Analysis and Optimization Of Drive Shaft Housing Of Marine Engine Using FEA

Abstract

Vibration and noise are the critical design features for mechanical components. Theboat contains a number of components which are main source of vibration, such aspropeller, main engine and structure. The vibrations are transmitted by the engine mountsystem to the boat. Engine is mounted by means of drive shaft housing. So drive shafthousing is a critical component to be considered for reducing noise and failure due tovibration. Here we have taken the drive shaft housing of a marine outboard engine ofboat. In this component generally lower mode frequencies are closer to resonance. So,they are increased to a safe level.The main objective of this project was to increase the frequency, using topologyoptimization, of first few modes which were intersecting the engine order lines. Theshape of the drive shaft housing was optimized in such a way that the frequency ofresonance prone modes was increased. For this purpose an initial modal analysis wasperformed. In addition stresses were also considered at the time of Optimization. Theareas where stresses were exceeding the yield limit were provided smooth change inshape or fillets.First of all the static and modal analysis was done. Here the meshing was doneusing Hypermesh 9.0 and analysis was done using Abaqus solver. At the end of the stressand modal analysis the Campbell diagram was plotted and it was found that frequenciesof mode 1 was intersecting the engine order lines so the mode frequency was to beincreased to a safe value. The increase in frequency was achieved by topologyoptimization of the component.The topology optimization was done using the optistruct software. The result ofoptimization analysis was studied in the form of density plots. From the density plots ofoptimization analysis, the original geometry was modified using CAD package. Aftermodifying the geometry, static and modal analysis was performed using Abaqus solver.And results were compared with the actual one.At the end of static and modal analysis, it was observed that the frequency wasincreased up to about 16% with reduction in mass of about 5% and also reducedAnalysis and Optimization of Drive Shaft Housing using FEAdisplacement of about 38%. It was also observed that regions, in which stresses wereexceeding the accepted stress levels, were also reduced.Thus it is seen that topology optimization can be used for improvement of somedesign features keeping other features in safe limits.