Press fit (interference fit)

Contact pressure, transmissible force and torque, and the tangential/radial/equivalent stresses in an interference fit, from Lamé’s equations in the elastic regime.

✓ validated against legacyoriginal: /calculators/e3_8.htm

Inner bore of inner ring, dᵢmmInterface diameter, dmmOuter diameter of outer ring, dₒmmContact length, LmmDiametral interference, δmmFriction coefficient, µYoung’s modulus inner, EᵢGPaPoisson inner, νᵢYoung’s modulus outer, EₒGPaPoisson outer, νₒ

Contact pressure, p13.15 MPa

Friction force, F2.28 kN

Maximum torque, T26.22 Nm

Stresses

σt inner ring @ dᵢ-107.82 MPa

σt inner ring @ d-94.68 MPa

σt outer ring @ d15.52 MPa

σt outer ring @ dₒ2.37 MPa

σe inner ring @ dᵢ107.82 MPa

σe inner ring @ d88.84 MPa

σe outer ring @ d24.85 MPa

σe outer ring @ dₒ2.37 MPa

Interference δ is typically δ/d ≈ 0.001 and should be corrected for surface roughness. Assumes stresses stay below the elastic limit.

Method & references

Lamé’s equations for thick-walled cylinders (elastic regime).
Default values represent a bronze bush in a steel flange.

The computation is a literal port of the original client-side JavaScript from /calculators/e3_8.htm. Results are verified equal to the original by an automated golden-master test. No formula has been re-derived or “improved”.