ESM 4015-4016: Creative Design
Modification of the Orthofix Axial Fixator
Morgan Matteson
Matthew A. Runion
Advisor: Prof. Michael Madigan, ESM Dept., Virginia Tech
The Orthofix Dynamic Axial Fixator is an external fixation device that
treats fractures and abnormalities that occur in the femur bone. Orthofix,
an orthopedic fixation company base in
At the end of this project we hope to have a fully functioning final prototype, as well as, full design drawings to present to Orthofix and the design class in our final presentation. The final product will be easier to apply to the femur bone and will maintain the strength and stability of the current fixation device.
Design of a Method to Test Mechanical Properties of
Bio-Capsules
Stephanie Bryan
Melanie Yu
Advisors: Prof. David Dillard, ESM Dept., Virginia Tech
Prof. Kai-Tak Wan, University of Missouri-Rolla
The design and implementation of bio-capsules are becoming necessary in the pharmaceutical industry to transport drugs to cells. Although bio-capsules define a variety of devices, our study deals with micro-scale spherical shells having a thick elastic membrane that contain drugs or some other bio-mimetic device. A method to determine material properties of bio-capsules would aid in the design of bio-capsules and in the understanding of a bio-capsule’s specific applications. Scanning probe microscopes like the atomic force microscope (AFM) can apply a point indentation on a micro-scale particle such as a bio-capsule, and research has been performed to relate the mechanical response of an indentation to a capsule’s elastic modulus and Poisson’s ratio.
Polymer particles provided by Expancel are about 10 mm in diameter with an elastic membrane that expands when heated, and they have been designed with similar properties to the bio-capsules previously described. The Expancels are going to be tested using an atomic force microscope, the results of which will be interpreted with contact mechanics theories. Since accurate methods of testing the Expancels using the AFM do not exist, the purpose of this project is to design and develop techniques to mount and test the particles on an AFM probe in order to obtain the proper data needed to find the mechanical properties.
A method for testing these Expancels to find their mechanical properties using an AFM will be designed. A micromanipulator will be used to isolate one cell, and the cell will be adhered to the probe. Johnson-Kendall-Roberts (JKR) principles will be used to analyze the surface between the polymer particle and the slide. A method to adhere the particle to the probe will be found. The probe will be placed in the AFM and a force-displacement curve will be produced, and the analysis of this curve will yield the desired mechanical properties of the cells.
The
Kristin Kessler
Elizabeth Kricorian
Joseph Fink
Advisor: Prof. Jack Lesko, ESM Dept., Virginia Tech
As the transportation structures of
Although the FRP deck will extend the life of the bridge, there are some concerns to be addressed in their application and use. Guidelines for the connection of the deck to the existing bridge frame do not currently exist, nor are there standards as with steel, that will instruct a designer of how the material will react to factors such as moments, point loads, and deflections. With this lack of guidance, each bridge in need of rehabilitation will have to be analyzed individually which costs time and money, both of which are not abundant in mass rehabilitation.
The objective of this project is to address the difficulties involved
in an FRP deck replacement of a through truss bridge (the
The Design and Construction of a Mechanical Device
to Restore Mobility in the Arms of the Disabled
Scott England
Advisor: Prof. Michael Madigan, ESM Dept., Virginia Tech
Millions of people worldwide are affected by paralysis of varying degrees. Technological advances in recent years have given an unprecedented degree of self-reliance to paraplegics, people suffering loss of use of their legs; however quadriplegics, or people suffering from total, neck-down paralysis, remain highly dependant on others for assistance in virtually every aspect of their lives. Many attempts are being made at restoring function in the arms with everything from implanted electrodes to cloned nerve tissue. However, all of these methods are years away from being available to the public. An external method of powering the arms would present no problems of implant rejection, far fewer moral questions than the use of cloned tissue and it could be widely adopted in the field more quickly than methods requiring surgery. The purpose of this project is to design a mechanical device that would restore the use of their arms to people who, for various reasons, have lost mobility in their arms. A complete, wheelchair-mounted system will be designed, with an emphasis on permitting the maximum range of motion while minimizing problems with construction and maintenance; also, a single-arm, working prototype of the mechanical system will be constructed. The current design features a system of winches positioned to allow for elevation, rotation, flexion, and extension of the shoulder, and for flexion and extension of the elbow. A series of small electric motors will power the winches, one motor per winch, with the winch’s diameter designed such that movement of the arm across the extreme range of motion will take approximately three seconds at full power. Myoelectric sensors will be used to provide continuous feedback for controlling the device, so the design will only work for patients that have some residual electrical activity in the affected extremity. Once the mechanics of the device are perfected, alternate control systems could be installed to provide treatment for patients where myoelectric sensors would not work.
Improved Stent Design through Finite Element Analysis
Ian Blandford
David Wadden
Advisors: Prof. Saad Ragab, ESM Dept., Virginia Tech
Prof. Joel Berry,
Cardiovascular disease represents one of the chief causes
of death each year in the
Determination of Biomechanical Properties for Arteries
Containing Plaque
Karey Edens
Charles Rosseau
Advisors: Prof. Romesh Batra, ESM Dept., Virginia Tech
Prof. Norman Dowling, ESM Dept., Virginia Tech
Stents clearly indicate their efficacy within mechanical treatments for percutaneous coronary revascularizations. Arteries become blocked by a build-up of fat and cholesterol called plaque that can cause the artery to become less ductile, subsequently increasing the velocity of the blood. This factor is of great concern in the medical field because these arteries thicken naturally with age due to the forces exerted by the wave speed traveling though the arterial portion of the cardiovascular system. Stents provide a minimally invasive means of reducing the stenosis or diseased lesion from creating a possibly life-ending heart attack or stroke. It has been shown however that restenosis is still present, thus turning the focus to the interaction between the stent and the arterial wall.
