PSI - Issue 28

Lucas F.R.C. da Silva et al. / Procedia Structural Integrity 28 (2020) 1426–1430 Lucas F. R. C. da Silva et al / Structural Integrity Procedia 00 (2019) 000–000

1428

3

Table 1. EN10025 chemical composition and mechanical properties of S350GD steel Chemical Composition (max %)

Mechanical Properties � (MPa) � (MPa) ԑ � ��� ≥350 420 16

C

Si

Mn

P

S

S350GD

0.20

0.60

1.70

0.10

0.045

Several fatigue tests were performed with M12×30 bolts (DIN933, Grade 8.8), M12 washer (DIN 125) and M12 nuts (Grade 8). Two types of connection geometries (single (1+1) and multiple (4+4) bolts), two plate widths (80mm and 70mm), two preload levels (preloaded bolts: 70% Fu and snug tight bolts: 25%×70% Fu ), two-hole manufacturing processes (punching and drilling), and three stress R-ratios ( R =0.1, R =0.3, R =0.5). The plates that are part of the bolted joints are made of S350GD steel grade.

Table 2. Overview of experimental tests. Bolt Arrangement Preload Level Hole

Bolt Type

Stress R-Ratio

Repetitions

Observations

Production

M12 M12 M12 M12 M12 M12 M12

Single Single Single Single Single

Snug Tight Snug Tight Snug Tight Snug Tight Preloaded Snug Tight Snug Tight

Punched Punched Punched Punched Punched Punched

0.1 0.1 0.3 0.5 0.1 0.1 0.1

12

Reference Condition Reduced Net Section

4 4 4

- - - - -

12

Multiple Multiple

9 9

Drilled

3. Experimental Results In this section will be analyzed the experimental data obtained. In order to analyze all single bolt connections is necessary to apply a mean stress correction. Taras and Greiner (2010) proposed a mean stress correction for loads under R different from 0 to R=0.

Fig. 2. Experimental results according to ASTM E 379 for snug tight bolts