Stress concentration factor (SCF) of CHS gap TT-joints reinforced with CFRP

Abstract

The current study focuses on estimating the fatigue life of circular hollow section (CHS) gap TT-joints reinforced with carbon fibre reinforced polymer (CFRP) sheets based on S–N curve method. In the S–N curve, the fatigue life of a tubular joint can be predicted from the hot spot stress (HSS) which can be easily calculated from the stress concentration factor (SCF) of the tubular joint. The SCF and the fatigue life of the CFRP-reinforced and unreinforced TT-joints under axial loads were experimentally measured. The experimental results show that the maximum SCF of CHS TT-joints reinforced with CFRP sheets decreases by 14%, and the fatigue life increases by 47%. Thereafter, finite element (FE) models for both CFRP-reinforced and unreinforced TT-joints were established and verified by the experimental results. A parametric study is also carried out to investigate the effects of the number of CFRP layers and the geometrical parameters on the SCF. Finally, through regression analysis on the numerical SCF results of 704 FE models, parametric equations are proposed to estimate the SCFs at the saddle and at the crown of CFRP reinforced CHS gap TT-joints.