A forged steel link with uniform diameter of 30 mm at the

A forged steel link with uniform diameter of 30 mm at the centre is subjected to an axial force that varies from 40 kN in compression to 160 kN in tension. The tensile (S_u), yield (S_y) and corrected endurance (S_e) strengths of the steel material are 600 MPa, 420 MPa and 240 MPa respectively. The factor of safety against fatigue endurance as per Soderberg's criterion is

Fatigue endurance, σ_en = 240 MPa
A = π/4 × (30)² × 706.5 × 10^–6 m²
Soderberg’s equation is

	1	=	σ_m	+	σ_a
	h		σ_y		σ_en.f

Now F_m =	160 + 40	= 100 kN
	2

∴ σ_m =	F_m	=	100 kN	= 141.54 MPa
	A		706.5 × 10 ^-6

and F_a =	160 - 40	= 60 kN
	2

∴ σ_a =	160 - 40	= 84.93 MPa
	60 × 10 ³

∴	1	=	141.54	+	84.93
	h		420		240

or h = 1.45