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系統識別號 U0026-2106201817044900
論文名稱(中文) 鋁合金板材電磁成形之可成形性研究
論文名稱(英文) Study on Formability Evaluation in Electromagnetic Forming Process of Aluminium Alloy Sheet
校院名稱 成功大學
系所名稱(中) 機械工程學系
系所名稱(英) Department of Mechanical Engineering
學年度 106
學期 2
出版年 107
研究生(中文) 鄭東辰
研究生(英文) Tung-Chen Cheng
學號 N18961377
學位類別 博士
語文別 英文
論文頁數 104頁
口試委員 指導教授-李榮顯
召集委員-李偉賢
口試委員-黃永茂
口試委員-許光城
口試委員-伏和中
中文關鍵字 電磁成形  成形性評估  成形極限圖  晶粒尺寸  應變率 
英文關鍵字 Electromagnetic forming (EMF)  Formability evaluation,  Forming limit diagram (FLD)  Grain size  Strain rate 
學科別分類
中文摘要 電磁成形(EMF)製程可以有效提升鋁合金的可成形性,製造出傳統製程難以成形的複雜幾何形狀。由於電磁成形製程的變形持續時間非常短而無法藉由一般的測量方法得到應力或應變數據,所以工程師很難取得高應變率下材料的成形極限圖(FLD)來做為設計產品時的參考。有鑑於此,本論文的主要目的是建立一個可用於電磁成形製程中鋁合金板材可成形性預測的方法。
本研究進行了一系列從巨觀到微觀之介觀尺度的電磁成形實驗,探討A5052鋁合金板材在高應變率下的成形性。在巨觀成形中,以電磁成形實驗搭配疊代模擬分析建構材料在高應變率下之成形極限值與應力應變曲線。高速成形實驗中,藉由平面線圈產生的電磁力將厚度0.5mm的鋁板推向沖頭;同時,透過CAE模擬分析來決定電磁成形實驗中使用的沖頭半徑和試片的形狀,以產生各種不同的應變值和應變路徑。此外,藉由疊代分析獲得之應力與應變值可用來建構Johnson-Cook材料模型,再結合能量準則便可應用於高應變率下鋁合金板材的成形性評估。
在巨觀微觀間之介觀尺度成形,為了探討晶粒尺寸和應變率對成形性的影響,本研究採用沖壓和電磁成形兩種製程,在0.012m/s到11.04m/s四種不同速度下進行FLD與極限拱頂高度(LDH)測試。使用厚度為0.5mm的A5052 H32鋁合金板材進行實驗並利用不同退火條件以獲得不同的顯微組織(T/D 值6.99〜27.17)。將FLD的應變數據與LDH測量值進行比較,藉以探討晶粒尺寸對成形性的影響。另外,本研究利用SEM和OM觀察測試樣品的斷裂表面和顯微組織,以進一步了解材料的破壞模式。根據上述的實驗結果與觀察,本論文在Zhuang的能量準則中加入尺寸效應參數而提出新的修正準則,並將其應用於介觀尺度之電磁成形。
本研究利用疊代模擬分析獲得試片在高能率成形下的應力與應變值並藉此建立Johnson-Cook模型。透過這個模型可以獲得不同應變率下的應力應變曲線,將其應用於製程模擬的結果與實驗所得之成形極限比較是相吻合。在巨觀微觀間之介觀尺度的電磁成形實驗中,根據LDH測試結果和SEM和OM的觀察,得出結論為高速成形時晶粒尺寸的減小增加了晶界破壞發生機率並且可能導致成形性下降。因此,對於介觀尺度成形,本論文提出的修正準則同時考量了晶粒尺寸和應變路徑的影響,其準確性藉由實驗數據獲得驗證,可應用於高速成形T/D值3.75〜27.17的A5052鋁合金板材的成形性預測。
綜上所述,本研究建立了電磁成形製程從巨觀到介觀尺度鋁合金板材成形性評估的方法。藉由Johnson-Cook模型構建的塑流應力曲線可用於預測材料的變形行為,而巨觀與巨觀微觀間之介觀尺度的成形製程,可以分別採用Zhuang的準則與本論文提出的修正準則來建構FLC進行可成形性評估。
英文摘要 Electromagnetic forming (EMF) process can effectively enhance the formability of aluminium alloy and fabricate complicated geometry which is difficult to be formed by conventional processes. Since the duration of deformation in EMF is extremely short to get the stress or strain data by conventional measuring method, it is also hard for engineers to obtain the FLD at high strain rate as reference when designing products. Hence, the main purpose of this dissertation is to establish a method that can be used for predicting formability of aluminium alloy sheet in EMF process.
