Residual Strength and Fatigue Lifetime of ... - Solid Mechanics

More documents

Recommendations

Info

Contents Preface Executive Summary Synopsis (in Danish) Publications Contents Symbols 1. Introduction 1 1.1 Background and Motivations ……………………………………………….. 1 1.2 Thesis Overview ……………………………………………………………. 3 1.3 Linear Elastic Fracture Mechanics …………………………………………. 5 1.4 Linear Elastic Fracture Mechanics in the Interfaces ……………………….. 7 1.5 Fatigue Crack Propagation in Sandwich Composites ……………………… 10 2 Face/Core Debond Propagation in Sandwich Columns 16 2.1 Background and Objectives ………………………………………………… 16 2.2 Experimental Set-up ………………………………………………………... 17 x i iii vi ix x xv
2.3 Experimental Results ……………………………………………………….. 19 2.4 Characterization of Face/Core Interface Fracture Resistance ………………. 22 2.5 Finite Element Model of the Debonded Columns ………………………….. 29 2.6 Comparison of Numerical and Experimental Results ………………………. 31 2.7 Conclusions …………………………………………………………………. 37 3 Failure of Uniformly Compressed Debond Damaged Sandwich Panels 39 3.1 Background …………………………………………………………………. 39 3.2 Test Specimens ……………………………………………………………... 40 3.3 Characterization of Face/Core Interface ……………………………………. 43 3.4 Panel Tests ………………………………………………………………….. 49 3.5 Panel Analysis ………………………………………………………………. 53 3.6 Conclusion …………………………………………………………………. 60 4 Fatigue Crack Growth Simulation in a Bimaterial Interface 63 4.1 Background …………………………………………………………………. 63 4.2 Cycle Jump Method ………………………………………………………… 65 4.3 2D Face/Core Fatigue Crack Growth in Sandwich Beams ………………… 67 4.4 3D Face/core fatigue crack growth in sandwich panels ……………………. 74 4.5 Conclusion ………………………………………………………………… 85 xi
Page 1: Residual Strength and Fatigue Lifet
Page 4 and 5: Published in Denmark by Technical U
Page 6 and 7: This page is intentionally left bla
Page 8 and 9: method to accelerate the simulation
Page 10 and 11: Synopsis Sandwich kompositter er i
Page 16 and 17: 5 Face/core Interface Fatigue Crack
Page 20 and 21: H11 bimaterial constant H22 bimater
Page 24 and 25: These peculiar damage modes often r
Page 26 and 27: 1.2 Overview of the Thesis In this
Page 28 and 29: Figure 1.3: Fracture modes, from Be
Page 30 and 31: In Equations (1.5) and (1.6) H11, H
Page 32 and 33: Figure 1.6: Schematic illustration
Page 34 and 35: The compact tension specimen (CT) i
Page 36 and 37: A Figure 1.10: CSB, DCB, TSD, DCB-U
Page 38 and 39: Chapter 2 Buckling Driven Face/Core
Page 40 and 41: (DIC) measurement system (ARAMIS 2M
Page 42 and 43: corresponds to the onset of debond
Page 44 and 45: Figure 2.7: Crack kinking into the
Page 46 and 47: (2.2) where and for plane str
Page 48 and 49: A modified version of the tilted sa
Page 50 and 51: previous observations of crack path
Page 52 and 53: of contact elements (CONTACT173 and
Page 54 and 55: the debond opening initially increa
Page 56 and 57: Table 2.4: Instability loads determ
Page 58 and 59: G (J/m2) 600 400 200 0 H100 IMP=0.1
Page 62 and 63: Hayman (2007) has described a damag
Page 64 and 65:
Table 3.1: Panel test specimens. La
Page 66 and 67:
sheet and the core thickness, respe
Page 68 and 69:
Load (N) 250 200 150 100 50 0 H130
Page 70 and 71:
Table 3.4: Parameters in the face/c
Page 72 and 73:
was used to monitor 3D surface disp
Page 74 and 75:
arising due to the junction between
Page 76 and 77:
(a) Debonded face sheet Figure 3.16
Page 78 and 79:
Figure 3.19 shows the determined en
Page 80 and 81:
H130 MMB H130 Panel H250 MMB Interf
Page 82 and 83:
3.6 Conclusion In this chapter the
Page 84 and 85:
This page is intentionally left bla
Page 86 and 87:
composite laminates under thermal c
Page 88 and 89:
S S y( t ) y( t ) ( t ) 2 1 12 2
Page 90 and 91:
listed in Table 4.1. The length and
Page 92 and 93:
The strain energy release rate, G,
Page 94 and 95:
high growth rate of G (see Figure 4
Page 96 and 97:
4.4 Face/Core Fatigue Crack Growth
Page 98 and 99:
Debond 310 mm Symmetry B. C. a Figu
Page 100 and 101:
B 2 1/ 2 ( S44 S55 S45) (4.17) wh
Page 102 and 103:
75), which illustrates possible ina
Page 104 and 105:
Figure 4.18 (a) presents the deflec
Page 106 and 107:
Debond radius (mm) 100 90 80 70 60
Page 108 and 109:
using the cycle jump method, more t
Page 110 and 111:
Chapter 5 Face/Core Interface Fatig
Page 112 and 113:
of this chapter, sandwich panels wi
Page 114 and 115:
H250 Specimen H100 Specimen H45 Spe
Page 116 and 117:
Figure 5.5: Test setup. Initially,
Page 118 and 119:
H100 Specimen Fibre bridging Figure
Page 120 and 121:
propagation, the crack continues to
Page 122 and 123:
Figure 5.14: Kinking of the crack i
Page 124 and 125:
Crack length [mm] Crack length [mm]
Page 126 and 127:
mode-mixity phase angle was chosen
Page 128 and 129:
should be taken into account for a
Page 130 and 131:
Figure 5.25: Kinking of the crack i
Page 132 and 133:
log (da/dN) (mm/cycle) 10 log G (J/
Page 134 and 135:
erroneous extrapolations in the tra
Page 136 and 137:
compared to the 65% efficiency obta
Page 138 and 139:
the case of uneven debond growth, t
Page 140 and 141:
Load (kN) 2 1.5 1 0.5 0 Panel 1 Pan
Page 142 and 143:
Figure 5.42: Zero and ninety degree
Page 144 and 145:
G(J/m 2 ) 180 150 210 120 150 100 5
Page 146 and 147:
110 q=qG=0.4 Test #1 100 Test #2 Te
Page 148 and 149:
panels were determined for differen
Page 150 and 151:
Chapter 6 Conclusion and Future Wor
Page 152 and 153:
toughness using MMB fracture toughn
Page 154 and 155:
For the specimens with H250 core th
Page 156 and 157:
Development of testing methods for
Page 158 and 159:
Page 160 and 161:
Bezazi A., Mahi A. E., Berthelot J.
Page 162 and 163:
Kanny K. and Mahfuz H. (2005), Flex
Page 164 and 165:
Ratcliffe J. and Cantwell W. J. (20
Page 166 and 167:
Page 168 and 169:
Out-of-plane displacement (mm) 1 0.
Page 170 and 171:
Out-of-plane displacement (mm) 3 2
Page 172 and 173:
A.5 Out-of-plane deflection of Debo
Page 174 and 175:
(a) Figure A.14: Out-of-plane defle
Page 176 and 177:
(a) (b) Figure A.18: Out-of-plane d
Page 178 and 179:
Load (kN) 250 200 150 100 50 250 30
Page 180 and 181:
Displacement (mm) 4 3 2 1 0 8 9 (a)
Page 182 and 183:
(a) (b) Figure B.11: Out-of-plane d
Page 184 and 185:
(a) (b) Figure B.15: Out-of-plane d
Page 188:
DTU Mechanical Engineering Section
show all

Residual Strength and Fatigue Lifetime of ... - Solid Mechanics

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?