Sail Membrane Numerics

Overview

Provide expert diagnosis and stabilization guidance for thin membrane or shell sail structures and their numerical solvers. Focus on instability, nonlinear convergence, conditioning, constraints/contact, tension-only behavior, and FSI coupling across solver types.

Workflow

1. Collect the minimal model context.
   • geometry, mesh, element type, and material model
   • loads, time integration, solver, preconditioner, tolerances
   • constraints, contact, and FSI coupling details
2. Validate solver and algorithm assumptions before tuning.
   • confirm symmetry, SPD, or linearity requirements
   • identify constraint or contact formulations that make the system indefinite
   • check explicit stability limits or implicit consistency
3. Classify the failure mode.
   • divergence vs stagnation vs oscillation vs energy growth
   • onset step: first step, nonlinear iteration, or after contact/FSI
4. Apply targeted fixes in priority order.
   • fix model issues (BCs, rigid body modes, tension-only handling)