PSI - Issue 28

Barış Tanrıkulu et al. / Procedia Structural Integrity 28 (2020) 1267 – 1275 Author name / Structural Integrity Procedia 00 (2019) 000–000

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2. Material and Methods 2.1. Test sample specifications

In this study conducted to compare the loosening behavior of fasteners, M8 x 1.25 x 50 8.8 DIN 933 bolts and M8 x 1.25 8 grade DIN 6923 with rip form and without rip nuts were used. Images of all 3 fasteners are given in Figure 1. 23MnB4 material was chosen as the material of bolts and nuts and all the fasteners were heat treated for 8.8 and 8 grade, respectively. All nuts and bolts were covered with Delta Protect KL100 VH301GZ coating, and the friction coefficient values, one of the important factor affecting loosening, were kept as around 0.12. Assembly plates preferred in this experimental study were used in two different hardness values, i.e. 175 HV and 300 HV. Thus, the effects of the nut rip form on the plate surface depending on hardness values were examined. All plates were grinded in order to stabilize the under head friction coefficient values for the loosening vibration tests. Drawing and image of the plates used in junker vibration tests are given in Figure 2.

Fig. 1. Technical drawings of DIN 933 bolt and DIN 6923 Nuts with and without rip form.