Currently, there is no way to determine the mechanical properties of the plaque inside of the arteries. If the strength of the plaque were known it would be possible to treat the diseased artery as a laminated composite circular cylinder. The formulation of tangential and radial arterial composite stresses could lead to selecting an appropriate balloon modulus and the appropriate expansion pressure to maximize stent effectiveness and minimize the probability of restenosis.
Expansion pressures that are too high can cause a vessel to rupture, while pressure that is not large enough will inadequately repress the plaque and can render a fairly ineffective procedure. The purpose of our project is to develop a method and device to determine the mechanical properties of clogged and unclogged arteries. Understanding how these properties affect the structural integrity of the vessel should lead to a more adequate method of determining the amount of pressure that should be applied during a medical procedure. By studying the tensile strength, yield strength and other mechanical properties found in the laboratory, a correlation between the strength of the plaque and the arteries and the force required to suppress an occlusion a desired percentage can be determined.
The project will involve building a pressurizing vessel in order to bring sample artery segments back up to vivo pressures, determining the tensile strength of samples on the tension testing device (Tytron 250 by MTS), and developing a new device to test the puncture strength of the vessels. From these tests we will determine the mechanical properties of clean and plaque filled arteries.
Catapult Competition Design Team
Julie Cooper
Michael Guilfoyle
Patrick McDonald
Advisor: Prof. Jack Lesko, ESM Dept., Virginia Tech
This project entails developing a catapult design from pultruded composite sections for entry into the European Pultrusion Technology Association catapult design competition. The competition will consist of distance contest and an accuracy contest. Certain guidelines and specifications are necessary for entry. These include that the catapult be constructed completely out of pultruded composite profiles, shoot a 6 kg bowling ball a minimal distance of 100 m, designed such that all energy for launch of the bowling ball come directly from composite materials, have a total weight under 200 kg, be mobile with man power, and be loaded and controlled by a maximum of three persons.
Catapult designs that were considered for construction included the Onager, the Trebuchet and the Scorpio. Initially the Trebuchet was considered but due to weight restrictions it was ruled out. The Onager has incredible power but is difficult to aim and control. The final design that was considered is the Scorpio, which is very similar to an oversize crossbow. Two beams attached with a cable or ropes are placed in a torsion bundle known as a skein. The projectile is placed on the cable that is pulled back, forcing the beams against the skeins, and then released, launching the projectile. This design produces a great deal of energy and allows the launch angle be adjusted easily.
Mechanics that are involved with the catapult competition include energy, distance and accuracy. Projectile motion equations were used to determine the launch angle, and the initial velocity needed to launch the bowling ball a minimum distance of 100 m. The energy found according to the initial velocity must come directly from pultruded composites thus determining the design for our catapult. The preliminary specifications will then be optimized to allow for the most amount of accuracy.
Development of a Submerged, Small-Scale
Concentric Canister Launcher
Chris Weiland
Advisors: Prof. Pavlos Vlachos, ESM
Dr. Jon Yagla, G Dept., Naval
The United States Navy is always searching for new technologies to secure its combat superiority. In support of this, a new launching system has been devised, termed the Concentric Canister Launcher (CCL). The CCL combines many attractive features, such as integrated gas management, plug-and-play capability, and a reduction in the radiated noise from an underwater submarine missile launch (flooding of the missile compartments in the current launching system is one of the main sources of radiated noise in a submarine). The unique design of the CCL may help reduce drag on a missile launched from below the water’s surface by creating a plume of exhaust gas directly over the missile’s flight path underwater, through which the missile will travel (as opposed to traveling through water). This gas plume should have the effect of increasing missile surface exit velocities and allowing a longer missile flight time.
No physical study has been attempted to characterize the developing exhaust gas plume and develop the current CCL design to a more efficient level of operation (only CFD has been attempted up to this point in time). This project will examine various methods for improving the design of the current CCL by constructing a sub-scale CCL unit and analyzing the physics of the developing exhaust gas plume. From the data obtained, a more efficient CCL unit will be designed, constructed, and compared to the current CCL design to examine the increase in efficiency.
Bubble-Image Based Non-Invasive
In-Field Pressure Measurements
Mel L. Butler
Alan K. Sturgis
Advisor: Prof. Pavlos Vlachos, ESM Dept., Virginia Tech
Currently, there is no established method for non-invasive global pressure measurements within the flow field. Current methods include pressure probes that need to be placed at the point of interest, thus interfering with the actual flow. In addition, conventional pressure probe measurements provide point measurements and are often limited by the resonant frequency of the transducer. The goal of this project is to develop a global non-invasive method of measuring pressure throughout a flow field.
We will develop a novel pressure measurement approach that overcomes the aforementioned limitations. This new method, bubble-image barometry (BIB), employs microscopic bubbles with controlled diameters that are released into a flow field in order to measure the pressure fluctuations. The bubbles, varying in size from 100 to 500 mm in diameter, respond instantaneously to certain rates of pressure fluctuations by changing diameter. High frequency velocity and pressure measurements will be obtained by sizing the bubble diameters with the use of Time-Resolved Digital Particle Image Velocimetry (TRDPIV). Time-Resolved Digital Particle Image Velocimetry will quantify the instantaneous displacement of bubbles, and image-processing techniques will be used to measure the size of the bubbles by counting pixels on the TRDPIV images. The calculated bubble diameter changes will be used to determine pressure fluctuations. These pressure calculations will then be compared to hydrostatic pressure changes calculated from the change in head along with turbulent flow pressure variations, which will be measured by pressure sensors. We will be able to measure pressure in a turbulent flow field with a noninvasive and non-interfering method by monitoring microscopic bubbles.