A stacking sequence redistributes load between differently oriented plies. This exercise uses a controlled laminate comparison to show how that redistribution changes the overall stiffness and the stresses carried by individual plies, even when the constituent material remains the same.
The copied IM7 pressure-vessel records are scaffolding. Replace the ply source and dimensions with the published T700/epoxy inputs; a pressure load is not an axial or torsional test.
Open this exercise in Workbench
Prepare the baseline
Record the initial ply order, angles and total thickness, then run the baseline before creating alternatives. Preserve the loading and geometry specified in the task so that the layup comparison remains meaningful. Inspect the laminate stiffness together with material-axis ply stresses; global stiffness alone does not show which ply is most highly stressed.
Worked procedure
1. Read the web walkthrough and NASA/TM–2014-216635. Create a stored orthotropic ply with E1/E2/G12 = 153/10.5/8.27 GPa, ν12 = 0.30; Xt/Xc = 2760/781 MPa and Yt/Yc/S = 76.5/233/89.6 MPa. Mark these as published estimates, not qualified allowables.
2. Assign that stored ply to all eight plies in [45/−45]4. Set tube OD/ID = 52.95/48.26 mm and total laminate wall thickness 2.345 mm (0.293125 mm per ply). Verify Geometry and laminate thickness agree.
3. Compare Ex, Gxy and νxy with 27.7 GPa, 39.6 GPa and 0.68. Check A16 and A26 are near zero. Keep the baseline unchanged and use a copy for carpet plots or angle optimization.
4. Create separate compatible axial tension, compression and torsion cases. Review the supported classical failure criterion and the paper’s estimated 179/176/290 MPa laminate strengths; do not claim an exact strength match from a stiffness comparison.
Review checkpoints
The stack is balanced; do not silently apply symmetry and change its sequence.
Material, dimensions, load basis and thickness convention must match before comparing results.
Model limits
Classical-laminate and first-ply screening. Manufacturing variation and qualification are excluded; the source describes estimated ply data.
Interpret the comparison
Explain the response in terms of orientation, symmetry and load sharing. Where a published stiffness comparison is provided, use it for that comparison only and retain the source’s qualification of the data. A match in elastic response is not an exact strength prediction, and a first-ply calculation should not be described as ultimate structural collapse.
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 laminate design
- Edit material properties and units
- Edit laminate materials, angles and thicknesses
- Review effective properties
- Geometry, loading and virtual tests
- 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.
References and source sections
References are retained with the formulations they support. Software instructions describe implementation scope; a cited source does not establish independent validation of a CDS calculation.