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Articles 661 - 690 of 763

Full-Text Articles in Mechanical Engineering

Gas-Diffusion Process In A Tubular Cathode Substrate Of A Sofc, Part Ii: Identification Of Gas-Diffusion Process Using Ac Impedance Method, Kevin Huang Apr 2004

Gas-Diffusion Process In A Tubular Cathode Substrate Of A Sofc, Part Ii: Identification Of Gas-Diffusion Process Using Ac Impedance Method, Kevin Huang

Faculty Publications

The effects of cathodic dc bias, bulk pO2, and effective O2 -diffusivity on ac impedance spectra of Siemens Westinghouse Power Corporation’s cathode-supported solid oxide fuel cells were systematically studied over a temperature range of 800 to 1000°C. It was found that the activation process dominated the overall electrode kinetics at 800°C, by which the applied dc bias reduced the electrode resistance considerably. With increasing the temperature to above 900°C, the activation process became effectively activated, leading to a visible arc at the lowest frequency on the impedance spectrum, which is relevant to the pore gas-diffusion process. …

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Gas-Diffusion Process In A Tubular Cathode Substrate Of An Sofc, Part I: Theoretical Analysis Of Gas-Diffusion Process Under Cylindrical Coordinate System, Kevin Huang Apr 2004

Gas-Diffusion Process In A Tubular Cathode Substrate Of An Sofc, Part I: Theoretical Analysis Of Gas-Diffusion Process Under Cylindrical Coordinate System, Kevin Huang

Faculty Publications

In this the first part of a two-part paper, the gas-diffusion process through a thick and porous tubular cathode substrate of a solid oxide fuel cell-(SOFC) was theoretically analyzed using classic Fick’s diffusion equation under the cylindrical coordinate system. The effects of current density, temperature, oxygen diffusivity or porosity, wall thickness, and bulk pO2 on the concentration (or pore in this paper) polarization were calculated and are presented graphically. The results clearly show a greater impact on pore polarization by current density, oxygen diffusivity, wall thickness, and bulk pO2, but not by temperature. In addition, …

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Synthesis Of Tin Oxide Nanostructures With Controlled Particle Size Using Mesoporous Frameworks, A. Cabot, J. Arbiol, E. Rossinyol, J. R. Morante, Fanglin Chen, Meilin Liu Mar 2004

Synthesis Of Tin Oxide Nanostructures With Controlled Particle Size Using Mesoporous Frameworks, A. Cabot, J. Arbiol, E. Rossinyol, J. R. Morante, Fanglin Chen, Meilin Liu

Faculty Publications

Tin oxide nanostructures with controlled narrow particle size distribution were synthesized inside silica mesoporous templates. In this way, particle growth was blocked by physically corseting the tin compound inside the silica frameworks, the pore diameter of which determines the final tin oxide crystallite size distribution. Template structures were subsequently eliminated by chemical methods to collect the unsupported semiconductor nanoparticles. Thus obtained tin oxed nanopowders, with particle sizes in the range between 6 and 10 nm, were structurally, chemically, and electically characterized. The results are compared with those obtained from the characterization of larger crystallite materials.

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Development Of Commercially Viable Compliant Mechanisms Using The Pseudo-Rigid-Body Model: Case Studies Of Parallel Mechanisms, Christopher A. Mattson, Larry L. Howell, Spencer P. Magleby Mar 2004

Development Of Commercially Viable Compliant Mechanisms Using The Pseudo-Rigid-Body Model: Case Studies Of Parallel Mechanisms, Christopher A. Mattson, Larry L. Howell, Spencer P. Magleby

Faculty Publications

Analysis and synthesis of compliant mechanisms has recently been the subject of significant study in the research community. This focus has led to a number of design approaches for developing compliant mechanisms. This paper describes the value of using the Pseudo-Rigid-Body Model (PRBM) to design compliant mechanisms for commercial products. Application of the PRBM is illustrated through the development of two parallel mechanisms: a bicycle derailleur and parallel-motion bicycle brakes. The PRBM allows compliant mechanisms to be modeled and analyzed as rigid-body mechanisms and significantly reduces the complexity of analysis. Mechanisms with straightforward properties are used to demonstrate the use …

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Surface States In Template Synthesized Tin Oxide Nanoparticles, A. Cabot, J. Arbiol, R. Ferre, J. R. Morante, Fanglin Chen, Meilin Liu Feb 2004

