Engineering Commons^™

The Effect Of Ultrasonic Power In Aluminum Wire Bonding Hardness Profiles, Matthew D. Mckay

Mechanical Engineering Master's Theses

Ultrasonic wire bonding is a critical process used widely across the microelectronics industry. Despite its ubiquity, there is a breadth of literature and ongoing active research into the basic principles of wire bonding. In particular, the effects of ultrasonic bonding on material properties are not fully understood. This thesis presents the effects of different ultrasonic bond powers on material properties. The changes in mechanical properties were measured by collecting Vickers microhardness data and nanoindentation data. The hardness in the bonded wire varied with two parameters: the distance from the bond interface, and the applied ultrasonic power. The hardness varied 5 …

Crystal Misorietation And Defect Generation During Contact Between Two Aluminum Substrates, Milad Khajehvand

Mechanical Engineering Master's Theses

With the use of molecular dynamics simulations, the nanoscale contact between two aluminum substrates at room temperature is studied. The so-called jump-to-contact (JC) phenomenon between (111) surfaces is observed to occur for interfacial distances below 5.8 ± 0.05 Å. This critical distance is approximately equal to 2.5 times the interplanar spacing of (111) planes in a perfect aluminum crystal at 300 K. The critical distance for JC is shown to be higher at higher contact temperatures because of the higher amplitude of atomic vibrations. The effect of employed interatomic potential on the critical distance is also discussed.

The critical distance …

Measuring The Vortex-Shedding Frequency Behind Staggered Cylinders In Cross-Flow, Christopher Clark

Mechanical Engineering Master's Theses

In this thesis, the Strouhal numbers from the downstream cylinder in a two cylinder configuration have been measured experimentally. Special apparatuses were designed to secure the cylinders in the wind tunnel as well as to hold a hot film anemometer probe in the center of the downstream cylinder’s wake. The cylinders were smooth, of equal diameter and extended the entire width of the wind tunnel. Because the cylinders used in this thesis were sufficiently long compared to their diameters and measurements were taken at center span, they were assumed to be infinite. The anemometer was calibrated according to King’s Law, …

Fuzzy-Model-Based (Fmb) Control Of A Spacecraft With Fuel Sloshing Dynamics, Lilit Mazmanyan

Engineering Ph.D. Theses

During the upper-stage separation and orbit injection, orbital control, and attitude maneuver, propellant slosh in partially-filled fuel tanks can cause dynamical instability or pointing errors. The spacecraft dynamics combined with propellant sloshing results in a highly nonlinear and coupled dynamic system that requires a complicated control law. This problem has been a long-standing concern for space missions. The purpose of this research is two fold. The first part is to investigate and develop nonlinear Takagi-Sugeno (T-S) fuzzy model-based controllers for a spacecraft with fuel sloshing considering the input constraints on the actuators. It includes i) a fuzzy controller/observer with a …

Additive Manufacturing Of A Motorcycle Helmet Utilizing 7-Axis 3d Printing, Kyle Mcmorrow, Caleb Alleva, Luke Correnti, Danny Eckstein, Adam Fontana, Pranav Prabhakar

Mechanical Engineering Senior Theses

This project analyzes the structural properties of 7-axis 3D printing versus traditional FDM printing. The team worked with AREVO Inc to manufacture a motorcycle helmet and test samples made from carbon fiber in a PEEK matrix. A drop-test rig was designed and constructed in-house to test a traditionally printed carbon fiber helmet alongside commercial helmets of identical geometry. The lighter weight printed helmet experienced significantly lower peak deceleration in the test headform (223 G’s versus 371 G’s for average commercial), but fractured along a print layer on impact. Had time allowed for printing of a helmet utilizing AREVOS’s true 3D …

Design Of Metamaterials With Graduating Poisson's Ratio Through Periodic Void Patterns, Xiaoming Liang

