Compression is the opposite of tension. Compression is the resistance to crushing, produced by two forces pushing toward each other in the same straight line. While an airplane is on the ground, the landing gear struts are under a constant compression stress. Cutting a piece of paper with a pair of scissors is an example of shearing action. Shear in an aircraft structure is a stress exerted when two pieces of fastened material tend to separate.
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.