激光表面强化数值仿真及应用
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摘要
随着计算机科学、数值计算方法的快速发展,能够建立合适的数值模型,描述材料激光强化的物理过程。只要通过少量的实验验证理论模型及数值模拟计算的准确性,就可以利用计算机对大量的实际材料热处理过程进行准确的数值模拟。这样就实现了基于计算机数值模拟的虚拟材料激光表面强化过程。通过大量的计算机数值模拟计算,可以建立材料热处理工艺参数与材料热处理后性能的定量关系。这些数值模拟计算结果可以用于优化热处理工艺参数。
基于多物理场耦合理论,采用有限元方法,建立了金属材料激光表面强化数值模型。数值模拟研究在激光作用下材料的温度场和流场分布,分析相变硬化区的宽度及深度与激光参数之间的定量关系;得到了激光产生熔池的温度场、熔池速度场及熔池的形状。数值模拟结果为激光加工的实际应用提供理论依据。论文主要包括以下内容:
建立了激光辐照45CrMo钢的有限元分析模型,对激光相变硬化过程的温度场和激光相变硬化区的宽度及深度进行了数值模拟,详细讨论了激光功率和扫描速度变化分别对硬化层层深及层宽影响的敏感性。研究结果表明:激光功率变化对层深与层宽的影响明显大于扫描速度变化所产生的影响。
基于多物理场耦合理论,数值模拟研究了激光与金属铝相互作用的温度场和流场,求解热传递与层流耦合的PDE方程。数值模拟中选取符合实际光束分布的激光参数,考虑了自然对流、表面张力梯度引起的Marangoni对流和热物理参数依赖于温度的实际情况.针对(?)γ/(?)T＜0、(?)γ/(?)T＞0、(?)γ/(?)T=0三种不同的表面张力梯度,计算得到了激光产生熔池的温度场、熔池速度场及熔池的形状.数值结果表明,熔池中Marangoni对流换热对熔池形貌影响较大,在激光加工过程中不可忽略.
With the development computer science, finite element method and finite difference method, it is possible to set up a model to describe the physical processes of laser strengthening processes. If some experimental works were carried out to demonstrate the accuracy of modelling and simulation results, then,laser strengthening processes can been accurately simulated by computer; so the virtual laser strengthening processes can been realized based on computer simulation. The relationship between the properties of materials and the technical parameters heat treatment processes can been set up by a large amount of computer numerical simulation works. These numerical simulation results are useful to optimize the technical parameters Laser heat treatment.
The theory of multi-physics coupling and finite element method are used to set up a model to describe the physical processes of laser strengthening processes. Then, the temperature field and stress field of these physical processes can been calculated accurately. The quantitative relationship between the laser parameters between laser parameters with the width and depth of harding area is Analyzed. The temperature distribution, the molten pool shapes and fluid flow have been computed,these numerical simulation results can provide the theoretical basis for the practical application of laser strengthening processing.
The main work and results of this master dissertation are as follow:
The finite element models used for modeling the distribution of temperature field in 45CrMo due to laser strengthening were created by using COMSOL software. The temperature field during laser transformation hardening process and the width and depth of laser transformation hardening zone were calculated. Discussed the sensitivity level of hardened layers effected by laser power and laser scanning speed. The results show that: Effects of changes in laser power on the layer depth is significantly greater than the changes in scanning speed.
An axisymmetric numerical model of a laser-induced molten pool has been developed for a laser interaction with Al plate. Based on mixture continuity equations, the coupled PDE of a laminar fluid flow and heat transfer is solved by the finite element method, taking into account the coupled effects of buoyancy, Marangoni forces and the thermophysical characteristics with temperature variations. The temperature distribution, the molten pool shapes and fluid flow have been computed for three calculation cases: (?)γ/(?)T<0、(?)γ/(?)T>0、(?)γ/(?)T=0, corresponding to three different surface tension gradients. The numerical results showed that fluid flow has a significant effect on the shape of the molten pool and can not be ignored during laser processing.
基于多物理场耦合理论,采用有限元方法,建立了金属材料激光表面强化数值模型。数值模拟研究在激光作用下材料的温度场和流场分布,分析相变硬化区的宽度及深度与激光参数之间的定量关系;得到了激光产生熔池的温度场、熔池速度场及熔池的形状。数值模拟结果为激光加工的实际应用提供理论依据。论文主要包括以下内容:
建立了激光辐照45CrMo钢的有限元分析模型,对激光相变硬化过程的温度场和激光相变硬化区的宽度及深度进行了数值模拟,详细讨论了激光功率和扫描速度变化分别对硬化层层深及层宽影响的敏感性。研究结果表明:激光功率变化对层深与层宽的影响明显大于扫描速度变化所产生的影响。
基于多物理场耦合理论,数值模拟研究了激光与金属铝相互作用的温度场和流场,求解热传递与层流耦合的PDE方程。数值模拟中选取符合实际光束分布的激光参数,考虑了自然对流、表面张力梯度引起的Marangoni对流和热物理参数依赖于温度的实际情况.针对(?)γ/(?)T＜0、(?)γ/(?)T＞0、(?)γ/(?)T=0三种不同的表面张力梯度,计算得到了激光产生熔池的温度场、熔池速度场及熔池的形状.数值结果表明,熔池中Marangoni对流换热对熔池形貌影响较大,在激光加工过程中不可忽略.
