# User Modules
User modules are the means by which users can feed their own data into a model for display by GSA either as contours in a Graphic View or tables in an Output View. Nodal, element and member user modules are available.
A nodal user module consists of one value per node in the model.
An element user module consists of values per position on the element. For 1D elements positions are expressed in terms of millionths of the way along the element. So for example position 0 is at end 1 of the element, position 1000000 is at end 2, and position 333333 is a third of the way along the element. Values must be specified at both ends of 1D elements (i.e. positions 0 and 1000000). For 2D elements a value is expected at each topology position plus a centre value, though if the ‘centre only 2D’ flag is set only the centre value is expected . User modules also have a name, a dimension (i.e. whether length, moment, etc. or dimensionless) and a flag for discrete or continuous contours. A discrete contour is one that represents the value that exists for that position and does not vary continuously along the element.
A member user module is similar to an element user module except that all members are 1D.
User modules may be supplied to GSA in text file (GWA) format. Refer to the Text File Format document for a definition of the format. Data should be supplied in SI units. User modules can be appended to a GSA model that has been saved in text file format and then opened or they can be imported into an existing model using the File | Import | Text (GWA file) menu command.
Once a user module has been fed into a model it remains part of the model, being saved in and read from the GWB file. The user module management dialogs allow user modules to be deleted and renamed.
When user modules are present in a model they are offered as contour and diagram options for Graphic Views and output options for Output Views. User module data are converted to the current units for display. Note that contouring of element and member user module data requires values to have been specified at all nodes on the element.
As well as outputting nodal user module data per node this data can be contoured on elements and can be output per topology item per element.
# Reading user modules from GWA files
When a user module is read from GWA file if the user module ID is specified as zero then the user module is appended to the current user modules: the new user module is created by the user module title record and the following user module records (with ID=0) supply values to the new user module.
If the specified imported user module ID references an existing user module and the imported user module title data are compatible with the existing user module then imported user module values are written into the existing user module, preserving the existing values except where overwritten by imported values. However if the title data are incompatible then the existing values are nulled. Title data are compatible if the ‘dimension’ and ‘is_centre’ fields are the same.
# Generating user modules
User modules can be generated from contoured data in a Graphic View, using the Graphics | Generate User Module command, and from displayed data in an Output View, using the Output | Generate User Modules command. An option to generate user modules is also offered in the Output Settings dialog box. (Hint: It is possible to generate user modules without first displaying the output by giving the New Output View command to open the Output Settings dialog directly.) When generating from an Output View separate user modules are generated for each component and for each case currently displayed.