Research Experiences for Undergraduates: Experimental Methods in Mechanical Engineering
Southern Methodist University
Dallas, TX
June 1 - July 24, 2009
RESEARCH LABORATORIES AND Available Projects
Laser Micromachining Laboratory
Laser Micromachining of Microchannels: The goal of his project it to develop a method of fabricating microchannels in polymer materials using a frequency-tripled ultraviolet Nd:YLF laser. The research will begin with single laser pulse experiments to determine the relation between laser parameters (energy density, spot size), material removal mechanisms (such as vaporization, explosive boiling, melt expulsion). The characteristics of the micromachining process will also be investigated, including the material removal rate, cross-section profile, and debris formation. The research will then study methods of fabricating high quality microchannels by scanning the laser over a polymer surface.
Laser Surface Texturing for Control of Wetting Properties: It is well known that surface roughness influences the wetting behavior of materials, such as contact angle. There is now a great deal of interest in using artificial surface roughening to develop superhydrophobic and superhydrophilic surfaces that mimic the Lotus effect for applications such as self-cleaning and antifogging surfaces. This project will study the effect of laser-induced surface texture on the wetting properties of surfaces. A laser will be used to induce roughening, for example by surface-tension effects in the laser-induced melt pool. Students will characterize surfaces before and after laser texturing to determine the effect on wetting properties such as equilibrium contact angle, advancing and receding contact angles, and roll-off angles.
Experimental Fluid Mechanics Laboratory
Flow Separation on Low Aspect Ratio Wings. Low aspect ratio wings are short and stubby. They are a hallmark of small flight-capable platforms such as micro air vehicles (MAVs) and insects. The flow over such wings is often unsteady because of flapping (for insect flight) or gusty wind conditions (for MAVs) leading to a complex, three-dimensional flow field. The evolution of the flow is important for understanding the lifting performance of the wings in gusty or flapping conditions, but is not well understood because of its complex, 3D nature. In this project, the 3D flow field generated by flow separating from low-aspect ratio wings under unsteady (gusty) flow conditions will be studied using a newly acquired TSI V3VTM system. The V3V system is a state of the art system for measuring 3D, unsteady velocity fields in a volume of the flow. It will be used to quantify the flow field for wings with aspect ratios of 1 – 2 at several angles of attack under impulsively started flow conditions.
Measurement of the Drag of ‘Robosquid’. ‘Robosquid’ is a mechanical underwater vehicle that propels itself using discrete jet pulses in a manner similar to biological squid. It is currently being used to investigate the efficiency of pulsed-jet propulsion for better understanding of biological jet propulsion (e.g., squid) and how to design efficient mini/micro-scale mechanical vehicles for a range of applications including surveillance and intravenous drug delivery. Proper assessment of the overall performance of Robosquid is facilitated by accurate measurements of its drag coefficient over a range of speeds (Reynolds numbers). This project will measure Robosquid’s drag for a range of speeds and for different inlet and nozzle configurations.
Research Center for Advanced Manufacturing
Micro-machining of Different Materials by High-speed Multi-wavelengths Laser. Center for Laser-aided Manufacturing (CLAM) (http://lyle.smu.edu/clam) is equipped with a Spectra physics HIPPO Q-switched Nd:YVO4 diode pumped laser system that has four modules with the wavelengths of 1064 um, 532 um, 355 um, and 266 um. The laser is integrated with a four-axis high-precision CNC positioning system and a high-speed scanner. The system will be used for micro-cutting, marking, and drilling of different materials such as plastics, ceramics, semiconductors, and metals. The study of the interaction between a pulsed laser beam of different wavelengths and different types of the target materials will be performed. CLAM is working with Synova Co. from Switzerland on acquiring a device for guiding the laser beam by waterjet. This additional capability will allow us to deal with the thermal issues present in micro-machining of the heat sensitive materials.
Rapid Manufacturing by Electron Beam. RCAM is equipped with the newest electron beam-based rapid manufacturing/prototyping machine, Model A2, manufactured by ARCAM Co. from Sweden (www.arcam.com). A thin layer of metal powder is spread across the powder bed in a vacuum environment. After the first layer is sintered a new layer of powder will be spread over the sintered one. This process will be repeated in order to build the desired 3D structure. The fully dense parts have been made of Ti-alloys and Cobalt-Chromium alloys that are of interest to a large number of industries. Currently, RCAM’s research team is developing a procedure to build the hybrid structures, that will consists of the lattice structures and the solids, by the electron beam-based direct metal deposition process. The hybrid structures are finding applications in custom designed bio-medical implants as well as in building light structures for aerospace and aircraft industries.
Hybrid Welding of Difficult-to Weld Materials. A robotized hybrid welding system that consists of a high-power fiber laser and one of the arc welding processes, either gas metal arc welding or gas tungsten arc welding, has been under the development at the Research Center for Advanced Manufacturing. The system will be used for welding high strength steels, aluminum alloys, and Titanium-alloys. The hybrid welding process combines the advantages of the laser welding and the arc welding processes. The outcome of this integration is a better weld quality, higher welding speed and higher process flexibility.
Laboratory for Micro- and Nano-Mechanics of Materials
3D Surface Profiling and Strain Measurements of Biomaterials and Tissues Using the V3V Imaging System. This project aims to utilize a newly acquired V3V imaging system by TSI for mechanical testing of biomaterials and tissues. The V3V imaging system is an advanced 3-camera system (tri-ocular) for tracking dense particles in 3D. Such a system would be evaluated in this project for biomechanics and biomaterials applications. One example would be used in mapping the 3D topography of faces and hands of people and their subsequent surface tissue deformation characteristics. Another example would be used in mapping the 3D displacement fields surrounding a fracturing bone sample.
Micromechanical Testing of Biomaterials and Tissues. This project will focus on the development and application of specially designed miniature tension and indentation testers for evaluating of mechanical properties of biomaterials and tissues. Both the miniature tension and indentation testers are compact, desktop, and computer-controlled using Labview. One aspect of the development effort will be directed at the better integration and synchronization of control and load data acquisition of the testers with digital image acquisition via a microscope during the test. The developed testers will be used for testing small bone samples and soft material samples.
Micro Sensor Laboratory
Micro-Optical Sensors for Ultra-Fine Measurements. Micro-spheres made of optical materials are used to build sensors with extremely high sensitivity. Typically the spheres are in the size range from several microns to hundreds of microns. We recently demonstrated the feasibility of several micro-optical sensors including those for temperature, force/strain, pressure and wall shear stress. The micro-beads are excited by coupling light from optical fibers. The technology exploits the morphology-dependent shifts in resonant frequencies that are commonly referred to as the whispering gallery modes (WGM). A minute change in the size, shape or optical constants of the micro-bead causes a shift in the resonant frequency (or the WGM). This optical phenomenon can lead to many additional sensors that can be used for a wide range of scientific and industrial applications; any physical stimuli that can directly or indirectly change the size, shape or optical constants (thereby causing a shift in the WGM) can be detected with resolutions that are beyond what can be realized by the existing mechanical sensors. Further, since the typical deformations (strain) are in the order of a nanometer, these sensors essentially have no moving parts. This sensor concept can be extended to a system of distributed sensors providing spatial data resolved in time and space.
Contact Information
Dr. David A. Willis
(214) 768-3125
Dr. Paul S. Krueger
(214) 768- 1296
Funded by the National Science Foundation Grant Number 0649032