Line Spring Element Library

Nodes 1, 2, and 3 on the element define side B and nodes 4, 5, and 6 define side A (see Figure 1). The sign of the crack is defined by the surface of the shell from which the crack originates, which you identify when you define the depth of the crack (see Line Spring Elements for Modeling Part-through Cracks in Shells). If the crack originates from the positive surface of the shell, sign(crack)=1.0; if the crack originates from the negative surface of the shell, sign(crack)=−1.0.

The vector $\mathbf{q}$ is defined by the right-hand rule from the cross product of the tangent, $\mathbf{t}$, which is positive going from node 1 to node 3 of the element, and the normal, $\mathbf{n}$, defined when the coordinates are given (or by a user-defined normal definition). For element type LS3S the vector $\mathbf{q}$ must point into the model (away from the symmetry plane). For element type LS6 the vector $\mathbf{q}$ must point from side A to side B.