… for torsion

# Matplotlib compatibility patch for Pyodide
import matplotlib
if not hasattr(matplotlib.RcParams, "_get"):
    matplotlib.RcParams._get = dict.get

… for torsion#

The constitutive relation for torsion is defined by:

\[M_t = GI_t \chi\]

This is treated in chapter 6.2.1 of the book Engineering Mechanics Volume 2 (Hartsuijker and Welleman, 2007).