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Topology Optimization of Composite Lattice Core Sandwich Structures for Bending Loading
The goal of this thesis is to carry out topology optimizations of sandwich structures with ultra-lightweight composite lattice cores, in order to increasing their specific performance under bending loading.
Background: Owing to their high specific strength and stiffness characteristics, composite lattice structures, consisting of a repeating unit cell of pyramidally arrange composite rods, have recently gained increasing interest for use as core material in ultra-lightweight sandwich applications. As the lattice members of the core deform predominantly in stretchning and compression upon application of an external load, these structures can reach superior specific performance than state of the art core materials such as honeycombs and foams.
Motivation: Given the great number of design parameters characterizing nthe pyramidal unit cell, the specific strength and stiffness of composite lattice structures can be increased through optimization of these design parameters. For multi-axial load cases with non-symmetric load distribution, further increases in structural performance can be achieved by varying the lattice topology throughout the core in order to create a stiffness gradient. This way, the core topology can be tailored to optimally carry the external loads.
Background: Owing to their high specific strength and stiffness characteristics, composite lattice structures, consisting of a repeating unit cell of pyramidally arrange composite rods, have recently gained increasing interest for use as core material in ultra-lightweight sandwich applications. As the lattice members of the core deform predominantly in stretchning and compression upon application of an external load, these structures can reach superior specific performance than state of the art core materials such as honeycombs and foams.
Motivation: Given the great number of design parameters characterizing nthe pyramidal unit cell, the specific strength and stiffness of composite lattice structures can be increased through optimization of these design parameters. For multi-axial load cases with non-symmetric load distribution, further increases in structural performance can be achieved by varying the lattice topology throughout the core in order to create a stiffness gradient. This way, the core topology can be tailored to optimally carry the external loads.
The objective of this thesis is to perform a numerical topology optimization of a sandwich beam with pyramidal composite lattice core for a 3 point-bending load case. The major tasks are:
• Numerical characterization of the bending performance of a reference composite lattice core sandwich beam based on an existing parametrized numerical model
• Establish an optimization framework enabling
multi-parameter optimizations of lattice core sandwich structures
• Optimization of a sandwich beam, initially considering periodicity of the unit cell throughout the lattice core
• Optimization of the sandwich beam, allowing variation of the lattice topology in the core, and including further design variables parameters.
• For MT level: Manufacturing and testing of
the optimized sandwich beam in 3-point-bending
The objective of this thesis is to perform a numerical topology optimization of a sandwich beam with pyramidal composite lattice core for a 3 point-bending load case. The major tasks are: • Numerical characterization of the bending performance of a reference composite lattice core sandwich beam based on an existing parametrized numerical model • Establish an optimization framework enabling multi-parameter optimizations of lattice core sandwich structures • Optimization of a sandwich beam, initially considering periodicity of the unit cell throughout the lattice core • Optimization of the sandwich beam, allowing variation of the lattice topology in the core, and including further design variables parameters. • For MT level: Manufacturing and testing of the optimized sandwich beam in 3-point-bending
Christoph Karl
ETH Zurich- Laboratory of Composite Materials and Adaptive Structures
Leonhardstr. 21, LEE O225
8092 Zurich, Switzerland
tel: +41 44 632 0840
email: karlc@ethz.ch
Christoph Karl
ETH Zurich- Laboratory of Composite Materials and Adaptive Structures Leonhardstr. 21, LEE O225 8092 Zurich, Switzerland