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Development and Characterization of Interface Bonding Concepts in Composite Lattice Core Sandwich Structures
In order to increase the performance of composite lattice core sandwich structures and to prevent premature interface failure, this thesis aims to develop and characterize improved solutions for creating the core-to-facesheet interface bonding in such structures.
Background:
At CMASLab, a novel processing technique (Continuous Lattice Fabrication - CLF) has been developed, which allows for fabricating ultra-lightweight sandwich structures, consisting of high-strength composite facesheets and a cellular CFRP lattice core. These structures can reach superior structural performance than state-of-the-art sandwich materials and offer great potential for integrated functionality and load-tailored design, thus providing new opportunities for designing aerospace structures.
Motivation
The performance of CLF sandwich structures under inplane loading conditions is currently limited by the strength of the lattice-to-facesheet interface. While one half of the interfaces is created by thermoplastic welding (fusion bonding) and free-form extrusion of the continuously reinforced CFRP rods from one facesheet, the interfaces at the opposing rod ends are realized by adhesively bonding the rod ends to the facesheet. This bonding method involves significant room for improvement, including an increase in the overall interface strength as well as a more efficient fabrication.
Background: At CMASLab, a novel processing technique (Continuous Lattice Fabrication - CLF) has been developed, which allows for fabricating ultra-lightweight sandwich structures, consisting of high-strength composite facesheets and a cellular CFRP lattice core. These structures can reach superior structural performance than state-of-the-art sandwich materials and offer great potential for integrated functionality and load-tailored design, thus providing new opportunities for designing aerospace structures.
Motivation The performance of CLF sandwich structures under inplane loading conditions is currently limited by the strength of the lattice-to-facesheet interface. While one half of the interfaces is created by thermoplastic welding (fusion bonding) and free-form extrusion of the continuously reinforced CFRP rods from one facesheet, the interfaces at the opposing rod ends are realized by adhesively bonding the rod ends to the facesheet. This bonding method involves significant room for improvement, including an increase in the overall interface strength as well as a more efficient fabrication.
To increase the performance of composite sandwich structures with open lattice core, improved solutions for creating the core-to-facesheet interface are to be developed and characterized within this thesis. The major tasks are:
• Development of concepts for joining extruded CFRP rods fabricated by CLF with flat composite facesheets
• Manufacturing of specimens and experimental characterization of the interface bonding strength through shear and peel-off tests
• Improvement of the interface design for maximum strength, considering both design aspects and processing parameters
• Validation of the developed interface design based on experimental testing of a CLF sandwich structure
To increase the performance of composite sandwich structures with open lattice core, improved solutions for creating the core-to-facesheet interface are to be developed and characterized within this thesis. The major tasks are: • Development of concepts for joining extruded CFRP rods fabricated by CLF with flat composite facesheets • Manufacturing of specimens and experimental characterization of the interface bonding strength through shear and peel-off tests • Improvement of the interface design for maximum strength, considering both design aspects and processing parameters • Validation of the developed interface design based on experimental testing of a CLF sandwich structure
Christoph Karl
ETH Zurich - CMASLab
CLA E 32.2
Tannenstrasse 3
8092 Zurich
Tel: +41 44 632 0840
Email: karlc@ethz.ch
Christoph Karl ETH Zurich - CMASLab CLA E 32.2 Tannenstrasse 3 8092 Zurich Tel: +41 44 632 0840 Email: karlc@ethz.ch