Paper Title
DYNAMIC CHARACTERIZATION AND VIBRATION BEHAVIOR OF ALUMINUM–SILICON CARBIDE COMPOSITE SHAFT

Abstract
The use of Metal Matrix Composites (MMCs) in rotating machines is increasing due to the improvement of their stiffness, weight and ability to suppress vibration. This paper presents experimental work investigating the dynamic performance of Aluminum6061–Silicon Carbide composites (Al–SiC) shafts. Specifically, composite shaft samples have been tested at varying rotational speeds and loads. The experimental testing involved two Al–SiC composite shaft samples which had 75 g and 50 g of SiC reinforcement within the shaft material. These composite shafts were tested with an experimental set up consisting of a motor to provide rotating motion to the composite shaft. In addition, the composite shaft was subjected to specific loads as an experimental condition by adding notched loads to the shaft at mid-span. The loads would simulate the loads on the shaft under actual operating conditions. The vibration response was measured at different rotational speeds (600 RPM – 1350 RPM) using an accelerometer-based data acquisition system. Theoretical calculations of natural frequencies and deflection compared to experimental results were used to confirm that the combination of rotational speed and load placed on the shaft were both within acceptable parameters of operation at a speed of1350 RPM; thus, there was no resonance condition in this test sample. Additionally, using the relationship between applied load and rotational speed, a physics based scaling approach was used to analyze vibration amplitudes caused by both rotational speed and load. The data demonstrate that the amount of vibration in the rotating shafts increases when the speed of rotation or the weight of the applied load increases; however, the 75 gm SiC (silicon carbide) reinforced shaft had significantly less vibration than the 50 gm SiC(approximately 18-20% lower) at the same rotation speeds and loads due to its increased stiffness & decrease in deflection compared to the 50 gm SiC shaft under these conditions. The conclusion is that SiC reinforcement levels have a major effect on the improved dynamic stability of composite drive shafts. Keywords - Metal Matrix Composite, Al–SiC, Rotating Shaft, Vibration Analysis, Load Effect, Experimental Validation