Multi-physics modeling of the fabrication and dynamic performance of all-metal auxetic-hexagonal sandwich-structures

• Auxetic sandwich structures are studied using a multiphysics computational approach.
• The study focuses on the role of processing steps and the resulting microstructure.
• Dynamic response of as-processed, blast-loaded sandwich structures is also studied.
• Sensitivity of sandwich structure behavior to processing has been clearly shown.

In the present paper, various computational methods and tools are used to investigate the effect of the prior processing and the resulting microstructure on the performance of all-metal sandwich-structures with an auxetic-hexagonal core. Specific fabrication processes analyzed in the present work include: (a) sheet-metal fabrication using cold flat rolling; (b) a simple stamping process used to impart the desired corrugation to the as-cold rolled sheet-metal blanks; and (c) laser welding used to join the corrugated and stacked adjacent blanks over their areas of contact. The computational analyses employed yielded the results which clearly revealed how each of the three fabrication processes affects the grain microstructure of the sheet-metal blanks, the presence of residual stresses within the sandwich-structure as well as the presence of distortions. In the last portion of the present work, a series of transient nonlinear dynamics finite-element computational analyses is carried out in order to demonstrate how the prior fabrication processes and the material microstructure, residual stresses and distortions yielded by them affects the dynamic performance of the all-metal auxetic sandwich-structures subjected to blast loading. The results obtained clearly showed that the effect of prior processing must be taken into account in order to obtain accurate insight into the dynamic response of sandwich structures when subjected to blast loading.

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