Surface States In Template Synthesized Tin Oxide Nanoparticles, A. Cabot, J. Arbiol, R. Ferre, J. R. Morante, Fanglin Chen, Meilin Liu

Faculty Publications

Tin–oxide nanoparticles with controlled narrow size distributions are synthesized while physically encapsulated inside silica mesoporous templates. By means of ultraviolet-visible spectroscopy, a redshift of the optical absorbance edge is observed. Photoluminescence measurements corroborate the existence of an optical transition at 3.2 eV. The associated band of states in the semiconductor gap is present even on template-synthesized nanopowders calcined at 800 °C, which contrasts with the evolution of the gap states measured on materials obtained by other methods. The gap states are thus considered to be surface localized, disappearing with surface faceting or being hidden by the surface-to-bulk ratio decrease.

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Microstructures By Design: Linear Problems In Elastic-Plastic Design, Brent L. Adams, B. Henrie, M. Lyon Jan 2004

Microstructures By Design: Linear Problems In Elastic-Plastic Design, Brent L. Adams, B. Henrie, M. Lyon

Faculty Publications

Materials microstructure is considered to be a design variable in the methodology called microstructure sensitive design (MSD). Based upon existing homogenization relations, relating the first-order representation of microstructure (the local state distribution function) to elastic and yield properties, the paper describes the construction of properties closures. These establish the theoretically-possible combinations of properties achievable by the set of all possible microstructures, which is called the microstructure hull. Exemplary homogenization relations are shown to be, typically, hypersurfaces (often hyperplanes) in the Fourier space in which the microstructure hull resides. All points lying on (or to one side of) the hypersurface, that …

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Microstructure Design Of A Two Phase Composite Using Two-Point Correlation Functions, Brent L. Adams, H. Garmestani, G. Saheli Jan 2004

Microstructure Design Of A Two Phase Composite Using Two-Point Correlation Functions, Brent L. Adams, H. Garmestani, G. Saheli

Faculty Publications

This work has been funded under the AFOSR Grant no. F49620-03-1-0011 and Army Research Lab contract no. DAAD17-02-P-0398 and DAAD 19-01-1-0742. Two-point distribution functions are used here as to introduce "Microstructure Sensitive Design" in two-phase composites. Statistical distribution functions are commonly used for the representation of microstructures and also for homogenization of materials properties. The use of two-point statistics allows the composite designer to include the morphology and distribution in addition to the properties of the individual phases and components. Statistical continuum mechanics is used to make a direct link between the microstructure and properties (elastic and plastic) in terms …

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Coordinated Uav Target Assignment Using Distributed Tour Calculation, David H. Walker, Timothy W. Mclain, Jason K. Kowlett Jan 2004

Coordinated Uav Target Assignment Using Distributed Tour Calculation, David H. Walker, Timothy W. Mclain, Jason K. Kowlett

Faculty Publications

In this chapter a method for assigning unmanned aerial vehicle agents to targets through the use of preplanned vehicle tours is presented. Assignments are based on multi-target tours that consider the spread of the targets and the sensor capabilities of the vehicles. In this way, the individual agents and the team as a whole make better use of team resources and improve team cooperation. Planning and assignments are accomplished in reasonable computational time through the use of heuristics to reduce the problem size.

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Dynamic Modeling Of Compliant Constant-Force Compression Mechanisms, Cameron Boyle, Larry L. Howell, Spencer P. Magleby, Mark S. Evans Dec 2003

Dynamic Modeling Of Compliant Constant-Force Compression Mechanisms, Cameron Boyle, Larry L. Howell, Spencer P. Magleby, Mark S. Evans

Faculty Publications

A mathematical dynamic model is derived for compliant, constant-force compression-mechanisms, based on the pseudo-rigid-body model simplification of the device. The compliant constant-force compression mechanism (CFCM) is a slider mechanism incorporating large-deflection beams, which outputs near-constant-force across the range of its designed deflection. The equation of motion is successfully calibrated with empirical data from five separate mechanisms, comprising two basic configurations of CFCMs. The dynamic equation is derived from a generalized pseudo-rigid-body model. This allows every configuration to be represented by the same model, so a separate treatment is not required for each configuration. An unexpected dynamic trait of the constant-force …

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Multiple Uav Cooperative Search Under Collision Avoidance And Limited Range Communication Constraints, Randal W. Beard, Timothy W. Mclain Dec 2003

Multiple Uav Cooperative Search Under Collision Avoidance And Limited Range Communication Constraints, Randal W. Beard, Timothy W. Mclain

Faculty Publications

This paper focuses on the problem of cooperatively searching, using a team of unmanned air vehicles (UAVs), an area of interest that contains regions of opportunity and regions of potential hazard. The objective of the UAV team is to visit as many opportunities as possible, while avoiding as many hazards as possible. To enable cooperation, the UAVs are constrained to stay within communication range of one another. Collision avoidance is also required. Algorithms for team-optimal and individually-optimal/team-suboptimal solutions are developed and their computational complexity compared. Simulation results demonstrating the feasibility of the cooperative search algorithms are presented.

