Analysis of the mechanical response of impact loaded composite sandwich structures with focus on foam core shear failure
Tim Berend Block
Diese Publikation zitieren
Tim Berend Block, Analysis of the mechanical response of impact loaded composite sandwich structures with focus on foam core shear failure (2014), Logos Verlag, Berlin, ISBN: 9783832595340
62
Accesses
Accesses
Beschreibung / Abstract
Sandwich structures are an economically and structurally efficient way of designing large integral composite parts. In the aerospace industry pre-impregnated face sheets and honeycomb core structures can be considered as industry standard while e.g. naval structures and wind turbine blades typically use vacuum infusion technology with polymer foam cores. Application of the less costly infusion technology in the aeronautical industry requires a thorough understanding of the damage tolerance including low velocity impact as a frequent source of damaging events.
At low impact energies damage in composite foam core sandwich structures is limited to core crushing and local face sheet delaminations. Higher impact energies may initiate the competing failure modes face sheet rupture and core shear failure depending on impact, geometric and material parameters. Face sheet rupture leads to severe local damage with typically good visibility, while core shear failure leads to cracks and rear face sheet debonding of the foam core with less visibility.
This work investigates the low velocity impact response of sandwich structures with carbon fiber reinforced plastic (CFRP) face sheets and a polymeric foam core using experiments at room temperature and at -55 Grad Celsius. An analytically derived failure mode map is presented as a simple tool for design guidelines while the explicit finite element method is applied for a more detailed description of the sandwich impact process. Both models are used to analyze the impact response and describe relevant sensitivity parameters of sandwich structures.
At low impact energies damage in composite foam core sandwich structures is limited to core crushing and local face sheet delaminations. Higher impact energies may initiate the competing failure modes face sheet rupture and core shear failure depending on impact, geometric and material parameters. Face sheet rupture leads to severe local damage with typically good visibility, while core shear failure leads to cracks and rear face sheet debonding of the foam core with less visibility.
This work investigates the low velocity impact response of sandwich structures with carbon fiber reinforced plastic (CFRP) face sheets and a polymeric foam core using experiments at room temperature and at -55 Grad Celsius. An analytically derived failure mode map is presented as a simple tool for design guidelines while the explicit finite element method is applied for a more detailed description of the sandwich impact process. Both models are used to analyze the impact response and describe relevant sensitivity parameters of sandwich structures.
Inhaltsverzeichnis
- BEGINN
- 1 Introduction
- 1.1 Motivation
- 1.2 Objective
- 1.3 Thesis structure
- 2 State of the art of composite sandwich technology
- 2.1 Application of composite sandwich structures
- 2.2 Materials and manufacturing
- 2.3 Fundamentals of composite sandwich theory
- 2.4 Chapter summary
- 3 Impact response of composite sandwich structures
- 3.1 Definitions
- 3.2 Literature review
- 3.3 Classification of the structural impact response
- 3.4 Contact behavior and indentation of sandwich panels
- 3.5 Sandwich failure modes during impact
- 3.6 Chapter summary
- 4 Experimental investigation of the impact response
- 4.1 Test matrix and setup
- 4.2 Test results at room temperature
- 4.3 Test results at low temperatures
- 4.4 Classification of damage types
- 4.5 Comparison with analytical model
- 4.6 Chapter summary
- 5 Numerical simulation of impact on CFRP foam core sandwich structures
- 5.1 General aspects
- 5.2 Modeling of the CFRP face sheets
- 5.3 Modeling of the foam core
- 5.4 Modeling of the sandwich structure
- 5.5 Simulation of low velocity impact
- 5.6 Chapter summary
- 6 Sandwich failure mode parameters
- 6.1 Approach
- 6.2 Thermal loads
- 6.3 Boundary conditions
- 6.4 Impactor geometry and velocity
- 6.5 Material properties of face sheet and core
- 6.6 Chapter summary
- 7 Concluding remarks
- 7.1 Summary of performed work
- 7.2 Limitations and implications
- 7.3 Future work