Metadata-Version: 2.4
Name: 3pc-lambuck
Version: 1.0.0
Summary: Python library for buckling analysis of shear deformable anisotropic laminates and sandwich plates.
Author: Omprakash Seresta
Author-email: oseresta@gmail.com
License: MIT
Project-URL: Blog, https://3pcomposites.com/blogs-1/f/3pcsolver003-buckling-of-simply-supported-composite-plates
Project-URL: Analysis Tools, https://3pcomposites.com/analysis-tools
Project-URL: Documentation, https://drive.google.com/drive/folders/1jDb-P5BOgJ-moVU20B7D8oVeHjHLAHTm
Keywords: laminate-buckling composites buckling-analysis sandwich-plates anisotropic aerospace-engineering mechanics fsdt clt
Classifier: Programming Language :: Python :: 3
Classifier: License :: OSI Approved :: MIT License
Classifier: Operating System :: OS Independent
Requires-Python: >=3.6
Description-Content-Type: text/markdown
License-File: LICENSE
Requires-Dist: 3pc-material
Requires-Dist: 3pc-ply
Requires-Dist: 3pc-laminate
Requires-Dist: 3pc-panel
Requires-Dist: 3pc-loads
Requires-Dist: 3pc-utils
Requires-Dist: numpy
Requires-Dist: scipy
Dynamic: author
Dynamic: author-email
Dynamic: classifier
Dynamic: description
Dynamic: description-content-type
Dynamic: keywords
Dynamic: license
Dynamic: license-file
Dynamic: project-url
Dynamic: requires-dist
Dynamic: requires-python
Dynamic: summary

# 3pc-lambuck

`3pc-lambuck` is a Python library for buckling analysis of shear deformable anisotropic laminates and sandwich plates. It provides a `Lambuck` class to solve the generalized eigenvalue problem to calculate critical buckling loads and mode shapes based on first-order shear deformation theory (FSDT) and classical laminate theory (CLT).

## Installation

Use the package manager [pip](https://pip.pypa.io/en/stable/) to install `3pc-lambuck`. Since the package and its dependencies are available on PyPI, you can install them directly:

```bash
pip install 3pc-lambuck
```

## API Reference

### `Lambuck` Class

The primary component of this package is the `Lambuck` class, which takes a panel and a load case to compute buckling metrics.

```python
from lambuck.lambuck import Lambuck
```

#### Required Parameters

When initializing `Lambuck`, the following parameters are required:

*   **`panel`** *(Panel)*: An instance of the `Panel` class (from `3pc-panel`) containing the laminate definition and geometry.
*   **`loads`** *(Loads)*: An instance of the `Loads` class (from `3pc-loads`) containing the load case and environmental conditions.
*   **`number_of_terms`** *(int)*: Number of terms to include in the Ritz/Fourier series expansion.
*   **`number_of_points_x`** *(int)*: Number of evaluation points along the x-axis.
*   **`number_of_points_y`** *(int)*: Number of evaluation points along the y-axis.

#### Calculated Properties

The class calculates the following properties:

*   **`NT`, `NC`**: Thermal and hygral in-plane load vectors.
*   **`pairs`**: List of $(m, n)$ pairs for Ritz terms.
*   **`K33`**: Part of stiffness matrix dependent on tensile loads.
*   **`F33`**: Matrix representing load-dependent contribution.
*   **`lambdaEV`**: Eigenvalues of the generalized eigenvalue problem $K = \lambda F_{33}$.
*   **`vr`**: Right eigenvectors.
*   **`lambda_cr`**: Critical eigenvalue (same as `lambda1`).
*   **`vr_cr`**: Critical right eigenvector.
*   **`mn_cr`**: Critical $(m, n)$ pair.
*   **`lambdaP`**: Sorted list of positive eigenvalues.
*   **`lambda1`, `lambda2`, `lambda3`, `lambda4`, `lambda5`**: The first five critical (lowest positive) eigenvalues.
*   **`mn1`, `mn2`, `mn3`, `mn4`, `mn5`**: Dominant $(m, n)$ pairs for the first five eigenvalues.
*   **`Nxxcr1`, `Nyycr1`, `Nxycr1`** to **`Nxxcr5`, `Nyycr5`, `Nxycr5`**: Critical buckling loads (for modes 1 to 5).