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The Distribution Of Internal Interfaces In Polycrystals, Brent L. Adams, Bassem S. El-Dasher, Gregory S. Rohrer, Anthony D. Rollett, David M. Saylor, Paul Wynblatt Nov 2003

The Distribution Of Internal Interfaces In Polycrystals, Brent L. Adams, Bassem S. El-Dasher, Gregory S. Rohrer, Anthony D. Rollett, David M. Saylor, Paul Wynblatt

Faculty Publications

This work was supported by the MRSEC program of the National Science Foundation under Award Number DMR-0079996. Recent advances both in experimental instrumentation and computing power have made it possible to interrogate the distribution of internal interfaces in polycrystals and the three dimensional structure of the grain boundary network with an unprecedented level of detail. The purpose of this paper is to review techniques that can be used to study the mesoscopic crystallographic structure of grain boundary networks and to summarize current findings. Recent studies have shown that grain surfaces within dense polycrystals favor the same low energy planes that …

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Predictive Joint Motion Limiting In Robotic Applications, Edward Red, Brian Fielding Oct 2003

Predictive Joint Motion Limiting In Robotic Applications, Edward Red, Brian Fielding

Faculty Publications

Three joint space algorithms slow the Cartesian path motion when it appears that joint motion is approaching a joint, speed, or acceleration limit. All three algorithms use quadratic curve fitting to predict where the joint motion is heading, followed by a prediction as to how much time would elapse until a limit is reached.

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A Texture Evolution Model In Cubic-Orthotropic Polycrystalline System, Brent L. Adams, H. Garmestani, D. S. Li Sep 2003

A Texture Evolution Model In Cubic-Orthotropic Polycrystalline System, Brent L. Adams, H. Garmestani, D. S. Li

Faculty Publications

This work has been funded under the AFOSR Grant # F49620-03-1-0011 and Army Research Lab Contract # DAAD17-02-P-0398 and DAAD 19-01-1-0742. B.L. Adams acknowledges support of Army Research Office, Proposal No. 42566-MS. The authors express their sincere gratitude to Professor Surya Kalidindi, for helpful suggestions and correspondence for the derivation of the processing path functions. A new methodology based on a conservation principle in the orientation space is developed to simulate the texture evolution in a cubic-orthotropic polycrystalline system. A least squares error method was used to improve the accuracy of the simulation results obtained from the texture evolution function. …

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Autonomous Vehicle Technologies For Small Fixed Wing Uavs, Derek B. Kingston, Randal Beard, Timothy Mclain, Michael Larsen, Wei Ren Sep 2003

Autonomous Vehicle Technologies For Small Fixed Wing Uavs, Derek B. Kingston, Randal Beard, Timothy Mclain, Michael Larsen, Wei Ren

Faculty Publications

Autonomous unmanned air vehicle flight control systems require robust path generation to account for terrain obstructions, weather, and moving threats such as radar, jammers, and unfriendly aircraft. In this paper, we outline a feasible, hierarchal approach for real-time motion planning of small autonomous fixed-wing UAVs. The approach divides the trajectory generation into four tasks: waypoint path planning, dynamic trajectory smoothing, trajectory tracking, and low-level autopilot compensation. The waypoint path planner determines the vehicle's route without regard for the dynamic constraints of the vehicle. This results in a significant reduction in the path search space, enabling the generation of complicated paths …

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Learning Real-Time A* Path Planner For Sensing Closely-Spaced Targets From An Aircraft, Jason K. Howlett, Michael A. Goodrich, Timothy W. Mclain Aug 2003

Learning Real-Time A* Path Planner For Sensing Closely-Spaced Targets From An Aircraft, Jason K. Howlett, Michael A. Goodrich, Timothy W. Mclain

