PSI - Issue 37

ScienceDirect Structural Integrity Procedia 00 (2019) 000 – 000 Structural Integrity Procedia 00 (2019) 000 – 000 Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceD rect Available online at www.sciencedirect.com ScienceDirect

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

Procedia Structural Integrity 37 (2022) 857–864

© 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of Pedro Miguel Guimaraes Pires Moreira Abstract A domain of 1x1 mm was chosen and divided in 4x4 squares on each side. A soft (purple) and a rigid (blue) material distribution with an elastic modulus ratio of 1:10 can be inkjet printed together in equal parts, following an initial pattern. The simulated annealing algorithm used in this work is similar to the Greedy algorithm but accepts less favorable solutions at a current iteration to make possible further calculations. The objective function is formulated as maximizing the effective stiffness on both in-plane directions. Finite element analyses are performed by using the PyAnsys software under an MIT License and a domain with 16 Q8 elements which represents by symmetry a quarter of RVE. The simulated annealing algorithm provided better results than the Greedy algorithm in all analyzed cases, but it does not always converge to a global optimum. © 2022 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) ICSI 2021 The 4th International Conference on Structural Integrity A simulated annealing algorithm for stiffness optimization Alexandru VASILE a,b , Iulian Constantin COROPE Ț CHI a,b , Ș tefan SOROHAN b, Cătălin Radu PICU b,c , Dan Mihai C NSTANTINESCU b * a Military Technical Academy „Ferdinand I”, Bulevardul George Coşbuc nr. 39 -49, 050141, Bucharest, Romania b University POLITEHNICA of Bucharest, Spl iul Ind pendeţei nr. 313, 060042 Buchar est, Romania, c Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, NY, USA 12180 Abstract A domain of 1x1 mm was chosen and divided in 4x4 squares on each side. A soft (purple) and a rigid (blue) material distribution with a elastic odulu ratio of 1:10 can be inkjet printed t g ther in qual parts, fol owi g n initial pattern. The s mulated annealing a gorith used in this work is similar to the G eedy al orithm but acce ts less favorable solutions a current iteration to make possible further calculations. The objective function is formulated as maximizing the effective stiffness on both n-plane directions. Finit elem nt na yses are p rformed by using the PyAnsys software under an MIT Licen e a d a domain with 16 Q8 lements which r presents by symmetry a quarter of RVE. The simulated ann ali g algorithm provid d better results than the Gre dy algorit m in all analyzed cases, but it does not always converge to a global optimum. © 2022 Th Authors. Publ shed by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review u der re ponsibility of Pedro Miguel Guimara s Pires Moreira K ywords: inkjet printing, simulated annealing algorithm, stiffness optimization 1. Introduction Optimal design of a structure has always been a topic of interest for engineers and since the technological develop ents that emerged in the field of nanofabrication, imaging technologi s and developm n of additive manufacturing capabilities, interest has sparked i this direction in the last decades. Researchers are try ng to mimic the behavior of certain materials found in nature or are trying to create structures that display novel properties that surpass t ose of traditio al materials. To do so engineers used numeric l modelling, created algorithms that a m at optimizing structures. From the first step, that is topology optimization to the atter ICSI 2021 The 4th International Conference on Structural Integrity A simulated annealing algorithm for stiffness optimization Alexandru VASILE a,b , Iulian Constantin COROPE Ț CHI a,b , Ș tefan SOROHAN b, Cătălin Radu PICU b,c , Dan Mihai CONSTANTINESCU b * a Military Technical Academy „Ferdinand I”, Bulevardul George Coşbuc nr. 39 -49, 050141, Bucharest, Romania b University POLITEHNICA of Bucharest, Splaiul Independeţei nr. 313, 060042 Buchar est, Romania, c Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, NY, USA 12180 Peer-review under responsibility of Pedro Miguel Guimaraes Pires Moreira Keywords: inkjet printing, simulated annealing algorithm, stiffness optimization 1. Introduction Optimal design of a structure has always been a topic of interest for engineers and since the technological developments that emerged in the field of nanofabrication, imaging technologies and development of additive manufacturing capabilities, interest has sparked in this direction in the last decades. Researchers are trying to mimic the behavior of certain materials found in nature or are trying to create structures that display novel properties that surpass those of traditional materials. To do so engineers used numerical modelling, created algorithms that aim at optimizing structures. From the first step, that is topology optimization to the latter

* Corresponding author e-mail address : dan.constantinescu@upb.ro * Corresponding author e-mail address : dan.constantinescu@upb.ro

2452-3216 © 2022 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of Pedro Miguel Guimaraes Pires Moreira 2452-3216 © 2022 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review u der responsibility of Pedro Miguel Guimara s Pires Moreira

2452-3216 © 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of Pedro Miguel Guimaraes Pires Moreira 10.1016/j.prostr.2022.02.019