Performance Comparison of Composite and Steel Shafts Based on Stress–Strain Response and Fatigue Life

• Date: 2026
• Author Affiliations: Chikwado Enyinnaya Abner — Ogbonnaya Onu Polytechnic; Kelechi Uchenna Ugoji — Federal Polytechnic of Oil and Gas, Bonny; Ibim Abba Green — Federal Polytechnic of Oil and Gas, Bonny; Shamsu Umar — Federal Polytechnic of Oil and Gas, Bonny; Ndukam Billy Igbere — Federal Polytechnic of Oil and Gas, Bonny
• Keywords: keywords
• Main Authors: Abner, Chikwado Enyinnaya, Ugoji, Kelechi Uchenna, Green, Ibim Abba, Umar, Shamsu, Igbere, Ndukam Billy
• Format: Article
• Language: English
• Published: Інститут енергетичних машин і систем ім. А. М. Підгорного Національної академії наук України 2026
• Online Access: https://journals.uran.ua/jme/article/view/367946
• Journal Title: Energy Technologies & Resource Saving

The increasing demand for lightweight, high-performance rotating machinery has sparked growing interest in replacing traditional steel shafts with advanced composite alternatives. This study provides a comparative analysis of stress–strain behavior and fatigue life for steel and composite shafts with identical geometries, subjected to combined axial and torsional loading. The investigation combines analytical modeling, MATLAB-based numerical simulations, and fatigue life predictions using the stress–life (S–N) approach. Under the applied loading, the composite shaft shows a higher elastic strain (1.20×102) than steel (8.2×101), reflecting its lower effective modulus. Fatigue analysis demonstrates that the composite shaft can sustain nearly 1.94 times the fatigue stress amplitude of steel at 10⁷ cycles, highlighting its superior high-cycle fatigue resistance. Moreover, the composite shaft achieves a remarkable 79.6% weight reduction (3.77 kg vs. 18.50 kg for steel) and a higher safety factor (9.38 compared to 6.21). Its stiffness-to-weight ratio is over three times greater than that of steel, indicating significantly improved structural efficiency. While the initial material cost for composites is higher, the results clearly show that composite shafts offer substantial advantages in applications where fatigue performance and weight savings are critical. These findings provide a solid analytical and numerical foundation for informed material selection and the design optimization of rotating shafts.