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TR U S S ( 3 D )
Use the Truss interface to model three-dimensional trusses or sagging cable-like
structures. The Truss interface is defined on edges in 3D.
Variables and Space Dimensions
The degrees of freedom (dependent variables) are the global displacements u, v, and
w in the global x, y, and z directions, respectively.
Theory Background for the Truss Interface
Trusses are modeled using Lagrange shape function. The Lagrange shape function
makes it possible to specify both normal strains and Green-Lagrange strains to handle
small strains as well as large deformations.
STRAIN-DISPLACEMENT RELATION
The axial strain n is calculated by expressing the global strains in tangential derivatives
and projecting the global strains on the edge.
t
 n = t  gT t
where t is the edge tangent vector and gT is defined as
 xT  xyT  xzT
 gT =  xyT  yT  yzT
 xzT  yzT  zT
T H E O R Y F O R T H E TR U S S I N T E R F A C E
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