The Implications of Research for the Design of Machine Elements Embodying Counterformal Surfaces in Contact

Many machine elements embody interacting surfaces which are counterformal thus causing concentration of stress on to a small area. Failure of such elements may occur due to excessive Hertzian stress leading to plastic deformation, surface disintegration, fatigue, or thermal distress (scuffing). The implications of recent research, notably that on elastohydrodynamic lubrication, are discussed and the need for specifying reliability at the outset of the design process is emphasized. Considerable progress has been made in applying the concept of elastohydrodynamic lubrication to the rating of rolling-contact bearings but there is still much scope for more precise methods. Particular attention should be paid to changes in surface texture during running-in and their possible effect on fatigue.