We will have an opening for a postdoctoral position at the CC&B, University of Milan in the group of Prof. Zapperi. We are looking for candidates with strong programming skills who are interested in working at the frontier between academic and industrial research. The candidates should have a Ph. D in computer science, computational materials science, physics, mathematics or engineering. The position will be for 1 year, renewable to a second one and funded by the METACTOR project on Algorithmic design of 3D-printed metamaterial actuators with improved functionality and lifetime which will be carried on in collaboration with ICMATE-CNR, Lecco. The goal is to develop algorithmic methods for the automatic design of mechanical metamaterial actuators made by NiTi alloys, concentrating on their superelastic and shape memory properties.Interested candidates should send their CV to: stefano.zapperi@unimi.it

In the works below, an isogeometric analysis combined with adjoint sensitivity analysis is used for the design of mechancial metamaterials. A detailed introduction to isogeometric analysis (IGA), formulation and implementation of adjoint sensitivity analysis in the nonlinear regime for auxetics design is included in the thesis and papers below. The work presents a holistic physics-based approach for structural shape optimization using IGA. Kindly cite the work if you find useful.

Publications:

1. Pokkalla, D.K., Wang, Z., Teoh, J.C., Poh, L.H., Lim, C.T. and Quek, S.T., 2022. Soft Missing Rib Structures with Controllable Negative Poisson’s Ratios over Large Strains via Isogeometric Design Optimization. Journal of Engineering Mechanics, 148(11), p.04022063.

2. Pokkalla, D.K., Poh, L.H. and Quek, S.T., 2021. Isogeometric shape optimization of missing rib auxetics with prescribed negative Poisson’s ratio over large strains using genetic algorithm. International Journal of Mechanical Sciences, 193, p.106169.

3. Pokkalla, D.K., Wang, Z.P., Poh, L.H. and Quek, S.T., 2019. Isogeometric shape optimization of smoothed petal auxetics with prescribed nonlinear deformation. Computer Methods in Applied Mechanics and Engineering, 356, pp.16-43.

4. Wang, Z.P. and Kumar, D., 2017. On the numerical implementation of continuous adjoint sensitivity for transient heat conduction problems using an isogeometric approach. Structural and Multidisciplinary Optimization, 56(2), pp.487-500.

Thesis:

1. Pokkalla, D.K. 2020. Isogeometric Shape Optimization of Auxetics with Prescribed Nonlinear Deformation.

Dear Colleagues, Our recent publication on the Journal of Applied Mechanics:

We study the elastodynamics of a periodic metastructure incorporating a defect pair that enforces a parity-time (PT) symmetry due to a judiciously engineered imaginary impedance elements– one having energy amplification (gain) and the other having equivalent attenuation (loss) mechanism. We show that their presence affects the initial band structure of the periodic Hermitian metastructure and leads to the formation of numerous exceptional points (EPs) which are mainly located at the band edges where the local density of modes is higher. The spatial location of the PT-symmetric defect serves as an additional control over the number of emerging EPs in the corresponding spectra as well as the critical non-Hermitian (gain/loss) strength required to create the first EP–a specific defect location minimizes the critical non-Hermitian strength. We use both finite element and coupled-mode-theory-based models to investigate these metastructures, and use a time-independent second-order perturbation theory to further demonstrate the influence of the size of the metastructure and the PT-symmetric defect location on the minimum non-Hermitian strength required to create the first EP in a band. Our findings motivate feasible designs for experimental realization of EPs in elastodynamic metastructures.

Read the full article here: https://doi.org/10.1115/1.4055618

PhD positions are available at the University of Minnesota in the group of Prof. Stefano Gonella. The positions are in the general area of mechanics and physics of solids, with emphasis on mechanical and elastic metamaterials, architected solids and wave physics. Current topics of interest include: Topological metamaterials; Tunable and programmable metastructures; Mechanics of cellular multilayer materials; Multiphysical interactions of vibrating metastructures.

The research will involve a combination of theoretical, computational and experimental work, providing the students with a complete and holistic training and a diverse research experience.

The ideal candidate is a highly motivated and creative individual with background in engineering, physics, materials science or mathematics, solid foundations in mechanics, coding experience and strong communication skills.

The position is expected to start in the fall of 2023.

Applicants should submit a resume (indicating names and contact of references) via email to Prof. Stefano Gonella at sgonella@umn.edu.

Qualified candidates will be contacted to schedule a follow-up interview (e.g., Zoom or Skype) and encouraged to submit a formal application to the PhD program.

The University of Minnesota is one of the most comprehensive and prestigious public universities in the United States. The campus is located in the vibrant heart of the Minneapolis-Saint-Paul metropolitan area (the Twin Cities), one of the major economic, artistic and cultural hubs in the nation, just blocks from theaters, museums, professional sports venues and endless outdoors recreation opportunities.