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.

scholarly journals Symmetric waterbomb origami

2016 ◽  
Vol 472 (2190) ◽  
pp. 20150846 ◽  
Author(s):  
Yan Chen ◽  
Huijuan Feng ◽  
Jiayao Ma ◽  
Rui Peng ◽  
Zhong You
Keyword(s):  
Degrees Of Freedom ◽  
Degree Of Freedom ◽  
Solar Panels ◽  
Deployable Structures ◽  
Single Degree Of Freedom ◽  
Folding Process ◽  
Multiple Degrees Of Freedom ◽  
Single Degree ◽  
Flat Roofs ◽  
Additional Constraints

The traditional waterbomb origami, produced from a pattern consisting of a series of vertices where six creases meet, is one of the most widely used origami patterns. From a rigid origami viewpoint, it generally has multiple degrees of freedom, but when the pattern is folded symmetrically, the mobility reduces to one. This paper presents a thorough kinematic investigation on symmetric folding of the waterbomb pattern. It has been found that the pattern can have two folding paths under certain circumstance. Moreover, the pattern can be used to fold thick panels. Not only do the additional constraints imposed to fold the thick panels lead to single degree of freedom folding, but the folding process is also kinematically equivalent to the origami of zero-thickness sheets. The findings pave the way for the pattern being readily used to fold deployable structures ranging from flat roofs to large solar panels.

scholarly journals Evaluation of Soil–Structure Interaction in Structure Models via Shaking Table Test

2021 ◽  
Vol 13 (9) ◽  
pp. 4995
Author(s):  
Seongnoh Ahn ◽  
Gun Park ◽  
Hyungchul Yoon ◽  
Jae-Hyeok Han ◽  
Jongwon Jung
Keyword(s):  
Numerical Analysis ◽  
Soil Structure ◽  
Degrees Of Freedom ◽  
Degree Of Freedom ◽  
Shaking Table ◽  
Soil Structure Interaction ◽  
Single Degree Of Freedom ◽  
Structure Interaction ◽  
Multiple Degrees Of Freedom ◽  
Single Degree

Modeling the soil–structure interaction (SSI) in seismic design involves the use of soil response curves for single-degree-of-freedom (SDOF) structures; however, real structures have multiple degrees of freedom (MDOF). In this study, shaking-table-derived p-y curves for SDOF and MDOF superstructures were compared using numerical analysis. It was found that an MDOF structure experienced less displacement than an SDOF structure of the same weight, but the effect of increasing the DOF decreased at greater pile depths. Numerical analysis results estimated using the natural periods and mass participation rates of the structures were similar to those of shaking table tests. Abbreviations: finite element: FE; frequency response function: FRF; multiple degrees of freedom: MDOF; single degree of freedom: SDOF; soil–structure interaction: SSI.

Research on Dynamics Simulation of Moving and Stationary Vibration Screen

2013 ◽  
Vol 415 ◽  
pp. 451-456
Author(s):  
Shao Hua Xu ◽  
Wen Cheng Cao ◽  
Li Zeng
Keyword(s):  
Degrees Of Freedom ◽  
Dynamics Simulation ◽  
Simulation Research ◽  
Single Degree Of Freedom ◽  
Multiple Degrees Of Freedom ◽  
Single Degree ◽  
Runge Kutta Method ◽  
Modes Of Vibration ◽  
Stationary Vibration ◽  
Matlab Programming

The vibrating modes of vibration screen box can be divided into single degree of freedom excitation and multiple degrees of freedom excitation. This paper puts forward the conception of multiple degrees of freedom excitation and sets up the dynamic equation of multiple degrees of freedom excitation vibration screen while the characteristics of one freedom vibration screen are summarized. Through the MATLAB programming language, using the four order Runge-Kutta method, we do a dynamics simulation research on an instance for this type of vibration screen, and analyze the characteristics of this type of vibration screen.

