cross section crash boxes

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ABSTRACT OPTIMIZATION OF THE AXIAL CRUSHING BEHAVIOR OF CLOSED-CELL ALUMINUM FOAM FILLED WELDED 1050 AL SQUARE-CROSS SECTION CRASH BOXES The crushing behavior of partially Al closed-cell foam (Alulight AlSi10) filled 1050H14 Al crash boxes was investigated at quasi-static and dynamic deformation velocities. The quasi-static crushing of empty and filled boxes was further simulated using LS-DYNA. Finally, the crushing of partially foam filled 1050H14 crash boxes was optimized using the response surface methodology. The used optimization methodology was also applied to the boxes made of a stronger Al alloy, 6061T4 Al, and filled with a higher strength Al foam, Hydro Al closed cell foam, in order to clarify the effect of box material and foam filler strength on the crushing behavior of the filled boxes. Within the investigated tube thickness and foam relative density range, the energy absorption of 1050H14 boxes was optimized at 3 mm wall thickness and 0.1114 (Alulight) and 0.0508 (Hydro foam) foam filler relative density. The increase in specific energy absorption of 1050H14 crash box was 5.6% with Alulight and 21.9% for Hydro foam filling. The SEA values of empty, partially and fully foam filled boxes were predicted as function of box wall thickness between 1 and 3 mm and foam filler relative density between 0 and 0.2, using the analytical equations developed for the mean crushing loads. The analysis indicated that both fully and partially foam filled boxes were energetically more efficient than empty boxes above a critical foam filler relative density. Partial foam filling however decreased the critical foam filler density at increasing box wall thicknesses. iv
ÖZET KAPALI HÜCRELİ ALUMİNYUM KÖPÜK DOLDURULMUŞ KAYNAKLI 1050 AL KARE KESİTLİ EZİLME KUTULARININ OPTİMİZASYONU Bu çalışmada kısmi olarak aluminyum kapalı hücreli köpük (Alulight AlSi10) ile doldurulmuş 1050H14 Al ezilme kutularının ezilme davranışlarını quasi-statik ve dinamik deformasyon hızlarında incelenmiştir. Boş ve dolu ezilme kutularının quasi- statik ezilme davranışları LS-DYNA kullanılarak simule edilmiştir. Tezin son kısmında kısmi dolu 1050H14 Al ezilme kutularının ezilmeleri Cevap Yüzeyi Metodolojisi kullanılarak optimize edilmiştir. Uygulanan optimizasyon metodunda, ezilme kutusu ana malzemesi için daha kuvvetli aluminyum alaşımı 6061T4 ve dolgu malzemesi için yine daha yüksek mukavemete sahip Hydro Al kapalı hücreli köpük, ana malzeme ve dolgu malzemesinin dayanımının dolu tüplerin ezilme davranışlarına olan etkilerinin açık bir şekilde belirlenebilmesi için kullanılmışlardır. Araştırılan tüp kalınlığı ve nispi köpük yoğunluğu aralığında, 1050H14 Al kutuları 3 mm kalınlıkta ve 0.1114 (Alulight) ve 0.0508 (Hydro) köpük nispi yoğunluğunda optimize edilmişlerdir. 1050H14 ezilme kutusunun spesifik enerji absorbsiyonu artış oranı Alulight köpükler için %5.6 Hydro köpükler %21.9 olarak hesaplanmıştır. Boş, kısmi ve tam köpük dolu kutuların SEA değerlerinin tahminlenmesinde 1 ve 3mm aralığındaki kutu kesit kalınlığı ve 0 ile 0.2 aralıklarındaki nispi köpük yoğunluğunun fonksiyonu olan ortalama ezilme yükleri için geliştirilmiş analitik denklemler kullanılmışlardır. Analizler belirli kritik köpük dolgu yoğunluğunun üstünde kısmi ve tam köpük dolu ezilme kutularının boş kutulardan enerji açısından daha verimli olduklarını göstermiştir. Kısmi köpük doldurma işlemi kutu kesitinin artırılması durumunda kritik köpük yoğunluğunun düşmesine neden olduğu tespit edilmiştir. v
Page 1 and 2: OPTIMIZATION OF THE AXIAL CRUSHING
Page 3: ACKNOWLEDGEMENTS My PhD quest has b
Page 7 and 8: CHAPTER 4 EXPERIMENTAL DETAILS ....
Page 9 and 10: CHAPTER 8 ALUMINUM CRASH BOX OPTIMI
Page 12 and 13: Figure 3.7. Simulations of the defo
Page 14 and 15: Figure 4.9. Dimensions of tensile t
Page 16 and 17: Figure 6.21. Sequential deformation
Page 18 and 19: Figure 7.20. Sequential deformation
Page 20 and 21: LIST OF TABLES Table Page Table 4.1
Page 22 and 23: Figure 1. 1. The body in white stru
Page 24 and 25: Figure 1. 4. Commercial crash boxes
Page 26 and 27: CHAPTER 2 AL CLOSED CELL FOAMS: PRO
Page 28 and 29: The processing methods and mechanic
Page 30 and 31: Figure 2. 5 The preferred particle
Page 32 and 33: Figure 2. 8. Typical cellular struc
Page 34 and 35: Figure 2. 10. Manufacturing cost of
Page 36: Figure 2. 12. Laser assisted foamed
Page 41 and 42: Figure 2.16. Shear strength, normal
Page 43 and 44: Figure 2. 19. Yield strength vs. re
Page 45 and 46: Figure 2. 21. Unit cell geometry an
Page 47 and 48: Figure 2. 24. Load-displacement cur
Page 49 and 50: Figure 2. 26. The photographs of a
Page 51 and 52: CHAPTER 3 CRUSHING BEHAVIOR OF TUBU
Page 53 and 54: 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 6.12. Sequential deformation
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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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(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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