Portfolio Presentation

Steven Coakley

About MeI am a recent graduate of the Mechanical Engineering program at Northeastern University, and an active member of the NU Cycling team during the mountain bike season. Though I am interested in design work, I became a Mechanical Engineer for its broad applications, giving me the ability to be an effective member of a team in almost any industry setting. Along with mountain biking, I enjoy hiking and snowboarding, as well as travelling. I would like to join a group of people who are passionate about their work.

Mechanical EngineeringSample of Work 1

Project: Powerlink Stator Bracket

Problem: Design a bracket to attach a ~70 lb aluminum ring to a CT Scanner frame.

Challenges: • Maintain parallel faces – aluminum (stator) ring requires .030” gap from its corresponding

rotor ring in order to transfer data and power to the CT machine• Avoid operating frequencies – bracket and ring modes must remain well above the 30 Hz

operating frequency of the machine• Adjustability – must incorporate the ability to make fine adjustments in x-, y- and z- axes in

order to align the stator and rotor during assembly

Solution: • 6 mm thick C-channel cross section, simple sheet metal construction spanning

the width of the CT machine frame• Slotted plates for adjustment in each direction• Top and bottom bracket (top shown), each weighing ~14 lb• Y-axis adjustment via power screw in order to account for height change during operation due to drive wheel compression

Bracket in static operation – weight of aluminum ring is 70 lb yielding negligible deflection in the y-direction.

Modal analysis - initial design’s first mode occurred at 31 Hz. Following a study on the cross section’s moment of inertia, the first mode was increased to 41 Hz.

Mechanical EngineeringSample of Work 2

Project: Seal testing and validation

Problem: Create a full-scale fixture to test the effectiveness of a new seal design at 15,000 psi, in temperatures ranging from 40-250 °F

Challenges: • Must fit within existing pump casing• Seals must be tested at various gap sizes (to simulate component expansion and

contraction during operation)o 0.006”o 0.032”

• Fixture must withstand high pressure, as well as a temperature range without failing or compromising the tolerances

• Fixture must accommodate temperature monitoring equipment

Solution: • Fixture attaches to the outer flange of the original pump casing, extending inward

to reach the seal lands within• Chambers for running coolant and hot water exist underneath the seal grooves,

allowing for the temperature variation• Stress and displacement calculations ensured the seals would remain in contact

with the sealing face under pressure• Thermal analysis was performed to estimate the time needed to perform a cooling

and heating cycle• Two Pieces

o Large machined piece containing seal grooves and heating/cooling chambers o Standard pipe and flange used to minimize cost

Interim design under 15,000 psi load, nearing the yield stress of steel.

Pump casing designated for the test (flange OD on the right side is ~4ft). Test fixture is inserted and fastened to the right-side flange.

Mechanical EngineeringSample of Work 3

Project: Capstone Design* – Ratcheting Adjustable Wrench

Problem: Design a wrench to address flaws with current adjustable wrenches

Challenges: • Decrease tendency to slip and round bolt heads• Integrate a ratcheting system for ease of use• Design for strength, based on average household usage

*Winner 2011 Senior Capstone Design Award for Outstanding Project

Solution: • 6-sided iris style actuation - allows for contact on every bolt head face• Cartridge design - adjustment and locking (to hold each position) mechanisms

housed in a cylindrical system, allowing the unit to be simply placed in a handle• Conventional ratcheting - the cartridge design allows for conventional ratcheting,

with teeth on the outer diameter of the cartridge, and the ratcheting mechanism living within the handle

Load applied to wrench simulates 50 ft lbs of torque to tighten a grade 5, 5/8” bolt head, the worst case scenario.Highest stress occurs at the actuation pin nearest the ratchet mechanism, with a value of 293 ksi.

Prototype:

Ratchet pawl

Jaws

Slotted actuation plate

Handle

Center pin ring

Mechanical EngineeringApplication of skillsExperience gained through the various co-op positions I have held, as well as my Capstone senior design project, have taught me to utilize skills I learned throughout my engineering curriculum in real-world applications:• The ability to conceptualize ideas that fit a strict set of requirements• The ability to model those concepts, and to refine those models efficiently

throughout the design process• Feedback-oriented design process

o Effective brainstorming with a teamo Ability to receive and incorporate feedback from peers, resident

experts and outside sources • Structural and Modal analysis using SolidWorks Simulation

o Ensure it withstands the necessary loads and impactso Factor-of-safety design

• Experience creating the necessary drawings to take a product from 3D model to machined parto Learned to create properly toleranced and dimensioned drawings from

experienced drafters

Thank you for your consideration

I look forward to the opportunity to speak with you further about my qualifications, the position, and your company as a workplace. Please review my attached resume to learn more about me. I may be reached at your convenience via email.

Steven [email protected]