The effect of superposed stress systems on the strength of grip of built-up crankshaft webs

The subject of shrinkage fits as applied to marine crankshafts is briefly introduced and discussed. Particular emphasis throughout is placed on the problem of bellmouthing or opening out of crank webs, under the pulsating loading action of service conditions. There follows the presentation of a theoretical analysis to cover the grip strength of a shrinkage assembly subjected to various forms of loading. A new feature - "friction moment strength" - is suggested and shown to be critical to the onset and failure mechanism of bellmouthing. Small scale practical tests and results to illustrate the theory are recorded and discussed. The theory is further developed to cover fluctuating bending moment loading, and some practical fatigue test series are described and results noted and examined. The design and building of a hydraulic test machine to supply service type loading on a model crank is described in detail, including the work carried out on a simple test rig to check the principles of operation. One test carried out on the machine is recorded and discussed. General conclusions and discussions complete the report