Faculty Publications

This work develops an any-time path planner, based on the learning real-time A* (LRTA*) search, for generating flyable paths that allow an aircraft with a specified sensor footprint to sense a group of closely-spaced targets. The LRTA* algorithm searches a tree of flyable paths for the branch that accomplishes the desired objectives in the shortest distance. The tree of paths is created by assembling primitive turn and straight sections of a specified step size. The operating parameters for the LRTA* search directly influence the running time and path-length performance of the search. A modified LRTA* search is presented that terminates …

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A Self-Retracting Fully Compliant Bistable Micromechanism, Nathan D. Masters, Larry L. Howell Jun 2003

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

Faculty Publications

A new class of fully compliant bistable mechanisms with the added benefit of integrated self-retraction has been developed (hereafter identified as Self-Retracting Fully compliant Bistable Mechanism or SRFBM). A technique using tensural pivots to manage compressive loading in compliant mechanisms is introduced and implemented in the SRFBM. The elimination of traditional kinematic joints and their associated clearance allows a total displacement between stable positions of 8.5 m, and the mechanism size is less than 300 m square when using 2.0 m minimum line widths. Maximum actuation force is approximately 500 N. The SRFBM's small linear displacement and reasonable actuation force …

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Cooperative Path Planning For Timing Critical Missions, Timothy W. Mclain, Randal W. Beard Jun 2003

Cooperative Path Planning For Timing Critical Missions, Timothy W. Mclain, Randal W. Beard

Faculty Publications

This paper presents a cooperative path planning approach for teams of vehicles operating under timing constraints. A cooperative control approach based on coordination variables and coordination functions is introduced and applied to cooperative timing problems. Three types of timing constraints are considered: simultaneous arrival, tight sequencing, and loose sequencing. Simulation results demonstrating the approach are presented.

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Microstructure Sensitive Design Of An Orthotropic Plate Subjected To Tensile Load, Brent L. Adams, Mark Lyons, Joshua R. Houskamp, Surya R. Kalidindi May 2003

Microstructure Sensitive Design Of An Orthotropic Plate Subjected To Tensile Load, Brent L. Adams, Mark Lyons, Joshua R. Houskamp, Surya R. Kalidindi

Faculty Publications

Financial support for this work was provided by the Army Research Office, Proposal No. 42566-MS, Dr. David Stepp, Program Director and Army Research Lab, Dr. Scott Schoenfeld, Point of Contact. Microstructure Sensitive Design (MSD) is a newly developed mathematical framework that facilitates rigorous solutions to inverse problems in microstructure design of materials. In this paper, this methodology is applied to an orthotropic thin plate containing a circular hole subjected to an in-plane uniaxial tensile load. The primary design objective is to maximize the load carrying capacity of the plate while avoiding plastic deformation in the plate. Making use of the …

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Advances In Experimental Method And Analysis For Estimation Of Geometrically-Necessary Dislocations, Brent L. Adams, Bassem S. El-Dasher, Anthony D. Rollett Mar 2003

Advances In Experimental Method And Analysis For Estimation Of Geometrically-Necessary Dislocations, Brent L. Adams, Bassem S. El-Dasher, Anthony D. Rollett

Faculty Publications

The authors wish to thank The Alcoa Technical Research Center for supplying the specimens and performing the compression tests. This work was supported by the MRSEC program of the National Science Foundation under DMR-0079996 as well as Lawrence Livermore Laboratory DOE/DoD Joint Program. An behavior of grain boundaries of the polycrystalline materials over a wide range of length scales during plastic deformation is considered. Electron backscattering diffraction and orientation imaging microscopy provide automated scanning measurements of the lattice orientation near grain boundaries. These methods are useful to set the necessary length scales. The data are presented for directionally-solidified pure Al …

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A Joint Trajectory Generator For Motion Recovery, Edward Red, Wei Li Mar 2003

A Joint Trajectory Generator For Motion Recovery, Edward Red, Wei Li

Faculty Publications

This paper describes an adaptive S-curve used to recover a tool path upon a system crash in the Windows operating system (OS). For a mechanism such as a robot or machine tool, the joint values, being delivered as setpoints to the servo-controller, are dynamically recorded by the real-time operating system also residing on the computer. The real-time OS can control the abort and record pertinent motion data after Windows OS crash.

