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Mechanical Engineering Commons

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2008

Mechanical Engineering Publications

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Articles 1 - 14 of 14

Full-Text Articles in Mechanical Engineering

Obtaining A Relationship Between Process Parameters And Fracture Characteristics For Hybrid Co2 Laser∕Waterjet Machining Of Ceramics, Dinesh Kalyanasundaram, Pranav Shrotriya, Palaniappa A. Molian Dec 2008

Obtaining A Relationship Between Process Parameters And Fracture Characteristics For Hybrid Co2 Laser∕Waterjet Machining Of Ceramics, Dinesh Kalyanasundaram, Pranav Shrotriya, Palaniappa A. Molian

Mechanical Engineering Publications

A combined experimental and analytical approach is undertaken to identify the relationship between process parameters and fracture behavior in the cutting of a 1mm thick alumina samples by a hybrid CO2 laser∕waterjet (LWJ) manufacturing process. In LWJ machining, a 200W power laser was used for local heating followed by waterjet quenching of the sample surface leading to thermal shock fracture in the heated zone. Experimental results indicate three characteristic fracture responses: scribing, controlled separation, and uncontrolled fracture. A Green’s function based approach is used to develop an analytical solution for temperatures and stress fields generated in the workpiece ...


Simultaneous Three-Dimensional Geometry And Color Texture Acquisition Using Single Color Camera, Song Zhang, Shing-Tung Yau Dec 2008

Simultaneous Three-Dimensional Geometry And Color Texture Acquisition Using Single Color Camera, Song Zhang, Shing-Tung Yau

Mechanical Engineering Publications

A novel technique that uses a single color camera to capture high-resolution three-dimensional (3-D) geometry and the perfectly aligned color texture simultaneously is discussed. A projector projects three phase-shifted black-and-white fringe patterns onto the object, and a color camera captures the fringe images reflected by the object. From these three fringe images, both 3-D shape and the color texture are obtained. Moreover, since only three fringe images are required, this proposed technique permits real-time 3-D shape measurement. Experiments are presented to demonstrate the success of this technique.


Development Of A Dual-Handed Haptic Assembly System: Sharp, Abhishek Seth, Hai-Jun Su, Judy M. Vance Nov 2008

Development Of A Dual-Handed Haptic Assembly System: Sharp, Abhishek Seth, Hai-Jun Su, Judy M. Vance

Mechanical Engineering Publications

Virtual reality (VR) technology holds promise as a virtual prototyping (VP) tool for mechanical assembly; however, several developmental challenges still need to be addressed before VP applications can successfully be integrated into the product realization process. This paper describes the development of System for Haptic Assembly and Realistic Prototyping (SHARP), a portable virtual assembly system. SHARP uses physics-based modeling for simulating realistic part-to-part and hand-to-part interactions in virtual environments. A dual-handed haptic interface for a realistic part interaction using the PHANToM® haptic devices is presented. The capability of creating subassemblies enhances the application’s ability to handle a wide variety ...


Enhancing Co−Water Mass Transfer By Functionalized Mcm41 Nanoparticles, Haiyang Zhu, Brent H. Shanks, Theodore J. Heindel Oct 2008

Enhancing Co−Water Mass Transfer By Functionalized Mcm41 Nanoparticles, Haiyang Zhu, Brent H. Shanks, Theodore J. Heindel

Mechanical Engineering Publications

Organic groups are grafted to 250-nm-diameter MCM41 nanoparticles with a spherical morphology to enhance the CO−water volumetric mass-transfer coefficient (kLa) for synthesis gas fermentation. The results indicate that (i) 250-nm MCM41 nanoparticles show a higherkLa value than large silica particles (1.4 and 7 μm), (ii) surface hydroxyl groups on MCM41 nanoparticles play an important role in mass-transfer enhancement, (iii) organic groups grafted to MCM41 modify the mass-transfer enhancement, and (iv) mercaptan groups grafted to MCM41 show the most mass-transfer enhancement of 1.9 times that of no nanoparticle addition. The CO−water mass-transfer ...


Differential Surface Stress Sensor For Detection Of Chemical And Biological Species, K. Kang, Marit Nilsen-Hamilton, Pranav Shrotriya Oct 2008

Differential Surface Stress Sensor For Detection Of Chemical And Biological Species, K. Kang, Marit Nilsen-Hamilton, Pranav Shrotriya

Mechanical Engineering Publications

We report a sensor consisting of two micromachined cantilevers (a sensing/reference pair) that is suitable for detection of chemical and biological species. The sensing strategy involves coating the sensing cantilever with receptors that have high affinities for the analyte. The presence of analyte is detected by determining the differential surface stress associated with its adsorption/absorption to the sensing cantilever. An interferometric technique is utilized to measure the differential bending of the sensing cantilever with respect to reference. Surface stress associated with hybridization of single stranded DNA is measured to demonstrate the unique advantages of the sensor.


