Design and development of auxetic structure using a two-step hybrid optimization technique.

Structures that possess Negative Poisson's Ratio are known as auxetics. The successful application of auxetics requires appropriate design optimisation. Hence, in the present work, customised auxetics namely re-entrant honeycomb, missing rib and anti-tri-chiral has been developed using a two-step hybrid optimisation technique. The technique is based on the amalgamation of multiobjective optimisation and topological optimisation. A combined objective is set as maximum elastic moduli and minimum Poisson's ratio with prioritised objective as maximum elastic moduli and mass as the response constraint. Initially, an optimal shape of a unit cell based on the Pareto front has been chosen considering the prioritised objective. Thereafter, finite element simulation was performed to evaluate the auxetic behaviour followed by topological optimisation using the density-based method. Using the developed model, the morphological and mechanical properties of the designed auxetics have been compared. The re-entrant honeycomb structure has been found as the most reliable auxetics with the highest elastic modulus and auxetic behaviour. The induced maximum stress in the array and structure of re-entrant honeycomb was 320.7 MPa and 168.77 MPa respectively. The results revealed that the developed methodology can be utilised as an advanced tool for achieving topologically optimised auxetics with desired properties. [ABSTRACT FROM AUTHOR]