Modeling and Design of an Optically Powered Microactuator for a Microfluidic Dispenser

2005 ◽  
Vol 127 (4) ◽  
pp. 825-836 ◽  
Author(s):  
Mandar Deshpande ◽  
Laxman Saggere
Keyword(s):  
Solar Cell ◽  
Analytical Model ◽  
Potential Application ◽  
Analytical Models ◽  
Element Analysis ◽  
Input And Output ◽  
Flow Through ◽  
Liquid Chemical ◽  
Key Dimensions ◽  
Piezoelectric Unimorph

This paper presents systematic modeling and design of an optically powered piezoelectric microactuator for driving a microfluidic dispenser that could find a potential application in a retinal prosthesis. The first part of the paper treats a microactuator system comprised of a micron-scale piezoelectric unimorph integrated with a miniaturized solid-state solar cell. The microactuator design is tailored for driving a microfluidic dispenser to dispense a stored liquid chemical through its micron-sized outlet ports at a rate of about 1pl∕s when the integrated solar cell is irradiated by light at a power density of 3W∕m2, corresponding to the requirements of the potential application. The microactuator system design is accomplished by first obtaining analytical models for the solar cell characteristic behavior and the microactuator displacements and then combining them to obtain the key dimensions of the microactuator through a design optimization. An analysis of the performance characteristics of the microactuator and a finite element analysis validating the analytical model for the microactuator’s displacements and the peak stresses under the operating loads are presented. The latter part of the paper presents a design of a microfluidic dispenser utilizing the optically powered microactuator and satisfying the desired input/output requirements. An analytical model integrating various energy domains involved in the system, viz. opto-electrical, piezoelectric, mechanical and hydraulic, is derived for the liquid flow through the dispenser’s micron-sized outlet ports. Finally, the energetic feasibility of the microactuator design obtained for the specified input and output criteria is also discussed.

Updating of Non-Conservative Systems Using Inverse Methods

1997 ◽  
Author(s):  
Ladislav Starek ◽  
Milos Musil ◽  
Daniel J. Inman
Keyword(s):  
Analytical Model ◽  
Degrees Of Freedom ◽  
Ad Hoc ◽  
Natural Frequencies ◽  
Eigenvalue Problems ◽  
Model Updating ◽  
Analytical Models ◽  
Mode Shapes ◽  
Element Analysis ◽  
Modal Data

Abstract Several incompatibilities exist between analytical models and experimentally obtained data for many systems. In particular finite element analysis (FEA) modeling often produces analytical modal data that does not agree with measured modal data from experimental modal analysis (EMA). These two methods account for the majority of activity in vibration modeling used in industry. The existence of these discrepancies has spanned the discipline of model updating as summarized in the review articles by Inman (1990), Imregun (1991), and Friswell (1995). In this situation the analytical model is characterized by a large number of degrees of freedom (and hence modes), ad hoc damping mechanisms and real eigenvectors (mode shapes). The FEM model produces a mass, damping and stiffness matrix which is numerically solved for modal data consisting of natural frequencies, mode shapes and damping ratios. Common practice is to compare this analytically generated modal data with natural frequencies, mode shapes and damping ratios obtained from EMA. The EMA data is characterized by a small number of modes, incomplete and complex mode shapes and non proportional damping. It is very common in practice for this experimentally obtained modal data to be in minor disagreement with the analytically derived modal data. The point of view taken is that the analytical model is in error and must be refined or corrected based on experimented data. The approach proposed here is to use the results of inverse eigenvalue problems to develop methods for model updating for damped systems. The inverse problem has been addressed by Lancaster and Maroulas (1987), Starek and Inman (1992,1993,1994,1997) and is summarized for undamped systems in the text by Gladwell (1986). There are many sophisticated model updating methods available. The purpose of this paper is to introduce using inverse eigenvalues calculated as a possible approach to solving the model updating problem. The approach is new and as such many of the practical and important issues of noise, incomplete data, etc. are not yet resolved. Hence, the method introduced here is only useful for low order lumped parameter models of the type used for machines rather than structures. In particular, it will be assumed that the entries and geometry of the lumped components is also known.

Characterization and Modeling of Elastomeric Joints in Miniature Compliant Mechanisms

2013 ◽  
Vol 5 (4) ◽  
Author(s):  
Dana E. Vogtmann ◽  
Satyandra K. Gupta ◽  
Sarah Bergbreiter
Keyword(s):  
Analytical Model ◽  
Compliant Mechanisms ◽  
Analytical Models ◽  
Accurate Analysis ◽  
Element Analysis ◽  
Fea Model ◽  
Torsional Spring ◽  
Tension Tests ◽  
In Series ◽  
Efficient Exploration

Accurate analysis models are critical for effectively utilizing elastomeric joints in miniature compliant mechanisms. This paper presents work toward the characterization and modeling of miniature elastomeric hinges. Characterization was carried out in the form of several experimental bending tests and tension tests on representative hinges in five different configurations. The modeling portion is achieved using a planar pseudo rigid body (PRB) analytical model for these hinges. A simplified planar 3-spring PRB analytical model was developed, consisting of a torsional spring, an axial spring, and another torsional spring in series. These analytical models enable the efficient exploration of large design spaces. The analytical model has been verified to within an accuracy of 3% error in pure bending, and 7% in pure tension, when compared to finite element analysis (FEA) models. Using this analytical model, a complete mechanism—a robotic leg consisting of four rigid links and four compliant hinges—has been analyzed and compared to a corresponding FEA model and a fabricated mechanism.

