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It gives the contact stress as a function of the normal contact force, the radii of curvature of both bodies and the modulus of elasticity of both bodies. Hertzian contact stress forms the foundation for the equations for load bearing capabilities and fatigue life in bearings, gears, and any other bodies where two surfaces are in contact.
Hertz contact stress in the case of a male cylinder-female cylinder contact. When the clearance can not be neglected, it is then necessary to know the value of the half contact angle θ 0, which can not be determined in a simple way and must be measured. When this value is not available, the Hertz contact theory can be used.
The hoop stress equation for thin shells is also approximately valid for spherical vessels, including plant cells and bacteria in which the internal turgor pressure may reach several atmospheres. In practical engineering applications for cylinders (pipes and tubes), hoop stress is often re-arranged for pressure, and is called Barlow's formula.
If the cylinder and plane consist of the same materials then the normal contact problem is unaffected by the shear stress. The contact area is a strip x ∈ [ − a , a ] {\displaystyle x\in [-a,a]} , and the pressure is described by the (2D) Hertz solution.
The radial stress for a thick-walled cylinder is equal and opposite to the gauge pressure on the inside surface, and zero on the outside surface. The circumferential stress and longitudinal stresses are usually much larger for pressure vessels, and so for thin-walled instances, radial stress is usually neglected.
The rig also allows precise control over the loading conditions, including the magnitude of the load, contact pressure, and contact geometry. [ 10 ] [ 11 ] PCS Instruments Micro-pitting Rig (MPR) is a specialised testing instrument used in the field of tribology and mechanical engineering to study micro- pitting , a type of surface damage that ...
Normal contact stiffness is a physical quantity related to the generalized force displacement behavior of rough surfaces in contact with a rigid body or a second similar rough surface. [ 1 ] [ 2 ] Specifically it is the amount of force per unit displacement required to compress an elastic object in the contact region.
The contact area depends on the geometry of the contacting bodies, the load, and the material properties. The contact area between the two parallel cylinders is a narrow rectangle. Two, non-parallel cylinders have an elliptical contact area, unless the cylinders are crossed at 90 degrees, in which case they have a circular contact area.