Analysis of process-induced distortions and residual stresses of composite structures

Christian Brauner

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Christian Brauner, Analysis of process-induced distortions and residual stresses of composite structures (2013), Logos Verlag, Berlin, ISBN: 9783832593346

Beschreibung / Abstract

The increased application of composite materials in lightweight structures leads to new integral design of structural parts, using the example of, an integral composite landing flap of an Airbus A320 aircraft. This offers possibilities to simplify the process chain, to decrease manufacturing costs and to have fibre fair structural design. The critical disadvantage of large integral designs is that process-induced deformations are a risk factor during the design phase of the manufacturing process, because rework is not always possible. Especially, the aircraft industry with its demands on high qualities / tolerances and the application of hot curing resin systems, requires knowledge-based methods for virtual process design to avoid time- and effort-consuming iterations.

This thesis contributes to the understanding of the mechanism behind process-induced distortions and stresses related to the Resin Transfer Moulding (RTM) manufacturing process. The aim is to comprehend the phenomena, to identify related parameters and to present compensation strategies.

Inhaltsverzeichnis

  • BEGINN
  • 1 Introduction
  • 2 State of the art
  • 2.1 Manufacturing processes for composites
  • 2.2 Main sources and factors for process-induced distortions and residual stresses
  • 2.3 Material models
  • 3 Material characterisation – Single Components
  • 3.1 Cure kinetics
  • 3.2 Glass transition temperature
  • 3.3 Density
  • 3.4 Specific heat capacity
  • 3.5 Thermal conductivity
  • 3.6 Chemical Shrinkage
  • 3.7 Mechanical behaviour during the curing process
  • 3.8 Relaxation behaviour
  • 4 Material characterisation – Composite
  • 4.1 Heat of reaction
  • 4.2 Density
  • 4.3 Heat capacity
  • 4.4 Thermal conductivity
  • 4.5 Engineering constants
  • 4.6 Thermal expansion
  • 4.7 Chemical shrinkage
  • 4.8 Relaxation behaviour
  • 5 Formation of residual stress on the micro level
  • 5.1 Model description
  • 5.2 Results of the process simulation
  • 5.3 Study - Effects of matrix nonlinearities on the formation of residual stresses
  • 5.4 Study - Effects of micro residual stress / defects on the macro level
  • 6 Formation of residual stress on the macro level
  • 6.1 Simulation strategy
  • 6.2 Thermal analysis module
  • 6.3 Mechanical analysis module
  • 6.4 Validation test case 1
  • 6.5 Validation test case 2
  • 6.6 Conclusion
  • 7 Application - composite multi spar flap
  • 7.1 Model description
  • 7.2 Results
  • 7.3 Sensitivity of influencing factors
  • 7.4 Warpage compensation strategies
  • 7.5 Conclusion
  • 8 Further application based on non deterministic methods
  • 8.1 Sensitivity analysis
  • 8.2 Variability analysis
  • 8.3 Process optimisation
  • 8.4 Conclusion
  • 9 Summary
  • 10 Abbreviation
  • 11 Notation
  • 12 References
  • 13 List of Figures

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