Leaf Spring with Hole-Process Volume

4 Leaf Spring with Hole-Process Volume 

A multileaf spring of the type schematized in Fig. 7.32 is subjected to load cycles variable from 700 to 160 kg. Leaves have a width I — SO mm and thickness s — 6 mm and are made of quenched and tempered steel that has been subjected to shot peening that has introduced a residual compression stress equal to about — 400 MPa and surface hardness of about 260 HB with a mean surface roughness of 2.0 pm. Verify leaf spring to fatigue. The most stressed section of each leaf is the 

If friction between leaves and shear stress due to force F are neglected, considering the moment M alone acting on the leaf midsection, then the stress amplitude da acting on each leaf is 

The surface residual stress introduced by the shot peening process will not have any effect on the stress amplitude, but only on the mean stress that becomes 

Let s find the fatigue S-N curve of the material. On the base of Eq. (5.8) the traction strength cr of the shot peened material is 

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