PSI - Issue 46

Branko Nečemer et al. / Procedia Structural Integrity 46 (2023) 68 – 73 Branko Ne č emer et al. / Structural Integrity Procedia 00 (2019) 000–000

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etc. (Meena et al. (2019), Hou et al. (2015)). In the last decades, numerous researches have been performed in the field of the fatigue and fracture behaviour of cellular structures. In the review article presented by Ne č emer et al. (2019), different cellular structures are analysed regarding their mechanical response under static and dynamic loading. However, only a few researchers have focused on the fatigue and fracture behaviour of auxetic cellular structures. Choi et al. (1992) analysed the fracture toughness of copper foams with positive and negative Poisson’s ratio experimentally. The comparison of experimental results showed that the copper auxetic foam has a significantly higher fracture toughness compared to the copper foam with a positive Poisson’s ratio. Ne č emer et al. (2019) investigated the geometrical effect of the unit cell on the deformation behaviour of chiral auxetic cellular structures subjected to the multiaxial loading conditions. Kramberger et al. (2019) investigated the shape effect and distribution of unit cells on the fracture behaviour of 2D honeycomb and auxetic cellular structures under quasi static loading conditions. Ne č emer et al. (2019) investigated the orientation of the unit cell in the re-entrant auxetic structure on its fatigue behaviour. The same authors (Ne č emer et al. (2020)) investigated the fatigue behaviour of the chiral and re-entrant auxetic structures by using the inelastic energy approach. In this work, the computational investigation of the fatigue life of different two-dimensional auxetic honeycombs made of aluminium alloy 5083-H111 was studied. This research is based on the authors previous work, where the computational model was built and validated by Ne č emer et al. (2021). Figure 1 shows the analysed geometries of the auxetic honeycombs.

y

x

(d)

(e)

(b)

(c)

(a)

Fig. 1. Geometries of the analysed auxetic honeycombs: (a) Chiral structure; (b) Star-shaped structure; (c) S-shaped structure; (d) Double arrowhead structure, and (e) Re-entrant structure.

Strain along the loading direction [%]

-1.2 -1 -0.8 -0.6 -0.4 -0.2 0

0

0.5

1

1.5

2

Chiral structure Re-entrant structure Star-shaped structure Double arrow head structure S-shaped structure

Poisson's ratio [-]

Fig. 2. The Poisson’s ratio of the analysed honeycombs