Disc cams: tribological analysis using computer program A0015.
Abstract:ESDU 00015 provides details of a computer program (ESDUpac A0015) for analysing a disc cam/follower system. The following tribological aspects of the contact between the cam and follower can be examined.
- The surface and sub-surface stresses.
- The lubricant film thickness.
- The transient temperature rise ("flash" temperature).
The driving torque and power loss of the cam can also be determined as well as the life of a rolling element bearing follower.
The program determines the contact loads, with or without friction, in the operating cam/follower system and then determines the instantaneous contact dimensions, gross deflection (normal closure) and contact stresses. Critical stress points are located with respect to three criteria which consider yield failure, brittle failure and fatigue failure.
Where a Newtonian lubricant is present, the program can be used to predict the film thickness of the lubricant entrained into the contact. Computation of this lubricant film thickness includes an allowance for squeeze film effects at the points in the cycle where the entrainment velocity reverses.
Six types of cam follower are considered: both translating and swinging versions of flat-faced, domed, and roller followers. Also, follower motions involving any number of blended cam law portions can be analysed. The cam law of each portion can be selected from a supplied database of cam law expressions or can be specified by the user. Alternatively, a motion file from some other source may be imported. The follower load, arising from a spring closure or a process load, can similarly be selected from a database or be specified by the user.
Computed parameters of interest can be logged over a full, or partial, cycle of cam rotation and the values recorded in a file suitable for plotting. Alternatively, a single instantaneous point in the cycle can be examined in more detail and stress distribution contours, for example, examined.
ESDU 00015 documents the specification of input data for the program and describes the various output data that can be obtained. Guidance on interpretation of the output data is given in further documents in the Series devoted to specific tribological aspects.
|Data Item ESDU 00015
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