Which of the following is NOT a type of stress in aircraft structures?

In aircraft structures, understanding the different types of stress is crucial for ensuring safety and structural integrity. The three primary types of mechanical stress commonly encountered are torsion, compression, and bending.

Torsion refers to the stress that arises when an object is twisted, which can occur in components like wings or fuselage sections during flight due to aerodynamic forces. Compression stress happens when forces push on an object, causing it to shorten or buckle, which is particularly relevant in structural members that bear loads. Bending stress occurs when an external load is applied, causing the structural element to curve, resulting in tension on one side and compression on the other.

Adhesion, on the other hand, is not a type of mechanical stress but rather a property related to the attraction between two different materials or surfaces. While adhesion is important in the context of bonding materials or understanding how different components interact, it does not categorize the physical stresses experienced by aircraft structures during operations. Therefore, it is the correct identification for the option that does not represent a type of stress in aircraft structures.