Optimization of Piezoelectric Uniflex Microactuators

2009 ◽  
Author(s):  
Hareesh K. R. Kommepalli ◽  
Christopher D. Rahn ◽  
Srinivas A. Tadigadapa
Keyword(s):  
Large Amplitude ◽  
Piezoelectric Actuators ◽  
Small Strain ◽  
Large Displacement ◽  
Relative Performance ◽  
Analytical Models ◽  
Amplitude Response ◽  
Rf Switches ◽  
Controlled Motion

Microactuators provide controlled motion and force for applications ranging from RF switches to rate gyros. Large amplitude response in piezoelectric actuators requires amplification of their small strain. This paper studies the performance of a uniflex actuator in terms of its displacement and blocking force compared to uniflex and flextensional actuators. A uniflex microactuator combines the strain amplification mechanisms of a unimorph and flexural motion to produce large displacement and blocking force. Analytical models for displacement and blocking force for all the three actuators are used in optimization, to study their relative performance. The uniflex actuator outperforms both unimorph and flextensional actuators in displacement, but, the unimorph actuator generates more blocking force. The uniflex actuator can therefore be used in applications that demand higher displacement and lower blocking force compared to a unimorph actuator.

Displacement and Blocking Force Modeling for Piezoelectric Uniflex Microactuators

2008 ◽  
Author(s):  
Hareesh K. R. Kommepalli ◽  
Han G. Yu ◽  
Srinivas A. Tadigadapa ◽  
Christopher D. Rahn ◽  
Susan Trolier-McKinstry ◽  
...  
Keyword(s):  
Boundary Condition ◽  
Applied Voltage ◽  
Piezoelectric Actuators ◽  
Small Strain ◽  
Amplitude Response ◽  
Rf Switches ◽  
Symmetric Boundary Condition ◽  
Force Modeling ◽  
Controlled Motion ◽  
Parameter Ranges

Microactuators provide controlled motion and force for applications ranging from RF switches to rate gyros. Large amplitude response in piezoelectric actuators requires amplification of their small strain. This paper studies a uniflex microactuator that combines the strain amplification mechanisms of a unimorph and flexural motion to produce large displacement and blocking force. An analytical model is developed with three connected beams and a reflective symmetric boundary condition that predicts actuator displacement and blocking force as a function of the applied voltage. The model shows that the uniflex design requires appropriate parameter ranges, especially the clearance between the unimorph and aluminum cap, to ensure that both the unimorph and flexural amplification effects are realized. With a weakened joint at the unimorph/cap interface, the model accurately predicts the displacement and blocking force of four actuators.

Limit Loads of Buried Pipelines With Asymmetric Initial Imperfections

1990 ◽  
Vol 112 (4) ◽  
pp. 392-396 ◽  
Author(s):  
C. G. Koh ◽  
S. T. Quek
Keyword(s):  
Initial Imperfection ◽  
Limit Load ◽  
Small Strain ◽  
Large Displacement ◽  
Rigid Foundation ◽  
Buried Pipelines ◽  
Limit Loads ◽  
Initial Imperfections ◽  
Load Response ◽  
The Difference

The effect of asymmetric imperfection on the limit-load response of pipelines buried in shallow trenches is investigated. The pipeline is modeled as a long beam resting on a rigid foundation and a small strain, large displacement formulation is used. Three different asymmetric imperfection shapes for the beam are considered and the corresponding limit loads are compared with that for a symmetric imperfection. It is found that the shape of initial imperfection plays an important role. The difference between limit loads based on a symmetric imperfection and a nonsymmetric imperfection can be quite significant.

The large amplitude response of functionally graded non-uniform and imperfect nanotube

2021 ◽  
pp. 1-24
Author(s):  
Duquan Zuo ◽  
Guoling Ma ◽  
Yuejie Cao ◽  
Changchun Zhou ◽  
Jinjie Luo
Keyword(s):  
Large Amplitude ◽  
Functionally Graded ◽  
Amplitude Response

Large Displacement Elastoplastic Analysis of Space Trusses as a Mathematical Programming Problem

1998 ◽  
Vol 13 (3) ◽  
pp. 127-136 ◽  
Author(s):  
S.H. Xia ◽  
F. Tin-Loi
Keyword(s):  
Mathematical Programming ◽  
Programming Problem ◽  
Nonlinear Complementarity Problem ◽  
Geometrical Nonlinearity ◽  
Small Strain ◽  
Large Displacement ◽  
Elastoplastic Analysis ◽  
Programming Approach ◽  
Mathematical Programming Problem ◽  
Space Trusses

A mathematical programming approach is proposed for the large displacement elastoplastic analysis of space trusses. Features of the general methodology include the preservation of static-kinematic duality through the concept of fictitious forces and deformations, exact descriptions of equilibrium and compatibility for arbitrarily large displacements, albeit small strain, that can be specialized to any order of geometrical nonlinearity, and a complementarity description of the elastoplastic constitutive laws. The finite incremental formulation developed takes the form of a special mathematical programming problem known as a nonlinear complementarity problem for which a predictor-corrector type numerical scheme is proposed.