### Methods

#### `Lambuck.fromDict(**kwargs)`

Initializes a `Lambuck` instance using a dictionary of keyword arguments.

---

## Usage Examples

### Basic Initialization

Below is an example of performing a buckling analysis on a panel under a specific load case.

```python
from panel.panel import Panel
from loads.loads import Loads
from lambuck.lambuck import Lambuck

# Assuming pnl (Panel) and ld (Loads) are already defined
s001 = Lambuck(
    panel=pnl,
    loads=ld,
    number_of_terms=8,
    number_of_points_x=5,
    number_of_points_y=5
)

# Access critical buckling load and eigenvalue
print("Critical Eigenvalue:", s001.lambda_cr)
print("First critical eigenvalues (modes 1-5):", s001.lambda1, s001.lambda2, s001.lambda3, s001.lambda4, s001.lambda5)
```

## Commands

The package provides a command-line interface entry point. After installing, you can run the application using:

```bash
lambuck input.cfg
```

*(This entry point is defined in `lambuck.__main__:main`)*

### Options

*   **`config`** *(positional)*: Specify the configuration file (`.cfg`) to run the analysis.
*   **`-h, --help`**: Show the help message and exit.
*   **`-v, --version`**: Show the version number.
*   **`-s, --sample`**: Copy example files (materials, plies, laminates, etc.) to the current directory.

### Configuration File (`lambuck.cfg`)

The `lambuck` command requires a configuration file (typically named `lambuck.cfg`). Below is an example based on `lambuck/examples/composite006/lambuck.cfg`:

```ini
[files]
materials = materials.json
plies = plies.json
laminates = laminates.json
panels = panels.json
loads = loads.json
output = output.txt

[analysis]
number_of_terms = 8
number_of_points_x = 5
number_of_points_y = 5
```

#### `[files]` Section

This section defines the paths to the required input JSON files and the desired output file:

*   **`materials`**: Path to the materials JSON file. Follows the format expected by [`3pc-material`](https://pypi.org/project/3pc-material/).
*   **`plies`**: Path to the plies JSON file. Follows the format expected by [`3pc-ply`](https://pypi.org/project/3pc-ply/).
*   **`laminates`**: Path to the laminates JSON file. Follows the format expected by [`3pc-laminate`](https://pypi.org/project/3pc-laminate/).
*   **`panels`**: Path to the panels JSON file. Follows the format expected by [`3pc-panel`](https://pypi.org/project/3pc-panel/).
*   **`loads`**: Path to the loads JSON file. Follows the format expected by [`3pc-loads`](https://pypi.org/project/3pc-loads/).
*   **`output`**: Path to the text file where the buckling analysis results will be written.

#### `[analysis]` Section

This section specifies the analysis settings:

*   **`number_of_terms`**: Number of terms to include in the Ritz/Fourier series.
*   **`number_of_points_x`**: Number of evaluation points along the x-axis.
*   **`number_of_points_y`**: Number of evaluation points along the y-axis.

## Citation

If you use this library in your research or work, please cite it as follows:

**APA Format:**
> Rastogi, N., & Seresta, O. (2026). *3pc-lambuck: Python library for buckling analysis of shear deformable anisotropic laminates and sandwich plates*. PyPI. https://pypi.org/project/3pc-lambuck/

**BibTeX:**
```bibtex
@software{3pc_lambuck,
  author = {Rastogi, Naveen and Seresta, Omprakash},
  title = {3pc-lambuck: Python library for buckling analysis of shear deformable anisotropic laminates and sandwich plates},
  year = {2026},
  url = {https://pypi.org/project/3pc-lambuck/}
}
```
