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9 Contact Stresses

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444 TABLE 9-2 Formulas for <strong>Contact</strong> <strong>Stresses</strong><br />

TABLE 9-2 (continued) FORMULAS FOR CONTACT STRESSES, DIMENSIONS, AND CONTACT AREAS, AND RIGID-BODY APPROACHES a<br />

Case Formulas<br />

4b.<br />

Concentrated force on surface<br />

of semi-infinite body<br />

4c.<br />

Uniform pressure p over length ℓ<br />

on surface of semi-infinite body<br />

4d.<br />

Rigid cylindrical die of radius r<br />

on surface of semi-infinite body<br />

At an elemental area perpendicular to z axis of any point Q, the resultant stress is 3F cos2 θ<br />

2πr 2<br />

At surface point O1 outside loaded area<br />

d = 2p<br />

π E<br />

<br />

(ℓ + x1) ln c<br />

ℓ+x1 − x1 ln d x1<br />

<br />

+ pℓ 1−ν<br />

π E<br />

At surface point O2 underneath loaded area<br />

d = 2p<br />

π E<br />

<br />

(ℓ − x2) ln c<br />

ℓ−x2 + x2 ln d x2<br />

<br />

+ pℓ 1−ν<br />

π E<br />

where d = displacement relative to a remote point distance c from edge of loaded area<br />

At any point Q<br />

σc = p<br />

π (α + sin α)<br />

d = F(1 − ν2 )/2RE<br />

At any point Q on surface of contact<br />

F<br />

σc = √<br />

2π R R2−r 2<br />

(σc)max =∞ at edge (σc)min = F/2π R 2 at center

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