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c0a6da9 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 | # Constrained-LHS design
## Design coordinates
Each constrained Latin hypercube design uses seven normalized coordinates:
`[x, y, impact_speed, mass_ratio, theta_deg, phi_deg, material_index]`.
The continuous domains are:
| Parameter | Domain | Unit |
|---|---:|---|
| impact speed | [1732.05, 5196.15] | mm/s |
| mass ratio | [0.75, 1.25] | dimensionless |
| theta | [0, 15] | degree |
| phi | [0, 360] | degree |
Theta is measured from global +Z. Phi is measured in global XY from +X toward
+Y. Speed and angles are converted to the Cartesian velocity vector as
`v = speed * [sin(theta) cos(phi), sin(theta) sin(phi), cos(theta)]`.
Material is a three-level categorical coordinate with balanced counts. It
selects one of the rigid-impactor E/nu pairs listed in
`SIMULATION_PROTOCOL.md`; it is not a continuously interpolated material.
## Geometry-constrained position sampling
Impact positions are panel-shell centroids, not arbitrary points in a
rectangular three-dimensional box. The topological outer boundary is computed
from shell edges occurring in only one element. Candidate centroids must be at
least 80 mm from all outer-boundary nodes in XY.
The first two LHS coordinates are projected to the nearest available candidate
centroid in normalized XY, without reusing a centroid. Consequently:
- X and Y are space-filling design coordinates constrained by the mesh;
- Z is inherited from the selected shell centroid;
- the geometry JSON ranges are observed coordinate extrema, not continuous LHS
box bounds.
## Maximin selection and seeds
For a requested batch, 128 candidate seven-dimensional LHS designs are
generated. Material coordinates are mapped to category-bin centers for scoring,
and the design maximizing the normalized minimum pairwise distance is retained.
| Geometry | Construction | Seed |
|---|---|---:|
| `floorfrontR` | independent single batch | 20260728 |
| `trunkfloor` | independent single batch | 20260723 |
| `floorfrontdriver`, cases 001--100 | initial batch | 20260721 |
| `floorfrontdriver`, cases 101--200 | complementary nested extension | 20260722 |
| `floorfrontdriver`, cases 201--500 | independent augmentation | 20260722 |
Thus, the final set for each geometry contains 500 constrained-LHS cases, but
the `floorfrontdriver` set is not one monolithic 500-point Latin hypercube.
The three geometries share design bounds but use different eligible position
sets and are not case-wise paired.
|