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30th International Conference on Computational and Experimental Engineering and Sciences, ICCES 2024

作者： Ma, Guanghao Li, Luxian State Key Laboratory for Strength and Vibration of Mechanical Structures Shaanxi Key Laboratory of Environment and Control for Flight Vehicle School of Aerospace Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China

ISBN: (纸本)9783031829062

When incorporating bending-warping deformation in the beam theory by using the higher-order kinematics, the warping function plays an essential role in establishing the decoupled constitutive relations. In this paper, the concept, orthogonality conditions and normalized condition are first proposed for the warping function. A procedure is then suggested to determine the normalized warping functions. Four typical different types of warping functions, that is cubic, sinusoidal, hyperbolically sinusoidal, and exponential, are eventually obtained, which agree with the previous results but via such a unified procedure. The rigidity coefficients in the constitutive relations are also evaluated to exhibit the higher-order nature of bi-moment and bi-shear. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2025.

关键词： Bending (deformation)

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Influence of Dynamic Loads on Lubrication Characteristics of Misaligned Tilting-Pad Journal Bearings in Locomotive Crankshaft 3

Influence of Dynamic Loads on Lubrication Characteristics of...

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3rd International Conference on Rail Transportation, ICRT 2024

作者： Wang, Xinyuan Wang, Qiurui Wu, Dongze Zhu, Kaidi Yang, Lihua State Key Laboratory for Strength and Vibration of Mechanical Structures Shaanxi Key Laboratory of Environment and Control for Flight Vehicle School of Aerospace Engineering Xi'an Jiaotong Univ. Xi'an China No. 703 Research Institute of China State Shipbuilding Co. Ltd. Harbin China

ISBN: (数字)9780784485941

ISBN: (纸本)9780784485941

In diesel generator sets for railway locomotives, crankshafts typically adopt plain bearings for support. Tilting-pad journal bearings (TPJBs) can provide reliable support and minimize wear. Journal misalignment is unavoidably present due to factors including the working environment and external loads. The lubricating performance of TPJB is crucial to ensuring the reliable functioning of locomotive power systems under dynamic loads. Therefore, this paper conducts an analysis of TPJB with journal misalignment under alternating dynamic loads. A thermal-elasto-hydrodynamic (TEHD) model is established considering elastic deformation and the thermal effect of lubricating oil. The study investigates characteristics such as time-varying oil film thickness, pressure, and temperature, as well as stiffness and damping coefficients. The results indicate that journal misalignment and the direction of dynamic loads have a significant impact on the transient lubrication performance for TPJB. Furthermore, the stability improves when exposed to vertical stresses. © ASCE.

关键词： Crankshafts

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Nonlinear flow control mechanism of two flexible flaps with fluid-structure interaction

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Acta Mechanica Sinica 2025年第2期41卷 116-131页

作者： Jiakun Han Chao Dong Jian Zhang Gang Chen College of Science Xi’an University of Science and TechnologyXi’an 710054China Beijing Institute of Space Long March Vehicle Beijing 100076China Science and Technology on Space Physics Laboratory China Academy of Launch Vehicle TechnologyBeijing 100076China State Key Laboratory of Strength and Vibration for Mechanic Structures Shaanxi Key Laboratory of Service Environment and Control for Flight VehiclesSchool of Aerospace EngineeringXi’an Jiaotong UniversityXi’an 710049China

The flow control at low Reynolds numbers is one of the most promising technologies in the field of aerodynamics,and it is also an important source of the innovation for novel *** this study,a new way of nonlinear flow control by interaction between two flexible flaps is proposed,and their flow control mechanism is studied employing the self-constructed immersed boundary-lattice Boltzmann-finite element method(IB-LB-FEM).The effects of the difference in material properties and flap length between the two flexible flaps on the nonlinear flow control of the airfoil are *** is suggested that the relationship between the deformation of the two flexible flaps and the evolution of the vortex under the fluid-structure interaction(FSI).It is shown that the upstream flexible flap plays a key role in the flow control of the two flexible *** FSI effect of the upstream flexible flap will change the unsteady flow behind it and affect the deformation of the downstream flexible *** flexible flaps with different material properties and different lengths will change their own FSI characteristics by the induced vortex,effectively suppressing the flow separation on the airfoil’s upper *** interaction of two flexible flaps plays an extremely important role in improving the autonomy and adjustability of flow *** numerical results will provide a theoretical basis and technical guidance for the development and application of a new flap passive control technology.

