工程結構的輕量化一直是工程師追求的目標，在輕量化過程中，為了兼顧結構受到衝擊荷重下的安全性，結構設計上必須使用質量輕且能發揮其極限強度之材料。基於高強度鋼材與複合材料之輕質量且高強度之特性，逐漸成為吸能材料的新趨勢。
由於高強度鋼與複合材料製成之薄壁吸能構件之研究有限，尤其有關於複合材料薄壁管之吸能特性的研究大都以實驗為主，因此，本文透過有限元素軟體LS-DYNA建立分析模型，首先對於影響高強度鋼之薄壁圓管的吸能因素作深入探討後，再利用霍普金森桿針對高強度鋼材進行動態拉伸試驗，得到不同應變速率下之應力應變曲線，解決普遍使用Cowper-Symonds動態組成律時，應變速率不合理之現象。
此外，有鑒於緩衝元件於實際運用時連接上之考量，亦針對幾何不連續結構對於緩衝構件吸能之影響作詳細研究。最後，再利用複合材料來增強金屬薄壁圓管，探討兩種材料混合薄壁圓管的吸能能力。於分析各項影響吸能效率之參數下，期能使薄壁圓柱管於軸向壓縮衝擊時具有最佳的吸能特性。

Thin-walled circular cylindrical shells are excellent mechanism for energy absorption and have been widely used in engineering structures such as automobiles, aircraft, military facilities, bridge structures and other applications.
Numerous practical engineering systems must absorb various amounts of energy during impact events. Owing to the higher strength and excellent formability, high strength steel is gradually becoming more popular in replacing conventional steel. In recently years, fiber composite materials have been increasingly used in the development of advanced metal shell structures because of high load carrying capacity and low structural weight.
The commercial finite element program LS-DYNA was employed to evaluate the response and energy absorbing capacity of high-strength cylindrical metal tubes. In order to gain accurate numerical results, the stress–strain curves of different strain rates were obtained from tensile tests using Hopkinson Split Bar. In addition, due to shell structures often contain complex stiffeners and cutouts, as a result of practical needs; this study is also regarding the crushing behavior of high strength steel sections contain cutouts. Finally, the purpose is to develop a numerical method for evaluating the static and dynamic behavior of fiber-reinforced metal tubes under axial load. The effects of composite thickness, stacking orientations and material property of composite are also emphasized.

1.Alexander J.M., An approximate analysis of the collapse of thin cylindrical shells under axial loading, The Quarterly Journal of Mechanics and Applied Mathematics. 13(1) : 5-10, 1960.
2.Andrews K.R.F., England G.L., Ghani E., Classification of the axial collapse of cylindrical tubes under quasi-static loading, International Journal of Mechanical Sciences. 25: 687-696, 1983.
3.Abramowicz W., The effective crushing distance in axially compressed thin walled metal columns. Int. J. Impact. Eng. 1(3), 309-317, 1983.
4.Abramowicz W., Jones N., Dynamic axial crushing of circular tubes, International Journal of Impact Engineering. 2:263-281, 1984.
5.Abramowicz W., Jones N., Dynamic axial crushing of square tubes, Int. J. Impact Eng. 2(2):179-208, 1984.
6.Abramowicz W., Jones N., Dynamic progressive buckling of circular and square tubes, Int. J. Impact Eng. 4(4):243-270, 1986.
7.Arnold B, Altenhof W., Experimental observations on the crush characteristics of AA6061 T4 and T6 structural square tubes with and without circular discontinuities. Int J Crashworthiness. 9:73-87,2004.
8.Al E.I., Afizun A., Crushing behavior of pultruded composites. J. Mekanikal . 24:15-31, 2007.
9.Ahmad Z., Thambiratnam D.P., Crushing response of foam-filled conical tubes under quasi-static axial loading, Materials and Design. 30: 2393-2403, 2009.
10.Bertholf L.D., Karnes C.H., Two Dimensional Analysis of the Split Hopkinson Pressure Bar System. Journal of the Mechanics and Physics of Solid. 23:1-19, 1975.
11.Bardi F.C , Kyriakides S. , Plastic buckling of circular tubes under axial compression – partⅠ:Experments,” Int J Mech Sci. 48(8):830-841, 2006
12.Bambach M.R., Axial capacity and crushing of thin-walled metal, fibre-epoxy and composite metalfibre tubes. Thin Wall Struct. 48(6):440-452, 2010.
13.Cowper G.R., Symond P.S., Strain hardening and strain rate effects in the impact loading of cantilever beams, Brown University, Division of applied mathematics report. 28, 1957.
