Engineering Commons^™

Identification Of Macro- And Micro-Compliant Mechanism Configurations Resulting In Bistable Behavior, Brian D. Jensen

Theses and Dissertations

The purpose of this research is to identify the configurations of several mechanism classes which result in bistable behavior. Bistable mechanisms have use in many applications, such as switches, clasps, closures, hinges, and so on. A powerful method for the design of such mechanisms would allow the realization of working designs much more easily than has been possible in the past. A method for the design of bistable mechanisms is especially needed for micro-electro-mechanical systems (MEMS) because fabrication and material constraints often prevent the use of simple, well-known bistable mechanism configurations. In addition, this knowledge allows designers to take advantage …

A Self-Retracting Fully-Compliant Bistable Micromechanism, Nathan D. Masters

Theses and Dissertations

The purpose of this research is to present a class of Self-Retracting Fully-compliant Bistable Micromechanisms (SRFBM). Fully-compliant mechanisms are needed to overcome the inherent limitations of microfabricated pin joints, especially in bistable mechanisms. The elimination of the clearances associated with pin joints will allow more efficient bistable mechanisms with smaller travel. Small travel, in a linear path facilitates integration with efficient on-chip actuators. Tensural pivots are developed and used to deal with the compressive loading to which the mechanism is subject. SRFBM are modeled using the Pseudo-Rigid-Body Model and finite element analysis. Suitable configurations of the SRFBM concept have been …

Development Of In-Plane Compliant Bistable Microrelays, Troy Alan Gomm

Theses and Dissertations

Bistable microrelays have many possible applications and have the potential to reduce the size, weight, power consumption, and cost of products in which they are used. This research outlines the current state of microrelays, presents three new compliant bistable micromechanisms, and characterizes their performance as microrelays. The characterization includes a treatment of a new force-tester, a preliminary contact resistance study, contact-force measurements, switching time measurements, insertion loss, AC isolation, breakdown voltage, and DC isolation. This document also includes recommendations for further research.

The Pseudo-Rigid-Body Model For Dynamic Predictions Of Macro And Micro Compliant Mechanisms, Scott Marvin Lyon

Theses and Dissertations

This work discusses the dynamic predictions of compliant mechanisms using the Pseudo-Rigid-Body model (PRBM). In order to improve the number of mechanisms that can be modeled, this research develops and identifies several key concepts in the behavior of beam segments where both ends are fixed to a rigid body (fixed-fixed flexible segments). A model is presented, and several examples are discussed. The dynamic behavior of several compliant segments is predicted using the PRBM and the results are compared to finite element analysis and experimental results. Details are presented as to the transient behavior of a typical uniform rectangular cross section …

Thermal Microactuators For Microelectromechanical Systems (Mems), Rebecca Cragun

Theses and Dissertations

Microactuators are needed to convert energy into mechanical work at the microscale. Thermal microactuators can be used to produce this needed mechanical work. The purpose of this research was to design, fabricate, and test thermal microactuators for use at the microscale in microelectromechanical systems (MEMS). The microactuators developed were tested to determine the magnitude of their deflection and estimate their force. Five groups of thermal microactuators were designed and tested. All of the groups used the geometrically constrained expansion of various segments to produce their deflection. The first group, Thermal Expansion Devices (TEDs), produced a rotational displacement and had deflections …

On-Chip Actuation Of Compliant Bistable Micro-Mechanisms, Michael S. Baker

Theses and Dissertations

Two compliant bistable micro-mechanisms have been developed which can be switched in either direction using on-chip thermal actuation. The energy storage and bistable behavior of the mechanisms are achieved through the elastic deflection of compliant segments. The pseudo-rigid-body model was used for the compliant mechanism design, and for analysis of the large-deflection flexible segments. To achieve on-chip actuation, the mechanism designs were optimized to reduce their required rotation, allow them to be switched using linear-motion thermal actuators. The modeling theory and analysis are presented for several design iterations. Each iteration was successfully fabricated and tested using either the MUMPs or …

Electrodeposition Of Nickel-Copper Alloys And Nickel-Copper-Alumina Nanocomposites Into Deep Recesses For Mems, Amrit Panda

