Comparative study of composite scarf and strap joints for equivalent repair signature under uniaxial tension

Scarf joints are preferred in aerospace composite repairs that offer better strength, flushed surface and nearly uniform shear and peel stress distribution along the bond length. However, a shallow scarf angle repair of 2° to 3° as practiced requires significant parent material removal thus increasi...

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Bibliographic Details
Main Authors: Srinivasan, Dharun Vadugappatty, Padma, S. Ravisankar, Idapalapati, Sridhar
Other Authors: School of Mechanical and Aerospace Engineering
Format: Article
Language:English
Published: 2022
Subjects:
Online Access:https://hdl.handle.net/10356/162455
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Institution: Nanyang Technological University
Language: English
Description
Summary:Scarf joints are preferred in aerospace composite repairs that offer better strength, flushed surface and nearly uniform shear and peel stress distribution along the bond length. However, a shallow scarf angle repair of 2° to 3° as practiced requires significant parent material removal thus increasing the repair signature and cost. Scarfing the single side accessible, multi-layered composite structures is difficult. Herein, different repair designs based on 8.6° scarf, thin CFRP strap (0.5 mm and 1.1 mm), 0.5 mm thin Ti-6Al-4V straps (with and without pins) are used in bonding CFRP composites, their repair strength is measured through tensile testing. Results show that the failure load of the scarf and Ti-6Al-4V strap joints are similar implicating that the higher scarf angle designs can be replaced with Ti-6Al-4V straps for better repair efficacy. Failure analysis depicts that delamination due to the inner edge peel stresses is a critical failure mode of the strap repaired joints.