Equilibrium and the CSV contract

Validation preserves balance

M07 audits reactions and moments again. If a postprocessing change requires us to rebuild or solve the model, we must show that the M06 prerequisite remains satisfied:

force_error  < 0.005
moment_error < 0.005

Validation does not replace equilibrium; it depends on it.

Acceptance contract

The case receives passes=1 only when all of the following conditions are met:

• 126 nodes, 40 elements, 6 tip nodes, and at least one result set.
• Deflection error less than 5 %.
• Tip-face displacement spread below 1 %.
• Corner node consistent with M04 within the 0.1 %.
• Two top and two bottom nodes in the section.
• Correct tension and compression signs.
• Stress error less than 10 %.
• Stress asymmetry less than 5 %.
• Balance errors less than 0.5 %.

CSV — A complete record of the comparison

The macro generates m07_validation_audit.csv:

case,beam_l,mesh_h,n_nodes,n_elements,n_sets,n_tip,
uy_tip_avg,uy_tip_corner,uy_tip_min,uy_tip_max,uy_spread,
uy_ref,uy_error,x_section,n_top_section,n_bottom_section,
sx_top_avg,sx_bottom_avg,sigma_fea,sigma_ref,
stress_error,stress_symmetry,force_error,moment_error,passes

The CSV preserves model, measurement, reference, error and decision. This allows repeating the validation without reconstructing the interpretation from screenshots.

Guided practice

1. Calculate manually I, uy_ref and sigma_ref.
2. Run the model until SOLVE and confirm the set.
3. Inspect the deformation before extracting results.
4. Calculate the average and dispersion of tip_nodes.
5. Reproduce the M04 corner probe geometrically.
6. Extract S,X top and bottom in 0.2·L.
7. Compare PLNSOL and PLESOL.
8. Generate the CSV and justify each tolerance.