TORSION 4) Internal torque diagram: Sketch that expresses the law of change of the torque in each cross section along the axis. (1 the law of change of the torque Purpose ② value of z/ Imax and the position of its section→ strength calculation (critical section T x 1515 4) Internal torque diagram：Sketch that expresses the law of change of the torque in each cross section along the axis. Purpose ① the law of change of the torque ； ②Value of |T|max and the position of its section strength calculation（critical section） x T 