Definition
A stress that acts parallel to a surface within a material, tending to cause one part of the material to slide past the adjacent part. Shear stress occurs when two opposing forces act along the same plane but in opposite directions, as when a bolt resists loads trying to slice it across its shaft.
Plain English
A force trying to slide one part of a material sideways past another part, like scissors cutting paper.
Context Anchor
Seen in aircraft structures, fasteners, landing gear attachments, and basic discussions of loads on aircraft parts.
Derivation
Shear comes from the Old English sceran, meaning to cut or divide. Stress means an internal force within a material. Together: the internal cutting-style force inside a material when something tries to slice it.
Why Pilots Care
Recognizing shear stress helps pilots understand why aircraft structures have design limits and why maintenance inspections matter for continued airworthiness.
Analogy
Think of a deck of cards lying flat. Push the top card sideways while holding the bottom card still — the cards slide past each other. That sliding action is shear.
Grounding Statement
Picture a bolt holding two metal plates together while one plate is pulled sideways; the sideways load across the bolt creates shear stress.
Intuition Check
Stress here does not mean mental pressure; it means force inside a material. Shear does not only mean cutting with a tool; here it means a sideways sliding action across a surface.
Example Sentence 1
The bolts attaching the wing strut are loaded primarily in shear stress during flight.
Example Sentence 2
Mechanics check rivets and joints for damage caused by repeated shear stress in turbulent conditions.