cross section crash boxes

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usually applied (Marsolek and Reimerdes 2004, Meguid, et al. 2004b). Two methods of mass scaling are as follows (Santosa, et al. 2000), Scaling down of the material density increases the number of time increments. The total time of solution is decreased by increasing the loading rate of quasi-static simulation. Second way is scaling up the mass density with very low loading rates. This is caused to very large time step with reduced the number of time step. Quasi-static simulation of mass scaling must met two conditions. First, the total kinetic energy of entire simulation must be relatively very small as compared with the total internal energy of system. Second, the load vs. deformation behavior must be independent of deformation rate. These conditions must be satisfied in the total duration of simulation. In the simulation of the quasi-static crushing of empty and filled boxes, the material mass density was scaled down by a factor of 1000 and the deformation speed was increased to 2 m s -1 . Dynamic crush simulations results of G1 geometry boxes (implemented with the montage plates) were used as inputs to the crash boxes optimization. In dynamic simulations, a planar moving force contact algorithm was used to simulate the impact of 550 kg mass with an initial deformation velocity of 10 ms -1 . In the quasi-static compression simulations, the compression top and bottom plates were modeled as rigid walls. The planar forces and the geometric flat motion of rigid wall algorithms were applied to top and bottom compression plates, respectively (Figure 5.4(a)). In the modeling of the deformation of empty and partially filled aluminum crash boxes without montage plates, the planar flat rigidwall representing the bottom deformation plate was fixed, no translation and rotation, and the geometric flat motion rigid-wall representing the upper plate moved only in z direction, the motion in all other directions was restricted. In the simulation of empty and partially filled crash boxes with montage parts; however, no rigid wall algorithms were used. The top and bottom weld plates were created as separate parts and the bottom and top weld plates 88
were constrained. Since the width of the welding zone was measured 9 mm, the rotational motions of all nodes in a distance 6 mm from the top and bottom of tube were not allowed in all direction (Figure 5.4(b)). The translation motion of weld zone nodes was only allowed in Z direction. Similar constraints were also previously applied in the simulation of the crushing of 5018 Al tubes (Williams, et al. 2007). (a) (b) Figure 5.4. The model of a) crash box without montage plates and b) crash box with montage plates. The self contact of crush zone surfaces (contact between folds) was modeled with automatic single surface contact algorithm (Figure 5.5(a)). Automatic surface to surface contact algorithm was used to simulate the contact between foam filler and box wall and box edge and weld plates of crush boxes with montage plates (Figure 5.5(b)). The contact between crash zone and montage plates was modeled with automatic nodes to surface contact algorithm. Lastly, the static and dynamic friction coefficients were taken 0.3 and 0.2, respectively. 89
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OPTIMIZATION OF THE AXIAL CRUSHING
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ACKNOWLEDGEMENTS My PhD quest has b
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ÖZET KAPALI HÜCRELİ ALUMİNYUM K
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CHAPTER 4 EXPERIMENTAL DETAILS ....
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CHAPTER 8 ALUMINUM CRASH BOX OPTIMI
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Figure 3.7. Simulations of the defo
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Figure 4.9. Dimensions of tensile t
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Figure 6.21. Sequential deformation
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Figure 7.20. Sequential deformation
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LIST OF TABLES Table Page Table 4.1
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Figure 1. 1. The body in white stru
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Figure 1. 4. Commercial crash boxes
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CHAPTER 2 AL CLOSED CELL FOAMS: PRO
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The processing methods and mechanic
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Figure 2. 5 The preferred particle
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Figure 2. 8. Typical cellular struc
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Figure 2. 10. Manufacturing cost of
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Figure 2. 12. Laser assisted foamed
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Figure 2.16. Shear strength, normal
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Figure 2. 19. Yield strength vs. re
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Figure 2. 21. Unit cell geometry an
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Figure 2. 24. Load-displacement cur
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Figure 2. 26. The photographs of a
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CHAPTER 3 CRUSHING BEHAVIOR OF TUBU
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Figure 3.2. Diamond deformation mod
Page 57 and 58: deformation mode transition from ax
Page 59 and 60: Figure 3.8. Energy absorption of qu
Page 61: (a) (c) Figure 3.10. Deformation mo
Page 65 and 66: (a) (b) Figure 3.13. a) Schematic o
Page 67 and 68: (a) (b) (c) Figure 3.15. a) Load-di
Page 72 and 73: Figure 3.18. The crush terminology.
