Modeling and Load Capacity Analysis of Reciprocating Hybrid Linear Guideway With Annular Groove and Sloped Recesses

2020 ◽  
Vol 143 (6) ◽  
Author(s):  
Huanyu Du ◽  
Hongguang Li ◽  
Guang Meng
Keyword(s):  
Dynamic Characteristics ◽  
Normal Vibration ◽  
Linear Time ◽  
Load Capacity ◽  
Normal Direction ◽  
Capacity Analysis ◽  
Time Varying ◽  
Bearing Surface ◽  
Single Degree Of Freedom ◽  
Single Degree

Abstract In this work, we research a reciprocating hybrid linear guideway and study its load capacity. This hybrid guideway's bearing surface is designed with an annular groove and two sloped shallow recesses. The analysis is based on modeling by mass-conserving cavitation algorithm (p − θ cavitation algorithm), where a modified smoothing switch function is raised for better convergence. Focusing on the normal direction to reciprocation, the load-guideway system is simplified as a single-degree-of-freedom linear time-varying system and solved by Newmark-β method. Due to the hybrid guideway's time-varying dynamic characteristics, there is a normal vibration in reciprocation. By analyzing two typical load cases in detail, the results indicate that the hybrid guideway has greater load capacity than the hydrostatic guideway, and the normal vibration is small enough for most engineering situations.

Dynamic analysis of a ball screw feed system with time-varying and piecewise-nonlinear stiffness

2019 ◽  
Vol 233 (18) ◽  
pp. 6503-6518 ◽  
Author(s):  
Jianguo Gu ◽  
Yimin Zhang
Keyword(s):  
Dynamic Characteristics ◽  
Ball Screw ◽  
Time Varying ◽  
Feed System ◽  
Restoring Force ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Nonlinear Restoring Force ◽  
Abrupt Changes ◽  
Screw Feed

In this study, a single-degree-of-freedom model is established to investigate the dynamic characteristics of a single-nut double-cycle ball screw feed system by considering the contact states of the nonlinear kinematic joints. Based on fully considering the parameters of the ball screw feed system, the axial deformations and forces of the key components are calculated to construct a set of piecewise-nonlinear restoring force functions of the system displacement and worktable position. The variations of the contact stiffnesses of the kinematic joints and transmission stiffness of the system with different boundary conditions are analyzed and the results indicate that they all have abrupt changes when the system displacement reaches a critical value. The changing law of the system transmission stiffness in the whole stoke is discussed. Additionally, the effects of excitation force, worktable position and system mass on the dynamic characteristics of the system and its correlative components are analyzed.

On the Stability Properties of a Periodically Forced, Time-Varying Mass System

2009 ◽  
Author(s):  
W. T. van Horssen ◽  
O. V. Pischanskyy ◽  
J. L. A. Dubbeldam
Keyword(s):  
Periodic Solutions ◽  
Forced Vibrations ◽  
Time Varying ◽  
Mass System ◽  
Single Degree Of Freedom ◽  
Stability Properties ◽  
Single Degree ◽  
Existence Of Periodic Solutions ◽  
The Stability ◽  
Varying Mass

In this paper the forced vibrations of a linear, single degree of freedom oscillator (sdofo) with a time-varying mass will be studied. The forced vibrations are due to small masses which are periodically hitting and leaving the oscillator with different velocities. Since these small masses stay for some time on the oscillator surface the effective mass of the oscillator will periodically vary in time. Not only solutions of the oscillator equation will be constructed, but also the stability properties, and the existence of periodic solutions will be discussed.

3-DOF Outer Rotor Electromagnetic Spherical Actuator

2016 ◽  
Vol 10 (4) ◽  
pp. 591-598 ◽  
Author(s):  
Yusuke Nishiura ◽  
◽  
Katsuhiro Hirata ◽  
Yo Sakaidani ◽  
Keyword(s):  
Genetic Algorithm ◽  
Dynamic Characteristics ◽  
Degrees Of Freedom ◽  
Single Degree Of Freedom ◽  
Torque Density ◽  
Multiple Degrees Of Freedom ◽  
Single Degree ◽  
Outer Rotor ◽  
High Torque ◽  
Spherical Actuator

Conventionally, many single-degree-of-freedom (single-DOF) actuators have been used to realize devices with multiple-degrees-of-freedom (multi-DOF). However, this makes their structures larger, heavier, and more complicated. In order to remove these drawbacks, the development of spherical actuators with multi-DOF is necessary. In this paper, we propose a new 3-DOF outer rotor electromagnetic spherical actuator with high torque density and wide rotation angles. The dynamic characteristics are computed employing 3-D FEM and its effectiveness is verified by carrying out measurements on a prototype. Then, in order to realize further high torque density, the electromagnetic pole arrangement is optimized using Genetic Algorithm (GA) and the effectiveness of the optimized stator poles arrangement is verified.