Numerical Simulation of the Installation and Extraction Process of Spudcan Foundations in Clay

2009 ◽  
Author(s):  
Jun Liu ◽  
Yuxia Hu
Keyword(s):  
Plastic Material ◽  
Yield Criterion ◽  
Strain Analysis ◽  
Small Strain ◽  
Extraction Process ◽  
Interface Roughness ◽  
Large Displacement ◽  
Centrifuge Model Test ◽  
Element Analysis ◽  
Perfectly Plastic

This paper presents results from large displacement finite element analysis for spudcan foundation penetrating into and extracting from normally consolidated (NC) clay. The soil was idealized as an elastic-perfectly plastic material obeying a Mohr-Coulomb yield criterion and the large displacement analysis was carried out using Remeshing and Interpolating Technique with Small Strain (RITSS) model to simulate the full installation and extraction process. The numerical results were compared with centrifuge model test data and existing analytical solutions. A full parametric study was undertaken to quantify the influence on spudcan extraction process from soil strength profile, foundation interface roughness and penetration depth. The extraction results showed that the normalized uplift resistance after spudcan installation was much lower than that from small strain analysis, and it was also lower than that of pre-embedded case. Thus it is necessary to apply RITSS method in spudcan extraction simulation after installation.

A Harmonic Balance Approximation of Dynamic Snap-Through Boundaries in a Single-Degree-of-Freedom Structure

2013 ◽  
Author(s):  
Richard Wiebe ◽  
Lawrence N. Virgin
Keyword(s):  
Large Amplitude ◽  
Harmonic Balance ◽  
Harmonic Balance Method ◽  
Degree Of Freedom ◽  
Balance Method ◽  
Nonlinear Phenomena ◽  
Amplitude Response ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Analytical Approximations

Under dynamic loading, systems with the requisite condition for snap-through buckling, that is co-existing equilibria, typically exhibit either small amplitude response about a single equilibrium configuration, or large amplitude response that transits between the static equilibria. Dynamic snap-through is the name given to the large amplitude response, which, in the context of structural systems, is obviously undesirable. Structures with underlying snap-through static behavior may exhibit highly nonlinear and unpredictable oscillations. Such systems rarely lend themselves to investigation by analytical means. This is not surprising as nonlinear phenomena such as chaos run counter to the predictability of an analytical closed form solution. However, many unexpected analytical approximations of global stability may be obtained for simple systems using the harmonic balance method. In this paper a simple single-degree-of-freedom arch is studied using the harmonic balance method. The equations developed with the harmonic balance approach are then solved using an arc-length method and an approximate snap-through boundary in forcing parameter space is obtained. The method is shown to exhibit excellent agreement with numerical results. Arches present an ideal avenue for the investigation of snap-through as they typically have multiple, often tunable, stable and unstable equilibria. They also have many applications in both civil engineering, where arches are a canonical structural element, and mechanical/aerospace engineering, where arches may be used to approximate the behavior of curved plates and panels such as those used on aircraft.

scholarly journals The effects of heterogeneous mechanical properties on the response of a ductile material

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yichi Song ◽  
Andreas Schiffer ◽  
Vito L. Tagarielli
Keyword(s):  
Mechanical Properties ◽  
Scaling Law ◽  
Heterogeneous Material ◽  
Small Strain ◽  
Analytical Models ◽  
Elastic Response ◽  
Ductile Material ◽  
Numerical Predictions ◽  
Yield Behaviour ◽  
Computational Homogenisation

AbstractWe investigate numerically the small-strain, elastic–plastic response of statistically isotropic materials with non-uniform spatial distributions of mechanical properties. The numerical predictions are compared to simple bounds derived analytically. We explore systematically the effects of heterogeneity on the macroscopic stiffness, strength, asymmetry, stability and size dependence. Monte Carlo analyses of the response of statistical volume elements are conducted at different strain triaxiality using computational homogenisation, and allow exploring the macroscopic yield behaviour of the heterogeneous material. We illustrate quantitatively how the pressure-sensitivity of the yield surface of the solid increases with heterogeneity in the elastic response. We use the simple analytical models developed here to derive an approximate scaling law linking the fatigue endurance threshold of metallic alloys to their stiffness, yield strength and tensile strength.

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