Page 75 and 76: The quasi-static compression behavi
Page 77 and 78: Figure 3.22. The variation of speci
Page 79 and 80: Figure 3.24. Deformation modes of e
Page 81 and 82: Figure 3.27. SEA values of empty an
Page 83 and 84: Figure 3.29. (cont.) 3.5. Motivatio
Page 85 and 86: CHAPTER 4 EXPERIMENTAL DETAILS 4.1.
Page 87 and 88: (a) (b) Figure 4.3.Pictures of a) f
Page 89 and 90: oxes are shown in Figure 4.6. The l
Page 91 and 92: Figure 4.7. The method of trigger m
Page 93 and 94: 4.4. Compression Tests of Crash Box
Page 95 and 96: 4.5.2. Uniaxial Compression Testing
Page 97 and 98: Table 4.1 (Cont.) G1 T3 F2 G1T3F2 3
Page 99 and 100: Table 4.2 (Cont.) G1 T2.5 WP F2 G1T
Page 101: CHAPTER 5 SIMULATION AND OPTIMIZATI
Page 105: considered in axial and transverse
Page 116 and 117: 5.4. The Crashworthiness Optimizati
Page 118 and 119: great effect on the crushing behavi
Page 120: CHAPTER 6 EXPERIMENTAL RESULTS 6.1.
Page 124 and 125: Figure 6.3.Tensile stress-strain cu
Page 126 and 127: (a) (b) Figure 6.5. Sequential defo
Page 128 and 129: plate (Figure 6(b)). The trigger is
Page 130 and 131: (a) (b) Figure 6.9. Deformation seq
Page 132 and 133: Figure 6.12. Sequential deformation
Page 138 and 139: Figure 6.18. (cont.) (c) (a) (b) Fi
Page 140 and 141: Figure 6.20.(cont.). (b) (c) 6.5.4.
Page 142 and 143: Figure 6.21.(cont.) (b) (c) 122
Page 144 and 145: Figure 6.22.(cont.) (c) Figure 6.23
Page 146 and 147: Figure 6.24.(Cont.) (b) (c) (a) Fig
Page 148 and 149: Figure 6.26.(cont.) (b) (c) 6.6. Dy
Page 150 and 151: Figure 6.27. (cont.) (b) (c) 130
Page 152 and 153: CHAPTER 7 MODELING RESULTS OF FOAM,
Page 154 and 155: experimental tensile stress-strain
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significant effect of weld seem ope
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Figure 7.7. Deformation photo of fi
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Figure 7.11. Deformation photos of
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(a) (b) (c) Figure 7.14. Load-displ
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7.4. Simulation of Empty and Partia
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Figure 7.16. (cont.) (c) (a) Figure
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(a) (b) Figure 7.18. Sequential def
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Figure 7.19. (cont.) (b) (c) 150
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Figure 7.20. (cont.) (c) (a) Figure
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(a) (b) Figure 7.26. Experimental a
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The constructed response surface of
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Table 8.1. R 2 , Radj 2 and RMSE va
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(a) (b) Figure 8.7. Response surfac
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an empty tube wall thickness higher
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where, K is a dimensionless constan
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The dynamic simulation and analytic
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Figure 9.4. (cont.) (c) (d) Figure
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Figure 9.6. (cont.) (c) (d) (a) Fig
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Equation 9.7 can also be rewritten
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(a) (b) Figure 9.10. Energy-absorbi
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Figure 9.11. (cont.) (d) The variat
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foam filling were evaluated. The re
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13. The interaction between foam fi
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Arora, J. S.,2004,Introduction to O
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Dannemann, K. A. and Lankford, J.,
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Hall, I. W., Guden, M. and Yu, C. J
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Kim, D-K. and Lee, S., 1999, Impact
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Mamalis, A. G., Manolakos, D. E., I
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Pugsley, A. G. and Macaulay, M., 19
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T. Miyoshi, M. Itoh S. Akiyama A. K
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Zhao, H., Elnasri, I. and Girard, Y
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