With the development computer science, finite element method and finite difference method, it is possible to set up a model to describe the physical processes of laser strengthening processes. If some experimental works were carried out to demonstrate the accuracy of modelling and simulation results, then,laser strengthening processes can been accurately simulated by computer; so the virtual laser strengthening processes can been realized based on computer simulation. The relationship between the properties of materials and the technical parameters heat treatment processes can been set up by a large amount of computer numerical simulation works. These numerical simulation results are useful to optimize the technical parameters Laser heat treatment.
The theory of multi-physics coupling and finite element method are used to set up a model to describe the physical processes of laser strengthening processes. Then, the temperature field and stress field of these physical processes can been calculated accurately. The quantitative relationship between the laser parameters between laser parameters with the width and depth of harding area is Analyzed. The temperature distribution, the molten pool shapes and fluid flow have been computed,these numerical simulation results can provide the theoretical basis for the practical application of laser strengthening processing.
The main work and results of this master dissertation are as follow:
The finite element models used for modeling the distribution of temperature field in 45CrMo due to laser strengthening were created by using COMSOL software. The temperature field during laser transformation hardening process and the width and depth of laser transformation hardening zone were calculated. Discussed the sensitivity level of hardened layers effected by laser power and laser scanning speed. The results show that: Effects of changes in laser power on the layer depth is significantly greater than the changes in scanning speed.
An axisymmetric numerical model of a laser-induced molten pool has been developed for a laser interaction with Al plate. Based on mixture continuity equations, the coupled PDE of a laminar fluid flow and heat transfer is solved by the finite element method, taking into account the coupled effects of buoyancy, Marangoni forces and the thermophysical characteristics with temperature variations. The temperature distribution, the molten pool shapes and fluid flow have been computed for three calculation cases: (?)γ/(?)T<0、(?)γ/(?)T>0、(?)γ/(?)T=0, corresponding to three different surface tension gradients. The numerical results showed that fluid flow has a significant effect on the shape of the molten pool and can not be ignored during laser processing.
引文
[1]王家金.激光加工技术[M].北京:中国计量出版社,1992
[2]Rappaz M,.Carrupt B,Zimmermann M,et al.Eutectic solidification in the laser treatment of materials[J].Helv Phys ACTA,1987,60:924-936
[3]Xie,Kar.Mathematical modeling of melting during laser materials processing[J].AppLPhys,1997,81(7):3015-3022
[4]Allan H.Clauer,David F.Lahrman.Laser shock processing as a surface enhancement process[J].Key Engineering Materials,2001,197:121-144
[5]鲁金忠,张永康,孔德军等.激光冲击强化对TC4电子束焊缝机械性能的影响[J].江苏大学学报(自然科学版),2006,27(3):207-210.
[6]时党勇,李裕春,张胜明.基于ANSYS/LS-DYNA8.1进行显式动力分析[M].北京:清华大学出版社,2005.
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[8]J.B.Leblond,G:Mottet,J.Devaux.Mathematical models of anisothermal phase transformations in steels and predicted plastic behaviour[j].Materials Science and Technology,1985,1:p815
[10]T.Inoue,Zhigang.Coupling between stress,temperature,and metallic structures during processes involving phase transformations[J].Materials Science and Technology,1985,1:p845
[11]D.Y.Ju et al,Simulation of quenching-tempering process based on metallo-thermo-mechanics [J].Soc.Mater.Sci.Jpn.1996,45(6):p643
[12]S.Sjostrom,Interactionsand constitutive models for calculating quench stress in steel[J],Mater.Sci.Tech.1985,1:p823
[13]A.J.Fletcher,C.Lewis.Effect of free edge on thermal stresses in quenched steel plates[J].Materials Science and Technology,1985,1:p780
[14]Y.Nagasaka,J.K.Brimacombe,E.B.Hawbolt,LV.Samarasekera.Mathematical model of phasetransformations and elasto-plastic stress in the water spray quenching of steel bars[J].Metallurgical Transactions A,1993,24:p795
[15]T.Reti,Z.Fried,LFelde,Computer simulation of steel quenching process using a multi-phase transformation model[J].Computational Materals Science,2001,22:p261
[16]袁文庆,潘健生等,工件加热三维非稳态温度场的计算机模拟[J],金属热处理学报,1991,11(6):p35
[17]田东,胡明娟,潘健生等,T8钢淬火过程三维温度场计算及实验[J],上海交通大学学报1998,32(2):p109
[18]张永康,周立春,任旭东,李扬,鲁金忠.激光冲击TC4残余应力场的试验及有限元分析[J].江苏大学学报(自然科学版),2009,30(1):10-13
[19]张永康,戴希敏,蔡兰.激光冲击强化力学效应的数学模型[J].应用激光,1999,19(3):67-73
[20]任旭东,张永康,周建忠等.航空钛合金的激光冲击研究[J].华中科技大学学报,2007,35:150-152
[21]胡永祥,姚振强 胡俊.激光冲击强化残余应力场的数值仿真分析[J].中国激光,2006,33(6):846-851
[22]C.Hu and T.N.Baker,Prediction of laser transformation model[J].Acta metal.mater,1995,43:p3563
[23]姚善长.圆柱体工件激光相变硬化过程的理论研究[J],中国激光,1987 14(6):p321
[24]周南,乔登江.脉冲束辐照材料动力学[M].北京:国防工业出版社.2002.
