PSI - Issue 43

Matthias Oberreiterr et al. / Procedia Structural Integrity 43 (2023) 240–245 Author name / Structural Integrity Procedia 00 (2022) 000 – 000

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test frequency is about 105 Hz and the specimens were tested until burst failure; or defined as run-out number if ten million load cycles are reached. The crack propagation tests were realized at a Rumul ® Cracktronic resonance bending test rig with an alternating load stress ratio of = −1 . Finally, computed tomography (CT) is conducted by a Phoenix/X-ray ® Nanotom for alloy EN AC 46200 using a voxel- size of 4.5µm for the fine microstructure in ‘Position A’.

Fig. 1 Microstructure of the alloys EN AC 46200 (AlSi8Cu3) and EN AC 42100 (AlSi7Mg0.3)

3. Results and Discussion 3.1. Quasistatic and fatigue testing

The quasistatic investigations revealed strongly varying material properties in the ‘P osition A-C ’ , see Fig. 2. In case of fine microstructure, or low  2 -value, alloy EN AC 42100 possesses an increased ductility but reduced tensile strength (TS). Coarse microstructure, or high  2 -value, leads to quite brittle fracture.

Fig. 2 (a) Comparison of normalized quasistatic and (b) Fatigue tests of the investigated aluminium alloys

Table 2 Summary of normalized quasistatic and fatigue test data

σ , [-] 1.00

Position

TS [-]

YS 0.01 [-]

A [%]

k 1 [-] 5.06 5.05 6.49

N T [-] 1.0E6 3.7E6 2.3E6

1:T S,LLF [-]

A B C

3.40 2.25 2.89

1.60 1.35 1.45

1.46 0.18 8.11

1.26 1.14

0.56 0.97

1.39 A summary of the normalized data of the quasistatic investigations is given in Tab. 2. All fatigue and quasistatic test data are normalized to the mean long-life fatigue strength σ , of samples from ‘P osition A ’ . The second inverse slope k 2 of the S/N-curves in Fig. 2b is expressed as a function of the inverse slope in the finite life region 2 = 5 ⋅ 1 ,