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An exact nonlinear hybrid-coordinate formulation for flexible multibody systems

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Acta Mechanica Sinica 2007年第6期23卷 699-706页

作者： Jinyang Liu jiazhen hong LinCui Department of Engineering Mechanics Shanghai Jiaotong University Shanghai 200030 China

The previous low-order approximate nonlinear formulations succeeded in capturing the stiffening terms, but failed in simulation of mechanical systems with large deformation due to the neglect of the high-order deformation terms. In this paper, a new hybrid-coordinate formulation is proposed, which is suitable for flexible multibody systems with large deformation. On the basis of exact strain- displacement relation, equations of motion for flexible multi-body system are derived by using virtual work principle. A matrix separation method is put forward to improve the efficiency of the calculation. Agreement of the present results with those obtained by absolute nodal coordinate formulation （ANCF） verifies the correctness of the proposed formulation. Furthermore, the present results are compared with those obtained by use of the linear model and the low-order approximate nonlinear model to show the suitability of the proposed models.

关键词： Nonlinear hybrid-coordinate formulation Flexible multibody systems Large deformation

Multibody dynamic analysis using a rotation-free shell element with corotational frame

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Acta Mechanica Sinica 2018年第4期34卷 769-780页

作者： Jiabei Shi Zhuyong Liu jiazhen hong School of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong University

Rotation-free shell formulation is a simple and effective method to model a shell with large deformation. Moreover, it can be compatible with the existing theories of finite element method. However, a rotation-free shell is seldom employed in multibody systems. Using a derivative of rigid body motion, an efficient nonlinear shell model is proposed based on the rotation-free shell element and corotational frame. The bending and membrane strains of the shell have been simplified by isolating deformational displacements from the detailed description of rigid body motion. The consistent stiffness matrix can be obtained easily in this form of shell model. To model the multibody system consisting of the presented shells, joint kinematic constraints including translational and rotational constraints are deduced in the context of geometric nonlinear rotation-free element. A simple node-to-surface contact discretization and penalty method are adopted for contacts between shells. A series of analyses for multibody system dynamics are presented to validate the proposed formulation. Furthermore,the deployment of a large scaled solar array is presented to verify the comprehensive performance of the nonlinear shell model.

关键词： Flexible multibody dynamics Rotation-free shell Corotational frame Geometric nonlinearity

The application of porous Si photonic crystals for metal-resonance enhanced fluorescence

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Optoelectronics Letters 2019年第6期15卷 439-443页

作者： WANG Jia-jia jiazhen-hong Postdoctoral Station of Computer Science and Technology Xinjiang UniversityUrumqi 830046China School of Information Science and Engineering Xinjiang UniversityUrumqi 830046China

This paper has demonstrated the resonance fluorescence enhancement of R6G when gold nanoparticles(Au NPs) deposited in the porous Si photonic crystal device. Both of microcavity(MC) and distributed Bragg reflector(DBR) with different parameters are investigated for making the photon transmission of photonic crystal device play an optimal role in enhancing fluorescence resonance. While minor changes were observed on the DBR substrates, a significant change in the intensity of enhanced fluorescence varies with the defect modes of MC substrates. Particularly, the strongest enhancement has been presented as the MC defect mode wavelength located at the maximum absorption wavelength of Au NPs. In this case, the fluorescence intensity of R6G on MC device is 2.5 times of that of R6G based on DBR device.

关键词： porous resonance defect

Multi-variable approach of contact-impact issue in variable topology system

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Theoretical & Applied Mechanics Letters 2013年第1期3卷 58-62页

作者： Jiabei Shi jiazhen hong Zhuyong Liu School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University

Contact-impact processes occur at most cases in multibody systems. Sub-periods and sub-regional methods are frequently used recently, and different coordinates are introduced in both of the approaches. However, the sub-regional method seems to be more effective. Floating frame of reference formulation is widely used for contact treatment, which describes displacements by the rigid body motion and a small superposed deformation, and the coordinates depicting the deformation include finite element nodal coordinates and modal coordinates, the former deals with the contact/impact region, and the later describes the non-contact region. In this paper, free interface substructure method is used in modeling, and the dynamic equation of a single body is derived. Then, using the Lagrange equation of the first kind, the dynamic equations of multibody systems are established. Furthermore, contact-impact areas are treated through additional constraint equations and Lagrange multipliers. Using such approach, the number of system coordinates and the dimensions of mass matrix are significantly reduced with the modal truncation, therefore both of the efficiency and accuracy are guaranteed. Finite element method in the local contact region can deal with contact/impact between arbitrarily complex interfaces, whereas, additional contact constraints used in the nodal description region can avoid the customized parameters that are used in the continuous force model. C 2013 The Chinese Society of Theoretical and Applied Mechanics.[doi： 10.1063/2.1301307]

关键词： flexible multibody contact constraints

Waveguide Prism Based on Porous Silicon

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Semiconductor Photonics and Technology 2004年第1期10卷 28-30页

作者： jiazhen-hong CollegeofInform.Sci.&Eng. XinjiangUniversity.Urumqi830046CHN

The fabrication of the oxidized porous silicon waveguide prism is reported by selectively electrochemical anodisation process. The direction changes of light beams in TE and TM polarization out of this waveguide prism... 详细信息

关键词： Porous silicon Waveguide Prism

考虑附加质量的中心刚体—柔性悬臂梁系统的动力特性研究

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机械工程学报 2005年第2期41卷 33-40页

作者：蔡国平洪嘉振上海交通大学工程力学系上海200240

对考虑附加质量的中心刚体-柔性悬臂梁系统的动力特性进行研究。首先采用Hamilton原理和有限元离散化方法,在计入柔性梁由于横向变形而引起的轴向变形的二阶耦合量的条件下,给出该系统的刚柔耦合动力学方程(即一次近似耦合模型),以及... 详细信息

对考虑附加质量的中心刚体-柔性悬臂梁系统的动力特性进行研究。首先采用Hamilton原理和有限元离散化方法,在计入柔性梁由于横向变形而引起的轴向变形的二阶耦合量的条件下,给出该系统的刚柔耦合动力学方程(即一次近似耦合模型),以及相应的非惯性系下的动力学模型,然后通过数值仿真对系统的动力特性进行研究。仿真结果显示,即使是小的附加质量也会对系统动力特性产生重要影响,附加质量使得梁的响应幅值变大和响应频率降低,且会影响柔性梁和中心刚体的终点位置。附加质量的影响随系统大范围运动的角速度的增大而变大。当系统大范围运动为低速时,传统的混合坐标模型仍然会导致较大误差;当系统大范围运动为高速时,传统的混合坐标模型存在失效的可能。

关键词：柔性悬臂梁附加质量混合坐标模型一次近似耦合模型

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