• It has some mean values as well as amplitude value.

• The stresses which vary from a minimum value to a certain maximum value of the same nature [i.e. tensile or compressive ] are called as fluctuating stresses.

• It fluctuates between two values - maximum and minimum stress.

• The stress can be tensile or compressive [or else partly tensile or party compressive]

• Representation of fluctuating stress :-

[ I ] Mean stress = $\sigma_M$ = $\frac{\sigma_{Max} + \sigma_{Min}}{2}$

[ II ] stress Amplitude = $\sigma_a$ = $\frac{\sigma_{Max} - \sigma_{Min}}{2}$