Structures without Cables |
 
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Structures without Cables |
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Two definitions will help to clarify some issues here. The initial position of an element is the position defined by the user-specified nodal coordinates. The element undeformed orientation is the orientation in which there are no stresses or restoring forces in the element. The undeformed orientation is also termed the stress free configuration. Naturally, the local undeformed axes for an element define the undeformed orientation.
In the great majority of analyses, particularly in the case of structures defined without cables (the subject of this section), the initial position and the undeformed orientation are the same.
When that is the case, you are not required to specify the orientation of the undeformed axes for the element. Specifically, you should not specify the vectors V and W when defining elements directly. As mentioned already and discussed in detail below, the vectors V and W define the undeformed orientation for an element. This definition is unnecessary when the undeformed orientation coincides with the initial position of the element. So when you do not explicitly define V and W, this is your way of informing Flexcom that initial and undeformed configurations are coincident.
Further information on this topic is contained in the following sections:
•Default Local Undeformed Axes
•When Initial is not Undeformed