پاورپوینت FATIGUE FRACTURE

crack growth is slow
it initiate from stress concentration points
load is considerably below the design or yield stress level
the surface is smooth
the surface is bounded by a curve
bands may sometimes be seen on the smooth surface -”beachmarks”. They show the progress of the crack front from the point of origin
the surface is 90° to the load
final fracture will usually take the form of gross yielding (as the maximum stress in the remaining ligament increase!)
fatigue crack need initiation + propagation periods