Prev Chapter 3: Free Format Input Up Chapter 3: Free Format Input Subsection 3.1.1: Format Specification Versions Next
3.1 Free Format Overview
The free format organizes the FEBio input data into hierarchical XML elements. The root element is called febio_spec. This root element also defines the format version number (Note that FEBio and the input format specification follow different version numberings). This document describes version 3.0 of the FEBio specification [F] [F] FEBio continues to read some older formats, but they are considered to be obsolete. (see Section 3.1.1↓ below for more details on the different input specification formats). The root element will therefore be defined as follows:
<febio_spec version="3.0"> <!-- contents of file --> </febio_spec>
The different sections introduced in this chapter are child elements of this root element. The following sections are currently defined:
Module defines the physics module for solving the model.
Control specifies control and solver parameters.
Globals Defines the global variables in the model
Material Specifies the materials used in the problem and the material parameters.
Mesh Defines the mesh of the problem, including nodal coordinates and element connectivity.
MeshDomains Assigns materials and other formulation attributes to element sets.
MeshData Defines element, facet, edge or nodal data that can be mapped to material parameters or certain boundary conditions and loads.
Initial Defines initial conditions for dynamic problems, such as initial velocities, and for transient quasi-static problems.
Boundary Defines the boundary conditions that are applied on the geometry.
Loads Defines the loads applied to the model. This includes nodal loads, boundary loads and volume loads (or sources for heat transfer problems).
Contact This section defines all contact interfaces.
Constraints This section defines rigid and nonlinear constraints.
Discrete This section defines all the discrete elements (i.e. springs)
LoadData Defines the load controllers.
Ouput Defines additional data that is to be stored.
Step Defines different analysis steps, where in each analysis the boundary, loads, contact and initial conditions can be redefined.
The current format specification expects the different sections of the input file to be listed in the same order as given above. Not all sections are required. Empty sections can be omitted and some are optional. A minimal file must contain at least the Control, Material, Mesh, and MeshDomains sections. The rest of this chapter describes each of these sections in more detail.
Table of contents
- Subsection 3.1.1 Format Specification Versions
- Subsection 3.1.2 Notes on backward compatibility
- Subsection 3.1.3 Multiple Input Files