Files with the extension .prb contain all the information about general problem and intervals data. The general problem data is all the information required for performing the analysis and it does not concern any particular geometrical entity. This differs from the previous definitions of conditions and materials properties, which are assigned to different entities. An example of general problem data is the type of solution algorithm used by the solver, the value of the various time steps, convergence conditions and so on.
Within this data, one may consider the definition of specific problem data (for the whole process) and intervals data (variable values along the different solution intervals). An interval would be the subdivision of a general problem that contains its own particular data. Typically, one can define a different load case for every interval or, in dynamic problems, not only variable loads, but also variation in time steps, convergence conditions and so on.
The format of the file is as follows:
All the fields must be filled with words, where a word is considered as a string of characters without any blank spaces. The strings signaled between quotes are literal and the ones inside brackets are optional. The interface is case-sensitive, so any uppercase letters must be maintained. The default_field_value entry and various optional_value_i entries can be alphanumeric, integers or real numbers, depending on the type.
Note: There are other options available to expand the capabilities of the Problem Data window (see Special fields).