Experimental testing and numerical simulation of granules as crash absorber for double hull structures

Produktbeschreibung

In the maritime sector, the collision safety is an essential aspect of ship operation. Aiming at further ­improvements,­the­filling­of­the­cavity­in­a­double­hull­structure­with­granular­material­is­investigated­in­this­ ­thesis.­ In­order­to­do­so,­the­potential­of­different­granules­is­determined­experimentally,­along­with­thedescription of their material parameters as particles and as a bulk material, respectively. Furthermore, a ­simplified­side­hull­structure­is­designed­for­experimental­testing,­followed­by­a­numerical­study­of­differentmaterial models for the granules. This leads to the simulation of a realistic collision scenario, showing the potential in the maritime industry.

Contents
1 Introduction 1
1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 State of the art . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Purpose and scope of this thesis . . . . . . . . . . . . . . . . . . . . . . . . 4
1.4 Outline of this thesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Constitutive equations and numerical implementation 6
2.1 Constitutive equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1.1 Elasto-plastic material behaviour . . . . . . . . . . . . . . . . . . . 6
2.1.2 Mohr-Coulomb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.1.3 Hypoplastic material model . . . . . . . . . . . . . . . . . . . . . . 12
2.1.4 Damage modelling for elasto-plastic material . . . . . . . . . . . . . 15
2.2 Numerical implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.2.1 Finite element method . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.2.2 Discrete element method . . . . . . . . . . . . . . . . . . . . . . . . 23
3 Selection of granules and description of single grains 24
3.1 Selection of granules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.2 Determination of grain properties . . . . . . . . . . . . . . . . . . . . . . . 26
3.2.1 Single particle tests . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.2.2 Statistical representation . . . . . . . . . . . . . . . . . . . . . . . . 29
3.2.3 Numerical example . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4 Determination of bulk particle properties 40
4.1 Oedometer test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4.2 Triaxial test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
4.2.1 Experimental setup . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
4.2.2 Experimental results . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.2.3 Numerical simulation . . . . . . . . . . . . . . . . . . . . . . . . . . 45
4.3 Friction test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
4.4 Uniaxial compression test . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
4.4.1 Experimental setup . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
4.4.2 Experimental results . . . . . . . . . . . . . . . . . . . . . . . . . . 50
4.4.3 Numerical simulation and parameter fitting . . . . . . . . . . . . . 52
4.5 Tensile test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
5 Experimental investigation 64
5.1 Experimental setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
5.2 Experiments without stiffener . . . . . . . . . . . . . . . . . . . . . . . . . 66
5.2.1 Experiment 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
5.2.2 Experiment 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
5.2.3 Experiment 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
5.2.4 Experiment 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
5.2.5 Conclusion for experiments without stiffener . . . . . . . . . . . . . 77
5.3 Experiments with stiffener . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
5.3.1 Experiment 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
5.3.2 Experiment 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
5.3.3 Experiment 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
5.3.4 Conclusion of experiments with stiffener . . . . . . . . . . . . . . . 86
6 Numerical investigation 88
6.1 Simplified side hull structure . . . . . . . . . . . . . . . . . . . . . . . . . . 88
6.1.1 Simulations without granules . . . . . . . . . . . . . . . . . . . . . 89
6.1.2 Simulation with granules . . . . . . . . . . . . . . . . . . . . . . . . 95
6.2 Realistic side hull structure . . . . . . . . . . . . . . . . . . . . . . . . . . 106
6.2.1 Comparison of materials . . . . . . . . . . . . . . . . . . . . . . . . 107
6.2.2 Changes in hull design . . . . . . . . . . . . . . . . . . . . . . . . . 110
7 Conclusions and Outlook 113
Appendix 116
A Material parameter identification . . . . . . . . . . . . . . . . . . . . . . . 116
A.1 Experimental results for material models . . . . . . . . . . . . . . . 116
A.2 Numerical results for material models . . . . . . . . . . . . . . . . . 117
Bibliography 119

Keywords: Kollisionssicherheit, Doppelhülle, Martime Anwendung, Crash-Absorber, Kollisionsversuch, Granulate, Expandiertes Glass-Granulat, Experimentelle Untersuchung, Finite-Elemente-Methode, Collision safety, Double hull structure, Maritime applications, Crash absorber, Collision test, Granules, Expanded glass material, Experimental testing, Finite element method