Shear stress is the outcome of sliding one part over the other in opposite directions. The rivets and bolts in an aircraft experience both shear and tension stresses. Consider the bending of an object such as a piece of tubing. The wing spars of an aircraft in flight undergo bending stresses. When you wring out a chamois skin, you are putting it under torsion.
Torsion is produced in an engine crankshaft while the engine is running.
Forces that cause torsional stresses produce torque. A rubberband is extremely elastic, whereas a piece of metal is not very elastic. All the structural members of an aircraft experience one or more stresses. Sometimes a structural member has alternate stresses. It is under compression one instant of time and under tension the next.