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On-Chip Actuation Of An In-Plane Compliant Bistable Micromechanism, Michael S. Baker, Larry L. Howell Dec 2002

On-Chip Actuation Of An In-Plane Compliant Bistable Micromechanism, Michael S. Baker, Larry L. Howell

Faculty Publications

A compliant bistable micromechanism has been developed which can be switched in either direction using on-chip thermal actuation. The energy storage and bistable behavior of the mechanism is 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 design was optimized to allow it to be switched using linear motion thermal actuators. The modeling theory and analysis are presented for three design iterations, with two iterations fabricated in the MUMP's process and the third in the SUMMiT …

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Mapping The Mesoscale Interface Structure In Polycrystalline Materials, Brent L. Adams, C. L. Bauer, D. Casasent, A. Morawiec, S. Ozdemir, A. Talukder, Chialin T. Wu Nov 2002

Mapping The Mesoscale Interface Structure In Polycrystalline Materials, Brent L. Adams, C. L. Bauer, D. Casasent, A. Morawiec, S. Ozdemir, A. Talukder, Chialin T. Wu

Faculty Publications

This work was supported primarily by the MRSEC Program of the National Science Foundation under Award Numbers DMR-9632556 and DMR-0079996. A new experimental approach to the quantitative characterization of polycrystalline microstructure by scanning electron microscopy is described. Combining automated electron backscattering diffraction with conventional scanning contrast imaging and with calibrated serial sectioning, the new method (Mesoscale Interface Mapping System, MIMS) recovers precision estimates of the 3-dimensional idealized aggregate function G(x). This function embodies a description of lattice phase and orientation (limiting resolution ~ 1 degree) at each point x (limiting spatial resolution ~ 100 nanometers), and therefore contains a complete …

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Distributions Of Nobel Metal Pd And Pt In Mesoporous Silica, J. Arbiol, A. Cabot, J. R. Morante, Fanglin Chen, Meilin Liu Oct 2002

Distributions Of Nobel Metal Pd And Pt In Mesoporous Silica, J. Arbiol, A. Cabot, J. R. Morante, Fanglin Chen, Meilin Liu

Faculty Publications

Mesoporous silicananostructures have been synthesized and loaded with Pd and Pt catalytic noble metals. It is found that Pd forms small nanoclusters (3–5 nm) on the surface of the mesoporous structure whereas Pt impregnation results in the inclusion of Pt nanostructures within the silica hexagonal pores (from nanoclusters to nanowires). It is observed that these materials have high catalyticproperties for CO–CH4CO–CH4CO–CH4 combustion, even in a thick film form. In particular, results indicate that the Pt and Pd dispersed in mesoporous silica are catalytically active as a selective filter for gas sensors.

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Distributions Of Noble Metal Pd And Pt In Mesoporous Silica, J. Arbiol, A. Cabot, J. R. Morante, Fanglin Chen, Meilin Liu Oct 2002

Distributions Of Noble Metal Pd And Pt In Mesoporous Silica, J. Arbiol, A. Cabot, J. R. Morante, Fanglin Chen, Meilin Liu

Faculty Publications

Mesoporous silica nanostructures have been synthesized and loaded with Pd and Pt catalytic noble metals. It is found that Pd forms small nanoclusters (3–5 nm) on the surface of the mesoporous structure whereas Pt impregnation results in the inclusion of Pt nanostructures within the silica hexagonal pores (from nanoclusters to nanowires). It is observed that these materials have high catalytic properties for CO–CH4 combustion, even in a thick film form. In particular, results indicate that the Pt and Pd dispersed in mesoporous silica are catalytically active as a selective filter for gas sensors.

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Modeling The Thermal Behavior Of A Surface-Micromachined Linear-Displacement Thermomechanical Microactuator, Christian D. Lott, Timothy W. Mclain, John N. Harb, Larry L. Howell Sep 2002

Modeling The Thermal Behavior Of A Surface-Micromachined Linear-Displacement Thermomechanical Microactuator, Christian D. Lott, Timothy W. Mclain, John N. Harb, Larry L. Howell

Faculty Publications

Thermomechanical microactuators possess a number of desirable attributes including ease of fabrication and large force and displacement capabilities relative to other types of microactuators. These advantages provide motivation for improving thermomechanical microactuator designs that are more energy efficient and thus better suited for low-power applications. To this end, this paper describes the development and experimental validation of a finite-difference thermal model of a thermomechanical in-plane microactuator (TIM). Comparisons between the model and experimental results demonstrate the importance of including the temperature dependence of several parameters in the model. Strategies for reducing the power and energy requirements of the TIM were …

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Viewpoint: Experimental Recovery Of Geometrically Necessary Dislocation Density In Polycrystals, Brent L. Adams, Bassem S. El-Dasher, Anthony D. Rollett Aug 2002