关键词： Nonlinear flow control Flexible flap Fluid-structure interaction Flow separation IB-LB-FEM

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Without Paired Labeled Data: An End-to-End Self-Supervised Paradigm for UAV-View Geo-Localization

arXiv

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arXiv 2025年

作者： Chen, Zhongwei Yang, Zhao-Xu Rong, Hai-Jun State Key Laboratory for Strength and Vibration of Mechanical Structures Shaanxi Key Laboratory of Environment and Control for Flight Vehicle School of Aerospace Engineering Xi’an Jiaotong University Xi’an710049 China

UAV-View Geo-Localization (UVGL) aims to ascertain the precise location of a UAV by retrieving the most similar GPS-tagged satellite image. However, existing methods predominantly rely on supervised learning paradigms that necessitate annotated paired data for training, which incurs substantial annotation costs and impedes large-scale deployment. To overcome this limitation, we propose the Dynamic Memory-Driven and Neighborhood Information Learning (DMNIL) network, a lightweight end-to-end self-supervised framework for UAV-view geo-localization. The DMNIL framework utilizes a dual-path clustering-based contrastive learning architecture as its baseline to model intra-view structural relationships, enhancing feature consistency and discriminability. Additionally, a dynamic memory-driven hierarchical learning module is proposed to progressively mine local and global information, reinforcing multilevel feature associations to improve model robustness. To bridge the domain gap between UAV and satellite views, we design an information-consistent evolutionary learning mechanism that systematically explores latent correlations within intra-view neighborhoods and across cross-view domains, ultimately constructing a unified cross-view feature representation space. Extensive experiments on three benchmarks (University-1652, SUES-200, and DenseUAV) demonstrate that DMNIL achieves competitive performance against state-of-the-art supervised methods while maintaining computational efficiency. Notably, this superiority is attained without relying on paired training data, underscoring the framework’s practicality for real-world deployment. Codes will be released soon. Copyright © 2025, The Authors. All rights reserved.

关键词： Contrastive Learning

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Dynamic modeling and study of slipping and friction characteristics of four-point contact ball bearings under the angular misalignment

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Mechanical Systems and Signal Processing 2025年 234卷

作者： Li, Zihang Wang, Haoze Ji, Xilong Wang, Chongyang Cao, Kexin Yang, Lihua State Key Laboratory for Strength and Vibration of Mechanical Structures Xi'an Jiaotong University Shaanxi Xi'an710049 China Shaanxi Key Laboratory of Environment and Control for Flight Vehicle Xi'an Jiaotong University Shaanxi Xi'an710049 China School of Aerospace Engineering Xi'an Jiaotong University Shaanxi Xi'an710049 China

Four-Point Contact Ball Bearing (FPCBB) is utilized in aero-engines, wind power and industrial gearboxes due to its ability to withstand axial forces in both directions, its high-speed performance, and its space-efficient design. It has been demonstrated that the structural characteristics of multi-point contact have some advantages, and at the same time increase the friction between the balls and the raceways. In this study, a dynamic model of the FPCBB is developed by considering six degrees of freedom for the ball and cage, and five degrees of freedom for the inner ring, incorporating nonlinear collision and frictional interactions among components. The model accounts for potential multi-point contact between the ball and raceway, as well as the angular misalignment of the inner ring. The maximum error between the experimental and simulated cage speed is only 4.98%, confirming the model's accuracy. Based on this model, the vibration response of the bearing under angular misalignment, along with frictional characteristics are analyzed. Structural optimization is then performed based on these results. Additionally, the effects of angular misalignment and axial preload are evaluated. The findings indicate that the maximum PV value in the main load area under fixed-pressure preload is approximately 70% of that under locating preload. This study is aimed to provide a theoretical foundation for understanding the dynamic characteristics of these bearings under angular misalignment and for parameter selection in practical service applications. © 2025 Elsevier Ltd

