海洋工程结构单元入水砰击分析与仿真模拟
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摘要
结构物入水冲击问题广泛存在于船舶工业及海洋工程中,入水冲击的研究对于结构设计的重要性已经有70多年的历史。船舶在波涛中航行时,船艏、艉会频繁地与水面发生撞击,在结构上引起很大的瞬间压力,这种作用力可以导致船体和海洋结构物的严重损坏。因此,研究海洋结构物的入水过程中砰击载荷及其特性对确定船舶的设计载荷和保证船舶安全具有十分重要的现实意义。
本文的目的是运用ANSYS/LS-DYNA这一有限元显式非线性动力分析软件,对工程上常用剖面型式的二维船体结构入水问题进行仿真模拟,以此来分析这些结构在入水过程中的砰击载荷及其特性,以及结构的响应规律,主要包括如下内容:
1、通过前人的研究,了解到了国内外对海洋结构物入水问题的研究概况。并对现有的砰击理论进行了消化、吸收和整理,给出了二维平底体结构和二维楔形体结构入水的基本理论;
2、采用仿真的方法对二维平底体结构的入水冲击问题进行了分析,分析得到了刚性平底体结构入水过程中砰击面上的压力及其分布,并讨论了入水速度和结构质量对砰击压力的影响;在此基础上进一步分析了弹性效应(平底面厚度t、弹性模量E和弯曲刚度D)对弹性平底体结构入水过程中砰击压力和结构响应的影响;
3、采用仿真的方法对二维楔形体、U型体和球鼻艏体结构的入水问题进行了分析。分别给出了三种不同结构型式砰击面上的压力及其分布、流场内压力波云图和液面升高图,讨论了楔形体入水角度对砰击压力峰值的影响,并将U型体底面上砰击载荷变化规律与平底体结构进行对比,得到了一些有意义的结论。
The problem of water entry impact of the marine structure is widely existed in Naval Architecture and Ocean Engineering, and the research of water entry impact for structure design has been important for more than 70 years. When ships sail in the foul wave, both the bow and the stern would impact on water surface continually, and there will be great instantaneous pressure on structure surface which can lead to serious damage. So the research of impact pressure as well as it’s characteristic is practically important for structure design and safety.
In this thesis, the finite element software ANSYS/LS-DYNA is used to simulate two-dimensional water entry problem of marine structure in common use, and the analysis of impact pressure as well as the response of structure is done according to the simulation. Including:
1、According to prehuman’s research, we have known the general situation of water entry problem in and abroad, as well as digested and absorbed the existing theory. Then the basic theory of two-dimensional water entry problem of flat-bottom and wedge-shaped structure is given.
2、The two-dimensional water entry of flat-bottom marine structure is simulated, and the impact pressure as well as it’s distribution is gained. Then we discuss the effects of velocity and mass to impact pressure, and the effects of elasticity (including thickness of the flat bottom、elastic modul and flexual rigidity) to the response of structure.
3、The two-dimensional water entry of wedge-shaped、U-type marine structure and bulbous bow is simulated. We gain the impact pressure as well as it’s distribution, the pressure variety of liquid and the rise of free surface. Then we discuss the effects of angle to the peak impact pressure, and compare the pressure variety between flat-bottom and U-type structure. In the end, we gain a lot of significative conclusions.
本文的目的是运用ANSYS/LS-DYNA这一有限元显式非线性动力分析软件,对工程上常用剖面型式的二维船体结构入水问题进行仿真模拟,以此来分析这些结构在入水过程中的砰击载荷及其特性,以及结构的响应规律,主要包括如下内容:
1、通过前人的研究,了解到了国内外对海洋结构物入水问题的研究概况。并对现有的砰击理论进行了消化、吸收和整理,给出了二维平底体结构和二维楔形体结构入水的基本理论;
2、采用仿真的方法对二维平底体结构的入水冲击问题进行了分析,分析得到了刚性平底体结构入水过程中砰击面上的压力及其分布,并讨论了入水速度和结构质量对砰击压力的影响;在此基础上进一步分析了弹性效应(平底面厚度t、弹性模量E和弯曲刚度D)对弹性平底体结构入水过程中砰击压力和结构响应的影响;
3、采用仿真的方法对二维楔形体、U型体和球鼻艏体结构的入水问题进行了分析。分别给出了三种不同结构型式砰击面上的压力及其分布、流场内压力波云图和液面升高图,讨论了楔形体入水角度对砰击压力峰值的影响,并将U型体底面上砰击载荷变化规律与平底体结构进行对比,得到了一些有意义的结论。
The problem of water entry impact of the marine structure is widely existed in Naval Architecture and Ocean Engineering, and the research of water entry impact for structure design has been important for more than 70 years. When ships sail in the foul wave, both the bow and the stern would impact on water surface continually, and there will be great instantaneous pressure on structure surface which can lead to serious damage. So the research of impact pressure as well as it’s characteristic is practically important for structure design and safety.