Change in Dynamic Characteristics of Spindle for Machining Centers Caused by Chucking Mechanism of Clamped Toolholders

2012 ◽  
Vol 523-524 ◽  
pp. 521-526 ◽  
Author(s):  
Haruhisa Sakamoto ◽  
Yuhei Maeki ◽  
Shinji Shimizu
Keyword(s):  
Dynamic Characteristics ◽  
Transfer Functions ◽  
Dynamic Stiffness ◽  
Characteristic Parameters ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Machining Center ◽  
Vibration Model ◽  
Order Of Magnitude ◽  
Response Method

In this study, the effects of clamping toolholders on the dynamic characteristics of spindle systems are evaluated experimentally. In the experiments, the transfer functions are obtained by the impulse response method, and then, the dynamic characteristic parameters are identified based on the vibration model of single-degree of freedom. Two types of machining center spindles and four types of toolholders are evaluated. From the experimental results, the following are revealed: (1) the clamping toolholder enhances the vibration amplitude markedly compared with that of the spindle not clamping toolholder. (2) The different chucking mechanisms clearly change the dynamic stiffness of the spindle systems. (3) The order of magnitude of the dynamic stiffness of the spindle systems agrees well with that of the isolated toolholders. It is confirmed experimentally that clamping of the appropriate toolholder improves the dynamics stiffness of the spindle systems for machining centers.

scholarly journals Reduced-Order Modeling and Experimental Studies of Bilaterally Coupled Fluid–Structure Interaction in Single-Degree-of-Freedom Flapping Wings

2020 ◽  
Vol 142 (2) ◽  
Author(s):  
Ryan K. Schwab ◽  
Heidi E. Reid ◽  
Mark Jankauski
Keyword(s):  
Flapping Wing ◽  
Flapping Wings ◽  
Inertial Forces ◽  
Time Varying ◽  
Single Degree Of Freedom ◽  
Fluid Structure ◽  
Reduced Order ◽  
Structure Interaction ◽  
Aerodynamic Damping ◽  
Single Degree

Abstract Flapping wings deform under both aerodynamic and inertial forces. However, many flapping wing fluid–structure interaction (FSI) models require significant computational resources which limit their effectiveness for high-dimensional parametric studies. Here, we present a simple bilaterally coupled FSI model for a wing subject to single-degree-of-freedom (SDOF) flapping. The model is reduced-order and can be solved several orders of magnitude faster than direct computational methods. To verify the model experimentally, we construct a SDOF rotation stage and measure basal strain of a flapping wing in-air and in-vacuum. Overall, the derived model estimates wing strain with good accuracy. In-vacuum, the wing has a large 3ω response when flapping at approximately one-third of its natural frequency due to a superharmonic resonance, where the superharmonic occurs due to the interaction of inertial forces and time-varying centrifugal softening. In-air, this 3ω response is attenuated significantly as a result of aerodynamic damping, whereas the primary ω response is increased due to aerodynamic loading. These results highlight the importance of (1) bilateral coupling between the fluid and structure, since unilaterally coupled approaches do not adequately describe deformation-induced aerodynamic damping and (2) time-varying stiffness, which generates superharmonics of the flapping frequency in the wing’s dynamic response. The simple SDOF model and experimental study presented in this work demonstrate the potential for a reduced-order FSI model that considers both bilateral fluid–structure coupling and realistic multi-degrees-of-freedom flapping kinematics moving forward.

Study on Interference between Wires and Mobile Platform in a Wire-Driven Parallel Manipulator Based on ADAMS

2013 ◽  
Vol 694-697 ◽  
pp. 1671-1674
Author(s):  
Sui Lu Yue ◽  
Qi Lin ◽  
Yi Xin Chen ◽  
Zhao Wang
Keyword(s):  
Simulation Model ◽  
Parallel Manipulator ◽  
Virtual Prototyping ◽  
Mobile Platform ◽  
Time Varying ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Virtual Prototyping Technology ◽  
The Wire ◽  
Hinge Points

In this paper, to avoid interference between wires and a mobile platform in a wire-driven parallel suspension system, the simulation model of time-varying wires structure is established by applying the ADAMS virtual prototyping technology. The law of motion of hinge points is planned when the mobile platform performs a single degree of freedom pitch rotation. Using the simulation model of the time-varying wires structure, the interference is investigated. The results show that the simulation model is able to analyze the interference between wires and the mobile platform rapidly and provides an effective method for the design of the wire-driven parallel mechanism. Therefore, the interference can be avoided in the wire-driven parallel manipulator with time-varying wires structure, and the workspace of the mobile platform can be enlarged.

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