Parametric Instability Of A Traveling Plate Partially Supported By A Laterally Moving Elastic Foundation, V. Kartik, Jonathan A. Wickert Oct 2008

Parametric Instability Of A Traveling Plate Partially Supported By A Laterally Moving Elastic Foundation, V. Kartik, Jonathan A. Wickert

Mechanical Engineering Publications

The parametric excitation of an axially moving plate is examined in an application where a partial foundation moves in the plane of the plate and in a direction orthogonal to the plate's transport. The stability of the plate's out-of-plane vibration is of interest in a magnetic tape data storage application where the read/write head is substantially narrower than the tape's width and is repositioned during track-following maneuvers. In this case, the model's equation of motion has time-dependent coefficients, and vibration is excited both parametrically and by direct forcing. The parametric instability of out-of-plane vibration is ...


Broadband Measurement Of Rate-Dependent Viscoelasticity At Nanoscale Using Scanning Probe Microscope: Poly(Dimethylsiloxane) Example, Zhonghua Xu, Kyongsoo Kim, Qingze Zou, Pranav Shrotriya Sep 2008

Broadband Measurement Of Rate-Dependent Viscoelasticity At Nanoscale Using Scanning Probe Microscope: Poly(Dimethylsiloxane) Example, Zhonghua Xu, Kyongsoo Kim, Qingze Zou, Pranav Shrotriya

Mechanical Engineering Publications

A control approach to achieve nanoscale broadband viscoelasticmeasurement using scanning probe microscope(SPM) is reported. Current SPM-based force measurement is too slow to measure rate-dependent phenomena, and large (temporal) measurement errors can be generated when the sample itself changes rapidly. The recently developed model-less inversion-based iterative control technique is used to eliminate the dynamics and hysteresis effects of the SPM hardware on the measurements, enabling rapid excitation and measurement of rate-dependent material properties. The approach is illustrated by the mechanical characterization of poly(dimethylsiloxane) over a broad frequency range of three orders of magnitude (∼1 Hz to 4.5 KHz).


Inner-Loop Control For Electromechanical „Ema… Flight Surface Actuation Systems, Saeid Habibi, Jeff Roach, Greg R. Luecke Sep 2008

Inner-Loop Control For Electromechanical „Ema… Flight Surface Actuation Systems, Saeid Habibi, Jeff Roach, Greg R. Luecke

Mechanical Engineering Publications

This manuscript pertains to the application of an inner-loop control strategy to electromechanical flight surface actuation systems. Modular electromechanical actuators (EMAs) are increasingly used in lieu of centralized hydraulics for the control of flight surfaces in the aerospace sector. The presence of what is termed as a dead zone in these actuators significantly affects the maneuverability, stability, and the flight profiles of aircrafts that use this actuation concept. The hypothesis of our research is that flight surface actuation systems may be desensitized to the effects of dead zone by using a control strategy with multiple inner loops. The proposed strategy ...


Experimental And Numerical Investigations On Microcoining Of Stainless Steel 304, Gap-Yong Kim, Muammer Koç, Jun Ni Jul 2008

Experimental And Numerical Investigations On Microcoining Of Stainless Steel 304, Gap-Yong Kim, Muammer Koç, Jun Ni

Mechanical Engineering Publications

Increasing demands for miniature metallic parts have driven the application of microforming in various industries. Only a limited amount of research is, however, available on the forming of miniature features in high strength materials. This study investigated the forming of microfeatures in Type 304 stainless steel by using the coining process. Experimental work was performed to study the effects of workpiece thickness, preform shape, grain size, and feature size on the formation of features ranging from 320μmto800μm. It was found that certain preform shapes enhance feature formation by allowing a favorable flow of the bulk material. In addition, a flow ...