Development of a generalized analytical model for tubular braided-architecture composites

2017 ◽  
Vol 51 (28) ◽  
pp. 3861-3875 ◽  
Author(s):  
Garrett W Melenka ◽  
Jason P Carey
Keyword(s):  
Elastic Properties ◽  
Analytical Model ◽  
Volume Averaging ◽  
Analytical Models ◽  
Braided Composites ◽  
Element Analysis ◽  
Shear Moduli ◽  
Braided Structure ◽  
Braiding Angle ◽  
Analysis Models

Tubular braided composites are manufactured using a Maypole braiding machine which interlaces yarns in order to manufacture a braided structure. Braids can be produced in Diamond (1/1), Regular (2/2) and Hercules (3/3) patterns. In addition, axial yarns can be included in order to produce triaxial braid structures. Several analytical and finite element analysis models have been developed in order to predict the elastic properties of braided composites. Despite the fact that many models exist for braided composites, a comprehensive model has not been presented that can capture the variety of braiding patterns which can be manufactured using the braiding process. In this study, a new analytical model has been developed that can describe the elastic properties of Diamond, Regular and Hercules braids. The proposed analytical model uses a volume averaging stiffness method in order to account for yarn undulations and the orientation of braid yarns within the braid structure. The model presented here has been compared with the existing FEA and analytical models and has also been validated experimentally. Experimental validation comprised tensile and torsional tests in order to predict the longitudinal and shear moduli for both Diamond and Regular braid geometries. The experimental and proposed model results highlight the effect of braiding pattern and braiding angle on the mechanical properties.

Effect of Ply Stacking Sequence on Structural Response of Symmetric Composite Laminates

2014 ◽  
Author(s):  
Mosfequr Rahman ◽  
Saheem Absar ◽  
F. N. U. Aktaruzzaman ◽  
Abdur Rahman ◽  
N. M. Awlad Hossain
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Analytical Model ◽  
Composite Laminates ◽  
Structural Response ◽  
Laminated Composite ◽  
Analytical Models ◽  
Orthotropic Materials ◽  
Stacking Sequence ◽  
Element Analysis

In this work, the effect of ply stacking sequence on the structural response of multi-ply unidirectional fiber-reinforced composite laminates was evaluated using finite element analysis. The objective of this study was to develop a computational model to analyze the stress response of individual plies in a composite laminate for a given stacking sequence. A laminated composite plate structure under tensile loading was modeled in ANSYS. Stress profiles of the individual plies were obtained for each lamina. An Epoxy matrix with both unidirectional Graphite and Kevlar fibers was considered for the model. Three dimensional sectioned shell elements (SHELL181) were used for meshing the model. Several sets of stacking sequences were implemented, symmetrical to the mid-plane of the laminate. Symmetric stacking configurations of 6 layers stacked in ply angles of [0/45/-45]s, [0/60/-60]s, [0/45/90]s, and an 8-layered arrangement of [0/45/60/90]s were modeled for the analysis. The layer thickness was maintained at 0.1 mm. The results were compared against an analytical model based on the generalized Hooke’s law for orthotropic materials and classical laminate theory. A numerical formulation of the analytical model was implemented in MATLAB to evaluate the constitutive equations for each lamina. The stress distributions obtained using finite element analysis have shown good agreement with the analytical models in some of the cases.

Analytical model for harmonic response of dissimilar single-lap joints

2017 ◽  
Vol 232 (4) ◽  
pp. 457-472 ◽  
Author(s):  
Mohamed O Gafar ◽  
Khalid H Almitani ◽  
Ramzi Othman
Keyword(s):  
Analytical Model ◽  
Adhesive Bonding ◽  
Natural Frequencies ◽  
Transfer Functions ◽  
Lap Joints ◽  
Analytical Models ◽  
Main Concern ◽  
Element Analysis ◽  
Harmonic Response ◽  
Single Lap Joints

Adhesive bonding is increasingly used in automobile, marine and aeronautical structures. The dynamic response of adhesively bonded joints is therefore a main concern. This paper deals with the harmonic response of single-lap joints. A closed-form analytical solution is derived to account for the case of joints with dissimilar substrates. The transfer functions predicted by the analytical model match well the transfer functions predicted by a two-dimensional finite element analysis, and so do the natural frequencies. The numerical and analytical models show that the natural frequencies are sensitive to the order of substrates. Mainly, fixing the end of the stiffer substrate leads to natural frequencies that are mostly higher than those which are obtained by fixing the end of the softer substrate.