This study conducted a series of EMF experiments of aluminium sheet A5052 from the macro scale to the micro scale to investigate the formability at high strain rates. In the macro-scale forming, free-impact EMF experiments and iterated simulation were designed to research the flow stress and the forming limit at high strain rate. Aluminium sheet A5052-H32 with 0.5 mm thickness was propelled towards a punch, using the electromagnetic force generated by a flat spiral electromagnetic coil. Different values of the punch radius and the shapes of specimen used in the EMF experiments were chosen from the simulation results in order to generate various strain values and strain paths. Furthermore, the Johnson-Cook model was introduced using the flow stress data obtained by iteration analysis and the energy criterion was applied for the formability evaluation of aluminium sheet under high stain rates.
In order to understand the influences of grain size and strain rate on formability, FLD tests and the limit dome height (LDH) tests were conducted at four different speeds ranging from 0.012m/s to 11.04m/s via stamping and electromagnetic forming process. Aluminium sheets A5052 H32 with 0.5mm thickness were used for experiments and annealed at different conditions to obtain different microstructures (T/D ratios 6.99 ~27.17). The strain data of FLD were compared with the limit dome height measurement to clarify the influence of various grain sizes on formability. In addition, the fracture surface and the microstructure of the tested samples were observed by SEM and OM to understand the damage mode. A modified criterion based on Zhuang’s model was proposed and applied for macro-micro meso scale forming in EMF process.
This study constructed Johnson-Cook model based on the iterated effective stress-strain curve. Via the determined Johnson-Cook model, the flow stresses under different strain rates were obtained and applied for process simulation which showed good agreement with the measured forming limits. According to the results of LDH tests and the observation by SEM and OM, it is concluded that the smaller the grain size is in high-speed forming the probability of the grain boundary damage increases and it could cause the poor formability. For macro-micro meso scale forming, the proposed criterion which based on the effects of grain size and strain path, was verified by the experimental data. The proposed modified criterion can be applied for formability prediction of A5052 aluminium sheet with T/D ratio 3.75~27.17 under high-speed forming.
In summary, this study established a scheme that can be used for macro-scale and macro-micro meso scale formability evaluation of aluminium alloy sheet in EMF process. The flow stress constructed by Johnson-Cook model can be used for predicting the deformation behaviour, and the formability were evaluated by FLCs which were obtained by Zhunag's criterion and the proposed modified criterion for macro and macro-micro meso scale forming, respectively.
