cross section crash boxes

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same. The deformation patterns of dynamically and quasi-statically tested empty and partially filled crash boxes were also found to be very similar. 7. The simulation load values showed good correlation with experimental load values in both 2 and 3 mm thick empty and foam filled crash boxes with and without montage parts. The numerical mean load values of the crash boxes with 2.5 thickness were however slightly higher than experimental mean load values in the boxes with and without montage parts. 8. Experimental and numerical deformation patterns and load values of dynamically tested empty and partially filled crash boxes were found very much similar to each other. This further proved the validity of the rate insensitivity of the foam and box base material model used in the dynamic crash simulations. This also showed that the micro inertial effects, if any, had negligible effects on the load-displacement curves of empty and filled boxes. 9. Within the investigated tube thickness and foam relative density range, the energy absorption of 1050 H14 Al boxes was optimized at 3 mm box wall thickness and 0.1114 (Alulight) and 0.0508 (Hydro foam) foam filler relative density. The corresponding specific energy values of 1050 H14 Al boxes with these optimized parameters were however lower than that of empty box at 55 kN mean load. 10. Increasing box material strength however decreased the optimum tube wall thickness and foam relative density and increased the SEA. Increasing foam plateau stress provided further reduction in the values of the optimum parameters and increase in specific energy absorption. 11. The increases in SEA values with Alulight and Hydro foam filling of 1050H14 Al crash box were about 5.6% and 21.9%, respectively. The increases in SEA values with Alulight and Hydro foam filling of 6061T4 Al were however higher, 6.7% and 19.7%, respectively. 12. In all crash boxes tested and simulated, the stroke efficiency values decreased with foam filling below those of empty boxes. Based on the experimental and simulation results, it was shown that the stroke efficiency in filled boxes reached almost a constant value at about 0.55 after a foam plateau stress relative density ratio of 30. The crash efficiency of partially foam filled boxes also increased with increasing foam plateau stress- foam relative density ratio but the increase was shown to be less pronounced as compared with fully foam filling. 192
13. The interaction between foam filler and tube wall increased with decreasing foam plateau stress-relative density ratio. It was concluded that partially foam filling was not effective in the strengthening of the boxes at relatively high foam plateau stress-foam relative density ratios as in the fully foam filling. 14. An energy absorbing effectiveness factor was calculated for the investigated filled boxes. The static energy-absorbing effectiveness factors of partially filled boxes were shown to be higher than those of fully foam filled tubes. Theoretical analysis further showed that partially Alulight foam filling with relatively low plateau stress resulted in higher energy absorbing effectiveness factor than partially Hydro foam filling. 15. A design criterion was developed for the foam filling of boxes. At relatively low foam densities partially and fully foam filled boxes were energetically less efficient than empty boxes, while at increasing foam filler densities fully foam filing became the most efficient. Partially foam filling became the most efficient at relatively high foam filler densities and box wall thicknesses. 16. Present study clearly showed that in the designing with the crash boxes, the foam filler plateau stress and box base material strength should be high for higher energy absorptions. The selection of the fully and partially foam filling must be considered based on the foam filler density and tube wall thicknesses used. 193
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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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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
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deformation mode transition from ax
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Figure 3.8. Energy absorption of qu
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(a) (c) Figure 3.10. Deformation mo
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(a) (b) Figure 3.13. a) Schematic o
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(a) (b) (c) Figure 3.15. a) Load-di
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Figure 3.18. The crush terminology.
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The quasi-static compression behavi
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Figure 3.22. The variation of speci
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Figure 3.24. Deformation modes of e
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Figure 3.27. SEA values of empty an
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Figure 3.29. (cont.) 3.5. Motivatio
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CHAPTER 4 EXPERIMENTAL DETAILS 4.1.
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(a) (b) Figure 4.3.Pictures of a) f
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oxes are shown in Figure 4.6. The l
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Figure 4.7. The method of trigger m
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4.4. Compression Tests of Crash Box
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4.5.2. Uniaxial Compression Testing
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Table 4.1 (Cont.) G1 T3 F2 G1T3F2 3
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Table 4.2 (Cont.) G1 T2.5 WP F2 G1T
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CHAPTER 5 SIMULATION AND OPTIMIZATI
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considered in axial and transverse
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were constrained. Since the width o
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5.4. The Crashworthiness Optimizati
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great effect on the crushing behavi
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CHAPTER 6 EXPERIMENTAL RESULTS 6.1.
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Figure 6.3.Tensile stress-strain cu
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(a) (b) Figure 6.5. Sequential defo
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plate (Figure 6(b)). The trigger is
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(a) (b) Figure 6.9. Deformation seq
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Figure 6.18. (cont.) (c) (a) (b) Fi
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Figure 6.20.(cont.). (b) (c) 6.5.4.
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Figure 6.21.(cont.) (b) (c) 122
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Figure 6.22.(cont.) (c) Figure 6.23
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Figure 6.24.(Cont.) (b) (c) (a) Fig
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Figure 6.26.(cont.) (b) (c) 6.6. Dy
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Figure 6.27. (cont.) (b) (c) 130
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CHAPTER 7 MODELING RESULTS OF FOAM,
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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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Page 172 and 173: Figure 7.20. (cont.) (c) (a) Figure
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Page 182 and 183: The constructed response surface of
Page 184: Table 8.1. R 2 , Radj 2 and RMSE va
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Page 192 and 193: where, K is a dimensionless constan
Page 194 and 195: The dynamic simulation and analytic
Page 196: Figure 9.4. (cont.) (c) (d) Figure
Page 199 and 200: Figure 9.6. (cont.) (c) (d) (a) Fig
Page 203 and 204: Equation 9.7 can also be rewritten
Page 206: (a) (b) Figure 9.10. Energy-absorbi
Page 209 and 210: Figure 9.11. (cont.) (d) The variat
Page 211: foam filling were evaluated. The re
Page 215 and 216: Arora, J. S.,2004,Introduction to O
Page 217 and 218: Dannemann, K. A. and Lankford, J.,
Page 219 and 220: Hall, I. W., Guden, M. and Yu, C. J
Page 221 and 222: Kim, D-K. and Lee, S., 1999, Impact
Page 223 and 224: Mamalis, A. G., Manolakos, D. E., I
Page 225 and 226: Pugsley, A. G. and Macaulay, M., 19
Page 227 and 228: T. Miyoshi, M. Itoh S. Akiyama A. K
Page 229: Zhao, H., Elnasri, I. and Girard, Y
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