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Gear walk instability caused by brake-disc friction characteristics

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Chinese Journal of Aeronautics 2024年第2期37卷 343-359页

作者： Xiaoqiong DU Bin LI Wen CAI Linyin LUO School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Department of Mechanical Engineering University of MichiganAnn Arbor 48109USA AVIC General Huanan Aircraft Industry Co.Ltd. Zhuhai 519040China

A multi-body dynamic rigid-flexible coupling model of landing gear is established to study the gear walk instability caused by the friction characteristics of the brake disc.After validating the model with the experimental results,the influence of the landing gear structure and braking system parameters on gear walk is further investigated.Among the above factors,the slope of the graph for the friction coefficient of the brake disc and the relative velocity of brake stators and rotors is the most influential factor on gear walk instability.Phase trajectory analysis verifies that gear walk occurs when the coupling of multiple factors causes the system to exhibit an equivalent negative damping trend.To consider a more realistic braking case,a back propagation neural network method is employed to describe the nonlinear behavior of the friction coefficient of the brake disc.With the realistic nonlinear model of the friction coefficient,the maximum error in predicting the braking torque is less than 10%and the effect of the brake disc temperature on gear walk is performed.The results reveal that a more negative friction slope may contribute to a more severe unstable gear walk,and reducing the braking pressure is an effective approach to avoid gear walk,which provides help for future braking system design.

关键词： Gear walk Friction characteristics of brake disc Brake-induced vibration Negative damping rigid-flexible coupling Negative slope of braking torque

New method for multibody dynamics based on unknown constraint force

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Science China(Technological Sciences) 2024年第3期67卷 791-808页

作者： TIAN Ying JIA YingHong ZHANG Jun School of Astronautics Beihang UniversityBeijing 100191China Beijing Institute of Control Engineering Beijing 100190China National Laboratory of Space Intelligent Control Beijing 100190China

This paper presents a new method for the dynamics of multibody systems based on unknown constraint force. The method can uniformly solve multibody systems with typical configurations, including the system with rigid-flexible coupling, the system in tree topology, and the system with loop constraints. Unlike common methods, the proposed method can model the loop system without “cutting off” loop constraints, leading to the exact same modelling process as the tree-like system performs. Based on graph theory, a topological record matrix M_(rec) is proposed to capture the arbitrary system configuration. Moreover, constraint forces are selected as the key variables in semi-recursive framework. With the recursive kinematics relationship between adjacent bodies, the constraint force equation is further assembled to achieve the full-state system solution. The numerical simulations demonstrate the accuracy of the proposed method.

关键词： multibody system dynamic modelling rigid-flexible coupling unknown constraint force graph theory semi-recursive algorithm

rigid-flexible coupling Dynamic Analysis of Sub-Launched Vehicle During the Vertical Tube-Exit Stage

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Journal of Harbin Institute of Technology(New Series) 2015年第2期22卷 26-33页

作者： Weiyao Zhang Jingbo Gao Cong Wang School of Astronautics Harbin Institute of Technology

During the launching stage,hydrodynamic pressure and adapters' reaction loads can influence the vehicle's rigid motion as well as cause its structural vibration,which is a typical rigid-flexible coupling dynamic problem. This paper presents a 2-D rigid-flexible coupling model to calculate the vehicle's dynamic responses in that period.The vehicle was equivalent to a flexure beam with axial deformation. Hybrid coordinate and modal superposition methods were used to describe its large rigid displacement and small deformation. By the second Lagrange equation,the vehicle centroid's displacements,rotational angle and modal coordinates were chosen as generalized coordinates and then the vehicle 's rigid-flexible coupling dynamic equations were obtained. By numerical simulation,the results of vehicle's motion parameters and transverse internal loads were acquired.The calculation results showed that differences of the vehicle's motion parameters between the rigid-flexible coupling model and the rigid body assumption are noticeable and the peak magnitude of the vehicle's transverse internal loads in the rigid-flexible coupling model is higher remarkably than that in the rigid body assumption.

关键词： sub-launched vehicle rigid-flexible coupling hybrid coordinate dynamic responses

A Robust Strategy for Precise Fabrication of rigid-flexible coupling Dendrimers toward Self-Coordinated Hierarchical Assembly

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CCS Chemistry 2021年第4期3卷 1093-1104页

作者： Xing Wang Peiyuan Gao Juan Wang Yanyu Yang Yezi You Decheng Wu Beijing National Laboratory for Molecular Sciences Institute of ChemistryChinese Academy of SciencesBeijing 100190 University of Chinese Academy of Sciences Beijing 100049 College of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001 Hefei National Laboratory for Physical Sciences at the Microscale CAS Key Laboratory of Soft Matter ChemistryDepartment of Polymer Science and EngineeringUniversity of Science and Technology of ChinaHefei 230026

