## *SECTION PRINT

Keyword type: step

This option is used to print selected facial variables in file jobname.dat. The following variables can be selected:

• Fluid dynamic drag stresses (key=DRAG), only makes sense for 3D fluid calculations
• Heat flux (key=FLUX), only makes sense for heat calculations (structural or CFD)
• Section forces, section moments and section areas(key=SOF or key=SOM or key=SOAREA), only makes sense for structural calculations

The drag stresses are printed in the integration points of the faces. The output lists the element, the local face number, the integration point, the x-, y- and z- component of the surface stress vector in the global coordinate system, the normal component, the shear component and the global coordinates of the integration point. At the end of the listing the surface stress vectors are integrated to yield the total force on the surface.

The heat flux is also printed in the integration points of the faces. The output lists the element, the local face number, the integration point, the heat flux (positive = flux leaving the element through the surface defined by the parameter SURFACE) and the global coordinates of the integration point. At the end of the listing the heat flux vectors are integrated to yield the total heat flow through the surface.

The section forces, section moments and section areas are triggered by the keys SOF, SOM and SOAREA. All three keys are equivalent, i.e. asking for SOF (the section forces) will also trigger the calculation of the section moments and the section areas. This implementation was selected because the extra work needed to calculate the moments and areas once the forces are known is neglegible. The output lists

• the components of the total surface force and moment about the origin in global coordinates
• the coordinates of the center of gravity and the components of the mean normal
• the components of the moment about the center of gravity in global coordinates
• the area, the normal force on the section (+ is tension, - is compression) and the size (absolute value) of the shear force.

Notice that, for internal surfaces (i.e. surfaces which have elements on both sides) the sign of the force and the moment depends on the side the elements of which were selected in the definition of the *SURFACE. Please look at example beamp.inp for an illustration of this.

Since the section forces are obtained by integration of the stresses at the integration points of the faces, which are obtained by interpolation from the stress values at the facial nodes (which in turn are determined through extrapolation from the integration point values inside the volumetric elements and subsequent averaging over the elements to which the node belongs) they will not be accurate at locations where the stress jumps, such as at interfaces between different materials.

There are four parameters, SURFACE, NAME, FREQUENCYF and TIME POINTS. The parameter SURFACE is required, defining the facial surface for which the requested items are to be printed. The parameter NAME is required too, defining a name for the section print. So far, this name is not used.

The parameters FREQUENCYF and TIME POINTS are mutually exclusive.

The parameter FREQUENCYF is optional, and applies to nonlinear calculations where a step can consist of several increments. Default is FREQUENCYF=1, which indicates that the results of all increments will be stored. FREQUENCYF=N with N an integer indicates that the results of every Nth increment will be stored. The final results of a step are always stored. If you only want the final results, choose N very big. The value of N applies to *OUTPUT,*ELEMENT OUTPUT, *EL FILE, *ELPRINT, *NODE OUTPUT, *NODE FILE, *NODE PRINT, *SECTION PRINT,*CONTACT OUTPUT, *CONTACT FILE and *CONTACT PRINT. If the FREQUENCYF parameter is used for more than one of these keywords with conflicting values of N, the last value applies to all. A FREQUENCYF parameter stays active across several steps until it is overwritten by another FREQUENCYF value or the TIME POINTS parameter.

With the parameter TIME POINTS a time point sequence can be referenced, defined by a *TIME POINTS keyword. In that case, output will be provided for all time points of the sequence within the step and additionally at the end of the step. No other output will be stored and the FREQUENCYF parameter is not taken into account. Within a step only one time point sequence can be active. If more than one is specified, the last one defined on any of the keyword cards *NODE FILE, *EL FILE, *NODE PRINT or *EL PRINT will be active. The TIME POINTS option should not be used together with the DIRECT option on the procedure card. The TIME POINTS parameters stays active across several steps until it is replaced by another TIME POINTS value or the FREQUENCYF parameter.

The first occurrence of an *SECTION PRINT keyword card within a step wipes out all previous facial variable selections for print output. If no *SECTION PRINT card is used within a step the selections of the previous step apply, if any.

Several *SECTION PRINT cards can be used within one and the same step.

First line:

• *SECTION PRINT
• Enter the parameter SURFACE and its value.
Second line:
• Identifying keys for the variables to be printed, separated by commas.

Example:

*SECTION PRINT,SURFACE=S1,NAME=SP1
DRAG


requests the storage of the drag stresses for the faces belonging to (facial) set N1 in the .dat file. The name of the section print is SP1.

Example files: fluid2, beamp.