03.07 · NASA · AS4/3501-6 pressure-cylinder screening

Pressure loading produces different hoop and axial demands, and the end condition helps determine that balance. This exercise connects the vessel geometry and loading to the laminate response, then uses layup comparisons to explore how the same membrane demands are carried by different stacks.

The starter uses IM7/8552, not AS4/3501-6. Supply traceable AS4/3501-6 ply properties, thickness and the source diameter convention before comparison. Slits are intentionally outside this pristine-cylinder model.

Open this exercise in Workbench

Prepare the baseline

Check the radius or diameter convention and whether the ends are closed before running. Keep pressure and geometry unchanged during the ply-balance comparison. Where the exercise supplies membrane relations or published data, use them as a transparent check and document exactly which quantities are being compared.

Worked procedure

1. Read the web walkthrough and NASA-CR-195101 / NASA-CR-192618. Create a traceable AS4/3501-6 stored ply and replace the starter Micro source. Establish the source’s 305 mm cylinder diameter convention and corresponding Geometry inputs.

2. Build [90/0/45/−45]s and a separate [0/45/−45/90]s laminate at equal total thickness. Apply low internal pressure with closed ends and no unrelated axial load.

3. Run the pristine thin-wall membrane cases. Verify Nhoop = p r and Naxial = p r / 2; compare global strains, A-matrices and D16/D26. Use documented strength inputs for supported first-ply screening.

4. Document the excluded 12.7–50.8 mm axial slits and hand off loads/material state to a suitable local fracture model. Do not interpret a global first-ply result as slit failure pressure or delamination resistance.

Review checkpoints

The pressure-induced hoop-to-axial membrane load ratio is two for the stated closed-end case.

Similar in-plane stiffness does not imply identical local damage or bending response.

Model limits

Pristine-cylinder screening only. Slit-tip fracture, splitting, delamination, nonlinear local response and the source’s subcritical damage are not solved here.

Interpret the comparison

Keep global membrane behaviour separate from local damage tolerance. If the source discusses slits, cracks or delamination that the selected model does not resolve, document those exclusions rather than inferring their failure pressure from a pristine laminate calculation. Report both the useful global result and the additional analysis needed for the local question.

How information passes between models

Micro → Laminates: Predicted ply stiffness, strength, density and expansion properties.

Materials → Micro: Constituent stiffness, strength, density and thermal / moisture properties.

Mechanical → Simulation: SIMULATION selects this case and its analysis model; the case owns its applicable cycle and input references.

Laminates → Mechanical: Ply angles and thicknesses, stiffness, mass and ply properties.

Geometry → Mechanical: Part shape and dimensions, thickness or section definition, and model-specific geometric inputs. Each selected case consumes only the dimensions its model supports.

Models → Micro: Applied model assignment: Halpin–Tsai. Model parameters and formulation are used by Micro.

Models → Mechanical: Applied model assignment: CLT · Linear thin-wall membrane. Model parameters and formulation are used by Mechanical.

Further reading and evidence

• Related case study: NASA pressure cylinder
• Edit material properties and units
• Edit laminate materials, angles and thicknesses
• Geometry, loading and virtual tests
• Connected inputs and result freshness
• Run and review a model

Review the recorded validation scope. Retain the original inputs and solver notices with the results. Representative teaching data are not design allowables.