Advances in nanotechnology depend upon expanding the ability to create biologically inspired complex materials with well-defined multidimensional structures.Fabrication of hybrid hierarchical structures by combining colloidal organic and inorganic building blocks remains a challenge due to the difficulty in preparing a diverse spectrum of rigid-flexible coupling units of precise shape and size.Herewe reportageneral strategy for crafting amyriad of uniform aggregates via manipulating self-assembly of distinct dendimers with precisely controlled polyhed raloligomeric silse squioxane(POSS)-embedded cores integrating stiffness and ductility.The rigidity of POSS units exerts steric effects onself-amplification of hydrophobic do mains while the flexibility from internally ductile linkages provides ideal scenarios in establishing self-adaptive structural optimization,which subsequently drive the assemblies to proceed into hierarchical self-assembly via multiple coordination effects,generating highly complex multi compartment micelles(MCMs)without any preprocessing.Our facile approach enables a robust modular nanofabrication of well-organized dendrimers toward artificial functional systems with defined geometric architectures and intriguing functions for advanced biological applications.

关键词： dendrimer POSS hierarchical selfassembly rigid-flexible coupling phase separation coordinative interaction

Ride comfort evaluation for road vehicle based on rigid-flexible coupling multibody dynamics

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Theoretical & Applied Mechanics Letters 2013年第1期3卷 39-43页

作者： Guangqiang Wu Guodong Fan Jianbo Guo Automotive School Tongji University

In the present research two different whole vehicle multibody models are established respectively, including rigid and rigid-flexible coupling multibody vehicle models. The former is all composed by rigid bodies while in the later model, the flexible rear suspension is built based on the finite element method （FEM） and mode superposition method, in which the deformations of the components are considered. The ride simulations with different speeds are carried out on a 3D digitalized road, and the weighted root mean square （RMS） of accelerations on the seat surface,backrest and at the feet are calculated. The comparison between the responses of the rigid and rigid-flexible coupling multibody models shows that the flexibility of the vehicle parts significantly affects the accelerations at each position, and it is necessary to take the flexibility effects into account for the assessment of ride comfort. C 2013 The Chinese Society of Theoretical and Applied Mechanics. [doi： 10.1063/2.1301304]

关键词： ride comfort rigid-flexible coupling multibody system

Dynamic Simulation for rigid-flexible coupling Model of Gear Transmission System Based on ADAMS

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Journal of Donghua University(English Edition) 2016年第2期33卷 192-195页

作者：陈材石全王广彦戈洪宇 Department of Equipment Command and Management Mechanical Engineering College

The influence of the flexible body for the motion of gear transmission system is analyzed and the foundation for a more accurate assessment of gear transmission system is established when it has battle damage faults. By using Pro / E software,the virtual prototype model of gear transmission system in the speed reducer is established,and the rigid model and rigid-flexible coupling model are simulated respectively in ADAMS to obtain the data of gear meshing force. It can be concluded that rigid-flexible coupling model can reflect the real motion better than rigid model by comparing the simulation data of two models.

关键词： ADAMS gear transmission rigid-flexible coupling simulation

Nonlinear dynamic analysis on rigid-flexible coupling system of an elastic beam

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Theoretical & Applied Mechanics Letters 2012年第2期2卷 68-71页

作者： Feiyun Zhao Jinyang Liu Jiazhen Hong Shanghai Nuclear Engineering Research and Design Institute Shanghai 200233China Department of Engineering Mechanics Shanghai Jiao Tong UniversityShanghai 200240China

Previous work examined the effect of the attached stiffness matrix terms on stability of an elastic beam undergoing prescribed large overall motion. The aim of the present work is to extend the nonlinear formulations to an elastic beam with free large overall motion. Based on initial stress method, the nonlinear coupling equations of elastic beams are obtained with free large overall motion and the attached stiffness matrix is derived by solving sub-static formulation. The angular velocity and the tip deformation of the elastic pendulum are calculated. The analytical results show that the simulation results of the present model are tabled and coincide with the one-order approximate model. It is shown that the simulation results accord with energy conservation principle.

关键词： elastic beam nonlinear analysis initial stress method rigid-flexible coupling

Simulation analysis of launch dynamics for high fire rate gun based on rigid-flexible coupling

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Simulation analysis of launch dynamics for high fire rate gu...

A rigid-flexible coupling Three-finger Soft Gripper for Fruit Picking

第四届国际自动化测试与仪器仪表学术会议

作者： Guo Ying Su Zhongting Han Xiaoping Xue Jing Academy of Armored Force Engineering

A rigid-flexible coupling simulation model of high fire rate gun was built up based on multi-body dynamic and finite element method in order to study the effecting law of muzzle disturbance when the projectile comes out from the muzzle and the rule of muzzle disturbance because of the fire rate.The mode analysis of the high fire rate gun was carried and the natural frequency and mode shape of the first six vibration mode were obtained using ANSYS finite element analysis software considered the flexible character.The control function of pressure of every tube was designed aiming at the particularity of fire circular.The height and orientation vibration characteristic under different fire rate was received by simulation.The simulation result could afford the theory guidance and technique sustain of the improvement of high fire rate gun fire density.

关键词： high fire rate gun ANSYS ADAMS rigid-flexible coupling launch dynamics

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A Rigid-flexible Coupling Three-finger Soft Gripper for Frui...