In this thesis, the finite element software ANSYS/LS-DYNA is used to simulate two-dimensional water entry problem of marine structure in common use, and the analysis of impact pressure as well as the response of structure is done according to the simulation. Including:
1、According to prehuman’s research, we have known the general situation of water entry problem in and abroad, as well as digested and absorbed the existing theory. Then the basic theory of two-dimensional water entry problem of flat-bottom and wedge-shaped structure is given.
2、The two-dimensional water entry of flat-bottom marine structure is simulated, and the impact pressure as well as it’s distribution is gained. Then we discuss the effects of velocity and mass to impact pressure, and the effects of elasticity (including thickness of the flat bottom、elastic modul and flexual rigidity) to the response of structure.
3、The two-dimensional water entry of wedge-shaped、U-type marine structure and bulbous bow is simulated. We gain the impact pressure as well as it’s distribution, the pressure variety of liquid and the rise of free surface. Then we discuss the effects of angle to the peak impact pressure, and compare the pressure variety between flat-bottom and U-type structure. In the end, we gain a lot of significative conclusions.
引文
[1] T. Von Karman. The impact of seaplane floats during landing, National Advisory Committe for Aeronautics, Technical Memorandum,1929,321:2–8.
[2] H. Wagner. Uber stoss gleitvergange an oberflache von flussigkeiten, Zeitschrift f. ur Angewandte Mathematik und Mechanik,1932,12:192–215.
[3] W. H. Chu, H. N. Abramson. Hydrodynamic theories of ship slamming-review and extension, Journal of Ship Research,1961,9–21.
[4] R. E. D. Bishop, W. G. Price. Hydroelasticity of Ships, Cambridge University Press, Cambridge,1979.
[5] O. Belik, R. E. D. Bishop, W. G. Price. A simulation of ship responses due to slamming in irregular head sea, RINA,1983,125:237–253.
[6] J. Kvalsvold, O. Faltinsen. Hydroelastic modelling of wet deck slamming on multihull vessel, Journal of Ship Research,1995,39(3):225–239.
[7] R. Cointe. Free-surface flows closes to surface-piercing body, In: Miloh, T. (Eds.), Mathematical Approaches in Hydrodynamics, Society for Industrial and Applied Mathematics, Ph"aladelphia pp,1991,319–334.
[8] S. D. Howison, J. R. Ockendon, S. K. Wilson. Incompressible water-entry problems at small dead-rise angles. Journal of Fluid Mechanics,1991,222: 215-230.
[9] Z. N. Dobrovol’skaya. On some problems of similarity flowof fluid with a free surface, Journal Fluid Mechanics,1969,36:805–829.
[10] M. Greenhow. Wedge entry into initially calm water, Applied Ocean Research, 1987,9:214–223.
[11] L. E. Fraenkel, J. B. McLeod. Some results for the entry of a blunt wedge into water, Philosophical Transactions of the Royal Society of London A355,1997,523–535.
[12] X. Mei, Y. Liu, D. K. P. Yue. On the water impact of general two-dimensional sections, Applied Ocean Research,1999,21:1–15.
[13] R. Zhao, O. M. Faltinsen. Water entry of two-dimensional bodies, Journal of Fluid Mechanics,1993,246:593–612.
[14] A. Carcaterraa, E. Ciappi. Hydrodynamic shock of elastic structures impacting on the water: theory and experiments, Journal of Sound and Vibration,2004,271:411-439.
[15] A. Carcaterra, E. Ciappi, A. Iafrati, E. F. Campana. Shock spectral analysis of elastic systems impacting on the water surface. Journal of Sound and Vibration,2000,229(3):579-605.
[16] D. Battistin, A. Iafrati. Hydrodynamic loads during water entry of two-dimensional and axisymmetric bodies, Journal of Fluids and Structures,2003,17:633-664.
[17]王冰,叶天麒.边界元的耦合界面步进法分析物体撞水响应,航空学报,1999,18(5): 551-554.
[18] G. X. Wua, H. Sunb, Y. S. He. Numerical simulation and experimental study of water entry of a wedge in free fall motion, Journal of Fluids and Structures, 2004,19:277-289.
[19] G. X. Wu. Numerical simulation of water entry of twin wedges, Journal of Fluids and Structures,2006,22:99-108.
[20]卢炽华,何有声.二维弹性结构入水冲击过程中的流固耦合效应,力学学报,2000,32(2):129-140.
[21]钱勤,黄玉盈,王石刚,刘志宏,赵宇征,朱达善.任意的拉格朗日欧拉边界元-有限元混合法分析物体撞水响应,固体力学学报,1994,15(1):12-18.