論文目次 中文摘要 I
ABSTRACT II
致 謝 IV
TABLE OF CONTENTS V
LIST OF FIGURES VII
LIST OF TABLES X
NOMENCLATURE XI
CHAPTER 1 INTRODUCTION 1
1.1 MOTIVATION 1
1.2. LITERATURE REVIEW 2
1.2.1 Forming limit diagram and fracture criteria 2
1.2.2 Formability evaluation in high stain rate forming 4
1.2.3 Size effect on formability 7
1.3 OBJECTIVE AND METHODOLOGY OF THIS STUDY 9
1.4 OUTLINE OF THE STUDY 10
CHAPTER 2 THEORETICAL METHODS 12
2.1 EMF PROCESS 12
2.2 MATERIAL PROPERTY THEORY 14
2.2.1 Material characteristic under high stain rate 14
2.2.2 Modes of failure in high-speed forming 15
2.3 CRITERIA FOR FORMABILITY EVALUATION 18
CHAPTER 3 EXPERIMENTAL METHODS 22
3.1 MACROSCALE EMF EXPERIMENT 22
3.1.1 Experimental design 22
3.1.2 Specimen preparation 23
3.1.3 Apparatus 27
3.1.4 Impact velocity measurement 30
3.1.5 Experimental parameters 31
3.2 MACRO-MICRO MESO SCALE EMF EXPERIMENT 34
3.2.1 Specimen preparation 34
3.2.2 Apparatus 40
3.2.3 Strain measurement and metallography 43
CHAPTER 4 RESULTS AND DISCUSSIONS 46
4.1 MACRO SCALE EMF EXPERIMENT 46
4.1.1 Forming Limit Diagram 46
4.1.2 Johnson–Cook model construction 50
4.1.3 Strain path simulation and forming limits prediction 53
4.2 MACRO-MICRO MESO SCALE EMF EXPERIMENT 58
4.2.1 Comparison of forming limit diagrams 58
4.2.2 LDH measurements 69
4.2.3 Fracture mechanism 76
4.3 FORMABILITY EVALUATION IN HIGH-SPEED FORMING 82
CHAPTER 5 CONCLUSIONS AND FUTURE WORKS 90
5.1 CONCLUSIONS 90
5.2 FUTURE WORKS 92
REFERENCES 93
APPENDIX 99
參考文獻 Ashby, M.F., Embury, J.D., Coksley, S.H., Teirlinck, D., Fracture maps with pressure as a variable, Scripta Metallurgica, 19, 385-390. (1985)
Atkins, A. G., Possible explanation for unexpected departures in hydrostatic tension-fracture strain relations, Metal Science, 15, 81-83. (1981)
Balanethiram, V. S., Hu, X., Altynova, M., Daehn, G. S., Hyperplasticity: Enhanced Formability at High Rates. Journal of Materials Processing Technology, 45, 595-600. (1994)
Brozzo, P., Luka, de B., Rendina, R., A new method for the prediction of formability in metal sheets, Proc. 7th Biennial Conference on Sheet Metal Forming and Formability, International Deep Drawing Research Group, 9-13. (1972)
Campbell, J.D., Ferguson, W.G., Temperature and Strain-Rate Dependence of the Shear Strength of Mild Steel. Philosophical Magazine, 21, 169, 63-82. (1970)
Chen, C. H., Forming limit prediction of micro sheet metal forming due to grain size effect, Department of Mechanical Engineering, National Cheng Kung University, Tainan, Taiwan, Ph.D. dissertation. (2010)
Chiu, H. Y., Formability analysis of HA-188 cobalt-base superalloy in tube hydroforming, Department of Mechanical Engineering, National Cheng Kung University, Tainan, Taiwan, Master Thesis. (2011)
Cockcroft, M. G., Latham, D. J., Ductility and workability of metals, Journal of the Institute of Metals, 96, 33-39. (1968)
Daehn, G. S., Vohnout, V. J., Datta, S., Hyperplastic forming: process potential and factors affecting formability, Materials Research Society, 601, 247-252. (2001)
Dieter, G.E., Mechanical Metallurgy, SI metric edition adapted by David Bacon, MaGraw-Hill Book Company, London. (1988)
Freudenthal, A. M., The inelastic behavior of engineering materials and structures. New York: John Wiley & Sons. (1950)
Gau, J., Chen, P., Gu, H., Lee, R., The coupling influence of size effects and strain rates on forma-bility of austenitic stainless steel 304 foil, Journal of Materials Processing Technology, 213, 376-382. (2013)
Gau, J., Principe, C., Wang, J., An experimental study on size effects on flow stress and formability of aluminium and brass for microforming, Journal of Materials Processing Technology, 184, 42-46. (2007)
Geiger, M., Kleiner, M., Eckstein, R., Tiesler, N., Engel, U., Microforming. CIRP Annuals-Manufacturing Technology, 50, 2, 445-462. (2001)
