Dynamics analysis and design of metamaterial beams with multiple half-sine waves

2022 ◽  
Vol 186 ◽  
pp. 108448
Author(s):  
Meng-Xin He ◽  
Qian Ding
Keyword(s):  
Dynamics Analysis ◽  
Analysis And Design

Vibroacoustic Optimization of a Shell Structure Based on the Dynamics Analysis

2011 ◽  
Vol 58-60 ◽  
pp. 1077-1081
Author(s):  
Hai Hong Li ◽  
Yong Hui Chen ◽  
Shan Guo Guo
Keyword(s):  
Shell Structure ◽  
Thin Shell ◽  
Three Dimensional ◽  
Fem Analysis ◽  
Dynamics Analysis ◽  
Dynamics Modeling ◽  
Three Dimensional Model ◽  
Modeling And Analysis ◽  
Analysis And Design ◽  
Shape Pattern

Taken the computer case as an example, dynamics modeling and analysis of a thin shell structure is presented in this paper. Optimization is implemented with the goal to reduce the vibration. Four proposals of optimal design are simulated employing the FEM software. Those proposals differ in material, shape, pattern and connectivity. Some especial techniques are used to build the three-dimensional model and to finish the FEM analysis. The dynamics characteristics of the computer case are then investigated in modal analysis based on the dynamics theory. The result is acquired by comparing the modal parameters of those in different proposals. A preferable model takes also the manufacturing and cost into account. The skeleton is universal to dynamics analysis and design of other thin shell structure.

scholarly journals A Study on Dynamic Characteristics of Satellite Antenna System considering 3D Revolute Clearance Joint

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Zhengfeng Bai ◽  
Jijun Zhao
Keyword(s):  
Dynamic Characteristics ◽  
Antenna System ◽  
Contact Forces ◽  
Dynamics Analysis ◽  
Satellite Antenna ◽  
Revolute Joint ◽  
Analysis And Design ◽  
Revolute Clearance Joint ◽  
Clearance Joint ◽  
Axial Clearance

Clearances in the joints of real mechanisms are unavoidable due to assemblage, manufacturing errors, and wear. The dual-axis driving and positioning mechanism is one kind of space actuating mechanism for satellite antenna to implement precise guidance and positioning. However, in dynamics analysis and control of the satellite antenna system, it is usually assumed that the revolute joint in the satellite antenna system is perfect without clearances or imperfect with planar radial clearance. However, the axial clearance in an imperfect revolute joint is always ignored. In this work, the revolute joint is considered as a 3D spatial clearance joint with both the radial and axial clearances. A methodology for modeling the 3D revolute joint with clearances and its application in satellite antenna system is presented. The dynamics modeling and analysis of the satellite antenna system are investigated considering the 3D revolute clearance joint. Firstly, the mathematical model of the 3D revolute clearance joint is established, and the definitions of the radial and axial clearance are presented. Then, the potential contact modes, contact conditions, and contact detection of the 3D revolute clearance joint are analyzed. Further, the normal and tangential contact force models are established to describe the contact phenomenon and determine the contact forces in the 3D revolute clearance joint. Finally, a satellite antenna system considering the 3D revolute clearance joint with spatial motion is presented as the application example. Different case studies are presented to discuss the effects of the 3D revolute clearance joint. The results indicate that the 3D revolute clearance joint will lead to more severe effects on the dynamic characteristics of the satellite antenna system. Therefore, the effects of axial clearance on the satellite antenna system cannot be ignored in dynamics analysis and design of the satellite antenna system.

A Biomimetic Elastic Cable Driven Quadruped Robot: The RoboCat

2011 ◽  
Author(s):  
Elvedin Kljuno ◽  
J. Jim Zhu ◽  
Robert L. Williams ◽  
Stephen M. Reilly
Keyword(s):  
Kinetic Energy ◽  
Quadruped Robot ◽  
Effective Control ◽  
Kinematics And Dynamics ◽  
Dynamics Analysis ◽  
Bipedal Robots ◽  
Analysis And Design ◽  
And Control ◽  
Ground Impact ◽  
Transfer Potential

State of the art legged robots, such as the Honda’s series of bipedal robots ending in the latest advanced walking robot ASIMO, and the series of bipedal robots of Waseda University including the latest advanced robot WABIAN, employ joint-mount motors, which simplifies the analysis/design and traces the route for an effective control system, but results in legs that are heavy and bulky. Cable-driven robots overcome this shortcoming by allowing the motors to be mounted on or near the torso, thereby reducing the weight and inertia of the legs, resulting in lower overall weight and power consumption. To facilitate analysis and design, typical cable-driven robots use non-stretchable cables, which require at least n+1 motors for an n Degree-of-Freedom (DoF) joint. Therefore, for a robot with N joints, at least N additional motors are needed comparing to joint-mount motor drives. Moreover, the drive train of both joint-mount and cable-driven designs are rigid, which cannot effectively absorb ground impact shocks nor transfer potential energy to kinetic energy and vice versa when the robot is in motion, as biologic animals do. In this paper we present the design and test of a cat-size quadruped robot called RoboCat, which employs stretchable elastic cable-driven joints as inspired by biological quadruped animals. Although it complicates kinematics and dynamics analysis and design, the elastic cables allow n motors to be used for an n-DoF joint, thereby eliminating N motors for a robot with N joints comparing to non-stretchable cables, further realizing the weight and power savings of the cable driven design. Moreover, the elastic cable driven joints not only effectively absorb ground contact shock, but also effectively transfer potential and kinetic energy during walking or running, thereby improving the robot motion performance and energy efficiency. In the paper we will discuss the kinematics and dynamics analysis of elastic cable driven joints, implementation of elastic cable-driven joints on the Ohio University RoboCat, and control.

Computational fluid dynamics analysis and design optimization of a porous annular powder‐liquid mixer

2020 ◽  
Vol 8 (4) ◽  
pp. 1149-1164
Author(s):  
Long Feng ◽  
Zengliang Li ◽  
Mingchao Du ◽  
Zhaocheng Sun ◽  
Chunyong Fan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Design Optimization ◽  
Dynamics Analysis ◽  
Analysis And Design ◽  
Computational Fluid Dynamics Analysis
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