Decoupling Free Vibration System of Bridge Section Model

2011 ◽  
Vol 199-200 ◽  
pp. 891-894
Author(s):  
Ming Jing Zhang ◽  
Da Bo Xin
Keyword(s):  
Free Vibration ◽  
Degrees Of Freedom ◽  
Vibration System ◽  
Single Degree Of Freedom ◽  
Multiple Degrees Of Freedom ◽  
Single Degree ◽  
Data Measurement ◽  
Spring Suspension ◽  
Acquisition Device ◽  
Section Model

In the paper the free vibration system of bridge section model is designed in order to measure the wind-induced effects on the bridge section model in the wind tunnel. In the system the suspension device is constituted with decoupling sliding components and simple spring suspension. Meanwhile, a set of data measurement and acquisition device based on the Labview is provided in the system. The measurement on the wind-induced static force, flutter and vortex-induced vibration of the bridge section model can be conducted at single degree of freedom or multiple degrees of freedom.

A Method for Type Synthesis of Mechanisms Using Phase Diagrams

1994 ◽  
Author(s):  
Sio-Hou Lei ◽  
Ying-Chien Tsai
Keyword(s):  
Phase Diagram ◽  
Degrees Of Freedom ◽  
Practical Application ◽  
Type Synthesis ◽  
Planar Mechanisms ◽  
Simple Loop ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Spatial Mechanisms ◽  
Synthesis Of Mechanisms

Abstract A method for synthesizing the types of spatial as well as planar mechanisms is expressed in this paper by using the concept of phase diagram in metallurgy. The concept represented as a type synthesis technique is applied to (a) planar mechanisms with n degrees of freedom and simple loop, (b) spatial mechanisms with single degree of freedom and simple loop, to enumerate all the possible mechanisms with physically realizable kinematic pairs. Based on the technique described, a set of new reciprocating mechanisms is generated as a practical application.

PSEUDO PROBABILISTIC APPROACH TO TEST ISOMORPHISM AMONG KINEMATIC CHAINS

1997 ◽  
Vol 21 (2) ◽  
pp. 65-83 ◽  
Author(s):  
S. Shubhashis ◽  
M. Choubey ◽  
A.C. Rao
Keyword(s):  
Numerical Scheme ◽  
Degrees Of Freedom ◽  
Probabilistic Approach ◽  
Kinematic Chain ◽  
Single Degree Of Freedom ◽  
Reliable Test ◽  
Kinematic Chains ◽  
Single Degree ◽  
Unique Method ◽  
P Matrix

There is no dearth of methods to test isomorphism amongst kinematic chains. Search for a computationally easier, logically simple and unique method is still on. Present work is in quest of a reliable test to detect isomorphism among kinematic chains. Work presented here is more versatile as it incorporates more features of the kinematic chain which were not included earlier such as number and type of links, their relative dispositions in the kinematic chain, nature of adjacent links etc. The method proposed is based on the concept of pseudo-probability (pseudo means it appears to be, but not exactly. The approach does not follow in-toto the principles of probability and considerable liberty has been taken in interpreting the word probability hence the word pseudo is used along with the probability schemes). Using the resemblance of different coloured balls in an urn for the number and type of links in a kinematic chain, a matrix (named P-Matrix) representing the kinematic chain in totality is generated. For the sake of comparison a numerical scheme named, pseudo probability scheme, P-Scheme, is developed from the above P-Matrix and is used for testing isomorphism. In fact the method is more powerful in the sense that each row of the proposed P-Matrix is capable of representing the respective kinematic chain distinctly and can be used to compare the kinematic chains with same link assortments, uniquely. The proposed method, besides possessing the potential of testing the isomorphism among simple-joint, single degree of freedom kinematic chains is also capable of multi degrees of freedom and multiple-joint kinematic chains.