Goodwin, G. M., Application of strain analysis on sheet metal forming problems in the press shop, SAE paper, 680093. (1968)
Goods, S.H., Brown, L.M., The nucleation of cavities by plastic deformation, Acta Metallurgica, 27, 1-15. (1979)
Hiam, J., A. Lee, Factors influencing the forming-limit curves of sheet steel, Sheet Metal Industries, 55, 5, 631-641. (1978)
Hill, R., On discontinuous plastic states with special reference of localized necking in thin sheets, Journal of the Mechanics and Physics of Solids, 1, 19-30. (1952)
Holt, D.L., Babcock, S.G., Green, S.J., Maiden, C.J., The Strain-Rate Dependence of the Flow Stress in Some Aluminum Alloys. Transactions of the ASM: Transactions Quarterly, 60, 2, 152-159. (1967)
Hutchinson, J.W., Neale, K.W., Sheet necking-II time-independent behavior, Mechanics of Sheet Metal Forming, New York: Plenum Press, 127-150. (1978)
Jassen, P. J. M., Keijser, T. H. de, Geers, M. G. D., An experimental assessment of grain size effects in the uniaxial straining of thin Al sheet with a few grains across the thickness, Materials Science and Engineering A, 419, 238-248. (2006)
Johnson, G.R., Cook, W.H., A Constitutive Model and Data for Metals Subjected to Large Strains, High Strain Rates, and High Temperatures. Proceedings – 7th International Symposium on Ballistics, Hague, Netherlands, 541-547. (1983)
Johnson, G.R., Cook, W.H., Fracture Characteristics of Three Metals Subjected to Various Strains, Strain Rates, Temperatures and Pressures. Engineering Fracture Mechanics, 21, 1, 31-48. (1985)
Johnson J.N., Dynamic fracture and spallation in ductile solids, Journal of Applied Physics, 52, 4, 2812-2825. (1981)
Jose, M., Increased Formability and the Effects of the Tool/Sheet Interaction in Electromagnetic Forming of Aluminum Alloy Sheet, Master. thesis, The Ohio State University. (2005)
Kamal, M., Shang, J., Cheng, V., Hatkevich, S., Daehn, G. S., Agile manufacturing of micro-embossed case by a two-step electromagnetic forming process, Journal of Material Processing Technology, 190, 41-50. (2007)
Keeler, S. P., W. A. Backofen, Plastic instability and fracture in sheets stretched over rigid punches, Trans, ASM, 56, 1, 25-48. (1963)
Kiliclara , Y., Demirc, O. K., Engelhardtd, M., Rozgi´ce, M., Vladimirovb, I.N., Wulfinghoffa,S., Weddelingc, C., Giesc, S., Klosed, C., Reesea, S., Tekkayac, A.E., Maierd, H.J., Stieme, M., Experimental and numerical investigation of increased formability in combined quasi-static and high-speed forming processes, Journal of Materials Processing Technology, 237, 254-269. (2016)
Lee, R.S., Cheng, T.C., Luo, F. W., A novel formability test method for electromagnetic forming of aluminium sheet, Steel Res Int, 81, 9, 1042-1047. (2011)
Li, C., Liu, D., Yu, H., Ji, Z., Research on formability of 5052 aluminium alloy sheet in a quasi-static–dynamic tensile process, International Journal of Machine Tools & Manufacture, 49, 117–124. (2009)
Ma, H., Huang, L., Tian, Y., Li, J., Effects of strain rate on dynamic mechanical behavior and micro-structure evolution of 5A02-O aluminium alloy, Materials Science & Engineering A, 606, 233–239. (2014)
Marciniak, E., Kuczynsky, K., Limit strains in the processes of stretch forming sheet metal, International Journal of Mechanical Sciences, 9, 609-620.(1967)
McClintock, F. A., A criterion of ductile fracture by growth of holes, Journal of Applied Mechanics, Trans. ASME, 35, 363-371. (1968)
Meyers M.A., Aimone C.T., Dynamic fracture (spalling) of metals, Progress in Materials Science, 28, 1. (1983)
Meyers, M.A., Dynamic Behavior of Materials. John Wiley & Sons, Inc., New York. (1994)