On Brownian Dynamics Simulation Of Nanoparticle Aggregation, Sergiy Markutsya, Shankar Subramaniam, R. Dennis Vigil, Rodney O. Fox May 2008

On Brownian Dynamics Simulation Of Nanoparticle Aggregation, Sergiy Markutsya, Shankar Subramaniam, R. Dennis Vigil, Rodney O. Fox

Mechanical Engineering Publications

Accurate simulation and control of nanoparticle aggregation in chemical reactors requires that population balance equations be solved by using realistic expressions for aggregation and breakage rate kernels. Obtaining such expressions requires that atomistic simulation approaches that can account for microscopic details of particle collisions be used. In principle, molecular dynamics simulations can provide the needed microscopic information, but because of the separation in length scales between the aggregates and solvent molecules, such simulations are too costly. Brownian dynamics simulations provide an alternative to the molecular dynamics approach for simulation of particle aggregation, but there has been no systematic attempt to ...


Improved Method Of Co2 Laser Cutting Of Aluminum Nitride, Raathai Molian, Pranav Shrotriya, Pal Molian May 2008

Improved Method Of Co2 Laser Cutting Of Aluminum Nitride, Raathai Molian, Pranav Shrotriya, Pal Molian

Mechanical Engineering Publications

The traditional “evaporation∕melt and blow” mechanism of CO2 laser cutting of aluminum nitride (AlN) chip carriers and heat sinks suffers from energy losses due to its high thermal conductivity, formation of dross, decomposition to aluminum, and uncontrolled thermal cracking. In order to overcome these limitations, a thermochemical method that uses a defocused laser beam to melt a thin layer of AlN surface in oxygen environment was utilized. Subsequent solidification of the melt layer generated shrinkage and thermal gradient stresses that, in turn, created a crack along the middle path of laser beam and caused material separation through unstable crack ...


Fabrication Of High Aspect Ratio Porous Microfeatures Using Hot Compaction Technique, Peng Chen, Gap-Yong Kim, Jun Ni May 2008

Fabrication Of High Aspect Ratio Porous Microfeatures Using Hot Compaction Technique, Peng Chen, Gap-Yong Kim, Jun Ni

Mechanical Engineering Publications

High aspect ratio porous microfeatures are becoming more important in the modern industry. However, the fabrication of such features under a mass production environment remains a challenge when robustness, cost effectiveness, and high productivity requirements are required. In this study, the forming of such porous microfeatures using hot compaction was investigated. A hot compaction experimental setup was designed and fabricated that is capable of performing high temperature operation (700°C), quick heatup, and avoiding oxidation. 3D thermal simulation of the experimental setup was conducted to investigate the heat transfer performance and internal temperature distribution, which was then used as a ...


Finite Element Model For Hysteretic Friction Damping Of Traveling Wave Vibration In Axisymmetric Structures, X. W. Tangpong, Jonathan A. Wickert, A. Akay Feb 2008

Finite Element Model For Hysteretic Friction Damping Of Traveling Wave Vibration In Axisymmetric Structures, X. W. Tangpong, Jonathan A. Wickert, A. Akay

Mechanical Engineering Publications

A finite element method is developed to treat the steady-state vibration of two axisymmetric structures—a base substructure and an attached dampersubstructure—that are driven by traveling wave excitation and that couplethrough a spatially distributed hysteretic friction interface. The base substructure is representative of a rotating brake rotor or gear, and the damper is a ring affixed to the base under preload and intended to control vibration through friction along the interface. In the axisymmetric approximation, the equation of motion of each substructure is reduced in order to the number of nodal degrees of freedom through the use of a ...


Narrow-Linewidth Megahertz-Repetition-Rate Optical Parametric Oscillator For High-Speed Flow And Combustion Diagnostics, Naibo Jiang, Walter R. Lempert, Gary L. Switzer, Terrence R. Meyer, James R. Gord Jan 2008

Narrow-Linewidth Megahertz-Repetition-Rate Optical Parametric Oscillator For High-Speed Flow And Combustion Diagnostics, Naibo Jiang, Walter R. Lempert, Gary L. Switzer, Terrence R. Meyer, James R. Gord

Mechanical Engineering Publications

We demonstrate the ability to generate ultra-high-frequency sequences of broadly wavelength-tunable, high-intensity laser pulses using a custom-built optical parametric oscillator pumped by the thirdharmonic output of a "burst-mode" Nd:YAG laser. Burst sequences consisting of 6-10 pulses separated in time by 6-10 Îs are obtained, with average total conversion efficiency from the 355 nm pump to the near-IR signal and idler wavelengths of 33%. Typical individual pulse output energy for the signal and idler beams is in the range of 4-6 mJ, limited by the available pump energy. Line narrowing is demonstrated by means of injection seeding the idler wave ...