Spatial asymmetric/symmetric buckling of Mises truss with out-of-plane lateral linear spring

2021 ◽  
Vol 137 ◽  
pp. 103810
Author(s):  
William T.M. Silva ◽  
Klaus Q. Ribeiro
Keyword(s):  
Out Of Plane ◽  
Linear Spring

Dynamic Electromechanical Modeling of a Spring-Biased Dielectric Electroactive Polymer Actuator System

2014 ◽  
Author(s):  
Gianluca Rizzello ◽  
Micah Hodgins ◽  
David Naso ◽  
Alexander York ◽  
Stefan Seelecke
Keyword(s):  
Position Control ◽  
Compressive Force ◽  
Electromechanical Modeling ◽  
Out Of Plane ◽  
Polymer Actuator ◽  
Linear Spring ◽  
Actuator System ◽  
Plane Direction ◽  
Electromechanical Dynamics ◽  
Driving Circuit

This paper presents a dynamic electromechanical model for an actuator system based on a Dielectric Electro-Active Polymer (DEAP) membrane biased with a linear spring. The motion is generated by the deformation of the membrane caused by the electrostatic compressive force between two compliant electrodes applied on the surface of the polymer. A mass and a linear spring are used to pre-load the membrane, allowing stroke in the out-of-plane direction. The development of mathematical models which accurately describe the nonlinear system dynamics is a fundamental step in order to design model-based, high-precision position control algorithms. In particular, knowledge of the nonlinear electrical dynamics of the actuator driving circuit can be exploited during the control system design in order to achieve desirable features, such as self-sensing or control energy minimization. This work proposes an electromechanical physical model of the DEAP actuator system. By means of numerous experiments, it is shown that the model can be used to predict the current by measuring deformation and voltage (electrical dynamics), as well as predicting deformation and current by measuring the voltage (electromechanical dynamics).

Experimental Investigation of a Loaded Circular Dielectric Electro-Active Polymer Actuator Coupled to Negative-Rate Bias Spring Mechanism

2012 ◽  
Author(s):  
Micah Hodgins ◽  
Alex York ◽  
Stefan Seelecke
Keyword(s):  
Constant Force ◽  
Loading Rates ◽  
Stable Element ◽  
Stable Mechanism ◽  
Out Of Plane ◽  
Polymer Actuator ◽  
Linear Spring ◽  
Spring Mechanism ◽  
Plane Displacement ◽  
Force Equilibrium

A constant force input, a linear spring, and a bi-stable mechanism are separately tested as the biasing element of a circular/diaphragm DEAP. Each of the bias elements are systematically coupled to an unloaded 2 layer DEAP and are tested under various DEAP pre-deflections, bias element stiffness and electrical loading rates. The out-of-plane displacement output is measured as the voltage is cycled. The tests showed that the bi-stable element, with aid of a mechanical stop, gave the largest displacement output. This bi-stable element actuator is then tested against a hanging mass to examine the work capabilities against a constant force. However, the actuator failed to work even against a hanging mass of 20 grams. This change in behavior of the actuator is analyzed by considering the force equilibrium curves. Finally, suggestions are made for the design of future biasing methods in order to achieve higher actuator performance.

Large Amplitude Free Vibration Analysis of a Rotating Beam with Non-linear Spring and Mass System

2005 ◽  
Vol 11 (12) ◽  
pp. 1511-1533 ◽  
Author(s):  
S. K. Das ◽  
P. C. Ray ◽  
G. Pohit
Keyword(s):  
Free Vibration Analysis ◽  
Linear Constraint ◽  
Multiple Time Scales ◽  
Multiple Time ◽  
Rotating Beam ◽  
Mass System ◽  
Linear Partial Differential Equations ◽  
Non Linear ◽  
Out Of Plane ◽  
Linear Spring

The free, out-of-plane vibration of a rotating beam with a non-linear spring-mass system has been investigated. The non-linear constraint appears in the boundary condition. The solution is obtained by applying the method of multiple time-scales directly to the non-linear partial differential equations and the boundary conditions. The results of the linear frequencies match well with those obtained in the literature. Subsequent non-linear study indicates that there is a pronounced effect of the spring and its mass. The influence of the spring-mass location on frequencies is also investigated for the non-linear frequencies of the rotating beam.

Grain separation enhanced magnetic coercivity in Pt/Co multilayers.

1993 ◽  
Vol 51 ◽  
pp. 1038-1039 ◽  
Author(s):  
G.A. Bertero ◽  
R. Sinclair
Keyword(s):  
Remanent Magnetization ◽  
Strong Influence ◽  
Uniaxial Anisotropy ◽  
Magnetic Coupling ◽  
Recording Media ◽  
Magnetic Media ◽  
Signal To Noise ◽  
Out Of Plane ◽  
Longitudinal Recording ◽  
The Relationship

Pt/Co multilayers displaying perpendicular (out-of-plane) magnetic anisotropy and 100% perpendicular remanent magnetization are strong candidates as magnetic media for the next generation of magneto-optic recording devices. The magnetic coercivity, Hc, and uniaxial anisotropy energy, Ku, are two important materials parameters, among others, in the quest to achieving higher recording densities with acceptable signal to noise ratios (SNR). The relationship between Ku and Hc in these films is not a simple one since features such as grain boundaries, for example, can have a strong influence on Hc but affect Ku only in a secondary manner. In this regard grain boundary separation provides a way to minimize the grain-to-grain magnetic coupling which is known to result in larger coercivities and improved SNR as has been discussed extensively in the literature for conventional longitudinal recording media.We present here results from the deposition of two Pt/Co/Tb multilayers (A and B) which show significant differences in their coercive fields.

Anisotropy of Nanoindentation – a tool for the determination of nanocrystal orientation ?

2003 ◽  
Vol 779 ◽  
Author(s):  
David Christopher ◽  
Steven Kenny ◽  
Roger Smith ◽  
Asta Richter ◽  
Bodo Wolf ◽  
...  
Keyword(s):  
Crystal Surface ◽  
Scanning Force Microscopy ◽  
Depth Range ◽  
Dislocation Loops ◽  
Force Microscopy ◽  
Pile Up ◽  
Out Of Plane ◽  
Scanning Force ◽  
Dynamics Simulations

AbstractThe pile up patterns arising in nanoindentation are shown to be indicative of the sample crystal symmetry. To explain and interpret these patterns, complementary molecular dynamics simulations and experiments have been performed to determine the atomistic mechanisms of the nanoindentation process in single crystal Fe{110}. The simulations show that dislocation loops start from the tip and end on the crystal surface propagating outwards along the four in-plane <111> directions. These loops carry material away from the indenter and form bumps on the surface along these directions separated from the piled-up material around the indenter hole. Atoms also move in the two out-of-plane <111> directions causing propagation of subsurface defects and pile-up around the hole. This finding is confirmed by scanning force microscopy mapping of the imprint, the piling-up pattern proving a suitable indicator of the surface crystallography. Experimental force-depth curves over the depth range of a few nanometers do not appear smooth and show distinct pop-ins. On the sub-nanometer scale these pop-ins are also visible in the simulation curves and occur as a result of the initiation of the dislocation loops from the tip.

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