PSI - Issue 19

Motoki Nakane et al. / Procedia Structural Integrity 19 (2019) 284–293 Author name / Structural Integrity Procedia 00 (2019) 000–000

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2.3. Outline of fatigue test Fig. 4 shows the appearance of fatigue test. The fully reversed strain-controlled axial loading fatigue tests were conducted in air at ambient temperature. In this study, the fatigue life N f is defined as number of cycles for peak tensile stress drop 25% from its value at the half of that number of cycles in strain-controlled tests. For the stress controlled tests, N f is defined as number of cycles when the specimen is fractured.

Table 3. Grinding condition. Grinding wheel

Rotation and feeding speed Actual fabrication conditions †

Polishing amount 0.1 mm/per surface

Skilltouch WA60

† High speed level within the range of actual fabrication condition

Rolling direction

Feeding

direction Grinding scratch direction

Feeding direction Grinding scratch direction

(250)

(250)

(130)

(130)

Grinding area

Grinding area

(250)

(250)

(a) Parallel to axis (Type 1)

(b) Perpendicular to axis (Type 2)

Grinding range

Grinding range

(130)

(130)

圧延方向

圧延方向

圧延方向

圧延方向

素材板

素材板

(130)

(130)

素材板

素材板

グラインダ移動方向

Grinding range

Grinding range

グラインダ移動方向

Rolling direction

Rolling direction

グラインダ移動方向

グラインダ移動方向

Rolling direction

Rolling direction

Step 1

Step 2

Step 3

Step 4

Step 5

Step 6

(c) General grinding work process

Fig. 1 Schematics of grinding process and scratch direction.

Fig. 2 Fatigue test specimen.