Mechanical analysis of finned special-shaped tubes in bending-torsional coupling deformation

Abstract

Because of the excellent thermal conductivity and increased strength, finned special-shaped tube (FSST) is frequently utilized in a variety of industrial applications. However, duo to the complex section structure of FSST, the elastic–plastic evolution of the FSST section is more complex than that of circular and rectangular tubes, when FSST is subjected to various coupling effects of bending moment and torque. Moreover, until now, no literature has studied the bending-torsional-coupled deformation of FSST. In this study, based on the power-law stress–strain curve model and the Henky-Ilyushin equations, an analytical model that can precisely characterize the bending-torsional-coupled deformation of the FSST section is established by using the stress method. According to the boundary conditions divided by the geometric characteristics of FSST, the stress and strain distribution, elastic–plastic evolution, and the coupling relationship between the base circle and fins under different bending radii and unit torsion angles are discussed in detail. Besides, the relationship between bending radius and unit torsion angle and bending moment and torque on the section is presented based on the concept of section moment superposition. Finally, the rationality and accuracy of the proposed analytical model are verified by simplified finite element model (FEM), FEM, and practical tests.

Keywords

• Bend-twist coupling deformation
• Elastoplastic evolution of cross-section
• Aluminum alloy tube
• Mechanical model
• Stress method