416.1 When simulation is useful

Use to explore layouts or soils before tests. Simulation de-risks HVM bollard choices; tests still govern crash rated bollard claims.

Numerical models help you compare clear-gap options, evaluate run-up/angle scenarios from the Vehicle Dynamics Assessment, and rapidly screen foundation classes before committing to costly physical testing. Keep expectations clear: models inform design decisions for HVM schemes, but certification and warranty remain anchored to the as-tested configuration.

Good candidates for early modeling include frontage arrays with constrained utilities (depth-class conflicts), corner chicanes that change impact angle, and comparative checks of shallow vs deep sockets (foundation types).

416.2 Model inputs & assumptions

Declare vehicles, soils, and joints. Transparency keeps HVM bollard decisions credible.

Document the test vehicle mass/inertia, speed band, and approach angle; the soil profile and foundation class; and all connection details (sleeve-to-core, socket grout, anchor cages). Capture these in an assumptions register and reference the relevant pages (331 impact loads & foundations, 232 spacing rules).

State model type and solver, contact definitions, material data (elastic–plastic curves, rate effects), mesh size targets, and convergence criteria. Limit jargon; a short table of inputs improves review quality and makes cross-checks against certificates & reports faster.

416.3 Vehicle models & fidelity

Pick fidelity to match questions—rigid vs deformable. Fidelity limits bound crash rated bollard inferences.

Rigid body surrogates are efficient for array-level questions (e.g., angle/trajectory into a bollard array) and for screening sensitivity bands. Deformable models (shell/solid) are heavier but capture crush, lift, and under-ride that influence penetration and debris.

Choose fidelity based on the decision at hand: for certification adjacency or model correlation, use the tested vehicle class and match test photos/kinematics from 413 rating-decoding. For early concept screening, rigid models often suffice.

416.4 Soil/foundation modeling

Include stiffness/strain-rate effects (331). Soil realism supports HVM bollard base checks.

Foundation response dominates base rotation and lateral capacity. Represent soil with appropriate stiffness (k), damping, and—if needed—rate-dependent strength. Tie the foundation to the core geometry chosen in diameter & section selection (311), and test depth classes against utility constraints (243, 244).

Where slab interaction is critical, include punching-shear checks and realistic boundary conditions. Calibrate springs or continuum blocks so predicted base rotations match observed deflection vs permanent set trends.

416.5 Correlation to test data

Calibrate against certified results (413). Correlation legitimizes crash rated bollard predictions.

Use certified impact speed, vehicle class, and orientation to calibrate. Compare penetration (P-value), debris zone, vehicle lift, and residual set. Match time-history features (peak force, plastic hinge formation) and reproduce visible failure modes from test footage and stills referenced in the evidence & documentation pack (444).

Agree an acceptance band (e.g., ±5–10% for penetration/peak loads) with reviewers, and record calibration choices so future variants are traceable to the same baseline.

416.6 Sensitivity & uncertainty

Vary speed, angle, and mass (228). Bands help set HVM bollard safety margins.

Run one-at-a-time and combined variations around the credible worst case: approach speed, impact angle, and vehicle mass/ride-height. Present results as a sensitivity band with clear uncertainty budget. Where appropriate, show energy parity so substitutions are properly judged in equivalency assessments (414).

416.7 Using results in design

Translate outputs to spacing/foundation tweaks (232, 332). Results refine crash rated bollard layouts.

Turn model outputs into decisions: adjust clear-gaps, move the defend line, or upgrade the foundation class where base rotation demand exceeds limits. Cross-check any change against rating-critical dependencies (421) so certificates aren’t inadvertently invalidated.

Record the design freeze and decision trail in your submission pack (938), and reference the applicable spacing rules (232) and foundation types (332).

416.8 Reviewer questions to ask

Ask about mesh, contacts, and validation. Good answers speed HVM bollard approvals.

• Mesh density & sensitivity: was convergence checked?
• Contact algorithms & friction: what values and tests support them?
• Material data: strain-rate sources and temperature limits noted for hot climates (337)?
• Validation set: which certified tests (standard, speed, vehicle) were matched, and within what acceptance band?
• Scope boundaries: what inferences are out-of-scope for the as-tested configuration?

416.9 Documentation set

Provide models, inputs, and comparison plots (444). Docs make crash rated bollard simulations review-ready.

Bundle the model files, assumptions register, material data sheets, and change log with comparison plots (penetration vs time, base rotation, vehicle kinematics) and a short reader guide. Index everything in the submission index and include a versioned “calibration note” that points to the matched certificates in 444 Evidence & Documentation.

416 Numerical Simulation & Model Correlation — FAQ