Surface Toughening - Functionality and testing of a stress reducing technology of bonded joints using DCB and ENF specimen made of 8552/IM7 carbon composite and PVDF bonded with EA9695 film adhesive-Reference-Cited by-同舟云学术

Surface Toughening - Functionality and testing of a stress reducing technology of bonded joints using DCB and ENF specimen made of 8552/IM7 carbon composite and PVDF bonded with EA9695 film adhesive

Published:2024-05-03 Issue: Volume: Page:
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Author:

Schollerer Martin J.¹,Kosmann Jens¹,Völkerink Oliver²,Hühne Christian¹

Affiliation:

1. German Aerospace Center

2. Technische Universität Braunschweig

Abstract

Structural bonding has clear advantages over riveting or bolting, such as weight savings, corrosion and load transfer over a wide area. However, even with bonded joints, stress concentrations occur near the edges, which can lead to crack growth during operation and thus to failure of the entire joint. This is precisely the reason why adhesive bonding and subsequent bolting are used in today's aerospace industry. However, this hybrid solution adds up all the disadvantages of bonding with those of bolting, so the goal must be a bolt-free bonded joint where stress concentrations are significantly reduced. A technology of this type is surface toughening, which, when used locally, selectively reduces stress concentrations in the peel and shear components and redistributes the load to the less stressed nearby regions. In this paper, the functionality is demonstrated using a spring model and the effect is experimentally validated in Mode I and Mode II load directions using DCB and ENF specimens. PVDF is used as tough modifying material. With local surface toughening, the energy release rate GIC of the adhesive under Mode I is increased by 25%. Under Mode II, no further crack growth can be identified in the ENF tests.

Publisher

Research Square Platform LLC

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