PSI - Issue 42

Fatih Kocatürk et al. / Procedia Structural Integrity 42 (2022) 1206–1214 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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was determined as the w value for a specimen. Dimensional measurements were performed to determine the y value precisely before each specimen was tested. In order to determine the socket depth at the measurement stage, socket depth values were measured by using the comparator for N10 head socket form. Then, bolt head height, k, is measured with the caliper, and y values were determined by subtracting the socket depth value, s, from the head height value.

Fig. 4. Specimen that fractured after tensile tests.

4. Results and discussion According to Eq. (3), value for the selected bolt specimen was estimated as 2.82 mm. y-axis value of 1 , , that is shown in Fig. 3 was calculated as 2.33 mm and is evaluated by subtracting the half of radius from the value as = − R/2 = 2.33 − (0.63/2) = 2.02 . The half of the radius value was subtracted from value, since the specimens fractured from the middle of the radius in experimental studies. The analytical formulation was validated by conducting numerical analysis for different socket depth values in Kocatürk et al. (2020). A detailed statistical study was performed by recording 10 effective stress measurements (Von-Mises) from two regions on the bolts whose -values range between 2.10 and 3.45 mm: i) under-head, ii) thread regions. Higher stress values were observed in the thread region for -values of 3.10 mm and above. Also, higher stress values were observed in the under-head region compared to the thread region for y-values values less than 2.45 mm. As a result, the value of was determined as 2.78 mm in Kocatürk et al. (2020) considering numerical analysis. Table 1. Tensile test results for M8x1.25 8.8 grade bolts. Test samples y (mm) w (mm) Fracture Load (kN) 1 2.21 1.68 25.84 2 2.21 1.67 25.69 3 2.26 1.56 25.65 4 2.26 1.62 25.77 5 2.30 1.60 25.41 6 2.30 1.67 25.75 7 2.35 1.58 25.86 8 2.62 1.97 27.34 9 2.62 1.82 26.93 10 2.70 1.96 30.05 11 2.74 1.77 30.14 12 2.77 2.06 30.21 13 2.77 1.95 30.09