| # 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. |
|
|