Norris, D. M., Reaugh J. E., Moran,B., Quinones, D. F., A plastic strain mean-stress criterion for ductile fracture, Journal of Engineering Materials and Technology, Trans. ASME, 100, 279-286. (1978)
Oh, S., Chen, C. C., and Kobayashi, S., Ductile failure in axisymmetric extrusion and drawing, Part 2, Workability in extrusion and drawing, Journal of Engineering for Industry, Trans. ASME, 101, 36-44. (1979)
Oliveira, D. A., Worswick, M. J., Finn, M., Newman, D., Electromagnetic forming of aluminium alloy sheet: Free-form and cavity fill experiments and model, Journal of Materials Processing Technology, 170, 1-2, 350-362. (2005)
Oosterkamp, L., Djapic, Ivankovic, A., Venizelos G., High Strain Rate Properties of Selected Aluminium Alloys. Journal of Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing, 278, 1/2, 225-235. (2000)
Oyane, M., Criteria of ductile fracture strain, Japan Society Mechanical Engineering, 15, 1507-1513. (1972)
Oyane, M., Sato, K., Okimoto, K., Shima, S., Criteria for ductile fracture and their applications, Journal of Mechnical Working Technology, 4, 1, 65-81. (1980)
Raulea, L. V., Goijaerts, A. M., Govaert, L. E., Baaijens, F. P. T., Size effect in the processing of thin metal sheet, Journal of Materials Processing Technology, 115, 1, 44-48. (2001)
Rice, J. R., and Tracey, D. M., On the ductile enlargement of voids in triaxial stress fields, Journal of the Mechanics and Physics of Solids, 17, 201-217. (1969)
Rinehart J.S., Pearson J., Behavior of metals under impulsive loads, American Society for metals, Cleveland. (1954)
Sasawat M., M. KOC., Investigation of size effects on material behavior of thin sheet metals using hydraulic bulge testing at micro/meso-scales, International Journal of Machine Tools & Manufacture 48, 1014–1029. (2008)
Seth, M., Vohnout. V. J., Daehn, G. S., Formability of steel sheet in high velocity impact, Journal of Material Processing Technology, 168, 390-400. (2005)
Seth, M., High velocity formability and factors affecting it, Ph.D. dissertation, The Ohio State University. (2006)
Storen, S., Rice, J. R., Localized necking in thin sheets, Journal of the Mechanics and Physics of Solids, 23, 421-441. (1975)
Swift, H. W., Plastic instability under plane stress, Journal of the Mechanics and Physics of Solids, 1, 1-18. (1952)
Tanaka, K., Nojima, T., Strain Rate Change Tests of Aluminum Alloys Under High Strain Rate. Proceedings of The 19th Japan Congress on Materials Research, 48-51. (1975)
Thomson, R.D., Hancock, J.W., Ductile failure by void nucleation, growth and coalescence, International Journal of Fracture, 26, 99-112. (1984)
Thomas, J. D., Seth, M., Daehn, G. S., Bradley, J. R., Triantafyllidis, N., Forming limits for electromagnetically expanded aluminium alloy tubes: Theory and experiment, Acta Materialia, 55, 2863-2873. (2007)
Venter, R., Johnson, W., Malherbe, M. C., The limit strains of inhomogeneous sheet metal in biaxial tension, International Journal of Mechanical Sciences, 13, 299-308. (1971)
Vollertsen, F, Biermann, D., Hasen, H. N., Jawahir, I. S., Kuzman, K., Size effects in manufacturing of metallic components, CIRP Annuals-Manufacturing Technology, 58, 2, 566-587. (2009)
Xu, Z. T., Peng, L. F., Lai, X. M., Fu, M. W., Geo-metry and grain size effects on the forming limit of sheet metals in micro-scaled plastic deformation, Journal of Materials science and Engineering A, 611, 345-353. (2014)
Yan, S., Yang, H., Li, H., Yao, X., Microstructure evolution and flow localization characteristics of 5A06 alloy in high strain rate forming process, Procedia Engineering, 81, 1198-1203. (2014)
Zhuang, W. L., Simulation Analysis of Forming Limit of Sheet Metal by Using Finite Element Method. Department of Mechanical Engineering, National Cheng Kung University, Tainan, Taiwan, Master Thesis. (1990)
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