Mechanical report (concept)
Scope / model
- Rigid platform supported by axial struts (hexapod).
- Linear static under quasi-static accelerations; linear modal
estimate from 6-DOF stiffness/mass.
- This is a screening tool for early trades, not a qualified launch
loads analysis.
Mass model
- Primary: 45.0 kg
- Secondary: 6.0 kg
- Structure: 120.0 kg
- Radiator: 25.0 kg
- Platform total: 196.0 kg
Struts
- Material: CFRP, E=120.0 GPa
- Tube OD: 60.0 mm, wall: 2.0 mm
- Allowables (concept): tension 800 MPa, compression 500 MPa
Load cases (with safety
factor)
- Safety factor: 1.25
- axial_z: a = (0.00g, 0.00g, 6.00g)
- lateral_x: a = (2.00g, 0.00g, 0.00g)
- lateral_y: a = (0.00g, 2.00g, 0.00g)
Optimization
- Used
--optimize to minimize tube cross-section among
candidates at or above the configured OD and wall minima, subject to the
quasi-static and modal proxy constraints. The separate structural-FEM
gate must also pass before release.
- Selected: base radius 1.80 m, platform radius 0.90 m, OD 60.0 mm,
wall 2.0 mm
Modal (concept)
- Requirement proxy: first mode >= 25.0 Hz
- Modes (Hz): 48.6, 48.6, 92.8, 119.7, 119.7, 151.7
Margins (per strut)
| Strut |
L (m) |
Worst T (N) |
Worst C (N) |
FoS T |
FoS C |
Pcr (N) |
FoS buckling |
| 1 |
2.837 |
2272 |
-2486 |
128.30 |
73.30 |
22572 |
9.08 |
| 2 |
2.290 |
3668 |
-2588 |
79.48 |
70.40 |
34650 |
13.39 |
| 3 |
2.837 |
2272 |
-2702 |
128.30 |
67.44 |
22572 |
8.35 |
| 4 |
2.290 |
3668 |
-0 |
79.48 |
inf |
34650 |
inf |
| 5 |
2.837 |
2272 |
-0 |
128.30 |
inf |
22572 |
inf |
| 6 |
2.290 |
3668 |
-2006 |
79.48 |
90.82 |
34650 |
17.27 |
Stowed launch
restraint hardware (screening model)
- Adds removable launch restraint members in parallel with the hexapod
for launch only.
- Final restraint forces and modes are computed from the released
stowed geometry, not from a separate analytical ring proxy.
- Restraints: 6 members, material AL6061, base radius 1.00 m, platform
radius 1.10 m, OD 40.0 mm, wall 3.0 mm
- Stowed first-mode target: >= 35.0 Hz
- Launch restraint sizing/placement was selected by a small concept
optimizer under the stowed first-mode and buckling constraints.
- Stowed modes (Hz): 48.6, 48.6, 134.4, 151.7, 195.7, 195.7
- Worst launch restraint margins: compression FoS 2539.85, buckling
FoS 281.28
- Hexapod with restraints installed: worst compression FoS 66.27,
buckling FoS 8.21
Internal
support screening (translation-only proxy)
- Support groups are derived from the actual concept geometry
endpoints, not hand-entered lengths.
- Each group is screened as a rigid supported mass on axial members
under the same quasi-static acceleration set.
- This is intentionally simpler than the hexapod model:
translation-only load sharing, no joint moments or local bracket
bending. | Group | Mass (kg) | Members | Axes | OD (mm) | Worst FoS T |
Worst FoS C | Worst FoS buckling |
|---|---:|---:|---|---:|---:|---:|---:| | primary_mounts | 45.0 | 9 |
xyz | 20.0 | 28.61 | 28.61 | 292.67 | | secondary_mounts | 6.0 | 3 | xy
| 8.0 | 170.46 | 92.26 | 562.53 | | secondary_spiders | 16.8 | 12 | xyz
| 18.0 | 75.69 | 69.52 | 169.03 | | focal_supports | 13.2 | 3 | xyz |
30.0 | 204.20 | 60.49 | 22.18 | | radiator_mounts | 34.6 | 6 | xyz |
24.0 | 25.22 | 52.35 | 26.56 | | vgroove_supports | 9.6 | 9 | xy | 10.0
| 64.97 | 75.03 | 28.32 | | sunshield_supports | 14.4 | 12 | xyz | 36.0
| 968.56 | 907.47 | 338.05 | | sunshield_outriggers | 14.4 | 24 | xy |
12.0 | 939.70 | 587.31 | 530.39 |
Internal
support beam proxy (combined axial + bending)
- Adds a transverse inertial load proxy to each support member using
the real exported geometry and a simple beam assumption per group.
- This catches members that look fine axially but are too flexible or
too highly stressed in bending during launch acceleration. | Group |
Beam assumption | Worst FoS T | Worst FoS C | Worst bend (MPa) | Worst
tip defl. (mm) | |---|---|---:|---:|---:|---:| | primary_mounts |
pinned_pinned_center | 10.79 | 10.45 | 25.4 | 0.051 | | secondary_mounts
| pinned_pinned_center | 12.79 | 7.99 | 62.6 | 0.028 | |
secondary_spiders | fixed_fixed_center | 35.73 | 36.50 | 11.8 | 0.051 |
| focal_supports | pinned_pinned_center | 5.27 | 4.84 | 52.2 | 2.797 | |
radiator_mounts | fixed_fixed_center | 4.31 | 4.30 | 63.8 | 2.302 | |
vgroove_supports | fixed_fixed_center | 2.51 | 2.51 | 109.8 | 4.036 | |
sunshield_supports | cantilever_tip | 16.24 | 10.16 | 49.2 | 7.005 | |
sunshield_outriggers | fixed_fixed_center | 63.69 | 39.81 | 12.6 | 0.029
|
Limitations / next steps
- No joint modeling, preload, thermal strain, acoustic loads, random
vibration PSD, or deployment dynamics.
- Launch configuration (stowed sunshield) is not modeled; update
mass/inertia and attachment geometry accordingly.
- Internal support beam proxy is still a simplification: no bracket
plates, joint offsets, local contact stresses, or coupled modes.
- For qualification: replace with full FEM (mesh + joints + modes +
random vib + shock).