Experimental and Numerical Investigations of Fretting Fatigue Behavior for Steel Q235 Single-Lap Bolted Joints

Abstract

This work aims to investigate the fretting fatigue life and failure mode of steel Q235B plates in single-lap bolted joints. Ten specimens were prepared and tested to fit the S-N curve. SEM (scanning electron microscope) was then employed to observe fatigue crack surfaces and identify crack initiation, crack propagation, and transient fracture zones. Moreover, a FEM model was established to simulate the stress and displacement fields. The normal contact stress, tangential contact stress, and relative slipping displacement at the critical fretting zone were used to calculate FFD values and assess fretting fatigue crack initiation sites, which were in good agreement with SEM observations. Experimental results confirmed the fretting fatigue failure mode for these specimens. It was found that the crack initiation resulted from wear regions at the contact surfaces between plates, and fretting fatigue cracks occurred at a certain distance away from hole edges. The proposed FFD-relationship is an alternative approach to evaluate fretting fatigue life of steel plates in bolted joints.

Numerical estimation of fretting fatigue life of bolted joints using continuum damage mechanics and SEAM Tool

“…Using the numerical simulation results in section “Propagation life and path” and section “Initiation life,” the total fretting life is readily predicted by superimposing the initiation life (calculated by the CDM model) and propagation life (computed by the SEAM Tool). As shown in Figure 18, the results of FFD (Xu et al, 2016) and CDM + SEAM fall within the ± 2 N scatter bands, which are in good agreement with the observed experimental life. What’s more, the proposed method (CDM + SEAM) is better than FFD because it predicts not only the total fretting fatigue life but also the crack initiation location and propagation path reasonably.…”

“…The predicted total fatigue life versus experimental results by CDM + SEAM and FFD (Xu et al, 2016) ( µ = 0.45, k = 100%).…”

“…All specimens are made of commercial steel Q235B; the mechanical properties and chemical composition of steel Q235B are listed in Tables 1 and 2, respectively. This study is based on the experimental results reported in the previous work (Xu et al, 2016), including fretting fatigue test and electron microscopy of fracture specimens. Geometry size and experimental setup are shown in Figure 1.…”

“…The fretting fatigue testing program under different loading conditions is shown in Table 3. For more details of the test, refer to the work of Xu et al (2016).…”

An Experimental Study of Novel Cold Worked Penetrative Reinforcement of GFRP/ Aluminium Bonded Joints

“…Bolted joints use a shear loaded, threaded member to introduce a compressive force by torquing a nut onto the bolt. These fasteners, similar to rivets, increase the weight of a structure and often result in crack initiation sites caused by fretting damage [14].…”