Acknowledgements xxi

Preface xxiii

Introduction xxvii

Chapter 1 Phenomenological Aspects of Thermo-oxidative Ageing of OMCs 1

1.1 Effect of thermo-oxidation on the local mechanical behavior of the polymer 7

1.1.1 Oxidized layers 10

1.1.2 EIT measurements by UMI 14

1.1.3 Introduction to the parameter γ, an oxidation tracer 19

1.1.4 Characterizing the local mechanical behavior of the polymer 24

1.1.5 Oxidized material 33

1.2 Study of matrix shrinkage induced by thermo-oxidation in unidirectional OMCs 37

1.2.1 Virgin sample 40

1.2.2 Sample oxidized under 2 bar O₂ 47

1.2.3 Air-oxidized sample 53

Chapter 2 Modeling of Thermo-oxidative Ageing of OMCs 59

2.1 Thermodynamics of irreversible processes with internal variables 59

2.2 Development of an ageing-dependent behavior law for organic polymers 64

2.3 Taking into account the initial inelastic and chemical strains 77

Chapter 3 Identification and Simulations 79

3.1 Identifying the behavior law of thermo-oxidized polymers through the inverse analysis of ultra-micro-indentation tests 79

3.1.1 The method to identify the local mechanical behavior of virgin and oxidized polymers 79

3.1.2 Identification of local mechanical behavior of virgin polymers 83

3.1.3 Identifying the local mechanical behavior of the oxidized polymer 87

3.2 Identification of inelastic strains of chemical origin by inverse analysis of matrix shrinkage in unidirectional OMCs 93

3.2.1 Method for identifying inelastic strains in virgin and oxidized OMCs 96

3.2.2 Identification of inelastic strains and calculation of stresses in virgin OMCs 98

3.2.3 Identification of inelastic strains in oxidized OMCs 102

3.2.4 Validating the identification of inelastic strains of chemical origin 105

3.2.5 Numerical simulation of stresses induced by thermo-oxidation in UD OMCs 108

3.2.6 Rayleigh–Ritz approach for approximate computation of matrix shrinkage in OMCs 111

Conclusion and Perspectives 119

Bibliography 127

Index 133