lcf-strain-life

Readme | Physics Review | Agent Usage | Changelog | MIT License

An AI-agent-native toolkit for fatigue analysis of materials. It is a Python library plus an MCP server, so AI agents can run the whole analysis by calling tools.

Provide your own strain-controlled fatigue test data and get the standardized reduction, fitted material constants, life predictions, and plots. Results are reproducible and are saved for recall.

Why this exists: plenty of fatigue software exists, but none is built for AI agents to drive directly. The agent-native design over MCP is the point. Every capability is reachable through tools an agent can call.

Convention: all analysis uses true stress and true strain. Engineering input is converted at ingestion. The fatigue exponents b and c are negative throughout.

What it does

The toolkit is general purpose and material agnostic. It focuses on strain-life and per-cycle evolution, which the established stress-based high-cycle libraries such as pyLife, py-fatigue, and fatpack do not cover. It is input compatible with their pandas data shapes.

Related MCP server: STDF MCP Server

Install

python -m venv .venv
.venv\Scripts\activate            # Windows
pip install -e ".[mcp,dev]"

Requires Python 3.11 or newer.

Quick start, library

import lcf

# fit strain-life constants from per-test reduced data, here SAE 1137
fit = lcf.fit_strain_life(
    total_strain_amp=[0.009, 0.007, 0.005, 0.003, 0.002, 0.00175],
    stress_amp=[553, 522, 464, 405, 350, 319],         # MPa, half-life
    reversals=[4234, 7398, 14768, 77104, 437498, 3327958],
    E=208000,                                           # MPa
    min_plastic_strain=5e-4,   # exclude near-runout points from the plastic branch
)
print(fit.coffin_manson.eps_f, fit.coffin_manson.c)   # about 1.11, -0.62
print(fit.basquin.sigma_f, fit.basquin.b)             # about 1073 MPa, -0.084
print(fit.transition_reversals)                        # about 22,000 reversals

Quick start, MCP server

lcf-mcp                # runs the stdio MCP server
# or
python -m lcf

Register with Claude Code or Claude Desktop over stdio:

{ "mcpServers": {
    "lcf": { "command": "lcf-mcp" } } }

Documentation

• docs/PHYSICS_REVIEW.md is the science-only physics record: every equation defined and cited, no software detail. docs/PHYSICS_REVIEW.pdf is the same content typeset with a reviewer sign-off table, the file to share with a materials scientist for review.

• examples/ holds runnable scripts: a strain-life fit and a machine-style CSV ingestion.

• docs/AGENT_USAGE.md describes the MCP tools and the compute, save, recall pattern for AI agents using the toolkit.

• CHANGELOG.md is the chronological log of changes.

Project layout

src/lcf/            core library and MCP server
tests/              unit tests including golden-value validation, SAE 1137
examples/           runnable example scripts
docs/               the physics PDF and the agent usage guide

Authors and citation

David Fieser and Hugh Shortt. Both authors contributed equally to this project. To cite the software, use the "Cite this repository" button on GitHub or CITATION.cff.

License

MIT. See LICENSE.