Rotating Bending Fatigue Test of Solid Crankshafts : Part 1, Effect of Fillet Radius

抄録

The authors have carried out statical stress measurements and rotating bending fatigue tests on three model crankshafts (80 mm in pin diameter, 45 mm in web thickness, 106 mm in web breadth) having pin fillet radii of 8.0, 5.0 and 3.0 mm respectively. Rotating bending fatigue strengths of plain cylindrical specimens of several sizes taken axially and tangentially from the crank material (0.3% carbon steel) have also been studied. The following facts have been revealed by the tests. (1) The nominal fatigue limits of crankshafts represented in terms of crankpin (quotient of bending moment divided by the section modulus) are 6.80, 5.50 and 4.25 kg/mm² where the fillet radii are 8.0, 5.0, and 3.0 mm respectively. (2) The quotients of fatigue limit of 10 mm plain cylindrical specimens taken from the crank web perpendicularly to the metal flow of forging divided by the stress concentration factors (the ratio of actual stress at fillet to the nominal stress at crankpin) are nearly equal to the nominal fatigue limits of the crankshafts represented in terms of crankpin.