The torsional buckling behaviour of shafts with transverse holes

The paper presents the results of a parametric finite element study of the failure behaviour of shafts with a single row of transverse holes, subjected to torsional loading. The introduction of the holes reduces the peak torque at failure compared with the equivalent plain shaft and the reduction increases with increasing D/t (shaft diameter-wall thickness) ratio and d/D (hole diameter-shaft diameter) ratio and with the number of holes. Depending on the geometry used, either plastic collapse or elastic-plastic buckling failure modes can occur. For given values of n (number of holes) and D/t and d/D ratios, the failure torque varies by less than 5 per cent for L/D (shaft length-diameter) ratios in the range 0.6 to 4. The greatest reduction in the failure torque occurs when the D/t ratio is such that the number of circumferential lobes in the elastic buckling mode for the equivalent plain shaft is the same as the number of holes in the shaft.