Basic Syntax

A brief summary of the basic syntax is presented first. The syntax of an input file for MBDyn is structured in terms of statements. A statement follows the syntax:

       <card> [ : <arglist> ] ;

that is, a valid card name, depending on its nature, may be followed by a colon and by a list of (comma separated) arguments; it is always terminated by a semicolon. Statements are logically divided in blocks. Each block is opened by a begin statement and it is closed by an end statement:

       begin: <block> ;
              # block data
       end: <block> ;

The valid blocks (and their sequence) is:

• data
• <problem>
• control data
• nodes
• drivers (optional)
• elements
• parallel (only if the parallel solver is used and explicit directives are required)

The data block at present contains the type of problem that is solved by the analysis. The most significant one is initial value.

The <problem> block takes the name of the problem defined in the data block; it contains all the information required by the integration method to perform the desired simulation regardless of the nature of the problem.

The control data block mostly contains information about the problem that is required to ensure that a consistent model will be generated.

The nodes block contains all the nodes required by the simulation. They are separated from the rest of the data for historical reasons, because the nodes are defined as the entities that make degrees of freedom available to the simulation, so they must exist before any element is generated.

The drivers block is optional. It may contain some special driver data.

Finally, the elements block contains all the elements. They are defined as the entities that generate equations using the degrees of freedom provided by the nodes.

A layout of a typical input file is:

       begin: data;
           # global simulation data
           problem: initial value;
       end: data;

       begin: initial value;
           # problem-dependent data
       end: initial value;

       begin: control data;
           # global model data
       end: control data;

       begin: nodes;
           # nodes
       end: nodes;

       begin: drivers;
           # drivers
       end: drivers;

       begin: elements;
           # elements
       end: elements;