Brittle materials fail in torsion at a 45° plane forming an angle with the longitudinal axis due to their weak tensile strength. Ductile materials fail in torsion due to principle shear stress, with the failure plane perpendicular to the longitudinal axis. Brittle materials fail in compression due to shear at a 45° plane from the axis, while ductile materials fail in tension due to shear at a 45° plane forming cup and cone failure. In compression yielding, short compression members fail in compression with a failure plane at 90° to the compressive load.