Mechanical Engineering Master's Theses

It has been known that when introducing alternating elliptical extrusions in a solid material with a positive Poisson's Ratio, the material's effective Poisson's Ratio can become negative. Furthermore, the change in the effective Poisson's ratio depends on two factors: the elliptical extrusions' aspect ratio and the porosity. Using this phenomenon, a study is conducted by combining elliptical extrusions with different aspect ratios and porosity to construct a composite material with gradually varying Poisson's Ratio. Numerical and physical compression studies are conducted to characterize the material's effective properties. The results show that the material can effectively stabilize its own structure under …

3d Printed Soft Robotic Hand, Zack Kisner, Chris Szigeti, David Leonardo

Mechanical Engineering Senior Theses

Soft robotics is an emerging industry, largely dominated by companies which hand mold their actuators. Our team set out to design an entirely 3D printed soft robotic hand, powered by a pneumatic control system which will prove both the capabilities of soft robots and those of 3D printing. Through research, computer aided design, finite element analysis, and experimental testing, a functioning actuator was created capable of a deflection of 2.17” at a maximum pressure input of 15 psi. The single actuator was expanded into a 4 finger gripper and the design was printed and assembled. The created prototype was ultimately …

Active Control Stabilization Of High Power Rocket, Valeria Avila Guerrero, Angel Barranco, Daniel Conde

Mechanical Engineering Senior Theses

High power rockets could become dynamically unstable due to outside disturbances after takeoff. The instability is augmented when the rocket is "slow" off the launch rail, which happens when the thrust-to-weight ratio is less than 5:1. Due to these reasons, the objective of this project was to design and build an active control system that will make sure the rocket follows a straight path all the way to apogee. This will be done through a model-based design approach, in which a 6DOF mathematical model of the flight dynamics will be created.

Vibration Attenuating Medical Platform, Cameron Fisch, Noah Friedman, Tyler Gambill, David Harris, Kelek Olais

Mechanical Engineering Senior Theses

Millions of injured people are transported by ambulances each year. While the suspension systems of ambulances dampen the road vibrations felt by the passengers, they do not attenuate the vibration completely. To patients who have compromised physical states, vibration and displacement can aggravate their condition and cause additional pain. Our solution to this societal problem is the Vibration Attenuating Medical Platform (VAMP). VAMP consists of an aluminum and steel structure that is moved with a pneumatic piston. This prototype is designed to fit into existing ambulances and attenuate the vibrations not eliminated by the ambulances suspension. After conducting background research, …

6u Cubesat Platform For Disaster Relief Communications, Uchechukwu Agwu, Duncan Bradley, Corey Brown, Mani Gnanasivam, Grant Mishler, Steven Parks

Mechanical Engineering Senior Theses

Natural disasters can seriously damage telecommunications infrastructure in affected areas, drastically limiting the channels of communication between locals and emergency relief teams. In such situations it is critical to have readily-available communications infrastructures that can be deployed and utilized as soon after the event as possible. Our mission is part of a multi-year effort to provide satellite-based amateur radio communications to areas impacted by humanitarian crises to facilitate relief efforts. Specifically, we developed the mechanical subsystems of a 6U CubeSat, a small satellite, in order to provide expanded volume, enhanced power generation, and Earth referenced orientation control compared with previous …

3d Printed Carbon Fiber Electric Mountain Bike Frame, Chris Edwards, Fionn Ruder, Joseph Hurley, Micah Thomas, Mitch Spinelli, Parker Gribb

Mechanical Engineering Senior Theses

3D printing of carbon fiber composites has been a developing technology for about 5 years, and in this time, Arevo Labs has established itself as a leader in the field. Our team joined forces with Arevo, who sponsored our project as we showcased their new, innovative carbon fiber manufacturing process. To do so, we focused on the conceptual design, analysis, assembly, and material testing of an electric mountain-bike frame printed with Arevo’s continuous carbon fiber printing technology. Our bike consists of the main frame and a chain stay subsystem, which connects the rear wheel to the rest of the frame …

The Vessel For Autonomous Research Underwater (The Varuna), Tyler Briles, Shae Connor, Erin Guthrie, Anthony Jackson, Madeleine Peauroi