LSU Doctoral Dissertations

Electrodeposition is an important component in the fabrication of micro electro mechanical systems (MEMS). Nickel is the most commonly used material to produce three dimensional microstructures and few material alternatives have been demonstrated. In this dissertation, electrodeposited Ni-Cu alloys and nanocomposites are investigated as possible replacements for nickel in microsystems. Ni-Cu alloys are attractive for their corrosion resistance, magnetic and thermophysical properties. Alumina nanoparticulates included into metal matrices improve hardness and tribology of deposits. The Ni-Cu alloys and Ni-Cu-g-Al2O3 nanocomposites were electrodeposited from a citrate electrolyte, both at low and high pH. Electrodeposition experiments were performed in recessed microelectrodes 500 …

Manufacturing And Analysis Of A Liga Heat Exchanger For The Surface Of A Tube: A Cooling Simulation Of The Leading Edge Region Of A Turbine Blade, Christophe Marques

LSU Doctoral Dissertations

Fabricating nickel micro heat exchangers directly on planar or non-planar metal surfaces has been demonstrated using the LIGA micromachining process. These heat exchangers can effectively control the temperature of surfaces in high heat flux applications. Of particular interest is the temperature control of gas turbine engine components. The locations in the gas turbine engine where improved, efficient cooling is required includes gas turbine blades, stator vanes, the turbine disk, and the combustor liner. In this dissertation, the primary application of interest is the use of such heat exchangers to cool airfoils such as turbine blades. In the first part of …

The Rapid Template Fabrication Process For Producing A Liga Heat Exchanger Bonded To A Mechanical Seal, Jason Patrick Tuma

LSU Master's Theses

Mechanical seals are widely used in the chemical processing, aerospace, and automotive, industries. When a mechanical seal fails, considerable cost is typically involved in replacing the seal. Most seal failures are a result of high temperatures generated by frictional heating. Effectively removing the heat generated would significantly increase the mechanical seal’s work life and lead to significant monetary savings. One method of removing the heat generated is bonding an effective LIGA micro heat exchanger to the mechanical seal and forcing coolant through the heat exchanger. Previous work on this subject revealed promising results, especially for micro heat exchangers with microstructures …

Development Of A Micro Power Relay With Static Electrical Actuator, Ren Yang

LSU Master's Theses

In this thesis, a research about design and fabrication of a micro power relay is presented. Compared with the traditional electromagnetic relay and solid-state relay, MEMS micro power relay is introduced. After introducing the advantage and other people's research about the MEMS relay, some design and simulation about a new prototype micro power relay are done. Based on the design, UV-LIGA is used as the fabrication method. The bottom part and top part of the micro power relay are fabricated separately. After assembly the top part on the bottom part, some simple tests about the micro power relay are done. …

Predicting The Effects Of Dimensional And Material Property Variations In Micro Compliant Mechanisms, Jonathan W. Wittwer

Theses and Dissertations

Surface micromachining of micro-electro-mechanical systems (MEMS), like all other fabrication processes, has inherent variation that leads to uncertain material and dimensional parameters. To obtain accurate and reliable predictions of mechanism behavior, the effects of these variations need to be analyzed. This thesis expands already existing tolerance and uncertainty analysis methods to apply to micro compliant mechanisms. For simple compliant members, explicit equations can be used in uncertainty analysis. However, for a nonlinear implicit system of equations, the direct linearization method may be used to obtain sensitivities of output parameters to small changes in known variables. This is done by including …

Surface Micromachined Pressure Sensors, William P. Eaton Iv

Electrical and Computer Engineering ETDs

Surface micromachined pressure sensors were designed, modeled, fabricated, and tested. They employed a piezoresistive transduction mechanism and were based upon circular diaphragms, which vary from 50 to 1000 μm in diameter and 1 to 2 μm in thickness. The piezoresistors were placed in Wheatstone bridge configurations to provide simple signal amplification and first order temperature compensation.

Of the different micromachining techniques, surface-micromachining has the advantage of being the most similar to integrated circuit manufacturing. Hence an existing IC equipment set can be used to create mechanical structures. Furthermore, the monolithic integration of a mechanical device with control electronics is simpler …