Experimental Study of Bending Fatigue Characteristics of a Hybrid Aluminum/Composite Drive Shaft

Experiments were carried out to study the bending fatigue characteristics of a hybrid aluminum/composite drive shaft. A hybrid shaft was fabricated using a wetted filament winding method by winding glass and carbon fibers onto an aluminum tube with different winding angles, numbers of layers, and stacking sequence. The flexural moment fatigue life relationships were obtained and the failure modes of the hybrid shaft were studied. The results show that the fatigue life for a winding angle of 45° is larger than it is for 90°, for both glass and carbon fibers. For [±45] 3, carbon fiber/epoxy laminates enhance the fatigue strength of aluminum tube up to 40% and the hybrid specimen does not fail until 107 cycles under 14.7 N.m applied bending moment. In the hybridized specimens the percentage containing carbon and glass fiber are significantly affected by the fatigue life of the hybrid shaft at high and low level load. The results of a fatigue test on a macroscopic level indicate that the cracks initiating in the zones free of fibers or in the outer skin of resin, increase with increasing number of cycles until failure of specimen. On the other hand the micro damage shows that the delamination completely took place between the composite layer and the surface of the aluminum tube before the catastrophic failure of a hybrid specimen. In addition, the aluminum tube failure was perpendicular to the applied bending load and this phenomena is the same as for the aluminum shaft under a bending fatigue test. Furthermore, there is no fiber breakage observed from the rotating bending fatigue test.