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Numerical Modeling of the Core-to-Facesheet Interface Bond in Composite Lattice Core Sandwich Structures
To improve a numerical model for composite lattice core sandwich structures with respect to its capability to predict interface failure, the goal of this thesis is to develop an efficient numerical model for the core-to-facesheet interface bond in such ultra-lightweight structures.
Keywords: Composite Structures, Lightweight Structures, Sandwich Structures, Lattice Core, Aerospace Structures, Numerical Modeling, Finite Element Analysis, Finite Element Method
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 an open cellular CFRP lattice core. These structures can reach very high structural efficiency and offer great potential for integrated functionality and load-tailored design, providing new opportunities for designing aerospace structures.
Motivation: In CLF sandwich structures, the interface of the thermoplastic composite rods comprising the lattice core to the facesheets is created by fusion bonding (thermoplastic welding). A well-known failure mode in these sandwich structures is interface failure, which is expressed in the form of debonding of the composite rods from the facesheets. In a previous thesis, the core-to-facesheet interface bonds in CLF sandwich structures have been characterized experimentally in terms of their mechanical performace. In order to accurately predict the failure behavior of CLF sandwich structures, a numerical model is required that allows for capturing these interface failure modes.
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 an open cellular CFRP lattice core. These structures can reach very high structural efficiency and offer great potential for integrated functionality and load-tailored design, providing new opportunities for designing aerospace structures.
Motivation: In CLF sandwich structures, the interface of the thermoplastic composite rods comprising the lattice core to the facesheets is created by fusion bonding (thermoplastic welding). A well-known failure mode in these sandwich structures is interface failure, which is expressed in the form of debonding of the composite rods from the facesheets. In a previous thesis, the core-to-facesheet interface bonds in CLF sandwich structures have been characterized experimentally in terms of their mechanical performace. In order to accurately predict the failure behavior of CLF sandwich structures, a numerical model is required that allows for capturing these interface failure modes.
To improve the existing numerical models for CLF sandwich structures with respect to failure characterization, the goal of this thesis is to develop an efficient numerical model for the core-to-facesheet interface bonding. The major tasks are:
- Literature research on finite element analysis and interface/contact modeling of composite lattice core sandwich structures
- Exploration of candidate numerical interface models of different fidelity based on a single rod-to-facesheet interface bond
- Validation of the established numerical models based on experimental data for peel-off and shear; identification of the most efficient interface model
- Implementation of the interface model into the FE model of CLF sandwich structures and validation based on a representative load case
To improve the existing numerical models for CLF sandwich structures with respect to failure characterization, the goal of this thesis is to develop an efficient numerical model for the core-to-facesheet interface bonding. The major tasks are: - Literature research on finite element analysis and interface/contact modeling of composite lattice core sandwich structures - Exploration of candidate numerical interface models of different fidelity based on a single rod-to-facesheet interface bond - Validation of the established numerical models based on experimental data for peel-off and shear; identification of the most efficient interface model - Implementation of the interface model into the FE model of CLF sandwich structures and validation based on a representative load case
Christoph Karl
ETH Zurich - CMASLab
Tannenstrasse 3
8092 Zurich
Tel: +41 44 632 0840
Email: karlc@ethz.ch
Christoph Karl ETH Zurich - CMASLab Tannenstrasse 3 8092 Zurich Tel: +41 44 632 0840 Email: karlc@ethz.ch