Viewpoint: Experimental Recovery Of Geometrically Necessary Dislocation Density In Polycrystals, Brent L. Adams, Bassem S. El-Dasher, Anthony D. Rollett

Faculty Publications

The authors wish to thank The Alcoa Technical Research Center for supplying the specimens and performing the compression tests. This work was supported primarily by the MRSEC program of the National Science Foundation under DMR-0079996. Application of electron backscattering diffraction methods to recover estimates of the geometrically necessary dislocation density is described. The limitations of the method arising from the opacity of crystalline materials and the spatial and angular resolution limits are discussed.

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Experimental Demonstration Of Multiple Robot Cooperative Target Intercept, Timothy W. Mclain, Randal W. Beard, Jed M. Kelsey Aug 2002

Experimental Demonstration Of Multiple Robot Cooperative Target Intercept, Timothy W. Mclain, Randal W. Beard, Jed M. Kelsey

Faculty Publications

This paper presents experimental results for the simultaneous intercept of preassigned targets by a team of mobile robots. The robots are programmed to mimic the dynamic behavior of unmanned air vehicles in constant-altitude flight. In proceeding to their targets, robots must avoid both known static threats and pop-up threats. An overview of the cooperative control strategy followed is given, as well as a description of the robot hardware and software used. Experimental results demonstrating simultaneous intercept of targets by the robot team are presented.

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Autonomous Hierarchical Control Of Multiple Unmanned Combat Air Vehicles (Ucavs), Timothy Mclain, Randal W. Beard, Sai-Ming Li, Jovan D. Boskovic, Sanjeev Seereeram, Ravi Prasanth, Jayesh Amin, Raman K. Mehra Jun 2002

Autonomous Hierarchical Control Of Multiple Unmanned Combat Air Vehicles (Ucavs), Timothy Mclain, Randal W. Beard, Sai-Ming Li, Jovan D. Boskovic, Sanjeev Seereeram, Ravi Prasanth, Jayesh Amin, Raman K. Mehra

Faculty Publications

In this paper we present a hierarchical control scheme that enables multiple UCAVs to achieve demanding missions in hostile environments autonomously. The objective is to use a swarm of UCAVs for a SEAD type mission: fly the UCAVs in a formation to an enemy territory populated with different kinds of threats, collect enemy information or destroy certain targets, and return to the base, all without human intervention. The scheme is an integration of four distinct components, including: (1) high level Voronoi diagram based path planner to avoid static threats; (2) low level path planner to avoid popup threats; (3) differential …

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Nanofatigue Studies Of Ultrathin Hard Carbon Overcoats Used In Magnetic Storage Devices, Xiaodong Li, Bharat Bhushan May 2002

Nanofatigue Studies Of Ultrathin Hard Carbon Overcoats Used In Magnetic Storage Devices, Xiaodong Li, Bharat Bhushan

Faculty Publications

A technique to perform nanofatigue experiments was developed. This technique utilizes a depth-sensing nanoindenter with harmonic force. The nanofatigue behavior of 20 nm thick amorphous carbon coatings was studied. The contact stiffness was monitored continuously throughout the test. The abrupt decrease in the contact stiffness indicates fatigue damage has occurred. The critical load amplitude, below which no fatigue damage occurs, was identified. It was found that the filtered cathodic arc coating exhibits longer fatigue life than a direct ion beam coating. Failure mechanisms of the coatings during fatigue are also discussed in conjunction with the hardness,elastic modulus, and fracture toughness, …

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In-Plane Linear-Displacement Bistable Microrelay, Troy Gomm, Larry L. Howell, Richard H. Selfridge May 2002

In-Plane Linear-Displacement Bistable Microrelay, Troy Gomm, Larry L. Howell, Richard H. Selfridge

Faculty Publications

This paper investigates the Linear Displacement Bistable Mechanism (LDBM) for use in microrelays. The LDBM, thermal actuators, and contacts are integrated to demonstrate a relay design. The performance of the relay is characterized using relay performance metrics, including size (1.92 mm2), contact force (23.4 μN), switching time (340 μs), breakdown voltage (> 475 V), and isolation (> 235 V). The actuation voltage and current are 11 V and 85 mA, respectively. AC characteristics, including contact-to-contact crosstalk and AC isolation are also measured. The testing results demonstrate that it is feasible to use the LDBM as a microrelay and that it …

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