# Structural Analysis Family Guidance

Read only the family selected by the approved requirements. Coupled features apply each relevant section and define the coupling terms explicitly.

## Common

Check DOF ordering, boundary conditions, units, coordinate transforms, rigid-body modes, element orientation, residual convention, output location, and conservation or equilibrium identities.

## Linear static

Define linearization assumptions, stiffness symmetry expectations, load assembly, constraint treatment, reactions, patch tests, rigid-body/null-space checks, and mesh-convergence quantities.

## Nonlinear static

Define configuration and strain/stress measures, state update, residual and consistent tangent, load/time parameter, convergence norms, increment/cutback behavior, path dependence, and energy or work checks.

## Modal, eigenvalue, and buckling

Define matrix problem, boundary conditions, mass or geometric stiffness, eigensolver target, normalization, repeated-mode handling, sign/phase invariance, residual norms, and mode correlation. Distinguish linearized buckling from nonlinear collapse.

## Dynamics

Define mass and damping, initial conditions, time integration, stability and algorithmic dissipation, load history, time-step convergence, energy balance, frequency/phase measures, and modal truncation where applicable.

## Contact and constraints

Define gap and normal orientation, active-set/search semantics, normal and tangential laws, enforcement method, consistent contributions, state transitions, penetration/slip measures, and action-reaction checks.

## Material nonlinearity

Define admissible state, yield/failure surface, flow/evolution laws, integration algorithm, consistent material tangent, history initialization, loading/unloading cases, and single-point constitutive tests.

Do not apply an irrelevant checklist merely for completeness. If the family is ambiguous and the choice changes physical meaning or acceptance, return `needs-user-decision`.