PSI - Issue 60

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2023) 000 – 000

www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 60 (2024) 20–35

© 2024 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 the ICONS 2023 Organizers Abstract Cylindrical shells in one of ISRO’s solid rocket booster is fabricated from ultra -high strength steel (M250 Maraging steel) through rolled and welded construction. This steel being a fracture prone material, elastic-plastic fracture mechanics-based design is followed for the design of cylindrical shell. The no-flaw failure pressure i.e. elastic plastic failure pressure (P b ) of the cylinder is an important parameter in design. For a given diameter of cylindrical shell, P b is a function of shell thickness and mechanical property. If any unacceptable flaw is found on welds during NDT, repairs are carried out in the weld region. Mechanical properties of weld/weld repairs are lower when compared to parent material. It is seen that, at any location, if it is repaired twice, the strength reduces by 21% when compared to the parent metal property. Thus, the mechanical properties of the weld region dictate the overall design thickness of the cylindrical shell. A study is carried out to find the effect of length of weld repair zone on the P b . A parametric 3D FE model simulating the repair in long seam weld, cirseam weld and combination of long seam & cirseam weld in cylindrical shell is used for this purpose. It is found that the effect of parent metal property needs to be considered while estimating P b . Further while considering the repair in long seam, the length of repair also needs to be considered. P b is found to increase considering its effect. This study was helpful in establishing more realistic structural margins in a solid rocket booster case which had weld repair. © 2024 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 the ICONS 2023 Organizers Keywords: Gaganyaan, Elastic plastic fracture mechanics, no-flaw elastic plastic burst pressure, weld repair. Third International Conference on Structural Integrity 2023 (ICONS 2023) A study on the effect of weld repair on the structural margins of a solid rocket booster hardware Sreerag M N a, *, Siva Kumar G a , Kiran Kumar B a , Thomas Kurian a , Satheesh Kumar N b a HDRD, Solid Motors Group, SPRE, VSSC Thiruvananthapuram, ISRO-695022, India b Solid Propulsion and Research Entity, Vikram Sarabhai Space Centre, Thiruvananthapuram, ISRO-695 022, India

* Corresponding author. Tel.: +91 471 256 3812. E-mail address: sreeragmn@gmail.com, sreerag@vssc.gov.in

2452-3216 © 2024 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 the ICONS 2023 Organizers

2452-3216 © 2024 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 the ICONS 2023 Organizers 10.1016/j.prostr.2024.05.028