Characterization and Modeling of Elastomeric Joints in Miniature Compliant Mechanisms

2012 ◽  
Author(s):  
Dana E. Vogtmann ◽  
Satyandra K. Gupta ◽  
Sarah Bergbreiter
Keyword(s):  
Analytical Model ◽  
Compliant Mechanisms ◽  
Analytical Models ◽  
Accurate Analysis ◽  
Element Analysis ◽  
Torsional Spring ◽  
Tension Tests ◽  
In Series ◽  
Linear Spring ◽  
Analysis Models

Accurate analysis models are critical for effectively utilizing elastomeric joints in miniature compliant mechanisms. This paper presents work toward the characterization and modeling of miniature elastomeric hinges. The modeling portion is achieved using finite element analysis (FEA). Also presented is a 2-dimensional pseudo rigid body (PRB) analytical model for these hinges. Characterization was carried out in the form of several experimental bending tests and tension tests on representative hinges in 5 different configurations. The results of these experiments were then compared to the same tests modeled using FEA. We have represented the experimental results using FEA to within 12% error. This allows the use of FEA to model more complicated mechanisms’ behavior with some assurance of accuracy. Based on these tests and FEA models, a simplified 2-dimensional PRB analytical model was developed, consisting of a torsional spring, a linear spring, and another torsional spring in series. These analytical models enable us explore large design spaces efficiently. The accuracy of this model for geometries without corner effects has been verified to within 3% error when compared to FEA models in bending, and 17% in tension.

A Nonlinear Analytical Model for Flexible Pipe Crushing Analysis

2012 ◽  
Author(s):  
Celso P. Pesce ◽  
Guilherme R. Franzini ◽  
Marcos A. Rabelo ◽  
Roberto Ramos ◽  
Rodolfo T. Gonçalves ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Analytical Model ◽  
Analytical Modeling ◽  
Present Model ◽  
Analytical Models ◽  
Flexible Pipe ◽  
Element Analysis ◽  
Plastic Analysis ◽  
Nonlinear Analytical Model ◽  
Combined Action

This paper discusses a nonlinear analytical model for flexible pipe crushing analysis, improving analytical models previously published in OMAE2003, 2010 and 2011. Following that path, and still based on the concept of equivalent pipes and rings, the present model discusses a strategy to cope with an elastic-to-plastic analysis. Such a model considers the combined action of squeezing and concentrated loads applied as representing those due to the caterpillar shoes. Experimental results and finite element analysis are used to assess the pertinence of analytical modeling hypotheses.

Design of a cutting head for a crosscutting machine

2016 ◽  
Vol 231 (1) ◽  
pp. 5-17 ◽  
Author(s):  
D Croccolo ◽  
M De Agostinis ◽  
S Fini
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Structural Analysis ◽  
Dynamic Behavior ◽  
Analytical Model ◽  
Analytical Models ◽  
Rectangular Section ◽  
Element Analysis ◽  
Cutting Head ◽  
Numerical Finite Element

The present paper deals with the structural analysis and the re-design of a cutting head for an automatic crosscutting machine. The machine is already marketed, and can process rectangular section wooden slats. The principal goal of this work is to develop a new mechanism capable of enhancing the productivity of the machine by around 80%. The work has been carried out by means of both numerical finite element analysis tools and analytical models. In fact, a secondary aim of the research is to define an analytical model which can capture the dynamic behavior of the device: this tool will be helpful to the design engineer in order to save costs associated with the development of future head designs.

Evaluation of web reinforcements in prestressed concrete box girders through shear-transverse bending domains

2020 ◽  
pp. 136943322098170
Author(s):  
Michele Fabio Granata ◽  
Antonino Recupero
Keyword(s):  
Analytical Model ◽  
Prestressed Concrete ◽  
3D Analysis ◽  
Box Girders ◽  
Element Analysis ◽  
Cross Sectional ◽  
Interaction Domains ◽  
Global And Local ◽  
Resultant Forces

In concrete box girders, the amount and distribution of reinforcements in the webs have to be estimated considering the local effects due to eccentric external loads and cross-sectional distortion and not only the global effect due to the resultant forces of a longitudinal analysis: shear, torsion and bending. This work presents an analytical model that allows designers to take into account the interaction of all these effects, global and local, for the determination of the reinforcements. The model is based on the theory of stress fields and it has been compared to a 3D finite element analysis, in order to validate the interaction domains. The results show how the proposed analytical model allows an easy and reliable reinforcement evaluation, in agreement with a more refined 3D analysis but with a reduced computational burden.

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