With this option the user can define a user element, i.e. an element created by the user and not available by default in CalculiX. The following parameters are required: TYPE, INTEGRATION POINTS, MAXDOF and NODES.
The TYPE must begin with the letter U and is to be followed by a strictly positive integer not exceeding 9999. It is used in an *ELEMENT card to assign this type to specific elements.
INTEGRATION POINTS defines the number of integration points used in the numerical integration of this element type (maximum 256). It is used for allocation purposes. E.g stresses and strains are usually calculated at the integration points.
The parameter MAXDOF declares the maximum degree of freedom associated with nodes belonging to this element type (maximum 256). Translational degrees of freedom correspond to degrees of freedom 1,2 and 3 rotational degrees of freedom to 4,5 and 6. For instance, shell are beam elements usually contain rotational degrees of freedom, so MAXDOF=6. For volumetric elements MAXDOF is usually 3.
Finally, the parameter NODES specifies the number of nodes associated with this element type (maximum 256).
Example: *USER ELEMENT,TYPE=U1,INTEGRATION POINTS=0,MAXDOF=6,NODES=2
defines a user element of type U1 with no integration points (i.e. analytical integration), a maximum degree of freedom of 6 and 2 nodes.