A guide to classical flutter

1988 ◽  
Vol 92 (919) ◽  
pp. 339-355 ◽  
Author(s):  
L. T. Niblett
Keyword(s):  
Degrees Of Freedom ◽  
Normal Modes ◽  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Structural Coupling ◽  
Two Degrees Of Freedom ◽  
Single Degree ◽  
Lifting Surface ◽  
Classical Flutter ◽  
Comprehensive Study

Summary First essentials of classical flutter are demonstrated by a comprehensive study of the behaviour of a lifting surface with two degrees of freedom under the action of airforces limited to those in phase with displacement. Structural coupling between the coordinates is eliminated by taking the normal modes to be the deflection coordinates, and this results in conditions for stability with particularly concise forms. It is shown that the flutter stability can be seen to be very much a matter of the relative amplitudes of heave and pitch in the normal modes. In-quadrature airforces are then introduced and it is shown that they have little effect when the flutter is severe. They are of more importance in the milder forms of flutter, the extreme of which are shown to be little different from instabilities in a single degree of freedom.

Localization Phenomena of Nonlinear Vibrations in Three-Blade Wind Turbines

2013 ◽  
Author(s):  
Takashi Ikeda ◽  
Yuji Harata ◽  
Hisashi Takahashi ◽  
Yukio Ishida
Keyword(s):  
Wind Turbines ◽  
Degrees Of Freedom ◽  
Nonlinear Vibrations ◽  
Coupled System ◽  
Wind Pressure ◽  
Response Curves ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Frequency Responses ◽  
Time Histories

Vibration characteristics of three-blade wind turbines are investigated. The system is modeled by a coupled system of the flexible tower with two degrees of freedom and each blade with a single degree of freedom, and these blades are subjected to wind pressure which varies depending on the height from the ground. The vibrations of the three-blade wind turbines are theoretically analyzed to determine the natural frequency diagrams, frequency responses, stationary time histories and their FFT results. It is found that several peaks appear at the specific range of the rotational speed ω in the response curves because of both the wind pressure and the parametric excitation terms. In three-blade wind turbines, vibrations including predominant components of 3ω and its higher harmonics appear near these peaks. The response curves near the highest peak exhibit soft spring types due to the nonlinearities of the restoring moments of the blades. In the numerical simulations, “localization phenomena” in the blades, which vibrate at different amplitudes, are observed. The influence of an imperfection of the three blades is also examined.

Wave Propagation in Sandwich Structures With Multiresonators

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
J. S. Chen ◽  
Y. J. Huang
Keyword(s):  
Wave Propagation ◽  
Timoshenko Beam ◽  
Degrees Of Freedom ◽  
Wave Attenuation ◽  
Sandwich Beam ◽  
Sandwich Beams ◽  
Central Frequency ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
In Series

A new sandwich beam with embedded multiresonators is presented. Two continuum Timoshenko beam models are adopted for modeling sandwich beams. Numerical results show that multiple resonators can lead to multiple resonant-type bandgaps with remarkable wave attenuation. The effective mass is found to become negative for frequencies in the bandgaps where the wave is greatly attenuated. With two identical resonators connected in parallel, only one single bandgap can be found. If two resonators with equal masses and springs are connected in series, the central frequency of the second bandgap is approximated twice of the central frequency of the first gap. For the beam with series-connected resonators, a simple two degrees-of-freedom system is proposed and used for predicting the initial frequencies of the bandgaps while for the beam with resonators in parallel, two separate single degree-of-freedom systems are introduced.

Vibrations

2017 ◽  
pp. 44-93
Keyword(s):  
Degrees Of Freedom ◽  
Normal Modes ◽  
Mode Shapes ◽  
Continuous Systems ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Mdof Systems ◽  
Parametric Coupling ◽  
Bending Modes ◽  
Stability Concepts

Vibration concepts are reviewed. Single degree-of-freedom vibration (SDOF) are analyzed. Subsequently, the analysis is extended to two degrees-of-freedom (2DOF) systems and coupling in a 2DOF system. The analysis of parametric coupling is introduced. Two sections on energy flow and the modeling of damping follow. Normal modes and mode shapes for systems with multiple degrees-of-freedom (MDOF) will then be considered. By generalizing MDOF systems to continuous systems, we can analyze bending modes in plates. Experimental modal analysis is introduced to prepare the reader for later application of this technique to full-scale operational gates. The second section of this chapter reviews fundamental concepts of fluid-structure systems with resonance. The chapter concludes with a short discussion of stability concepts.

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