curtinengineering.com
Sean Curtin
Mechanical Engineering Student | Seeking Summer 2026 Internship
Hi, my name is Sean Curtin. I'm a mechanical engineering student at MassBay Community College. This portfolio contains some of the projects I am most proud of, showcasing my work in prototyping, 3D design, and mechanical fabrication.
Automotive Product Design: Volvo 960 Cup Holder
Problem:
The Volvo 960, designed in the late 1980s for small coffee cups, features fragile, obsolete cupholders that fail under the weight and size of modern drinks. Replacement OEM parts cost nearly $500, creating a pain point for a dedicated enthusiast community. The goal was to design a direct-fit, cost-effective solution that was structurally robust, aesthetically matching, and required no vehicle modification.
Process: Iterative Design & Engineering Validation
7 iterative prototype parts show the development process, with markings indicating fit and stress points for redesign.
This project exemplifies the engineering design loop, using rapid prototyping and Finite Element Analysis (FEA) to systematically solve a real-world problem.
• Reverse Engineering & CAD Modeling:
Precise measurements of the console storage slot were taken with digital calipers to ensure a perfect friction fit. The complex geometry was modeled in SolidWorks, prioritizing printability and minimal support material. The design was optimized to securely hold a 24oz Owala water bottle and a 12oz energy drink can—the primary use cases identified for modern users.
• Initial Prototyping & Failure:
The first functional prototypes, tested with the intended bottles, revealed two key failures:
• Tolerance Issues: Parts were not fitting correctly into the console slot.
• Structural Failure: The holders bent and felt unstable under the weight of the drinks, indicating insufficient strength.
• Engineering Analysis (FEA):
A static stress simulation was conducted, applying a 90N load (dynamically equivalent to over 5x the combined weight of the target drinks) to simulate aggressive driving forces. The analysis identified a critical stress concentration of 73.3 MPa at a sharp interior corner, far exceeding PLA's 50 MPa yield strength and confirming the root cause of the failure.
• Redesigns:
• For Fit: Adjusted tolerances and separated the cup holder from the mounting plate for a modular, secure fit.
• For Strength: Added reinforcing gussets at the base of the arm to the cup holders to better transfer structural loads into the mounting plate, eliminating flexure observed during physical testing.
Validation: The redesigned part was simulated again. FEA results showed a peak stress of only 14.77 MPa—an 80% reduction—achieving a Factor of Safety greater than 3.4.
Result:
A Validated, Robust Product: The final design can handle forces equal to a 17g impact—about the same as dropping a Volvo 960 from 15 feet. In other words, it’s far stronger than anything the car would face in everyday driving.
Impact:
I installed the product in my own car and it is ready for sale as both a physical product and digital file on platforms like Etsy and Printables, bringing enthusiasts an affordable, high-quality solution..
The final product installed and functioning in the vehicle, securely holding modern drink containers.
The process underscored the critical importance of tolerancing, iterative design, and material selection (e.g., using PETG for heat resistance) beyond theoretical design.
Aerodynamic Analysis & Mathematical Visualization
Presented at the MassBay STEM Expo Spring 2025
Problem:
Advanced engineering designs, like airfoils, are governed by mathematical functions of multiple variables. Visualizing these functions is key to understanding their performance.
Process:
I used Python (NumPy, Matplotlib) to model and graph these functions, creating visualizations of NACA airfoils, parabolic surfaces, and saddle shapes. This involved calculating partial derivatives and gradients to analyze their behavior.
Result:
I created an intuitive visual explanation of these concepts and was selected to present my work at the college-wide STEM Expo. The project bridges the gap between abstract calculus and tangible engineering applications.
Freelance Rapid Prototyping: Architecture Firm
Problem:
The client needed two handrail sections printed at full scale (4” height) for a design review with their client. The original .STL files were created by someone inexperienced with 3D printing, and there was uncertainty about scale and material efficiency. The deadline was tight — the parts had to be ready for a client meeting on Monday.
Process:
• File Verification & Scaling: Checked the client’s STL files and scaled them from 4 mm to 4 inches while maintaining design accuracy.• Material Planning: Calculated material usage and determined that hollow prints could save plastic without compromising structural feel.• 3D Printing: Printed both sections using black and silver PLA filament due to partial supply limitations.• Client Communication: Coordinated delivery timing and pricing directly with the client to meet their tight deadline.
Result:
Produced accurate, full-scale prototypes on time for the client meeting while maintaining design fidelity despite scaling and material adjustments.
Impact:
Earned positive feedback and repeat client trust, and was compensated fairly for rapid turnaround and problem-solving.
Full Design Repository
In addition to my featured projects, I actively design and publish functional 3D models to solve everyday problems. You can view all of my public designs, including mounts, tools, and mechanical components, on my Printables.com profile.
