PSI - Issue 54

Behzad V. Farahani et al. / Procedia Structural Integrity 54 (2024) 638–644 Behzad V. Farahani et al./ Structural Integrity Procedia 00 (2023) 000–000

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2. Experimental procedure In this study, a Middle Tension (MT) specimen made of an aluminum alloy (AA6082 – T6) was manufactured in accordance with the Standard Test Method for Measurement of Fatigue Crack Growth Rates ASTM E-647 (ASTM International, 2015). The specimen’s thickness was considered as B = 3.0 (mm) with a width of W = 80.0 (mm). An initial notch with a length of 16 (mm) and a width of 0.3 (mm) was built via an electrical discharge machining (EDM). Figure 1 depicts the studied MT specimen with its overall geometrical characteristics. The mechanical properties of the material are listed in Table 1.

Figure 1: A general view of MT specimen with the initial notch, dimensions are in mm.

Table 1: Material properties of AA6082-T6 aluminium alloy.

Property

Value

Elasticity modulus Poisson's ratio

E = 70 (GPa)

 = 0.33

Yield stress

 y = 250 (MPa)

Ultimate tensile strength UTS = 290 (MPa) To open the fatigue crack, the MT specimen was loaded in fatigue with test configurations reported in Table 2, using a standard servo-hydraulic MTS machine with a load capacity of 250 (kN).

Table 2: Fatigue loading conditions.

F Max

F min

F A

F m

R

f

10.0 (kN) 12.0 (Hz) It underwent different cyclic fatigue loadings with the purpose of generating a predefined crack length. Two travelling microscopes were setup in the front and the rear side of the specimen, to enable crack length monitoring on 1.0 (kN) 5.5 (kN) 4.5 (kN) 0.1