Embedded Files
Objectives
Objectives
To design and fabricate a simple mechanism using basic CAD, physical prototyping, and simulation principles. The catapult must be able to launch a projectile using spring force and demonstrate mechanical motion. This was to be completed within a 4-week timeline for the Introduction to Engineering Design course (MAE 1351) at UT Arlington, the project required simulation, prototyping, and performance demonstration of a spring-powered mechanism. The project required CAD modeling, motion simulation, hands-on prototyping, and performance validation of a spring-powered system.
Quick Summary
Quick Summary
Project Type: Individual
Duration: 4 weeks
Tools: SolidWorks, 3D Printer, McMaster-Carr
Focus: CAD, Simulation, Fabrication
Outcome: Functional spring-loaded mechanism with validated motion
Technical Details & Skills
Technical Details & Skills
CAD Tools: SolidWorks 3D Modeling, Assembly Mates
Simulation: Motion Analysis using springs, stoppers, force constraints, and motion stops
Drafting: 2D dimensioned drawings, exploded views, BOM
Prototyping: PLA 3D printing and mechanical fasteners
Research & Documentation: McMaster-Carr spring data, YouTube demos
Design Overview & Features
Design Overview & Features
The catapult features six main components:
Base – Supports the system and receives the arm’s impact
Two Sides – Structural elements supporting the roller and stopper
Stopper – Prevents the arm from over-rotating
Roller – Provides rotational motion for the arm
Throwing Arm – Launches the projectile under spring tension
The catapult design balances structural rigidity and dynamic motion, using a spring-based launch mechanism and rotational constraints.
CAD & Real Prototype Pair
CAD & Real Prototype Pair
Left: 3D-printed catapult assembly, fabricated in PLA and assembled with fasteners
Right: CAD model of full catapult assembly in SolidWorks with mates applied
Left: Side view of physical prototype showing roller and spring mount
Right: Close-up of CAD assembly highlighting throwing arm and rotation axis
Video Documentation
Video Documentation
Part Fabrication: Shows extrusion of spring mount using PLA filament
Part Fabrication: Prints of structural side walls using PolyPrinter
Resting Pose: Fully assembled prototype in initial state
Operation: Demonstrates spring-powered launch and smooth motion (0.25× speed)
SolidWorks Motion Study: Simulated throwing arm rotation with applied spring force and motion path chart
Simulation & Engineering Decision
Simulation & Engineering Decision
Used SolidWorks Motion Analysis with gravity applied in Y-axis
Interference detection modeled stopper behavior
Simulated spring behavior using McMaster-Carr values
Iterated design to select improved spring characteristics
Drawings & Documentation
Drawings & Documentation
Exploded Assembly Drawing with full BOM and part callouts
2D Drawing: Throwing Arm dimensions and hole placements
2D Drawing: Side plate dimensions, features, and notes
Challenges & Iteration
Challenges & Iteration
The original spring was too weak to trigger complete launch. Through iterative simulation and testing, I adjusted the spring rate and reduced free length using McMaster-Carr specs, improving launch motion and achieving stopper engagement as designed.
Outcomes & Contributions
Outcomes & Contributions
Designed and modeled a spring-loaded catapult using SolidWorks and assembly mates
Simulated rotational arm motion and spring compression using motion analysis
Fabricated prototype using PLA 3D printing and tested launch performance
Created engineering documentation including 2D drawings and exploded views
Iterated spring specs using simulation validation and physical testing
Skills Applied
Skills Applied
SolidWorks · Motion Analysis · CAD Drafting · 3D Printing · Design Iteration · Technical Drawing · Prototyping · Documentation
Reflection
Reflection
This project introduced me to full-cycle mechanical design: from CAD modeling and motion simulation to prototyping and performance validation. It strengthened my understanding of static and dynamic systems, and I gained confidence in using SolidWorks for mechanical systems and learned to iterate quickly between simulation results and real-world feedback. This early experience laid the foundation for my interest in mechanical systems, motion control, and real-world design validation
*Note: CAD files were created in SolidWorks (Student Edition, 2019) and submitted with MAE 1351 coursework. Files are not retained, but design documentation is included below.*
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View or Download Project Report (PDF)
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