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Investigating the Influence of Manufacturing Imperfections of thin-ply Composites on the Mechanical Performance of a Structure
This thesis should investigate the form and degree of manufacturing imperfections of thin-ply composite deployable structures and their influence on the mechanical performance. Based on manufactured structures, an FE-Model shall be built and the knockdown in mechanical performance predicted.
Due to their high specific strength and stiffness, fiber reinforced structures are commonly used in high-performance applications. Their ability to be manufactured in thicknesses around 100μm makes them especially interesting in the field of deployable structures.
Modern deployable structures are mainly used for the folding and deployment of satellites to reduce the stowage volume in a launcher vehicle. However these structures also get a rising interest in medical application for example in the field of heart stents. Thin-ply composites are considered a crucial material to further proceed in deep space exploration or might even find application in the human body.
However, these thin-ply composites impose challenges on the manufacturing process, especially for flat or cylindrical structures, resulting in residual deformation as well as thickness deviations.
Considering that the structure thicknesses of a thin-ply deployable structure are in the order of 20 fiber diameters, the sensitivity of the structure to material imperfections is very high, especially considering the buckling behavior. The imperfections in the structure are expected to drastically reduce the mechanical performance and the predictability, which has not been fully understood till now. A model to predict the knockdown in mechanical performance based on real life observations of manufactured structures will increase the confidence in those structures and can help design more efficient and predictable structures.
Due to their high specific strength and stiffness, fiber reinforced structures are commonly used in high-performance applications. Their ability to be manufactured in thicknesses around 100μm makes them especially interesting in the field of deployable structures. Modern deployable structures are mainly used for the folding and deployment of satellites to reduce the stowage volume in a launcher vehicle. However these structures also get a rising interest in medical application for example in the field of heart stents. Thin-ply composites are considered a crucial material to further proceed in deep space exploration or might even find application in the human body. However, these thin-ply composites impose challenges on the manufacturing process, especially for flat or cylindrical structures, resulting in residual deformation as well as thickness deviations. Considering that the structure thicknesses of a thin-ply deployable structure are in the order of 20 fiber diameters, the sensitivity of the structure to material imperfections is very high, especially considering the buckling behavior. The imperfections in the structure are expected to drastically reduce the mechanical performance and the predictability, which has not been fully understood till now. A model to predict the knockdown in mechanical performance based on real life observations of manufactured structures will increase the confidence in those structures and can help design more efficient and predictable structures.
The Thesis should provide important insight on the form and degree of manufacturing imperfections of thin-ply composite deployable structures and derive a finite element model of a representative structure, where the knock-down on mechanical performance can be predicted. This covers:
• Literature research on thin-ply composites, deployable structures and mechanical imperfection behavior
• Familiarizing with deployables, Abaqus/Python Interface, composite mechanics/manufacturing
• Manufacturing of representative deployable structures
• Create an imperfection model based on microscopic, shape and material observations
• Predict mechanical performance knockdown with a FEM-Modell
• Validate FEM-Modell with suitable experiments (MT)
The Thesis should provide important insight on the form and degree of manufacturing imperfections of thin-ply composite deployable structures and derive a finite element model of a representative structure, where the knock-down on mechanical performance can be predicted. This covers:
• Literature research on thin-ply composites, deployable structures and mechanical imperfection behavior
• Familiarizing with deployables, Abaqus/Python Interface, composite mechanics/manufacturing
• Manufacturing of representative deployable structures
• Create an imperfection model based on microscopic, shape and material observations
• Predict mechanical performance knockdown with a FEM-Modell
• Validate FEM-Modell with suitable experiments (MT)
ETH Zürich
Laboratory of Composite Materials and Adaptive Structures
Arthur Schlothauer
LEE O225
Leonhardstrasse 21 8092 Zürich
arthursc@ethz.ch
ETH Zürich
Laboratory of Composite Materials and Adaptive Structures