MITC shell kinematics describe a shell element as a three-dimensional continuum degenerated through the shell thickness, with midsurface nodal positions and director vectors defining points inside the shell.
How It Works
The study notes express reference and current shell positions using four-node shape functions plus a through-thickness coordinate multiplying nodal thickness and director vectors. The displacement field follows from the difference between current and reference positions. Incremental displacement is then split into nodal translation increments and director-vector increments caused by nodal rotations.
Why It Matters
This kinematic setup is the bridge between solid-like continuum measures and shell element degrees of freedom. It lets the element use three-dimensional strain and stress measures while keeping the computational cost close to a low-order shell element.
Practical Frame
Midsurface interpolation locates the shell surface.
Director vectors carry the through-thickness direction.
Nodal translations move the midsurface.
Nodal rotations update the directors.
The through-thickness coordinate connects director motion to bending behavior.
Connections
MITC4 Shell Element uses this kinematic structure in a four-node quadrilateral element.
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