Finite Element Analysis and Design Optimization of a Paddle Mixer Shaft

Mixing operations play a vital role in various industrial processes, with the structural integrity of mixer shafts being crucial for optimal performance and reliability. This study investigates the design, modeling, and Finite Element Analysis (FEA) of a paddle mixer shaft, comparing two configurations—one with stiffeners and one without. The shaft assembly, including components such as the pipe, end shafts, stiffeners, and paddles, was modeled using Pro-E software, while ANSYS 13.0 was used for FEA to assess stress distribution, deformation, and structural performance under applied loading conditions. A static analysis was conducted, considering self-weight, gravity, and applied pressure of 0.77 MPa, with uniform boundary conditions applied to both configurations. The results indicate that the stiffened paddle shaft exhibited lower maximum stress (105.26 MPa) and deformation (1.5 mm) compared to the shaft without stiffeners (173.05 MPa stress and 2.1 mm deformation). Theoretical calculations confirmed that stress values remained within permissible limits for Stainless Steel (SS), making the stiffened shaft the preferred design. Additionally, the study explores potential weight reduction by replacing SS with carbon/ epoxy composite materials, demonstrating significant weight savings while maintaining structural integrity. Manufacturing processes, material specifications, and experimental validation through hydrostatic and load trials confirmed the reliability of the selected design. The trials showed an 8% deviation between experimental and simulated deformation, reinforcing the accuracy of the FEA approach. This research underscores the importance of structural reinforcement in paddle mixer shafts and provides valuable insights into design optimization, material selection, and performance validation. Future studies could explore further weight reduction using advanced composites, ensuring both durability and cost-effectiveness. Major Findings: The study revealed that the stiffened paddle shaft exhibited superior structural performance, with lower maximum stress (105.26 MPa) and deformation (1.5 mm) compared to the unstiffened shaft (173.05 MPa stress and 2.1 mm deformation), highlighting the effectiveness of stiffeners in enhancing structural integrity. Experimental validation through a hydrostatic test at 7.7×10⁻² MPa showed an 8% deviation between Finite Element Analysis (FEA) predictions and experimental results, confirming the accuracy of the simulation approach. Additionally, the study explored the potential of replacing stainless steel with carbon/epoxy composites, demonstrating significant weight reduction while maintaining mechanical strength and durability, offering insights into future lightweight design optimizations.