The Bending Stress Concentration Factor of Solid Crankshaft

Abstract

The bending stress concentration factors were investigated on the single throw steel crank specimens (solid), of which crankpin diameter was 80 mm. As the result of these investigations the empirical formula of the stress concentration factor of crankshaft is given as follows : αk=Cf1 (ρ/d) f2 (ρ/d·δ/ρ·s/d) f3 (b/d) f4 (t/d) f5 (t/d·s/d) C=4.84 f1 (ρ/d)=0.420+0.160√(d/ρ-6.864) f2 (ρ/d·δ/ρ·s/d)=1+81 [0.769-(0.407-s/d)2]·δ/ρ·(ρ/d)2 f3 (b/d)=0.285 (2.2-b/d)2+0.785 f4 (t/d)=0.444 (d/t)1.4 f5 (t/d·s/d)=1-(s/d+0.1)2/(4t/d-0.7) (8⪈d/ρ⪈27, 0⪈δ/ρ⪈1, -0.3⪈s/d⪈0.3, 1.2⪈b/d⪈2.1, 0.36⪈t/d⪈0.56) where, αk=πd3σm/32MW, d : crankpin diameter, σm : maximum stress at crank fillet, MW : bending moment at center of web thickness, ρ : fillet radius, δ : recessed depth at fillet, b : web breadth, t : web thickness, and s=(d-dj)/2-r, dj : crankjournal diameter, r : a half stroke. The limit of uncertainty of the above formula based on 95 percent confidence limits is 6 percent, and this value is enough for practical application.