Elastic Contact Stress Formulae
Consider two bodies in contact identified with the suffixes 1 and 2.
Young's Modulus, E1
Poisson's ratio n1
Young's Modulus, E2 Poisson's ratio, n2 |
R1 and R2 are the principal radii of curvature of the two bodies (convex positive).
Effective curvature
Contact Modulus
Hertzian Contact Equations
Line contact (Width 2a; Load P'/unit length) |
Circular contact Diameter 2a; Load P |
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Semi-contact width or contact radius |
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Maximum contact pressure (Hertz stress) |
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Approach of centres |
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Mean contact pressure |
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Maximum shear stress |
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Maximum tensile stress | Zero |
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An initial estimate of the value of tmax for many materials is H/6 where H is the material hardness