3.4. I/O Modules

PyFEM provides a comprehensive set of I/O (Input/Output) modules for reading input files, writing simulation results, generating visualizations, and managing data during finite element analyses. These modules enable flexible output of mesh data, nodal results, time histories, and custom visualizations.

3.4.1. Overview

The I/O system consists of:

Input modules: Read problem definitions and restore saved states
Output writers: Export results in various formats (VTK, HDF5, text)
Data loggers: Track specific quantities during analysis (graphs, contours)
State management: Save and restore full analysis states

All output modules share a common configuration pattern and can be combined to produce multiple output formats simultaneously.

3.4.2. Configuration

Output modules are configured in the .pro input file using two components:

Module list: The outputModules property lists which modules to use
Module blocks: Each module has a configuration block with its parameters

3.4.2.1. Basic Syntax

outputModules = ["module1", "module2", "module3"];

module1 =
{
  type = "ModuleType";
  # module-specific parameters
};

module2 =
{
  type = "AnotherModuleType";
  # module-specific parameters
};

The name in the outputModules list corresponds to the configuration block name. The type parameter specifies which I/O module to instantiate.

3.4.2.2. Complete Example

Here’s a typical configuration that combines multiple output types:

outputModules = ["vtk", "graph", "contour"];

vtk =
{
  type         = "MeshWriter";
  elementGroup = "All";
  interval     = 1;
};

graph =
{
  type     = "GraphWriter";
  onScreen = true;
  columns  = ["disp", "load"];

  disp = { type = "state"; node = 21; dof = "v"; };
  load = { type = "lam"; };
};

contour =
{
  type     = "ContourWriter";
  nodes    = [10, 11, 12, 13, 14, 15];
  interval = 5;
};

  contour =
{
  type     = "ContourWriter";
  nodes    = [10, 11, 12, 13, 14, 15];
  interval = 5;
};

3.4.3. Available Modules

3.4.3.1. Input Modules

InputReader - Reads .pro files and restores analysis states from dumps
DataDump - Saves complete analysis state for restart or inspection

3.4.3.2. Output Writers

MeshWriter - Writes VTK files (.vtu) for visualization in ParaView
HDF5Writer - Writes HDF5 files for large-scale data storage
OutputWriter - Writes human-readable text summaries of nodal data

3.4.3.3. Data Loggers

GraphWriter - Tracks time histories and generates plots
ContourWriter - Outputs data along specified node contours

3.4.3.4. System Management

OutputManager - Coordinates all output modules during analysis

3.4.4. Common Parameters

Most output modules support these common parameters:

Parameter	Description
`type`	Module type (mandatory for all modules)
`interval`	Output frequency in analysis cycles (default: 1)
`filename`	Custom output filename (module-dependent default)
`onScreen`	Display output during analysis (where applicable)

3.4.5. Best Practices

Choose appropriate intervals: Use larger intervals for expensive output operations
Combine formats: Use VTK for visualization and text files for time histories
Save binary dumps: Use DataDump for long analyses to enable restarts
Monitor progress: Enable GraphWriter with onScreen = true for feedback

3.4.6. Module Reference

Click on any module below for detailed documentation, parameters, and examples: