Question

Calculate the fatigue stress concentration for a steel filleted shaft that is loaded in bending. Given Data: Sut = 440 MPa D (for larger cross-section) = 64 mm d (for smaller cross-section) = 32 mm r(fillet radius) = 4 mm

Answer 1

Answer:

$K_f = 1.422$

Explanation:

We know that relationship between fatigue and stress concentration factor

$K_f = 1+q(K_t-1)$

Where

$K_f$=fatigue concentration factor

$K_t$=stress concentration factor

q=Notch sensitivity

Here D/d=2 and r/d=0.125

Now from standard design data book $K_t=1.79$

For Sut=440 MPa and r= 4 mm

   q=0.8

Now by putting the values

$K_f = 1+q(K_t-1)$

$K_f = 1.8(1.79-1)$

$K_f = 1.422$