PSI - Issue 18

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

www.elsevier.com/locate/procedia

www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 18 (2019) 399–405

25th International Conference on Fracture and Structural Integrity The analysis of the worst-case distribution of the damage in composite material imposed by a low velocity impact Boris Fedulov a, b * and Alexey Fedorenko a a CDMM, Skolkovo Institute of Science and Technology, Bolshoy Boulevard 30, bld. 1, Moscow 121205, Russia b Lomonosov MSU, Faculty of Mechanics and Mathematics, Leninskiye Gory, Main Building, Moscow 119991, Russia Abstract Low velocity impact causes barely visible impact damage (BVID) in composite material, which can be missed at technical inspection. Usual cases during composite product lifetime are the tool drop, hailstones, runway debris etc. The proposed approach avoids the direct modelling of impact process and realizes the minimum possible residual strength for specific damage based on the worst distribution of matrix, fiber and interface micro damages and its accumulation after impact. The minimum possible residual strength condition is fulfilled by the decreasing the stiffness of the laminate via energy absorption form the impactor and composite material collision. It is assumed, that the portion of the kinetic energy of an impactor is transformed into microcracks of fractured matrix materials by several damage modes but the other portion is transformed back to the impactor. The presented method gives as a result the distribution of damage parameters, which reduces stiffness of the material using gradient descent method and provides the worst distribution of damage densities, which associated with the stiffness and gives the direct analogue to the structural topology optimization algorithm. The simple explanation of presented method can be formulated as a search of the worst case of damage distribution in the material for residual strength of the structure with restriction on total energy spent on material damaging. 25th International Conference on Fracture and Structural Integrity The analy s of th worst-ca distribution of the dam ge in composite material imposed by a low velocity impact Boris Fedulov a, b * and Alexey Fedorenko a a CDMM, Skolkovo Institute of Science and Technology, Bolshoy Boulevard 30, bld. 1, Moscow 121205, Russia b Lomonosov MSU, Faculty of Mechanics and Mathematics, Leninskiye Gory, Main Building, Moscow 119991, Russia Abstract Low velocity impact causes barely visibl impact damage (BVID) in c mposite material, which can be missed at technical inspection. Usual cases during composite product lifetime are the tool drop, hailstones, runw y debris etc. proposed a proach avoids the direct mo elli g of impact process and realizes the minimum possible r sidual strength for specific damage based on the w rst distribution of matrix, fiber and interface micro damages and its accumulation after impact. The mini um possible resid al strength condition is fulfilled by the decreasing the stiffness of the lamin te via energy absorption form the impactor an composite materi l collision. It is assumed, that the portion of the kinetic energy of an impactor is transformed into microcracks of fractured mat ix materials by seve al damage modes but the other portion is transformed back to the impactor. The presented method gives as a result the distribution f damage parameters, which reduces stiffness f the material using gr di nt descent method and provides the worst distribution of damage densities, whic associated with the stiffness and gives the direct analogue to the structural topology optimization algorithm. The simple explanation of presented method can be formulated as a search of the worst case of damage distribution in the material for residual strength of the structure with restriction on total energy spent on material damaging.

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. © 2019 The Authors. Published by Elsevier B.V. P er-review under responsibility of the Gruppo Italiano Frat ura (IGF) ExCo. Keywords: composite material, damage distribution, residual strength, topology optimization, failure.

Keywords: composite material, damage distribution, residual strength, topology optimization, failure.

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. * Boris Fedulov. Tel.: +7-916-131-66-51; fax: +7-495-939-20-90. E-mail address: fedulov.b@mail.ru * Boris Fedulov. Tel.: +7-916-131-66-51; fax: +7-495-939-20-90. E-mail address: fedulov.b@mail.ru

2452-3216  2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. 10.1016/j.prostr.2019.08.181