Interdisciplinary Design Senior Theses

Humans are intimately connected to the Earth’s ocean, and yet only 5% of it has been explored. Learning more about marine life and ocean chemistry can only improve our stewardship efforts. The addition of an Autonomous Underwater Vehicle to the Santa Clara University Robotic Systems Laboratory’s collection of marine robots will contribute to this quest for knowledge. It will assist researchers by providing a low-cost, easy-to-use, portable, reliable, and safe alternative to operator-controlled vehicles. This report describes our motivations for this project, the decisions we made in the design and manufacturing of the VARUNA, and tradeoff analyses of possible options. …

Numerical Analysis Of Fatigue Crack Growth Of Low Porosity Auxetic Materials Using The Contour J-Integral, Garivalde S. Dominguez

Mechanical Engineering Master's Theses

Recent studies suggest that auxetic materials such as porous metals with orthogonal periodic void patterns have an increased fatigue life compared to non-auxetic materials. This study provides numerical solution to support the existing experiments with the use of contour J-integral as a parameter of stress intensity factor for computing the number of fatigue life cycle of the materials with auxetic structures. Representative volume elements (RVEs) were constructed to characterize the physical test specimens with void patterns such as ellipse, slot, and stop-hole. Extended finite element method (XFEM) was performed to verify the direction of crack propagation on auxetic materials. Sixty-five …

Enhancing Mobility And Independence Of Wheelchair Users, Briar Blake, Paul Nauleau

Interdisciplinary Design Senior Theses

Conditions as simple as a leg fracture or more severe impairments such as paralysis and stroke may confine a person to a wheelchair. Wheelchairs help people with limited mobility transport themselves to different locations, but do not help the person leave the wheelchair. Users would need to do this to enter a car, use the restroom, take a shower, and sit at a table comfortably with family. The following design is a wheelchair attachment that serves to provide the user with increased mobility and independence. Wheelchair users struggle to get into and out of their chairs due to the unassisted …

Powering A Biosensor Using Wearable Thermoelectric Technology, Anneliese Bals, Noah Barnes, Rafael Bravo, Nicolas Garcia, Joseph O'Bryan, Dylan Santana

Interdisciplinary Design Senior Theses

Wearable medical devices such as insulin pumps, glucose monitors, hearing aids, and electrocardiograms provide necessary medical aid and monitoring to millions of users worldwide. These battery powered devices require battery replacement and frequent charging that reduces the freedom and peace of mind of users. Additionally, the significant portion of the world without access to electricity is unable to use these medical devices as they have no means to power them constantly. Wearable thermoelectric power generation aims to charge these medical device batteries without a need for grid power.

Our team has developing a wristband prototype that uses body heat, ambient …

Phoenix Y6, Sean Backes, Michael Destin, Alastair Hood, Bruce Iverson, Brian Meier, John Strong

Mechanical Engineering Senior Theses

The mission of this project is to design and fabricate a vertical take-off and landing (VTOL) fixed-wing drone for use by firefighters and other emergency services. This vehicle will be designed for uses that include surveying wildfires, as well as spotting vehicular accidents, urban fires, and floods. Current drones available on the market are expensive or not designed specifically for emergency response. Our goal is to develop a working prototype of a vehicle that will be able to collect and relay important data such as live video and thermal images in addition to other measurements such as air velocity and …

Frugal Clay Press For Nicaragua: Design Of A Human-Powered Clay Brick Press For Rural Application, Rafael Delfin C. Guerrero, Milan O. Copic, Kevin A. Ellis, L. Isaac Marcia

Mechanical Engineering Senior Theses

This team was connected to a brick-making social entrepreneurship in Ciudad Darío, Nicaragua. Travel to Nicaragua in March of 2018 determined that the entrepreneurship wanted a manual brick press to increase the mechanical properties of bricks while decreasing the time needed for the bricks to dry before being baked. Fabrication of a semi-functional beta prototype was completed in May of 2018. Prototype operational tests showed that one cycle of brick compression and retrieval took roughly 3.5 minutes to produce a single double-sized brick. Water absorptivity tests determined that compressed bricks of red art clay experienced a percent absorptivity of 20.5%, …