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Investigation of the Temperature-dependent Mechanical Performance of Composite Lattice Core Sandwich Structures
Given the wide temperature range which aerospace structures need to operate in, the goal of this
thesis is to investigate the effects of eleveated temperatures on the mechanical performance of novel thermoplastic composite lattice core sandwich structures developed at CMASLab.
Background: Owing to their high specific strength and stiffness, composite lattice structures have recently gained increasing interest for use as sandwich core materials in ultra-lightweight aerospace applications. By designing the lattice core in a way that its members deform predominantly in stretching and compression upon application of an external load, these structures can reach superior mechanical performance than state of the art core materials such as honeycombs and foams, while featuring high potential for integrated functionality.
Motivation: At CMASLab, a novel processing technique has been developed, enabling the fabrication of lattice core sandwich structures from thermoplastic composites (see figure). Experimental studies on the out-of-plane compression and shear response have demonstrated the superior mechanical performance of these novel structures compared to conventional sandwich cores. Different to thermoset based composites, thermoplastic composite materials feature temperature-dependent material properties with reduced strength and stiffness properties at elevated temperatures. As a result, the mechanical performance of the composite lattice structures is expected to decrease at higher temperatures.
Background: Owing to their high specific strength and stiffness, composite lattice structures have recently gained increasing interest for use as sandwich core materials in ultra-lightweight aerospace applications. By designing the lattice core in a way that its members deform predominantly in stretching and compression upon application of an external load, these structures can reach superior mechanical performance than state of the art core materials such as honeycombs and foams, while featuring high potential for integrated functionality.
Motivation: At CMASLab, a novel processing technique has been developed, enabling the fabrication of lattice core sandwich structures from thermoplastic composites (see figure). Experimental studies on the out-of-plane compression and shear response have demonstrated the superior mechanical performance of these novel structures compared to conventional sandwich cores. Different to thermoset based composites, thermoplastic composite materials feature temperature-dependent material properties with reduced strength and stiffness properties at elevated temperatures. As a result, the mechanical performance of the composite lattice structures is expected to decrease at higher temperatures.
Motivated by the fact that aerospace structures typically operate within a wide temperature range, the goal of this thesis is to investigate the effects of temperature on the mechanical performance of novel thermoplastic composite lattice core sandwich structures. The major tasks are:
• Literature research on composite lattice core sandwich structures; Familiarization with the fabrication process
• Experimental determination of the temperature dependent material properties of pultruded thermoplastic composite rods based on compression and tensile tests
• Fabrication of composite lattice core sandwich specimens with different core density levels.
• Experimental characterization of the compression response of the fabricated sandwich specimens at different temperature levels
• Correlation of the experimental results with existing finite element and analytical models
Motivated by the fact that aerospace structures typically operate within a wide temperature range, the goal of this thesis is to investigate the effects of temperature on the mechanical performance of novel thermoplastic composite lattice core sandwich structures. The major tasks are: • Literature research on composite lattice core sandwich structures; Familiarization with the fabrication process • Experimental determination of the temperature dependent material properties of pultruded thermoplastic composite rods based on compression and tensile tests • Fabrication of composite lattice core sandwich specimens with different core density levels. • Experimental characterization of the compression response of the fabricated sandwich specimens at different temperature levels • Correlation of the experimental results with existing finite element and analytical models
Christoph Karl
ETH Zurich - CMASLab
Leonhardstr. 21, LEE O225
8092 Zurich
Switzerland
tel: +41 44 632 0840
email: karlc@ethz.ch
Christoph Karl
ETH Zurich - CMASLab Leonhardstr. 21, LEE O225 8092 Zurich Switzerland