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Run npx skillmds@latest add ashfordeou/laminate-stiffness in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

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Is Laminate Stiffness free to use?

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Who published Laminate Stiffness?

ashfordeOU (@ashfordeou) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Laminate Stiffness by ashfordeou — Agent Skill

Name: Laminate Stiffness
Author: ashfordeOU

Laminate Stiffness

Use when you must compute the stiffness of a composite laminate with classical lamination theory: build the ply stiffness from the material constants, rotate it to the ply angle, and assemble the A matrix for a symmetric laminate. Produces the ply stiffness, the rotated stiffness with coupling terms, and the laminate A matrix used in strength and stability analyses. Trigger: composite laminate, classical lamination theory, ply stiffness, laminate a matrix, symmetric laminate, composites.

ashfordeOU 9d837d8 3 files · 7.8 KB Updated Sep 17, 2026

File contents

Composite Laminate Stiffness (structures/composites/laminate-stiffness)

Use when the task is composite laminate stiffness with classical lamination theory: ply stiffness, rotation, and the symmetric laminate A matrix.

Domain quick reference

A ply has orthotropic stiffness in material axes: Q11, Q12, Q22, Q66 from the engineering constants.
Rotation to the laminate axes produces Q-bar; the coupling terms Q16 and Q26 vanish for 0 and 90 degree plies.
The laminate A matrix sums Q-bar times ply thickness; for a balanced symmetric laminate the A16 and A26 terms vanish.
Composite airframe practice sits in the FAR-25 / CS-25 certification context for transport aeroplanes.

Workflow

Collect ply engineering constants E1, E2, nu12, G12.
Build the material stiffness with ply_stiffness.
Rotate each ply with rotated_ply_stiffness.
Assemble the A matrix with laminate_a_matrix.
Confirm the coupling terms are small for symmetric balanced laminates.

Pitfalls

Forgetting nu21 = nu12 * E2 / E1 in the denominator.
Assembling an unsymmetric stack and reading coupling terms as zero.
Mixing degrees and radians in the rotation.

Behavior contract (gate 3)

The ply, rotation, and A matrix logic is exercised by the gate 3 contract test: scripts/test_laminate_stiffness.py against scripts/laminate_stiffness_logic.py (stdlib unittest, offline). Run: python3 scripts/test_laminate_stiffness.py

Compliance

Standards referenced, not reproduced: FAR-25 is US government work (public domain) and CS-25 is a free EASA download; the CLT math is common mechanics, summary-only per standards-map.yaml.
compliance: STANDARDS-REF, gated: false.

---name: laminate-stiffnessdescription: Use when you must compute the stiffness of a composite laminate with classical lamination theory: build the ply stiffness from the material constants, rotate it to the ply angle, and assemble the A matrix for a symmetric laminate. Produces the ply stiffness, the rotated stiffness with coupling terms, and the laminate A matrix used in strength and stability analyses. Trigger: composite laminate, classical lamination theory, ply stiffness, laminate a matrix, symmetric laminate, composites.license: Apache-2.0---# Composite Laminate Stiffness (structures/composites/laminate-stiffness)Use when the task is composite laminate stiffness with classicallamination theory: ply stiffness, rotation, and the symmetriclaminate A matrix.## Domain quick reference- A ply has orthotropic stiffness in material axes: Q11, Q12, Q22, Q66 from the engineering constants.- Rotation to the laminate axes produces Q-bar; the coupling terms Q16 and Q26 vanish for 0 and 90 degree plies.- The laminate A matrix sums Q-bar times ply thickness; for a balanced symmetric laminate the A16 and A26 terms vanish.- Composite airframe practice sits in the FAR-25 / CS-25 certification context for transport aeroplanes.## Workflow1. Collect ply engineering constants E1, E2, nu12, G12.2. Build the material stiffness with ply_stiffness.3. Rotate each ply with rotated_ply_stiffness.4. Assemble the A matrix with laminate_a_matrix.5. Confirm the coupling terms are small for symmetric balanced laminates.## Pitfalls- Forgetting nu21 = nu12 * E2 / E1 in the denominator.- Assembling an unsymmetric stack and reading coupling terms as zero.- Mixing degrees and radians in the rotation.## Behavior contract (gate 3)The ply, rotation, and A matrix logic is exercised by the gate 3contract test: scripts/test_laminate_stiffness.py againstscripts/laminate_stiffness_logic.py (stdlib unittest, offline).Run:python3 scripts/test_laminate_stiffness.py## Compliance- Standards referenced, not reproduced: FAR-25 is US government work (public domain) and CS-25 is a free EASA download; the CLT math is common mechanics, summary-only per standards-map.yaml.- compliance: STANDARDS-REF, gated: false.

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