Performance Evaluation of Circular Cylindrical Shells Under Combined Axial Compression and Torsion

Cylindrical shells, prevalent across diverse industries, often encounter combined loading, including axial compression and torsion. Buckling poses a major threat to their structural integrity. This study proposes Carbon Fiber Reinforced Polymer (CFRP) as an innovative strengthening method for steel cylindrical shells subjected to combined loading. The main objective was to explore how CFRP strengthening influences the buckling behavior of steel shells and to evaluate the effects of various parameters such as thickness, stacking sequence, and imperfections. The research methodology involved three steps. First, model validation was achieved using experimental data and established theories from CFRP and steel cylindrical shell specimens. Then, three types of FE models were created: a steel shell, a CFRP shell, and a CFRP-strengthened steel shell, all with identical dimensions. These models underwent combined loading with continuous load and deformation measurements. Sensitivity analyses were subsequently conducted to evaluate the influence of geometry, material properties, and initial imperfections on buckling performance. The results indicated that increasing shell thickness significantly improves performance by boosting stiffness and load capacity, but at the cost of greater axial shortening. CFRP reinforcement offers similar benefits, with effectiveness depending on the specific implementation strategy. Conversely, axisymmetric imperfections have a detrimental effect, slightly reducing stiffness and load capacity. Finally, the sensitivity of various performance parameters is highly dependent on the design choices and specific model being analyzed. These findings provide valuable insights for steel cylindrical shell design in various engineering applications.