Undeformed Versus Initial Positions |
 
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Undeformed Versus Initial Positions |
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Another innovative facility offered by Flexcom is a capability for the specification of undeformed element orientations. In most applications, the geometry you define represents the structure undeformed or stress-free configuration. However, this need not necessarily be the case, and the position defined by the specified nodal coordinates may represent the configuration of a deformed structure. In this general case the definition of the stress free orientation and the definition of the nodal coordinates are completely independent, with the stress free orientation being defined on an element-by-element basis when specifying the structure connectivity. This facility offers considerable flexibility, but is of interest only to a limited number of users.
When you define the connectivity of an element, in the majority of cases you only specify the element number and its start and end nodes. However, you may optionally define an additional six inputs, indicating to Flexcom the stress free orientation of the element. This section explains the significance of these inputs, and illustrates the circumstances when you might be required to specify such data. The inputs are entitled V1, V2, V3, W1, W2 and W3. Together these inputs define two vectors V and W, which in their turn define the undeformed orientation of the element you are inputting. To understand the significance of this, a brief overview of the Flexcom coordinate axis systems is provided.
Further information on this topic is contained in the following sections:
•If you have constructed your model using lines, then the stress free orientation of any line may be explicitly defined by specifying the V1, V2, V3, W1, W2 and W3 entries under the *LINES keyword.
•If you have built your model using an older approach (i.e. via the old *NODE, *ELEMENT and *CABLE keywords), then the stress free orientation of any element may be explicitly defined by specifying the V1, V2, V3, W1, W2 and W3 entries under the *ELEMENT keyword. When the undeformed orientation of an element is explicitly defined and that element is then identified as the Master Element in generating further elements, the undeformed orientation of the master element becomes by default the undeformed orientation of the generated elements.
If you would like to see an example of how the stress free orientation of several lines are explicitly defined, refer to H04 - Pipe Laying.