Maximum Normal Stress Criterion
The maximum normal stress criterion also known as Coulomb’s criterion
is based on the Maximum normal stress theory. According to this theory
failure occurs when the maximum principal stress reaches the ultimate
strength of the material for simple tension.
This criterion is used for brittle
materials. It assumes that the ultimate strength of the material in tension
and compression is the same. This assumption is not valid in all cases.
For example, cracks decrease the strength of the material in tension considerably
while their effect is far less smaller in compression because the cracks
tend to close.
Brittle materials do not have a specific yield point and hence it is
not recommended to use the yield strength to define the limit stress for
this criterion.
This theory predicts failure to occur when:
s1
≥ slimit
where s1
is the maximum principal stress.
Hence:
Factor of safety = slimit /
s1
Related Topics
Performing
factor of safety check