Project Overview
This project explores how topology optimization combined with FDM additive manufacturing can produce a competition-grade racing drone frame that is significantly lighter and stiffer than a conventionally designed equivalent.
The final frame weighs 87 grams compared to 142 grams for the baseline design - while maintaining equivalent torsional stiffness under flight loads.
The Problem
Standard racing drone frames are cut from flat carbon fiber plate stock. This limits geometry to 2.5D shapes and wastes material.
The question: Can FDM-printed topology-optimized geometry match the structural performance of flat carbon fiber plate at lower weight?
Design Process
Step 1 - Define Load Cases
- Motor thrust - vertical force at each arm tip up to 800g per motor
- Crash impact - horizontal impulse load at arm tips
- Vibration - high-frequency excitation from props at 400-500Hz
- Torsion - twisting loads during aggressive maneuvers
Step 2 - Topology Optimization
Ran SIMP optimization in nTopology with:
- Objective: Minimize compliance (maximize stiffness)
- Constraint: Retain 35% of original volume
- Load cases: All four flight scenarios weighted by frequency
Step 3 - Material Selection
| Property | Standard PETG | CF-PETG | Improvement |
|---|---|---|---|
| Tensile Strength | 50 MPa | 78 MPa | +56% |
| Stiffness | 2.1 GPa | 5.8 GPa | +176% |
| Weight | 1.27 g/cc | 1.19 g/cc | -6% |
Results
- Baseline carbon frame failed at 2.8kg per arm
- Topology-optimized FDM frame failed at 2.6kg per arm
- 93% of baseline strength at 61% of the weight
Biggest advantage of FDM: Repairability. A crashed carbon fiber frame is total loss. A printed frame repairs in 45 minutes.
What I Would Do Differently
- Increase wall count to 8 at arm roots
- Embed carbon fiber rods along arm length
- Run fatigue analysis before physical testing
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