14.Campbell J.D., Dynamic plasticity: macroscopic and microscopic aspects, Materials Science Engineering .12: 3-21, 1973.
15.Cheng Qingwu, Altenhof William, Li Li, Experimental investigations on the crush behavior of AA6061-T6 aluminum square tubes with different types of through-hole discontinuities, Thin-Walled Struct. 44: 441-454, 2006.
16.Duffy J., Testing techniques and material behavior at high rates of strain, in: J.Harding (Ed.), Institute of physics Conference Series. 47: 1-15,1979.
17.Farley G.L., Jones R.M., Crushing characteristics of continuous fiber-reinforced composite tubes. J. Compos. Mater. 26(1):37-50, 1992.
18.Fan H.L., Fang D.N., Enhancement of mechanical properties of hollow-strut foams: analysis, Materials and Design. 30: 1659-1666,2009.
19.Gupta N., Consideration of axisymmetric axial collapse of round tubes, International Journal of Solid and Structures . 34:2611-2630, 1997.
20.Guillow S.R., Lu G., Grzebieta R.H., Quasi-static axial compression of thin-walled circular aluminium tubes. Int. J. Mech. Sci. 43(9):2103-2123,2001.
21.Galib D. Al., Limam A., Experimental and numerical investigation of static and dynamic axial crushing of circular aluminum tubes, Thin Walled Structures. 42: 1103-1137,2004.
22.Hopkinson B., A Method of Measuring the Pressure Produced in the Detonation of High Explosives or by the Impact of Bullets, Phil. Trans. Roy. Soc. London Series A. 213(10), 437-456, 1914.
23.Hu Hsuan-Teh, Wang Su Su, Optimization for buckling resistance of fiber composite laminate shells with and without cutouts, Compos. Struct. 22 :3-13, 1992.
24.Hanefi E.H., Wierzbicki T., Axial crush resistance and energy absorption of externally reinforced metal tubes, Compos. Part B Eng. 27: 387-394, 1996.
25.Huh, H., Kang, W. J., ”Crash-worthiness assessment of thin-walled structures with the high-strength steel sheet,” Int J Vehicle Design. 30(1/2):1-21, 2002.
26.H. Huh, W. J. Kang. “A Tension Split Hopkinson Bar for Investigating the Dynamic Behavior of Sheet Metals,” Experimental Mechanics. 2002.
27.Hage H. EI, Mallick P.K., Zamani N., Numerical modeling of quasi-static axial crush of square aluminum-composite hybrid tubes. Int J Crashworthiness. 9(6):653-664, 2004.
28.Han Haipeng, Cheng Jinquan, Taheri Farid, Neil Pegg, Numerical and experimental investigations of the response of aluminum cylinders with a cutout subject to axial compression, Thin-Walled Struct. 44 : 254-270, 2006.
29.Han Haipeng, Taheri Farid, Pegg Neil, Quasi-static and dynamic crushing behaviors of aluminum and steel tubes with a cutout, Thin-Walled Struct. 45 :283-300, 2007.
30.Han H., Taheri F., N. Pegg, Y. Lu, A numerical study on the axial crushing response of hybrid pultraded and ±45° braided tubes. Compos Struct. 80(2):253-264, 2007.
31.Huang J., Wang X., Numerical and experimental investigations on the axial crushing response of composite tubes. Compos. Struct. 91(2):222-228,2009.
32.Johnson W., Impact Strength of Materials. New York:Crane Russak, 1972.
33.Jones N., Structural Impact, Cambridge University Press, Cambridge (UK), 1989.
34.Kolsky H., An Investigation of the Mechanical Properties of Materials at Very　High Rates of Strain, Proc. Roy. Phys. Soc., London Series B. 62: 676-700, 1949 .
35.Kawata K., “A new testing method for the characterization of materials in high velocity tension, Inst. Phys. Conf. Set. 47: 71-80, 1979.
36.Karagiozova D., Jones, N., “Dynamic elastic-plastic bucking phenomena in rod due to axial impact,” Int J Impact Engng. 18(7-8):919-947, 1996.
37.Karagiozova D., Jones N., Dynamic elastic-plastic bucking of circular cylindrical shells under axial impact, International Journal of Solids and Structures. 37: 2005-2034, 2000.
38.Karagiozova D., Jones N., Dynamic buckling of elastic-plastic square tubes under axial impact-II: structural response, International Journal of Impact Engineering .30:167-192, 2004.
