BSc Final Thesis

CubeSat Release Mechanism.

3D-printed Hold-Down Release Mechanism for CubeSat missions

Mechanism mass: 15 g
Load held in traction testing: 140 N
Average burn-wire release time: 4 s
Thesis grade: 10/10

A 3D-printed, single-shot mechanism that holds a CubeSat’s solar panels closed through launch and releases them with a burn wire, load-tested to 40% above its design case.

The problem

Deployable solar panels and antennas have to stay folded against a CubeSat through the loads of launch, then release reliably, once, in orbit, without leaving any debris behind. That is the job of a Hold-Down Release Mechanism (HDRM). Commercial ones are expensive, so my thesis asked whether a low-cost, 3D-printed mechanism could do the same job.

What I did

I designed a single-shot HDRM 3D-printed in PLA: two releasing arms are held closed by a nylon line, and a NiChrome wire melts through that line by the Joule effect to release them. I used SolidWorks FEA to compare two joint geometries and picked a 1 mm accordion joint for the best balance of flexibility and strength, then redesigned the arms with a retaining tooth and lateral guides so the retention link can’t move sideways. I 3D-printed, assembled and tested the prototype.

CAD model of the mechanism: closed for launch (left) and open after release (right).

Highlights

01Single-shot HDRM 3D-printed in PLA, released by a NiChrome burn wire
02FEA-driven redesign: an accordion joint outperformed a simple circular one
03Held 140 N in traction, 40% above the 100 N design case, with no deformation
04Every requirement in the evaluation matrix verified — about TRL 4

Results

The 3D-printed HDRM prototype, closed and held by its nylon line — The final prototype in its closed position, held by a nylon line.

FEA of the releasing arm showing stress, displacement and strain — FEA of the releasing arm — von Mises stress, displacement and strain — used to compare joint geometries.

Traction test with the mechanism suspended under a 140 N load — Traction test: the mechanism held 140 N, 40% above the 100 N design case, with no deformation.

Burn-wire release circuit under test — Burn-wire release circuit: 1.15 A, 5.3 W, releasing in an average of 4 s.

Outcome

Every evaluation parameter was verified, which places the prototype at roughly TRL 4. Next steps would be space-grade materials, thermal-vacuum testing, and a reusable version based on shape-memory alloys.

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