During a high cycle fatigue test, a metallic specimen is

During a high cycle fatigue test, a metallic specimen is subjected to cyclic loading with a mean stress of + 140 MPa, and a minimum stress of – 70 MPa. The R-ratio (minimum stress to maximum stress) for this cycle loading is _______ (round off to one decimal place).

Here,
σ_mean = + 140 MPa
σ_min = – 70 MPa

σ_mean =	σ_max + σ_min	= 140
	2

=	σ_max - 70	= 140
	2

⇒ σ_max = 350 MPa
Now, minimum stress to maximum stress ratio is,

σ_min	=	- 70	= - 0.2
σ_max		350