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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  a    fatigue-life curves in Fig. 4 (a), which represent the dependence of the number of loading cycles to failure N on the average strain amplitudes  a ;  F a    fatigue-life curves in Fig. 4 (b), which represent the dependence of the number of loading cycles to failure N on the loading force amplitudes F a ;  ∆ W  fatigue-life curves in Fig. 4 (c), which represent the dependence of the number of loading cycles to failure N on the dissipated energy within one loading cycle ∆ W . The computational results have shown that the fatigue life curves of the Chiral and Star-shaped structures almost coincided for all three considered presentation forms. These structures also demonstrated the highest fatigue resistance at the higher amplitude strain levels compared to the other auxetic honeycombs. Furthermore, the Re entrant structure showed the lowest fatigue resistance at higher amplitude strain levels but, at the same time, withstood the higher loads compared to the other analysed auxetic honeycombs. The computational results have also shown that the Chiral and Star-shaped structures have had the highest dissipated energy within one loading cycle. The computational investigation of the fatigue behaviour of five different auxetic honeycombs made of the aluminium alloy AA 5083-H111 was proposed in this study. The computational analyses were performed using the ANSYS software package. The strain life approach was applied for the fatigue life calculation, based on the Coffin Manson model with a Morrow mean stress correction. Based on the obtained computational results, the following conclusions can be made:  The analysed auxetic honeycombs have shown a different Poisson’s ratio. The lowest (negative) Poisson’s ratio was observed for the Chiral structure, while the highest Poisson’s ratio was observed for the S-shaped auxetic structure.  The computational results have shown significantly different stiffnesses of analysed auxetic structures. Based on this finding, the experimental results were presented in three various forms:  From the  a    fatigue-life curves, it was found that the Chiral and Star-shaped structures reached a significantly longer fatigue life than other analysed structures at the same average strain amplitude  a .  From the F a    fatigue-life curves, it was found that the Re-entrant structure demonstrated the lowest fatigue resistance at higher amplitude strain levels but, at the same time, showed the highest loads compared to the other analysed auxetic honeycombs.  From the ∆ W  fatigue-life curves, it was found that the Chiral and Star-shaped structures showed the highest dissipated energy within the one loading cycle. 4. Conclusion

Acknowledgement

The authors acknowledge the financial support of the Research Core Funding (No. P2-0063) and the basic research project (No. J2-8186) from the Slovenian Research Agency.

References

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