39.Langseth M., Hopperstad O.S., Static and dynamic axial crushing of square thinwalled aluminum extrusions, Int. J. Impact Eng.18:949-968, 1996.
40.Langseth M., Hopperstad O.S., Berstad T., Crashworthiness of aluminum extrusions: validation of numerical simulation, effect of mass ratio and impact velocity, International Journal of Impact Engineering. 22: 829-854, 1999.
41.LS-DYNA Theoretical Manual, V.971, Livermore Software Technology Corporation, Livermore, CA, USA.2006.
42.Mamalis A.G. , Manolakos D.E. , Ioannidis M.B. , Kostazos P.K. , Papapostolou D.P., Axial collapse of hybrid square sandwich composite tubular components with corrugated core: numerical modelling. Compos. Struct. 58(4):571-582,2002.
43.Marsolek J., Reimerdes H.G., Energy absorption of metallic cylindrical shells with induced non-axisymmetric folding patterns, International Journal of Impact Engineering. 30:1209-1212, 2004.
44.Mark W. Hilburger, James H., Starnes Jr. Buckling behavior of compression-loaded composite cylindrical shells with reinforced cutouts. Int J Non-linear Mechanics .40:1005-1021, 2005.
45.Mark J., Holst G., Michael J., Axially compressed cylindrical shells with local settlement, Thin-Walled Structures .43: 811-825, 2005.
46.Mamalis A.G., Manolakos D.E., Ioannidis M.B., Papapostolou D.P., The static and dynamic axial collapse of CFRP square tubes: finite element modelling. Compos. Struct. 74(2):213-225, 2006.
47.Narayanaswami R, Adelman HM., ”Evaluation of tensor polynomial and Hoffman strength theories for composite materials,”Journal of Compos Mater.11(4):366-377, 1977.
48.Nicholas T., Tensile testing of materials at high rates of strain. Experimental Mechanics. 21: 177-185, 1981.
49.Pugsley A.G., Macaulay M., The large scale crumpling of thin cylindrical columns. Q. J Mech. Appl. Math.13:1-9,1960.
50.Pugsley A.G., On the crumpling of thin tubular struts. Q. J Mech. Appl. Math.32:1-7, 1979.
51.Ramakrishna S., Hamada H., Energy absorption characteristic of crashworthy structural composite materials, Key engineering material. 141-143:585-620, 1998.
52.Peixinho N., Pinho A., Study of viscoplasticity models for the impact behavior of high-strength steels, Transactions of the ASME. 2:114-123, 2007.
53.Rossi A., Fawaz Z., Behdinan K., Numerical simulation of the axial collapse of thin-walled polygonal section tubes, Thin-Walled Structures 43: 1646-1661, 2005.
54.Rajendran R., Moorthi A., Basu S., Numerical simulation of drop weight impact behaviour of closed cell aluminium foam, Materials and Design .30: 2823-2830, 2009.
55.Staab G.H., Gilat A., A direct-tension split Hopkinson bar for high strain-rate testing. Journal of Experimental Mechanics.31:232-235, 1991.
56.Singace A., Elsobky H., Further experimental investigation on the eccentricity factor in the progressive crushing of tubes, International Journal of Solid and Structures. 33:3517-3538, 1996.
57.Schneider, F., Jones, N., ”Influence of spot-weld failure on crushing of thin-walled structural sections ,” Int J Mech Sci. 45(12):2061-2081, 2003.
58.Wierzbicki T., Optimum design of integrated front panel against crash, Report for Ford Motor Company, Vehicle Component Dept.1983.
59.Wang X., Lu G., Axial crushing force of externally fibre-reinforced metal tubes. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science. 216(9):863-874, 2002.
60.Wei Z.G., Yu J.L., R.C. Batra, Dynamic buckling of thin cylindrical shells under axial impact, International Journal of Impact Engineering. 32: 575-592, 2005.
61.Yamashita M., Gotoh M., Sawairi Y., A numerical simulation of axial crushing of tubular strengthening structures with various hat-shaped cross-sections of various materials, Key Engineering Materials. 233: 193-198, 2002.
62.Yamashita M., Gotoh M., Sawairi Y., Axial crush of hollow cylindrical structures with various polygonal cross-sections numerical and experiment, Journal of Materials Processung Technology.140:59-64, 2003.
63.Yu H., Guo Y., Lai X., Rate-dependent behavior and constitutive model of DP600 steel at strain rate from 10-4 to 103 s-1, Materials and Design.30 :2501-2505, 2009.