00:01
Hello students, let us first study about surface finish.
00:07
We know that fatigue happens due to propagation of micro cracks under cyclic loading.
00:23
These micro cracks propagate generally from the surface.
00:26
The roughness waves may be termed as micro cracks which are easy to get propagated under cyclic loading.
00:33
If surface roughness is more, then endurance strength is less.
00:48
Vice versa, if roughness is less, then endurance strength will be more.
00:58
We use surface finish factor to modify endurance strength that is used in the calculation of fatigue properties.
01:05
If 10 % of endurance strength is reduced due to roughness, we can multiply 0 .9 to the endurance strength which is theoretical value because it shows 10 % of decrease in the endurance strength.
01:40
Hence, we can multiply 0 .9 here.
01:43
So that in the calculation purpose, we can use endurance strength obtained after fatigue propagation will be equal to 10 % into theoretical endurance strength where k value is 0 .9.
02:03
Next we need to study about surface coating...