Analytical and experimental studies on the sequential flaring-buckling behavior of combined bi-tubes in blind bolts

Jiaming Feng, Yuyin Sun, Wanjun Jin, Ridong Liao*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Combined bi-tubes are innovatively applied in modern composite blind bolts to provide the clamping force. In this study, the sequential flaring-buckling behavior of combined bi-tubes under axial compression on expanding dies was experimentally and analytically investigated. First, axial compression tests were performed on bi-tubes in three different dimension groups. Based on the test results, deformation modes and force–displacement curves were obtained to assess the specific energy absorption (SEA), clamping energy (ECL), and energy transfer ratio (ETR). The results show that bi-tubes have superior energy-absorbing capacity and clamping efficiency. SEA can reach 21 kJ/kg, and the ECL accounts for 50 ± 6 % of the total energy dissipated. Afterwards, a theoretical solution for flaring-buckling bi-tubes, which involves the flaring forming force, friction, and critical buckling force, was derived on the basis of an equal-thickness circular tube. A comparison of forces and deformation modes from analytical and experimental approaches leads to the observations that the analytical theory can assess the sequential flaring-buckling bi-tubes within acceptable proximity, the maximum deviations of flaring forming forces and critical buckling forces being 3.3 % and 6.6 %, and that it can effectively predict diverse deformation modes, i.e., a single bell-shaped bulb on the clamped structure, an upper bulb close to the platen, or double bulbs. This study is expected to provide guidance for the optimal design of the clamping structure on aircraft and automobiles.

Original languageEnglish
Article number113158
JournalInternational Journal of Solids and Structures
Volume308
DOIs
Publication statusPublished - 1 Feb 2025

Keywords

  • Axial compression
  • Combined bi-tubes
  • Deformation modes
  • Energy transfer
  • Sequential flaring-buckling

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