Commands specifying loads, constraints, element properties and materials

Overview

For the definition of loads, constraints, element properties and materials, commands are provided that allow the definition of the most important data types used by the “Neutral PATRAN Interface” and the “NASTRAN Interface” (see chapter “Interfaces to FE-Programs“).

The following commands are available:

Node forces	Define and assign forces or displacements on nodes
Element loads	Define and assign distributed loads on elements
Distributed loads	Define distributed loads on surface elements, calculate statically equivalent forces
Surface pressure	Define constant pressure on surface elements, calculate statically equivalent forces
Resultant	Calculate the resultant of node forces
Material	Define material properties
Cross-section	Define and assign cross section properties on elements
Constraints	Define and assign constraints on nodes
Check NASTRAN	Check assignments for the NASTRAN interface
Save to file	Save data to a binary file
Load from file	Load data from a binary file
Plot load data	Plot assignments
Record	Show some information of assignments
Delete all	Delete all data in memory

Command “Node forces” serves to assign forces or moments or displacements to individual nodes. With command “Element loads” individual elements are assigned distributed loads corresponding to the NASTRAN interface. Command “Distributed loads” allows defining a distributed load on element surfaces that is immediately transformed to statically equivalent node forces on the corner nodes of the elements. Command “Surface pressure” allows assigning elements a constant pressure normal to the element surface where the elements may be three dimensionally curved; this pressure is also immediately transformed to statically equivalent node forces on the corner nodes of the elements.

The data defined with these commands is stored in a binary file with extension .lqd.

These commands are only available if a FE-structure is loaded and processed. Node forces, element loads and properties are assigned to nodes and elements of the currently processed FE-structure where the external IDs of the nodes and elements are used, therefore these external IDs should not be changed after loads and constraints are defined.

Node forces and constraints may be defined in reference to a local coordinate system where the vector components are interpreted as

v = v₁e₁ + v₂e₂ + v₃e₃

With v₁, v₂, v₃ = given vector components and e₁, e₂, e₃ = basis vectors of the global or a local coordinate system. The basis vectors are node dependent with cylindrical and spherical coordinate systems and oriented in direction of increasing coordinate values.

If node forces or moments are written into a NASTRAN- or PATRAN-file it can be specified that the vectors defined in local coordinate systems should at first be transferred into the global coordinate system.

Command description

Node_forces.htm

Element_load.htm

Surface_loads.htm

Surface_pressure.htm

Material.htm

Cross_sections.htm

Constraints.htm

Resultant.htm

Load_FromFile.htm

Save_ToFile.htm

Plot9.htm

Information9.htm

Delete_all9.htm

Check_NASTRAN.htm