Effect of Internal Support on the Tensile Properties and Fracture Mode of 304 Stainless Steel Thin-Walled Tubes

Abstract

Steel–tube composite structures contain multiple tubular components under tension. The enhancement of the mechanical properties of tubes under ultimate operating conditions is crucial for improving structural safety. In this study, 110 pieces of 304 stainless steel thin-walled tubes (SSTWTs) under five internal support conditions are investigated. The ultimate tensile strength, ultimate extension, and fracture energy of different groups of specimens are measured to understand the variation mechanism of fracture modes. The elastic modulus of tube filler is treated as a variable to establish a uniaxial tensile fracture matrix of 304 SSTWTs with different tube fillers and loading rates. The results demonstrate that flexible tube fillers can effectively limit the lateral necking of 304 SSTWTs. Under the middle fracture mode, the maximum increments in the ultimate strength, extension, and fracture energy of tubes are 10.81%, 24.56%, and 35.94%, respectively. Furthermore, as the support rigidity increases, the ultimate strength exhibits an overall increasing trend, while the extension and fracture energy initially increase and then decrease. Overall, this study provides a novel route for enhancing the performance of steel–tube composite structures under ultimate loading conditions, which is of great significance for improving the safety of the structural design and reducing the engineering construction cost.

Mechanical analysis of enhancement in tensile performance of thin-walled circular tubes by internal support

“…Loading equipment was Shenzhen Wance 100-ton HUT106D microcomputer-controlled electrohydraulic servo universal testing machine (located at the Army Engineering University of PLA in Nanjing, China) with axial tensile speed of 15 mm/min. 23 Under each working condition, four effective components were stretched and the macroscopic features of components after break are presented in Figure 13. Also, tensile loaddisplacement curve of components under different working conditions are shown in Figure 14.…”

“…Hang 22 evaluated the deformation and destruction properties of PU-filled double skin steel tubes (PFDST) under axial compression, carried out numerical simulation of the PFDST member under axial tension using finite element software, and adopted finite element regression method to derive calculation equations for ultimate tensile bearing capacity of PFDST components. Gao et al 23 performed tensile fracturing tests on 304 stainless steel thin-walled circular tube components under flexible supporting operating condition and obtained the change rules of ultimate tensile strength, elongation, and fracturing energy versus loading rate and internal support elastic modulus.…”

Effects of Size, Section Pattern, and Material on the Tensile Performance of Filled Thin‐Walled Tubes

“…Measured sizes are summarized in Table 3. PTFE with measured elastic modulus of 231 MPa was applied as internal supporting material [19]. e cold shrinkage assembly method was used to make PTFE produce a certain amount of initial support prestress on circular tubes.…”

“…e loading device was microcomputer-controlled electrohydraulic servo universal testing machine (Shenzhen Wance 100-ton HUT106D, located at the Army Engineering University of PLA in Nanjing, China). e axial strain rate was set to 15 mm/min [19]. Four effective specimens were stretched under each working condition, and the macroscopic morphologies of specimens made of different materials after fracture are presented in Figure 15.…”

“…Hang [18] performed numerical simulations on PU-filled double skin steel tube (PFDST) components under axial tension using finite element analysis and derived the equation of ultimate tensile capacity of PFDST components through finite element regression method. Gao et al [19] conducted tensile fracture tests on 304 stainless steel thin-walled tube (SSTWT) components under different supporting conditions (PU, polytetrafluoroethylene (PTFE), acrylonitrile butadiene styrene (ABS), and Q235 steel) and determined the variations of their ultimate tensile strength, elongation, and fracture energy by the elastic modulus of internal supporting material. e maximum increase in ultimate tensile strength, elongation, and fracture energy was found to be 10.81%, 24.56%, and 35.94%, respectively.…”