Gravity and Build Orientation as Material-State Variables: Sedimentation, Buoyancy, Drainage and Cure Asymmetry

Gravity and build orientation are treated here as material-state variables because they alter composition, drainage and resin retention before and during cure. In the dilute creeping-flow limit, settling grows with density mismatch and particle size squared and falls with viscosity; at higher loading, yield stress and particle interactions change that scaling. Orientation also changes drainage paths and trapped- resin volumes even when optical settings are unchanged. The evidence chain combines time-resolved vertical concentration profiles, mass or CT-based through-height analysis, rheology after controlled aging and drainage/refill imaging in representative orientations. A pre-print dwell series then provides a direct basis for setting the maximum allowable vat dwell between remixing events and for deciding when orientation-specific controls are required.

ER-359.