[22]陈震.海洋结构物入水砰击载荷与响应研究.上海交通大学博士学位论文.上海交通大学图书馆.2005.
[23] KEN TAGAKI. Influence of elasticity on hydrodynamic impact problem[ J ]. J . Kansai Soc. N. A., Japan,1994,(222):97-106.
[24]黄震球,张文海.减小平底船底部砰击的试验研究.武汉造船工程学会年会论文集(下),1985,253-258.
[25]孙辉,卢炽华,何有声.二维楔形体冲击入水时的流固耦合响应的实验研究,水动力学研究与进展,2003,18(1):104-109.
[26]顾懋祥,程贯一,张效慈.平头旋转壳撞水水弹性效应的研究[J],水动力研究与进展,1991(6):42-51.
[27]岳亚丁.流固冲击压力和流固冲击下的结构动力屈曲.华中理工大学博士学位论文.华中科技大学图书馆.1992.
[28] R. Aithal, G. Steven Gipson. Instability of damped curved pipes,Journal of Engineering Mechanics,American Society of Civil Engineers116,1990,77-90.
[29]金伏生.入水冲击问题变分原理及其它,应用数学和力学,1992,13(6):543-552.
[30] S. Falch. A Numerical Study of Slamming of Two-dimensional Bodies, Dr. Thesis, Division of Marine Hydrodynamics, The Norwegian Institute of Technology, 1986.
[31]夏斌,陈震,肖熙.弹性平底海洋结构物入水冲击的仿真分析.中国海洋平台,2005,20(1):22-28.
[32]陈震,肖熙.平底结构砰击压力峰值分析,上海交通大学学报,2006,40(6):983-987.
[33]陈震,肖熙.平底结构砰击压力的分布,中国造船,2005,46(4):97-103.
[34]陈震,肖熙.空气垫在平底结构入水砰击中作用的仿真分析,上海交通大学学报,2005,39(5):670-673.
[35]陈震,肖熙.基于神经网络的平底结构砰击压力预报,海洋工程,2005,23(2):26-31.
[36]倪樵,李其申,黄玉盈.平底物体撞水响应分析,华中科技大学学报,2001,29(4):99-101.
[37] S. L. Chuang. Experiments on flat-bottom slamming [J]. Journal of Ship Research,1966,10(1):10-27.
[38] J. H. G. Verhagen. The impact of a flat plate on a water surface [J]. Journal of Ship Research,1967,12:211-223.
[39] Grant Lewison, W. M. Maclean. On the Cushioning of Water Impact by EntrappedAir [J], Journal of Ship Research,1968,6:116-130.
[40]李国钧,黄震球.平底物体对水面的斜向冲击,华中理工大学学报,1995,23(1):145-147.
[41]李世其,郑际嘉,岳亚丁.平底圆筒底部垂直撞水的实验及数值计算,航空学报,1996,17(3):265-272.
[42]黄震球,张文海.减小平底体砰击的试验研究.武汉造船工程学会年会论文集(下),1985:245-252.
[2] H. Wagner. Uber stoss gleitvergange an oberflache von flussigkeiten, Zeitschrift f. ur Angewandte Mathematik und Mechanik,1932,12:192–215.
[3] W. H. Chu, H. N. Abramson. Hydrodynamic theories of ship slamming-review and extension, Journal of Ship Research,1961,9–21.
[4] R. E. D. Bishop, W. G. Price. Hydroelasticity of Ships, Cambridge University Press, Cambridge,1979.
[5] O. Belik, R. E. D. Bishop, W. G. Price. A simulation of ship responses due to slamming in irregular head sea, RINA,1983,125:237–253.
[6] J. Kvalsvold, O. Faltinsen. Hydroelastic modelling of wet deck slamming on multihull vessel, Journal of Ship Research,1995,39(3):225–239.
[7] R. Cointe. Free-surface flows closes to surface-piercing body, In: Miloh, T. (Eds.), Mathematical Approaches in Hydrodynamics, Society for Industrial and Applied Mathematics, Ph"aladelphia pp,1991,319–334.
[8] S. D. Howison, J. R. Ockendon, S. K. Wilson. Incompressible water-entry problems at small dead-rise angles. Journal of Fluid Mechanics,1991,222: 215-230.
[9] Z. N. Dobrovol’skaya. On some problems of similarity flowof fluid with a free surface, Journal Fluid Mechanics,1969,36:805–829.
[10] M. Greenhow. Wedge entry into initially calm water, Applied Ocean Research, 1987,9:214–223.
[11] L. E. Fraenkel, J. B. McLeod. Some results for the entry of a blunt wedge into water, Philosophical Transactions of the Royal Society of London A355,1997,523–535.
