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Emprirical Optimization of the Interface Strength in Ultra-lightweight Composite Lattice Core Sandwich Structures
The shear performance of composite sandwich structures is governed by the strength of the core-to-facesheet interfaces. The goal of this work is to empirically idenfity an optimum processing window allowing to increase the interface strength in thermoplastic composite lattice core sandwich structure.
Background: Owing to their outstanding stiffness and strength, composite lattice structures have recently gained increasing interest for use as sandwich core materials in ultra-lightweight aerospace applications. By virtue of their stretch-dominated behavior, these structures can reach superior mechanical performance than state of the art core materials such as honeycombs and foams, while providing great potential for multifunctionality.
Motivation: At CMASLab, novel high-performance composite lattice core sandwich structures are being developed, which are fabricated based on a thermoplastic spot-welding process. While the structures were shown to possess outstanding compression strength and stiffness, their mechanical performance under load cases involving shear is governed by the strength of the thermoplastically welded core-to-facesheet interfaces. The interface strength, in turn, is affected by the processing parameters used during fabrication, such as welding temperature, pressure, and speed.
Background: Owing to their outstanding stiffness and strength, composite lattice structures have recently gained increasing interest for use as sandwich core materials in ultra-lightweight aerospace applications. By virtue of their stretch-dominated behavior, these structures can reach superior mechanical performance than state of the art core materials such as honeycombs and foams, while providing great potential for multifunctionality.
Motivation: At CMASLab, novel high-performance composite lattice core sandwich structures are being developed, which are fabricated based on a thermoplastic spot-welding process. While the structures were shown to possess outstanding compression strength and stiffness, their mechanical performance under load cases involving shear is governed by the strength of the thermoplastically welded core-to-facesheet interfaces. The interface strength, in turn, is affected by the processing parameters used during fabrication, such as welding temperature, pressure, and speed.
The goal of this thesis is to empirically idenfity an optimum processing window to maximize the interface bonding strength in thermoplastic spot-welded composite lattice core sandwich structures. The major tasks are: • Design of Experiments: proper definition of the range of processing parameters to be investigated • Fabrication of core/facesheet interface specimens according to the defined process parameter combinations, using a robotic spot-welding setup • Experimental determination of the interface peel-off strength based on core member push-out tests • Definition of an optimum processing window, comprising welding temperature, pressure, and speed, based on the experimental results
The goal of this thesis is to empirically idenfity an optimum processing window to maximize the interface bonding strength in thermoplastic spot-welded composite lattice core sandwich structures. The major tasks are: • Design of Experiments: proper definition of the range of processing parameters to be investigated • Fabrication of core/facesheet interface specimens according to the defined process parameter combinations, using a robotic spot-welding setup • Experimental determination of the interface peel-off strength based on core member push-out tests • Definition of an optimum processing window, comprising welding temperature, pressure, and speed, based on the experimental results
Christoph Karl
PhD Candidate
ETH Zurich - CMASLab
Leonhardstr. 21, LEE O225
8092 Zurich, Switzerland
Tel: +41 44 632 0840
Email: karlc@ethz.ch
Christoph Karl PhD Candidate ETH Zurich - CMASLab Leonhardstr. 21, LEE O225 8092 Zurich, Switzerland