PSI - Issue 35

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

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Procedia Structural Integrity 35 (2022) 51–58

© 2021 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 IWPDF 2021 Chair, Tuncay Yalçinkaya © 2021 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 IWPDF 2021 Chair, Tuncay Yalçinkaya Abstract I this study, the fracture problem occurring in the ben ing areas of th sheet metal panel produced by the hem ing process wa investigated by numerical method. The part is produced with cold-rolled continuous galvanized DX51D grade material which is c mmonly used. As is kno n, ther is no upper yield stre s limit v lue for this m terial according to EN 10346:2015. In addition to this, for this teel grade when the yield and tensile stress s increa e, uctility c pabi ity d cr as s significantly. Also, when metal forming imulations are done with only uniaxial t nsile test data of material, unexpecte failur s co ld arise for th hemming process. Therefore, the type of stress that oc urred on the ma erial by th proc ss applied in the produc ion should be carefully examin d and material data shoul be extracted fo dominant stress typ . The use of this material without limiting mecha ical prop ties can caus unexp cted c acks and tear , especially in pr cess s with high plastic deformation such as hemming. In order to observe the fracture occurrence, the stress triaxiality factor of the material was examin d and the dominant str ss triaxiality v lue with stra n to fract r p th in the hemming process was determined with finite ele nt analysis. Due to th ir similar mechanical properties, being used as raw material f r DX51D and having ductile fracture par meters available in the liter ture, hot-rolled S235JR and S275JR materials are chosen to obs rve fracture event in num ric l analysis. Equivalent strain to fracture-stress triaxiality and lode angl curves were used with the Hosford-Coulo b du tile fracture model to examine the effects on the hemming process. Al numerical calculations were performed in the commercial Altair RADIOSS softwa e tha can p rfor hi h n nlinearity calculations. Finally, a performance comparison was made between materials and the experiment for the hemming process. © 2021 The Authors. Published by ELSEVIER B.V. This is an ope acces article under the CC BY-NC-ND lice se (https://cre tivecommons.org/licenses/by-nc-nd/4.0) Peer- review under responsibility of IWPDF 2021 Chair, Tuncay Yalçinkaya 2nd International Workshop on Plasticity, Damage and Fracture of Engineering Materials Ductile fracture of DX51D material sheet metal panel produced by hemming process İbrahim Yelek *, Mehtap İpek *Borçelik Çelik Sanayii Ticaret A.Ş., Bursa 16601, Turkey Abstract In this study, the fracture problem occurring in the bending areas of the sheet metal panel produced by the hemming process was investigated by numerical method. The part is produced with cold-rolled continuous galvanized DX51D grade material which is commonly used. As is known, there is no upper yield stress limit value for this material according to EN 10346:2015. In addition to this, for this steel grade when the yield and tensile stresses increase, ductility capability decreases significantly. Also, when the metal forming simulations are done with only uniaxial tensile test data of material, unexpected failures could arise for the hemming process. Therefore, the type of stress that occurred on the material by the process applied in the production should be carefully examined and material data should be extracted for dominant stress types. The use of this material without limiting mechanical properties can cause unexpected cracks and tears, especially in processes with high plastic deformation such as hemming. In order to observe the fracture occurrence, the stress triaxiality factor of the material was examined and the dominant stress triaxiality value with strain to fracture path in the hemming process was determined with finite element analysis. Due to their similar mechanical properties, being used as raw material for DX51D and having ductile fracture parameters available in the literature, hot-rolled S235JR and S275JR materials are chosen to observe fracture event in numerical analysis. Equivalent strain to fracture-stress triaxiality and lode angle curves were used with the Hosford-Coulomb ductile fracture model to examine the effects on the hemming process. All numerical calculations were performed in the commercial Altair RADIOSS software that can perform high nonlinearity calculations. Finally, a performance comparison was made between materials and the experiment for the hemming process. 2nd International Workshop on Plasticity, Damage and Fracture of Engineering Materials Ductile fracture of DX51D material sheet metal panel produced by hemming process İbrahim Yelek *, Mehtap İpek *Borçelik Çelik Sanayii Ticaret A.Ş., Bursa 16601, Turkey

Keywords: Hosford-Coulomb ductile fracture model; hemming process; sheet metal; stress triaxiality Keywords: Hosford-Coulomb ductile fracture model; hemming process; sheet metal; stress triaxiality

* Corresponding author. E-mail address: iyelek@borcelik.com * Corresponding author. E-mail address: iyelek@borcelik.com

2452-3216 © 2021 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 responsibilit y of IWPDF 2021 Chair, Tuncay Yalçinkaya 2452-3216 © 2021 The Authors. Published by ELSEVIER B.V. This is an ope access article under the CC BY-N -ND license (https://cre tivecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibilit y of IWPDF 2021 Chair, Tuncay Yalçinkaya

2452-3216 © 2021 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 IWPDF 2021 Chair, Tuncay Yal ç inkaya 10.1016/j.prostr.2021.12.047