Cables |
 
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Cables |
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A powerful feature in Flexcom is the cable pre-static step, which you can invoke to provide the full finite element analysis with a first approximation to the static configuration of a structure with low bending stiffness. To invoke this option, you identify all or parts of a structure as forming a cable or a number of cables between specified end points, these end points being nodes of the finite element discretisation. The static cable profile between the end points is then computed by the pre-static step, using the cable catenary equations, prior to a full finite element analysis with bending and torsion included.
The advantage of this facility is that it allows you to define nodes in terms of an (unknown) cable profile. Without this feature, you would have no alternative other than to perform an initial static analysis in a known configuration (typically a straight line) where you would be able to define the nodal coordinates using one of the methods described above. From this you would then move the cable to the required catenary configuration. This point is discussed in considerable detail in Cable Pre-Static Step.
The rest of this section goes into considerable detail about cables and the Flexcom cable pre-static step, and provides guidelines and recommendations for their use. Much of this information is useful in understanding the internal workings of Flexcom and in correctly employing cables in your model building. However, the use of cables has to a large extent been superseded by the Lines capability, and the majority of guidelines presented in the rest of this section are automatically adhered to when cables are generated automatically from lines. So unless you propose to use cables in preference to lines, you can skip reading this section on cables and proceed directly to Lines.
Further information on this topic is contained in the following sections:
•Defining Nodes in Terms of Cables
•*CABLE is used to specify that part of the structure forms a cable between specified end points
•*NODE,CURVILINEAR is used to specify nodes at particular locations along a cable, or to specify a number of equally spaced nodes along a cable segment between two nodes.