Metadata-Version: 2.4
Name: 3pc-sandbuck
Version: 1.0.0
Summary: Python library for buckling analysis of shear deformable anisotropic sandwich plates under combined in-plane loading.
Author: Omprakash Seresta
Author-email: oseresta@gmail.com
License: MIT
Project-URL: Blog, https://3pcomposites.com/blogs-1/f/3pcsolver007-global-buckling-analysis-of-sandwich-panels
Project-URL: Analysis Tools, https://3pcomposites.com/analysis-tools
Project-URL: Documentation, https://drive.google.com/drive/folders/1jDb-P5BOgJ-moVU20B7D8oVeHjHLAHTm
Keywords: sandwich-plates buckling-analysis composites anisotropic aerospace-engineering mechanics fsdt clt in-plane-loads
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-sandwich
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-sandbuck

`3pc-sandbuck` is a Python library for buckling analysis of shear deformable sandwich plates under combined in-plane loading. It provides a `Sandbuck` class to solve the generalized eigenvalue problem for critical buckling loads, mode shapes, and displacement patterns.

## Installation

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

```bash
pip install sandbuck
```

## API Reference

### `Sandbuck` Class

The primary component of this package is the `Sandbuck` class, which takes a panel, a load case, and coordinates/Fourier-expansion parameters to solve the sandwich buckling governing equations.

```python
from sandbuck.sandbuck import Sandbuck
```

#### Required Parameters

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

*   **`panel`** *(Panel)*: An instance of the `Panel` class (from `3pc-panel`) containing the face sheet laminates and sandwich core definition.
*   **`loads`** *(Loads)*: An instance of the `Loads` class (from `3pc-loads`) containing the in-plane load components.
*   **`number_of_terms`** *(int)*: Number of terms in the double Fourier series expansion.
*   **`number_of_points_x`** *(int)*: Number of points along x-direction to calculate values.
*   **`number_of_points_y`** *(int)*: Number of points along y-direction to calculate values.

#### Calculated Properties

The class calculates the following properties:

*   **`pairs`**: List of pairs `(i, j)` for all `i, j = 1, 2, ..., M`, where `M` is the number of terms.
*   **`K33`**: Load-dependent part of the stiffness term K33 for all pairs.
*   **`lambdaEV`**: Eigenvalues of the generalized eigenvalue problem.
*   **`vr`**: Right eigenvectors of the generalized eigenvalue problem.
*   **`lambda_cr`**: Critical eigenvalue (lowest positive eigenvalue).
*   **`vr_cr`**: Critical right eigenvector.
*   **`mn_cr`**: Critical `(m, n)` pair.
*   **`lambdaP`**: Sorted list of positive eigenvalues.
*   **`lambda1` to `lambda5`**: First to fifth critical (positive) eigenvalues.
*   **`mn1` to `mn5`**: Dominant `(m, n)` pairs corresponding to eigenvalues `lambda1` to `lambda5`.
*   **`Nxxcr1` to `Nxxcr5`**, **`Nyycr1` to `Nyycr5`**, **`Nxycr1` to `Nxycr5`**: Critical buckling load components for the first 5 modes.
*   **`w1` to `w5`**: Out-of-plane displacement mode shapes for the first 5 modes.
*   **`w1loc` to `w5loc`**: Out-of-plane displacement values at grid locations.

### Methods

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

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

---

## Usage Examples

### Basic Initialization

Below is an example of performing a sandwich buckling analysis.

```python
from panel.panel import Panel
from loads.loads import Loads
from sandbuck.sandbuck import Sandbuck

# Assuming pnl (Panel) and ld (Loads) are already defined
sb = Sandbuck(
    panel=pnl,
    loads=ld,
    number_of_terms=4,
    number_of_points_x=11,
    number_of_points_y=11
)

# Access calculated results
print("Critical eigenvalue:", sb.lambda_cr)
print("Critical buckling load Nxxcr1:", sb.Nxxcr1)
```

## Commands

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

```bash
sandbuck input.cfg
```

*(This entry point is defined in `sandbuck.__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, cores, laminates, panels, loads, config) to the current directory.

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

The `sandbuck` command requires a configuration file (typically named `sandbuck.cfg`). Below is an example based on `sandbuck/examples/example001/sandbuck.cfg`:

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

[analysis]
number_of_terms = 4
number_of_points_x = 11
number_of_points_y = 11
```

#### `[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/).
*   **`cores`**: Path to the cores JSON file.
*   **`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 sandwich buckling analysis results will be written.

#### `[analysis]` Section

This section specifies the analysis settings:

*   **`number_of_terms`**: Number of terms in the double Fourier series expansion.
*   **`number_of_points_x`**: Number of grid points along the x-direction.
*   **`number_of_points_y`**: Number of grid points along the y-direction.

## Citation

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

**APA Format:**
> Seresta, O. (2026). *3pc-sandbuck: Python library for buckling analysis of shear deformable sandwich plates under combined in-plane loading*. PyPI. https://pypi.org/project/3pc-sandbuck/

**BibTeX:**
```bibtex
@software{3pc_sandbuck,
  author = {Seresta, Omprakash},
  title = {3pc-sandbuck: Python library for buckling analysis of shear deformable sandwich plates under combined in-plane loading},
  year = {2026},
  url = {https://pypi.org/project/3pc-sandbuck/}
}
```
