Strength through defects: A novel Bayesian approach for the optimization of architected materials

Zacharias Vangelatos; Haris Moazam Sheikh; Philip S Marcus; Costas P Grigoropoulos; Victor Z Lopez; George Flamourakis; Maria Farsari

doi:10.1126/sciadv.abk2218

Strength through defects: A novel Bayesian approach for the optimization of architected materials

Sci Adv. 2021 Oct 8;7(41):eabk2218. doi: 10.1126/sciadv.abk2218. Epub 2021 Oct 8.

Authors

Zacharias Vangelatos^{1

2}, Haris Moazam Sheikh^{1

3}, Philip S Marcus^{1

3}, Costas P Grigoropoulos^{1

2}, Victor Z Lopez⁴, George Flamourakis⁵, Maria Farsari⁵

Affiliations

¹ Department of Mechanical Engineering, University of California, Berkeley, Berkeley, CA 94720, USA.
² Laser Thermal Lab, University of California, Berkeley, Berkeley, CA 94720, USA.
³ Computational Fluid Dynamics Laboratory, University of California, Berkeley, CA 94720, USA.
⁴ California Institute of Technology, Pasadena, CA 91125, USA.
⁵ Institute of Electronic Structure and Laser (IESL), Foundation of Research and Technology-Hellas (FORTH), Heraklion 70013, Crete, Greece.

Abstract

We use a previously unexplored Bayesian optimization framework, “evolutionary Monte Carlo sampling,” to systematically design the arrangement of defects in an architected microlattice to maximize its strain energy density before undergoing catastrophic failure. Our algorithm searches a design space with billions of 4 × 4 × 5 3D lattices, yet it finds the global optimum with only 250 cost function evaluations. Our optimum has a normalized strain energy density 12,464 times greater than its commonly studied defect-free counterpart. Traditional optimization is inefficient for this microlattice because (i) the design space has discrete, qualitative parameter states as input variables, (ii) the cost function is computationally expensive, and (iii) the design space is large. Our proposed framework is useful for architected materials and for many optimization problems in science and elucidates how defects can enhance the mechanical performance of architected materials.