Definition 1 of 2
Definition
The ability of a material, fastener, or joint to resist forces that act in opposite directions across a single plane, attempting to slice or slide one part past the other. In aircraft structures, shear strength is most often measured in the rivets, bolts, and bonded joints that hold load-bearing members together.
Plain English
How much sideways slicing force a part can take before it fails. Imagine two hands pulling a sheet of paper in opposite directions until it tears along a line — shear strength is what stops that from happening.
Context Anchor
Seen in airframe maintenance when selecting or inspecting rivets, bolts, sheet-metal joints, and structural repairs.
Derivation
From the Old English 'sceran', meaning to cut or slice. The word still carries that same idea — a shearing force is one that tries to cut a part along a line, the way scissors (also called shears) cut paper.
Why Pilots Care
Determines whether fasteners and joints in airframe structures will hold under flight loads.
Analogy
Think of holding a deck of cards and pushing the top half sideways while the bottom half stays still. The sliding force between the two halves is like shear.
Intuition Check
Shear strength is not about pulling a part straight apart. It is about resisting a sideways sliding or cutting action through the part.
Example Sentence 1
The technician selected a rivet with adequate shear strength for the load the wing skin joint would carry.
Example Sentence 2
During the inspection the technician verified that the replacement skin panel met the required shear strength for the fuselage repair.