lcf-strain-life

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/reference holds the equations, symbols, and physics.

• docs/design/WORKFLOW.md describes the data flow and the compute, save, recall model.

• docs/decisions holds the Architecture Decision Records, one per major design choice.

• CHANGELOG.md is the chronological log of changes.

• CLAUDE.md holds the rules and positioning for AI agents working on the repo.

Project layout

src/lcf/            core library and MCP server
tests/              unit tests including golden-value validation, SAE 1137
docs/reference/     equations, physics, symbol tables
docs/design/        workflow and research-derived implementation reference
docs/decisions/     ADRs, the decision log

License

MIT. See LICENSE.