 | David M. Experimental and numerical investigation of polymer composite energy absorbers under dynamic loading: Diss. … Dr.-Ing. / Deutsches Zentrum für Luft- und Raumfahrt, Institut für Bauweisen und Strukturtechnologie, Stuttgart. - Köln: DLR, 2015. - ix, 113 p.: ill. - (Forschungsbericht; 2015-04). - Bibliogr.: p.103-109. - ISSN 1434-8454
|
1 Introduction ................................................. 1
1.1 Background .............................................. 1
1.2 Objective and Aims ...................................... 3
1.3 Thesis Layout ........................................... 3
2 Literature Review ............................................ 5
2.1 Energy Absorption ....................................... 5
2.1.1 Energy Absorption Performance Parameters ......... 5
2.1.2 Woven Fabrics .................................... 8
2.1.3 Mechanical Characteristics of Woven Fabrics ...... 9
2.1.4 Crushing Modes and Mechanisms in the Axial
Crushing of FRP Composite Tubes .................. 9
2.1.5 Dominant Energy Absorbing Mechanisms ............ 14
2.1.6 Strain Rate Effects in the Axial Crushing of
FRP Composite Tubes ............................. 15
2.2 Phenomenological Modelling of the Crushing Modes ....... 16
2.2.1 Extended Meso-scale Composite Model ............. 19
2.2.2 Fabric Reinforced Composites Damage Model ....... 20
2.2.3 Interface Delamination Model .................... 23
3 Experimental Investigation of Strain Rate Effects in the
Axial Crushing of DLR Segment Specimen ...................... 26
3.1 Experimental Testing and Analytical Methodology ........ 26
3.2 Quasi-static and Dynamic Crush Tests on DLR Segment
Specimen ............................................... 27
3.2.1 Test Specimens .................................. 27
3.2.2 Quasi-static Crush Test ......................... 28
3.2.3 Dynamic Crush Test .............................. 30
3.2.4 HRCT-Scan Imaging ............................... 32
3.2.5 Results and Discussion .......................... 34
3.3 Effect of Stacking Sequence on the Crush Response ...... 37
3.3.1 Test Specimens ................................... 37
3.3.2 Quasi-static Crush Test ......................... 37
3.3.3 Dynamic Crush Test .............................. 38
3.3.4 Results and Discussion .......................... 39
3.4 Interrupted Crush Test of the Global Splaying Failure
Crush Mode ............................................. 42
3.4.1 Chamfer Trigger Mechanism ....................... 42
3.4.2 Results and Discussion .......................... 43
3.5 Passive Infrared Imaging of the Global Splaying
Failure Crush Mode ..................................... 44
3.5.1 Passive Infrared Imaging ........................ 44
3.5.2 Passive Infrared Imaging Methodology ............ 44
3.5.3 Results and Discussion .......................... 45
4 Numerical Analysis of Crush Response Modes .................. 48
4.1 Crush Modelling Methodology ............................ 48
4.2 Material Model Characterisation ........................ 48
4.2.1 Fabric Composite Global Ply Model
Characterisation ................................ 49
4.2.2 Interface Delamination Model (Pickett Model) .... 55
4.3 Global Splaying Failure Crush Mode ..................... 63
4.3.1 Finite Element Model ............................ 63
4.3.2 Numerical Trigger ............................... 64
4.3.3 Element Elimination Method and Boundary
Conditions ...................................... 66
4.3.4 Results and Discussion .......................... 68
4.4 Local Fragmentation Failure Crush Mode ................. 73
4.4.1 Material Model Characterisation (Dynamic) ....... 73
4.4.2 Numerical Trigger ............................... 75
4.3.1 Element Elimination Method and Boundary
Conditions ...................................... 75
4.3.2 Results and Discussion .......................... 75
4.5 Effect of Stacking Sequence on the Numerical Crushing
Response ............................................... 79
5 Further Application of Crush Modelling Methodology .......... 82
5.1 Crashworthiness Working Group of the CMH-17 ............ 82
5.2 Material Model Characterisation ........................ 84
5.3 Finite Element Model ................................... 85
5.4 Numerical Trigger ...................................... 85
5.4.1 Global Splaying Failure Crush Mode
(Corrugated Plate Specimen) ..................... 85
5.4.2 Lamina Bending Mode (C-Channel & Small Corner
Specimen) ....................................... 85
5.4.3 Local Buckling Crush Mode (Square tube
Specimen) ....................................... 86
5.5 Element Elimination Method and Boundary Conditions ..... 87
5.6 Results and Discussion ................................. 88
5.6.1 Global Splaying Failure Crush Mode
(Corrugated Plate Specimen) ..................... 88
5.6.2 Lamina Bending Mode (C-Channel & Small Corner
Specimen) ....................................... 90
5.6.3 Local Buckling Crush Mode (Square Tube
Specimen) ....................................... 93
5.6.4 Crush Performance Comparison of the Varied
Crush Modes ..................................... 96
6 Conclusion and Outlook ...................................... 97
7 References ................................................. 103
8 Appendices ................................................. 110
Appendix A .................................................... 110
Appendix В .................................................... 111
Appendix C .................................................... 112
|
|
