Definition
A localized point on a structural part where stress concentrates because of a change in shape or surface condition — such as a scratch, nick, gouge, sharp corner, hole, or tool mark. Under load, stress builds up at this point to a level much higher than the average stress in the surrounding material, making it the likely starting point for a crack or fatigue failure.
Plain English
A small flaw or sharp feature on a part that acts like a weak spot, pulling extra force into itself and becoming the place where a crack is most likely to start.
Context Anchor
Seen in aircraft maintenance when inspecting metal, composite, or other structural parts for damage, cracks, corrosion, sharp edges, or poor repairs.
Derivation
‘Stress’ comes from Latin strictus, meaning ‘drawn tight.’ ‘Riser’ is anything that rises or goes up. Together: a spot where stress rises sharply above the surrounding level. The name describes exactly what happens — stress climbs at that point.
Why Pilots Care
Unchecked stress risers can cause fatigue cracks that weaken the airframe and lead to failure.
Analogy
Think of tearing open a sealed snack bag. It’s tough to rip until you make a small notch — then it tears easily right from that notch. A stress riser does the same thing in metal.
Intuition Check
Stress does not mean mental pressure here; it means force inside a material. A stress riser is not something that carries more load safely—it is a spot where force builds up and damage can start.
Example Sentence 1
The technician smoothed and blended the deep scratch on the wing skin to remove the stress riser before returning the aircraft to service.
Example Sentence 2
Filing smooth edges removed the stress riser that could have started a crack under repeated loads.