| Abstract |
This project focuses on the computational design of acoustic and mechanical metamaterials, integrating sophisticated numerical techniques such as multiscale material models and topology optimization. The key idea is to design the underlying structure (mesoscopic level) of the material such that the envisaged macroscopic properties are obtained and, thus, the targeted functionality of the material is reached. The internal structure of the material and the overall macroscopic properties are linked by means of computational multiscale methods and the structure design is addressed using multiobjective optimization. In order to reduce the computational cost associated with the designs, reduced-order modeling techniques and off-line precomputed material catalogs can be also employed. Metamaterials, conceived as engineered structural assemblies, exhibit superior properties in comparison to materials found in nature and, therefore, they are regarded as key enabling materials for a large number of engineering applications. Examples of such apparently unphysical properties are effective negative mass, negative refractive index and negative bulk modulus/Poissons ratio. Strategical engineering applications derived from these uncommon properties are found in acoustic engineering, e.g. stop-band acoustic metamaterials and acoustic cloaking devices or in mechanical engineering, e.g. exploiting micro-buckling effects for negative stiffness and shook absorbing materials. Metamaterials own their unusual mechanical properties to their artificially fabricated microstructures rather than the composition of their constituents. In such scenario, reliable multiscale algorithms coupled with multi-objective optimization techniques are regarded key to enable a full multiscale computational design. To this end, a novel multiscale design approach, based on an extended homogenization framework and a multiobjective optimization tool is devised to solve and design the micro and macro scale problems. The extended homogenization techniques are required to deal with inertial and dissipative effects within its scale transition relations as well as combining different macro and meso-discretizations such as beam elements to realistically simulate micro-bucking phenomena. The envisaged algorithms might result into computationally demanding procedures and, therefore, model order reduction strategies as well as off-line pre-computed material catalogs can potentially alleviate the overall cost. The ultimate goal of the project is to study the manufacturability of the designed structures such that, with the help of up-to-date additive manufacturing techniques, a number of early prototypes can be generated. |