PSI - Issue 28

Yifan Li et al. / Procedia Structural Integrity 28 (2020) 1148–1159 Author name / Structural Integrity Procedia 00 (2019) 000–000

1152

5

Fig. 3. Large aluminium alloy triangular lattice plate specimen used for fatigue testing.

Fig. 4. The details of manufactured struts: (a) strut dimensions (b) photograph of the specimen

3.2. Measurement of mechanical behavior of aluminium alloy Tensile tests were conducted on three sheet-type specimens that were designed according to ASTM E8/E8M-16a, to obtain the mechanical property of the 1050A aluminium alloy used in the lattice plates. An Instron 8872 hydraulic tensile testing machine with 5kN load cell was used for tensile test on a displacement-based control with 0.25 mm/min velocity. As the elongation of 1050A aluminium alloy is larger than the full range of the mechanical axial extensometer, the machine will be stopped to remove extensometer and restart again until specimen broke. Stress strain relationship obtained from waisted sheet specimens is shown in Fig. 5. The yield stress and ultimate tensile strength were measured at the same time as σ y = 93.70 MPa and the ultimate tensile strength as σ uts = 101.88 MPa to support the subsequent FE simulation. The elastic modulus measured in the experiment is E = 64.91 GPa for 1050A aluminium and the Poisson’s ratio for this material is v = 0.33 (Kvačkaj et al. 2011). The elongation of 1050A aluminium is nearly 12%.

120

True curve Experimental curve

offset yield strength

105

90

75

60

45

Stress (MPa)

30

15

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0

Strain

Fig. 5. The stress-strain relationship of aluminium 1050A measured in tensile tests.