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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prescribed to the upper edge of the analysed auxetic honeycombs. The displacement was defined as one closed sinusoidal loading cycle that equated to the amplitude strain. The computational analyses were performed in a strain control ( R =  1) at different strain amplitudes, where the strain was controlled through the whole length of the analysed geometry. The analysed geometries were discretised using 2D plane stress linear finite elements with a global size of 0.15 mm. Each analysed geometry was discretised with ∼ 30,000 elements. For the fatigue life calculation, the strain life approach was applied with consideration of a Morrow mean stress correction. In the framework of the ANSYS software, the strain-life parameters  f ', b ,  f ', c , K ' and n ' were integrated into the material model. The strain-life parameters were determined from the low cycle fatigue tests of the based material (AA 5083-H111) presented in research work [12].

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

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

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

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Fig. 4. (a)  a    fatigue-life curves; (b) F a    fatigue-life curves; (c) ∆ W  fatigue-life curves

3. Computational results

In this section, the computational results of the fatigue resistance of different auxetic honeycombs are presented. The computational analyses were performed at different amplitude strain levels. According to the Coffin-Manson model, the strain life approach was considered with a Morrow mean stress correction in the computational fatigue life calculation. Based on the significantly different stiffness of the analysed auxetic honeycombs, the comparisons of the computational results are presented in three various forms: