确性。最后,以试验修正后的机翼前缘数值模型为依托,研究分析鸟体俯仰和偏航12种撞击姿态下机翼前缘的损伤变形情况和冲击响应规律。结果表明,仿真分析和试验结果通过一致性验证;蒙皮凹坑和凹陷范围随鸟体姿态角增大而增大,鸟体剩余能量随之降低;俯仰角增大,前缘结构吸收的能量更多,蒙皮高应力区增大,结构更易破坏。因此对于鸟撞威胁影响更大的重要飞机结构的抗鸟撞安全评估应计入鸟体姿态的影响。研究结果可在飞机抗鸟撞设计与适航评估方面提供重要参考。
基金support by the National Basic Research Program of China (973) (2012CB025903)the National Natural Science Foundation of China (10871159)Basic Research Program of China(2005CB321704)
文摘In this work, the transient free surface of con- tainer filling with non-linear constitutive equation＇s fluids is numerically investigated by the smoothed particle hydrody- namics （SPH） method. Specifically, the filling process of a square container is considered for non-linear polymer fluids based on the Cross model. The validity of the presented SPH is first verified by solving the Newtonian fluid and Oldroyd- B fluid jet. Various phenomena in the filling process are shown, including the jet buckling, jet thinning, splashing or spluttering, steady filling. Moreover, a new phenomenon of vortex whirling is more evidently observed for the Cross model fluid compared with the Newtonian fluid case.
基金This work is supported by Academic Research Fund Tier 2,Ministry of Education-Singapore(MOE2019-T2-2-147)T.C.acknowledges support from the National Key Research and Development Program of China(2019YFA0709100,2020YFA0714504).
文摘Creation of arbitrary features with high resolution is critically important in the fabrication of nano-optoelectronic devices.Here,sub-50 nm surface structuring is achieved directly on Sb2S3 thin films via microsphere femtosecond laser irradi-ation in far field.By varying laser fluence and scanning speed,nano-feature sizes can be flexibly tuned.Such small patterns are attributed to the co-effect of microsphere focusing,two-photons absorption,top threshold effect,and high-repetition-rate femtosecond laser-induced incubation effect.The minimum feature size can be reduced down to~30 nm(λ/26)by manipulating film thickness.The fitting analysis between the ablation width and depth predicts that the feature size can be down to~15 nm at the film thickness of~10 nm.A nano-grating is fabricated,which demonstrates desirable beam diffraction performance.This nano-scale resolution would be highly attractive for next-generation laser nano-lithography in far field and in ambient air.
文摘A mathematical model of CE reaction schemes under first or pseudo-first order conditions with different diffusion coefficients at a spherical electrode under non-steady-state conditions is described. The model is based on non-stationary diffusion equation containing a non-linear reaction term. This paper presents the complex numerical method (Homotopy perturbation method) to solve the system of non-linear differential equation that describes the homogeneous processes coupled to electrode reaction. In this paper the approximate analytical expressions of the non-steady-state concentrations and current at spherical electrodes for homogeneous reactions mechanisms are derived for all values of the reaction diffusion parameters. These approximate results are compared with the available analytical results and are found to be in good agreement.
