Please enable JavaScript.
Coggle requires JavaScript to display documents.
Fatigue (The S-N Curve fatigue_SN_01 (image (maximum stress, minimum…
Fatigue
What is Fatigue?
It is a type of fracture of the material that is exposed to dynamic loads (variations in time) 
FULLY ALTERNATE EFFORT goes from a maximum stress effort (positive) to a minimum compression effort (negative) at the same point
-
The S-N Curve
The S-N curve, a.k.a., Stress Life Method, is the basic method presenting fatigue failure in high cycles (N > 105) which implies the stress level is relatively low and the deformation is in elastic range.
While S-N curve is clear and straight forward on addressing the service life under fatigue, its accuracy leaves some room to be improved.
-
-
-
-
How to Prevent Fatigue?
Stronger, capable materials
-
-
-
Fatigue type of failure
Beach Zone/Fast Break Zone
The fast break zone is one where the material does not withstand more efforts due to the decrease in the cross-sectional area and end up breaking abruptly.
-
-
Material Desing
Internal Composition
Material properties
The surface finish of the material with which the mechanical element was manufactured reduces the resistance of the material to fatigue.
-
Toughness
If we increase the hardness of a material, we make the mistake of converting to brittle. (Fragile elements DO NOT WORK under fatigue)
The modification of the resistance of the material by temperature is also an important criterion to point out in the failure due to fatigue because the materials change their properties when the temperature rises.
Geometry
Size Factor (kb)
-
Stress Concentrator :
Irregular edges and surfaces, concentrate efforts and fail.
Due to the abrupt area change.