Fatigue crack growth in CFRP-strengthened steel plates

Abstract

a b s t r a c tIn this paper fatigue crack growth in steel plates reinforced by using carbon fiber reinforced (CFRP) strips is investigated from the experimental, numerical and analytical point of view. Single edge notched tension (SENT) specimens were strengthened with different reinforcement configurations and tested at a stress ratio R of 0.4. Different initial damage levels were considered and the experimental results showed that the reinforcement application can effectively reduce the crack growth rate and significantly extend the fatigue life. Numerical models (finite elements) were also developed to evaluate the stress intensity factor (SIF) and the crack opening displacement (COD) profile. Based on the numerical results, an analytical model was proposed to predict the fatigue crack growth rate and the fatigue crack growth curves. The analytical results are validated by comparing the fatigue crack growth curves to the experimental ones.

Fatigue Behaviour of CFRP Strengthened Out-of-Plane Gusset Welded Joints with Double Cracks

“…where R is the stress ratio, R ys = σ max /σ y is the ratio of the maximum stress of applied cyclic loading to the yield stress of the steel plate, and pcf is the plastic constraint factor, which was taken as 1.68 [11]. The predicted fatigue lives of all the test specimens are plotted in Figure 17, which shows that the numerical simulation agreed well with the experimental results.…”

“…A crack is fully open only for a part of the load cycle [55]. It was indicated that the crack closure effect was more pronounced for CFRP strengthened specimens [11], and for single-sided repaired specimen, the crack closure effect and secondary bending effect were assumed to be counteracted [56]. Therefore, in this study, the fatigue crack propagation life of bare specimens and single-sided repaired specimens was evaluated using Equation (2), and the material constants C and m were taken as 6.77ˆ10´1 3 and 2.88, respectively (da/dN in mm/cycle and ∆K in MPa¨mm 1/2 ), as recommended by the British Standards Institution [57].…”

“…The major semi-axis b was assumed equal to the crack size within the CFRP area, and the minor semi-axis c was located in a direction orthogonal to the crack. Here, the aspect ratio c/b was set to be 1/5 [11]. In consideration of mesh convenience, the debonding zone was modelled as displayed in Figure 13b.…”

“…Experimental results demonstrated that CFRP materials could effectively extend fatigue life and retard crack propagation of defective specimens, and the retrofitting efficiency was highly dependent on bond configuration, CFRP stiffness, prestress level and initial damage degree [4][5][6][7][8][9]. Stress intensity factor (SIF) at crack tip and fatigue crack propagation have also been studied numerically, where parametric analysis was performed to optimise this strengthening method [10][11][12][13][14]. In addition to research on retrofitting damaged steel plates, research on strengthening steel beams has also been conducted [15][16][17][18][19][20][21][22][23][24].…”

Fatigue performance of CFRP patched pre-cracked steel plates after extreme environmental exposure

“…Several studies from around the world have shown the ability of CFRPs to significantly improve the fatigue life of centrally notched [21][22][23][24] and edge notched steel [25,26]. Liu et al [21] used high modulus CFRP sheeting materials to improve the fatigue life of pre cracked steel plates.…”