关键词： Degrees of freedom (mechanics)

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Dynamic analysis of rigid-flexible coupling spacecraft based on Euler parameters

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Scientific Reports 2025年第1期15卷 1-12页

作者： Ji, Yi Zhang, Huan School of Astronautics Harbin Institute of Technology Harbin 150001 China Frontier Science Center for Interaction between Space Environment and Matter Harbin 150001 China National Key Laboratory of Modeling and Simulation for Complex Systems Harbin 150001 China MOE Key Laboratory of Dynamics and Control of Flight Vehicle Beijing Institute of Technology Beijing 100081 China

With the development of aerospace technology, rigid-flexible coupling spacecraft with strong nonlinearity dominates, bringing huge challenges for numerical tools. This paper aims to accurately and quickly analyze the dynamic behavior of rigid-flexible coupling spacecraft. In our work, rigid body and flexible body are both described by Euler parameters for avoiding singular angles. Then, for this type of strong nonlinear dynamic system, the BN-stable method that is unconditionally stable for nonlinear initial value problems proposed by the first author is introduced to solve the transient responses. To keep the accuracy of the numerical rotation matrix, the relation between the angular velocity and Euler parameters, and the constraint in the level of velocity, are introduced to reformulate the original BN-stable method. Through the dynamic analysis for rigid satellite bodies and flexible solar wings, we find that the proposed strategy can effectively simulate the dynamic responses of spacecraft, and compared to the currently popular strategy, our strategy enjoys considerable advantages in accuracy, stability, and dissipation. © The Author(s) 2025.

关键词： BN-stability Dynamic analysis Euler parameters Rigid-flexible coupling Rotation matrix

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Hybrid deep neural network based prediction method for unsteady flows with moving boundary

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Acta Mechanica Sinica 2021年第10期37卷 1557-1566,I0003页

作者： Ren-Kun Han Zhong Zhang Yi-Xing Wang Zi-Yang Liu Yang Zhang Gang Chen State Key Laboratory for Strength and Vibration of Mechanical Structures Shannxi Key Laboratory for Environment and Control of Flight VehicleSchool of Aerospace EngineeringXi’an Jiaotong UniversityXi’an710049China Science and Technology on Reliability and Environment Engineering Laboratory Beijing Institute of Structure and Environment EngineeringBeijing100076China

Any motion, forced or free, of boundary affects the flow field around this boundary. A new kind of reduced order model (ROM) based on hybrid deep neural network is proposed to model flow field evolution process of unsteady flow around moving boundary. This hybrid deep neural network can map the relationship between the flow field at the next time step and the flow field and boundary positions at the previous time steps. Based on the learned information, the hybrid deep neural network can quickly and accurately predict the flow field. Unsteady flows around forced oscillation cylinder with various amplitudes, frequencies, and Reynolds numbers are simulated to establish the training and testing datasets. The prediction results of the hybrid deep neural network and the computational fluid dynamics (CFD) simulation results are consistent with high accuracy. The forces on the moving boundary can be integrated through the predicted flow field data. Good performance makes this new ROM method can be used in many fluid dynamics research fields, which needs fast and accurate simulation.

关键词： Deep neural network Flow fields prediction Moving boundary

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Anisotropic phononic crystal structure with low-frequency bandgap and heat flux manipulation

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Science China(Physics,Mechanics & Astronomy) 2020年第2期63卷 93-103页

作者： Ting Guo XiongWei Yang Qian Geng Zhen Li YueMing Li Xian Wang Hu Zhang State Key Laboratory for Strength and Vibration of Mechanical Structures Shaanxi Key Laboratory of Environment and Control for Flight Vehicle School of Aerospace Xi’an Jiaotong University

