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

More documents

Recommendations

Info

This page is intentionally left blank. 62
Chapter 4 Fatigue Crack Growth Simulation in a Bimaterial Interface 4.1 Background Interface fatigue crack growth is one of the most critical damages that layered structures, such as monolithic fibre reinforced or sandwich composites, may experience. Design against fatigue failure of these types of structures is associated with many challenges due to the complexity of the interface fracture problem. To assess the lifetime and behaviour of layered structures exposed to cyclic loading, experiments are typically conducted on intact specimens and on specimens with a pre-existing (known) crack. This requires special testing facilities and is usually very costly and time-consuming. Due to the difficulties and expenses associated with conducting fatigue experiments, considerable efforts have been made in recent years to simulate fatigue crack growth by applying numerical methods. Maziere and Fedelich (2010) simulated 2D fatigue crack propagation using the finite element method and implementation of the strip-yield model. Their model assumes that, at each cycle, the crack growth results from the variation of the crack tip opening displacement (CTOD). They used cohesive elements with linear-elastic, perfectlyplastic behaviour to simulate crack growth. Kiyak et al. (2008) simulated fatigue crack growth under low cycle fatigue at a high temperature in a single crystal superalloy. To simulate the crack growth, they implemented a node release technique and released the nodes in each cycle according to an experimentally measured crack growth rate. The simulation results were compared with results from experiments on the single edge notch specimens of the Ni-based single crystal superalloy PWA1483 at 950C on the basis of computed crack tip opening displacement (CTOD). Shi and Zhang (2009) simulated the interfacial crack growth of fibre reinforced composites under tension–tension cyclic loading using the finite element method. In their model, the energy release rate is calculated and applied to Paris’ law in order to calculate the crack growth rate. Ramanujam et al. (2008) studied the fatigue growth of fibre reinforced 63
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 12 and 13:
Page 14 and 15:
Contents Preface Executive Summary
Page 16 and 17:
5 Face/core Interface Fatigue Crack
Page 18 and 19:
Page 20 and 21:
H11 bimaterial constant H22 bimater
Page 22 and 23:
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 60 and 61: This page is intentionally left bla
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 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

Create successful ePaper yourself

Delete template?

Save as template?