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Dynamic Modeling of Variable Stiffness and Damping for Spatial Linkage Weft Insertion Mechanism with Clearance
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作者 LI Bo HU Kai +2 位作者 JIN Guoguang WEI Zhan SONG Yanyan 《Journal of Donghua University(English Edition)》 EI CAS 2020年第6期470-482,共13页
In order to further analyze the influence of clearance on the kinematic performance of spatial linkage weft insertion mechanism,it is necessary to study the dynamic characteristics of contact impact force model with t... In order to further analyze the influence of clearance on the kinematic performance of spatial linkage weft insertion mechanism,it is necessary to study the dynamic characteristics of contact impact force model with the variable stiffness and damping coefficient.Firstly,the parameters in the output process of the system are solved by describing of the flexible joint clearance.Then,based on Lankarani-Nikravesh contact force model,the contact impact stiffness and damping coefficient is modified from fixed values to time-varying coefficients.The dynamic model of spatial linkage weft insertion mechanism with modified clearance is established by Lagrange method,and the dynamic characteristics of the system are calculated.The results show that the joint clearance can directly affect the output performance of the mechanism.With the increase of the clearance value,the curve fluctuations of acceleration,driving torque and collision force are obvious,and it will be further intensified with the increase of spindle speed,which greatly affects the stability of mechanism and fabric quality.Finally,the virtual prototype is established by the SolidWorks software and simulated by the ADAMS software.The simulation results are compared with the numerical results,which verifies the accuracy of the modeling method in this paper. 展开更多
关键词 rapier loom spatial linkage weft insertion mechanism CLEARANCE contact impact force model dynamic analysis
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A modified discrete element model for sea ice dynamics 被引量:5
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作者 LI Baohui LI Hai +2 位作者 LIU Yu WANG Anliang JI Shunying 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2014年第1期56-63,共8页
Considering the discontinuous characteristics of sea ice on various scales,a modified discrete element model(DEM) for sea ice dynamics is developed based on the granular material rheology.In this modified DEM,a soft... Considering the discontinuous characteristics of sea ice on various scales,a modified discrete element model(DEM) for sea ice dynamics is developed based on the granular material rheology.In this modified DEM,a soft sea ice particle element is introduced as a self-adjustive particle size function.Each ice particle can be treated as an assembly of ice floes,with its concentration and thickness changing to variable sizes under the conservation of mass.In this model,the contact forces among ice particles are calculated using a viscous-elastic-plastic model,while the maximum shear forces are described with the Mohr-Coulomb friction law.With this modified DEM,the ice flow dynamics is simulated under the drags of wind and current in a channel of various widths.The thicknesses,concentrations and velocities of ice particles are obtained,and then reasonable dynamic process is analyzed.The sea ice dynamic process is also simulated in a vortex wind field.Taking the influence of thermodynamics into account,this modified DEM will be improved in the future work. 展开更多
关键词 sea ice dynamics modified discrete element model contact force model numerical simulation
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Dynamics Analysis of Square Unit and its Combined Mechanism with Joint Clearance
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作者 Jianfeng Li Sanmin Wang +2 位作者 Bo Li Changjian Zhi Qi'an Peng 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2018年第6期59-65,共7页
The deployable mechanisms consisting of square units are widely applied in aeronautics and astronautics,biomedicine, architecture and other fields, and joint clearance in such a mechanism is unavoidable. This study is... The deployable mechanisms consisting of square units are widely applied in aeronautics and astronautics,biomedicine, architecture and other fields, and joint clearance in such a mechanism is unavoidable. This study is carried out to accurately investigate the dynamic property of the mechanism.Firstly,a dynamics model was built by considering the motion characteristics between elements of joint with clearances. Secondly,based on Floures contact force model and LuGre friction force model,the tangential and normal contact force of revolute pair element with clearance were calculated respectively. Finally,square combined mechanisms' dynamic analytical method considering joint clearance was investigated, and constraint renege problem was resolved by adopting Baumgarte stable constraint method in integration process.Analytical result indicates that the impact of joint clearance on dynamic property of square combined mechanism should not be neglected. 展开更多
关键词 square unit and its combined mechanism CLEARANCE Floures contact force model dynamics
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