This study presents a two-dimensional phononic crystal with heat flux manipulation and wide bandgaps of out-of-plane modes within the low-frequency range. The anisotropic matrix made of spiral-multilayered materials with different thermal conductivities, and the coating layer inserted with metal are designed for heat flux manipulation. Rubber-coated metal cylinders are periodically embedded in the anisotropic matrix to obtain the low-frequency bandgaps of out-of-plane modes. Numerical simulation is carried out to validate the heat and elastic characteristics of the spiral-multilayered anisotropic structure and reveal the effects of the laying angle and temperature on the bandgaps. Subsequently, a spiral-multilayered plate with periodic structures is studied, which shows an obvious vibration attenuation in the frequency ranges of the bandgaps and a deflected heat flux from the initial propagation direction. In the experimental investigation, the multi-phase spiral-multilayered anisotropic plate is simplified to a single-phase anisotropic plate made of aluminum. The characteristics of this type of anisotropic phononic crystal structure may pave the way for the design of a new kind of thermo-acoustic metamaterial serving in combined thermal and acoustic environments.

关键词： heat flux manipulation bandgap anisotropic structure thermal stress spiral-multilayered structure

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Elastic twisting metamaterial for perfect longitudinal-torsional wave mode conversion

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Applied Mathematics and Mechanics(English Edition) 2023年第4期44卷 515-524页

作者： Shengjie YAO Yijun CHAI Xiongwei YANG Yueming LI State Key Laboratory for Strength and Vibration of Mechanical Structures Shaanxi Key Laboratory of Environment and Control for Flight VehicleSchool of AerospaceXi’an Jiaotong UniversityXi’an 710049China

In this work,we design a twisting metamaterial for longitudinal-torsional(L-T)mode conversion in pipes through exploring the theory of perfect transmodal FabryPerot interference(TFPI).Assuming that the axial and radial motions in pipes can be decoupled,we find that the metamaterial can be designed in a rectangular coordinate system,which is much more convenient than that in a cylindrical *** calculation with detailed microstructures shows that an efficient L-T mode conversion can be obtained in pipes with different *** addition,we fabricate mode-converting microstructures on an aluminum pipe and conduct ultrasonic experiments,and the results are in good agreement with the numerical *** expect that the proposed LT mode-converting metamaterial and its design methodology can be applied in various ultrasonic devices.

关键词： elastic wave mode conversion elastic metamaterial ultrasonic device

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Treatment of Wall Boundary Conditions in High-Order Compact Gas-Kinetic Schemes

arXiv

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arXiv 2025年

作者： Zhang, Jiawang Ji, Xing Xu, Kun Department of Mathematics Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong State Key Laboratory for Strength and Vibration of Mechanical Structures Shaanxi Key Laboratory of Environment and Control for Flight Vehicle School of Aerospace Engineering Xi’an Jiaotong University Xi’an China Department of Mechanical and Aerospace Engineering Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong Shenzhen Research Institute Hong Kong University of Science and Technology Shenzhen China

The boundary layer represents a fundamental structure in fluid dynamics, where accurate boundary discretization significantly enhances computational efficiency. This paper presents a third-order boundary discretization for compact gas-kinetic scheme (GKS). Wide stencils and curved boundaries pose challenges in the boundary treatment for high-order schemes, particularly for temporal accuracy. By utilizing a time-dependent gas distribution function, the GKS simultaneously evaluates fluxes and updates flow variables at cell interfaces, enabling the concurrent update of cell-averaged flow variables and their gradients within the third-order compact scheme. The proposed one-sided discretization achieves third-order spatial accuracy on boundary cells by utilizing updated flow variables and gradients in the discretization for non-slip wall boundary conditions. High-order temporal accuracy on boundary cells is achieved through the GKS time-dependent flux implementation with multistage multi-derivative methodology. Additionally, we develop exact no-penetration conditions for both adiabatic and isothermal wall boundaries, with extensions to curved mesh geometries to fully exploit the advantages of high-order schemes. Comparative analysis between the proposed one-sided third-order boundary scheme, third-order boundary scheme with ghost cells, and second-order boundary scheme demonstrates significant performance differences for the third-order compact GKS. Results indicate that lower-order boundary cell treatments yield substantially inferior results, while the proposed third-order treatment demonstrates superior performance, particularly on coarse grid configurations. Copyright © 2025, The Authors. All rights reserved.

关键词： Mesh generation

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