Maximum Constant Pressure and Shear Stress Calculations.

Line Contact

Parameter

Symbol

Equation

Contact half-width

b

Maximum Hertzian Contact Pressure

Pmax

Pmax = 2 * F ∕ π.l.b

Maximum Contact Shear Stress

Ʈmax

Ʈmax = 0.3 * Pmax

The Maximum Contact Shear Stress,Ʈmax, is at a depth below the Cam and Roller Surfaces at about Z = 0.786×b.

You should make sure that the of case hardness depth is a minimum of 1.41×b, even better to make sure it is 2×b

Typical Stress against Depth from Contact Surface

Notes

Modulus of elasticity (Young’s modulus): The rate-of-change of unit tensile or compressive stress with respect to unit tensile or compressive strain for the condition of uni-axial stress within the proportional limit. Typical values: Aluminum: 69 GPa ; Steel: 200GPa.

Poisson’s ratio: The ratio of lateral unit strain to longitudinal unit strain under the condition of uniform and uni-axial longitudinal stress within the proportional limit. Typical values: 0.3.

Proportional Limit: The largest value of stress up to which a linear relation still exist between stress and strain (Hooke’s Law).

Cylindrical contact: The contact of two Cylinders parts where contact point turns to a rectangular area equal to a width 2b.

Shear stress: A form of a stress acts parallel to the surface (cross section) which has a cutting nature.

Stress: Average force per unit area which results strain of material.