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In this study, the CFRP shafts made up of T700-SC multilayered composites have been designed to replace the steel shaft of a ship. An important design variable to be considered when designing composite material intermediate shafts is the natural frequency for resonance avoidance at critical rotational speed and torsional strength for axial load. In order to satisfy these, strength and modal analysis were performed. In order to minimize the deformation of the shape due to the residual stress after mandrel removal, it was laminated by axial symmetry. The fibers orientation angle has a great influence on the natural frequency of the drive shaft. The carbon fiber should be closely oriented at $30^{\circ }$ to improve the modulus of elasticity in the direction of length of the intermediate shaft and to increase the natural frequency. Also, the optimum fiber orientation for maximum torsional strength should be close to $45^{\circ }$. The stacking pattern and the stacking order were finally decided considering the results of the finite element analysis (FEA).

The purpose of this study is to determine the correct estimation of the laminate patterns for composites intermediate shaft. The laminate patterns in the filament winding process are an important factor in determining the strength and life of the final structure. In this study, the structural safety was analyzed for the laminate patterns in four cases. In addition, this work evaluated the range of laminated angles for optimal thickness selection. The laminate patterns and the order of the layers were determined by considering the results of the finite element analysis. The shear stress equation of the hollow shaft for torsional loads showed that the thickness of the structure varied with the diameter ratio. At the maximum diameter ratio (the smallest shaft thickness), the required shear strength for the structure was 36.6 MPa. Also, the most stable stress distribution was selected at $15^{\circ }$ to $75^{\circ }$. The shear modulus according to the laminated angle was considered to give the best strength value when stacked at $45^{\circ }$. The research results in this study suggest that the design of an optimized intermediate shaft of composite materials can be supplemented.