Metal Diaphragm Coupling Perfomance
The performance of a Metal Diaphragm Coupling is to a large extent determined by its endurance limit. The endurance limit can be estimated by calculations but must be confirmed through testing. The author cites data obtained from a comprehensive test program conducted in the Research and Development facilities of Koppers Company, Inc. in connection with the development of an improved version of the Single Diaphragm Coupling. Failure of the coupling's disk, or diaphragm, occurs through fatigue when it is stressed above its endurance limit; the mode of failure depends on the angular misalignment and axial displacement. Full scale tests conducted in the laboratory under a variety of extreme conditions confirmed the operating limits and provided a pictorial reference which may be used as a tool to identify probable causes of disk failures. A special test rig was used to obtain S-N (stress versus number of cycles) curves for diaphragms made of various materials, for various treatments, surface finishes, etc. The large number of tests performed gave a good insight into the influence of various factors on the endurance limit and on the consistency of the endurance limit from disk to disk.
Calistrat, M. M. (1976). Metal Diaphragm Coupling Perfomance. Texas A&M University. Gas Turbine Laboratories. Available electronically from