[12] X. Mei, Y. Liu, D. K. P. Yue. On the water impact of general two-dimensional sections, Applied Ocean Research,1999,21:1–15.
[13] R. Zhao, O. M. Faltinsen. Water entry of two-dimensional bodies, Journal of Fluid Mechanics,1993,246:593–612.
[14] A. Carcaterraa, E. Ciappi. Hydrodynamic shock of elastic structures impacting on the water: theory and experiments, Journal of Sound and Vibration,2004,271:411-439.
[15] A. Carcaterra, E. Ciappi, A. Iafrati, E. F. Campana. Shock spectral analysis of elastic systems impacting on the water surface. Journal of Sound and Vibration,2000,229(3):579-605.
[16] D. Battistin, A. Iafrati. Hydrodynamic loads during water entry of two-dimensional and axisymmetric bodies, Journal of Fluids and Structures,2003,17:633-664.
[17]王冰,叶天麒.边界元的耦合界面步进法分析物体撞水响应,航空学报,1999,18(5): 551-554.
[18] G. X. Wua, H. Sunb, Y. S. He. Numerical simulation and experimental study of water entry of a wedge in free fall motion, Journal of Fluids and Structures, 2004,19:277-289.
[19] G. X. Wu. Numerical simulation of water entry of twin wedges, Journal of Fluids and Structures,2006,22:99-108.
[20]卢炽华,何有声.二维弹性结构入水冲击过程中的流固耦合效应,力学学报,2000,32(2):129-140.
[21]钱勤,黄玉盈,王石刚,刘志宏,赵宇征,朱达善.任意的拉格朗日欧拉边界元-有限元混合法分析物体撞水响应,固体力学学报,1994,15(1):12-18.
[22]陈震.海洋结构物入水砰击载荷与响应研究.上海交通大学博士学位论文.上海交通大学图书馆.2005.
[23] KEN TAGAKI. Influence of elasticity on hydrodynamic impact problem[ J ]. J . Kansai Soc. N. A., Japan,1994,(222):97-106.
[24]黄震球,张文海.减小平底船底部砰击的试验研究.武汉造船工程学会年会论文集(下),1985,253-258.
[25]孙辉,卢炽华,何有声.二维楔形体冲击入水时的流固耦合响应的实验研究,水动力学研究与进展,2003,18(1):104-109.
[26]顾懋祥,程贯一,张效慈.平头旋转壳撞水水弹性效应的研究[J],水动力研究与进展,1991(6):42-51.
[27]岳亚丁.流固冲击压力和流固冲击下的结构动力屈曲.华中理工大学博士学位论文.华中科技大学图书馆.1992.
[28] R. Aithal, G. Steven Gipson. Instability of damped curved pipes,Journal of Engineering Mechanics,American Society of Civil Engineers116,1990,77-90.
[29]金伏生.入水冲击问题变分原理及其它,应用数学和力学,1992,13(6):543-552.
[30] S. Falch. A Numerical Study of Slamming of Two-dimensional Bodies, Dr. Thesis, Division of Marine Hydrodynamics, The Norwegian Institute of Technology, 1986.
[31]夏斌,陈震,肖熙.弹性平底海洋结构物入水冲击的仿真分析.中国海洋平台,2005,20(1):22-28.
[32]陈震,肖熙.平底结构砰击压力峰值分析,上海交通大学学报,2006,40(6):983-987.
[33]陈震,肖熙.平底结构砰击压力的分布,中国造船,2005,46(4):97-103.
[34]陈震,肖熙.空气垫在平底结构入水砰击中作用的仿真分析,上海交通大学学报,2005,39(5):670-673.
[35]陈震,肖熙.基于神经网络的平底结构砰击压力预报,海洋工程,2005,23(2):26-31.
[36]倪樵,李其申,黄玉盈.平底物体撞水响应分析,华中科技大学学报,2001,29(4):99-101.
[37] S. L. Chuang. Experiments on flat-bottom slamming [J]. Journal of Ship Research,1966,10(1):10-27.
[38] J. H. G. Verhagen. The impact of a flat plate on a water surface [J]. Journal of Ship Research,1967,12:211-223.
[39] Grant Lewison, W. M. Maclean. On the Cushioning of Water Impact by EntrappedAir [J], Journal of Ship Research,1968,6:116-130.
[40]李国钧,黄震球.平底物体对水面的斜向冲击,华中理工大学学报,1995,23(1):145-147.
[41]李世其,郑际嘉,岳亚丁.平底圆筒底部垂直撞水的实验及数值计算,航空学报,1996,17(3):265-272.
[42]黄震球,张文海.减小平底体砰击的试验研究.武汉造船工程学会年会论文集(下),1985:245-252.