Geometric Properties for Truss Elements |
 
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Geometric Properties for Truss Elements |
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The following user inputs are used to assign geometric property data to Truss Elements.
•Axial Stiffness: Most simulations typically use a linear elastic material model, where the the governing input is a linear axial stiffness (EA). Alternatively you may specify a non-linear relationship for axial stiffness EA, which relates axial force and axial strain.
•Mass: Mass is input per unit length. This is is a measure of the inertia of the structure with respect to translation.
•Various Diameters
•Outer diameter Do: This is a required input. Dd, Db and Dc all default to Do if not explicitly specified. Do is also used for computing the cross-section area, and it is used as the external diameter for stress calculations unless you specify otherwise.
•Internal diameter (Di): This is used for computing the buoyancy contribution of internal fluid, if present. It is also used as the inner diameter for stress calculations unless you specify otherwise. Di defaults to a value of zero.
•Drag diameter (Dd): This is the effective outer diameter for hydrodynamic force evaluation using Morison’s Equation. Dd defaults to Do if not explicitly specified.
•Buoyancy diameter (Db): This is the effective outer diameter for buoyancy force calculations. Db defaults to Do if not explicitly specified. Db is also used in some circumstances in the calculation of the added mass/inertia components of the Morison’s Equation hydrodynamic force – this is discussed in Element Diameter and Hydrodynamic Forces.
•Contact diameter (Dc): This is the effective diameter for contact calculations, and is relevant only when your Flexcom analysis includes guide surface contact, line clashing or pipe-in-pipe contact. Flexcom uses this input to determine when contact occurs. Dc defaults to the largest of Db, Dd or Do if not explicitly specified.
•*GEOMETRIC SETS is used to assign geometric properties to element sets (see OPTION=TRUSS).
•*FORCE-STRAIN is used to define force-strain curves for non-linear materials.