[25]M.Davis et al.Heat Hardening of Metal Surface with A Scanning Laser Beam[J].Beamed.GRA.1984,84:19
[26]刘江龙等.高能束热处理[J].机械工业出版社,1997.8
[27]曾大文,谢长生.激光熔覆温度场和流场数值模拟研究现状和发展趋势[J],材料科学与工程,Vol.15,No.41997
[28]Y.K.Zhang,Y.Y.Gu,X.Q.Zhang et al.Study of the mechanism of overlays acting on laser shock waves[J].J.Appl.Phys,2006,10:161
[29]姚国凤.激光熔凝加工中温度场的数值模拟.博士学位论文.中国科学院力学研究所.
[30]王既成,邵敏.有限单元法基本原理和数值方法[M].清华大学出版社,1997.3
[31]聂铁军等,数值计算方法[M],西北工业大学出版社,1990.6
[32]C.L.Chan,J.Mazumder and M.M.Chen,Effect of surface tension gradient driven convection [J].Appl.Phys.1988,pp.6166-6174
[33]O.Manca,B.Morrone,and V.Naso,Quasi-steady-state three-dimensional temperature distribution induced by a moving circular Gaussian heat source in finite depth solid[J],Int.J.Heat mass trasfer 1995,Vol.38,No.7,pp.1305-1315.
[34]A.F.A.Hoaldley et al,Int.J.Meth.Heat Fluid Flow,1994;4:61
[35]X.P.Lin,X.F.Peng,B.X.Wang and D.M.Christopher,Influence of Marangoni flow on the melting process[J].Porg.Nat.Sci.7(1997),pp.616-623.
[36]Reed N H,Hill T R.Triangle mesh methods for Neutron transport equation[R].Los Alamos Scientific Laboratory,Report LAUR-73-497,1973
[37]Cockburn B,Shu C W.The Runge-Kutta local projection P-discontinuous Galerkin method for scalar comservation law[J].MAN1991,337:337-361
[38]R.C.Reed,Z.Shen,J.M.Robinson,et al..Laser transformation hardening of steel:effects of beam mode,beam size,and composition.Materials Science and Technology,1999,v15:109-118
[39]李俊昌,R.谢瓦利埃,J.M.兰热.激光热处理温度场及相变硬化带的快速计算[J].中国激光,1997,VolA24,No.7
[40]管一弘等.激光淬火温度场及材料性能的数值模拟[J].中国激光,1999年3月,第26卷,第三期.
[41]M.Davis et al.Heat Hardening of Metal Surface with A Scanning.Laser Beam[J].Beamed.GRA.1984,84:19
[42]陈继明 许向阳 肖荣诗.激光现代制造技术[M].北京:国防工业出版社,2007
[43]E.M.Sparrow,S.V.Patankar,S.Ramadhyni,Analysis of melting in the presence of natural convection in the melted region[J].ASME J.Heat Transfer 99(1977) 520-526
[44]S.Kou,Y.H.Wang.Three-dimensional convection in laser melted pools[J].Metall.Trans.A,1986,17(A):2265-2270
[45]Modest,M.F.and Abakians,H.,1986,Heat Conduction in a Moving Semi-Infinite Solid Subjected to Pulsed Laser Beam[J].Heat Transfer,108:597-601.
[46]Shankar,V.and Gnamamuthu,D.,1987,Computational Simulation of Laser Heat Processing of Materials[J].Therm.Heat Transfer,1:182-3.
[47]X.F.Peng,X.P.Lin,D.J.Lee,Y.Yan,B.X.Wang.Effects of initial molten pool and Marangoni flow on solid melting[J].International Journal of Heat and Mass Transfer,Volume 44,Issue 2,January 2001,pp.457-470
[48]M.Van Elsen,M.Baelmans Solutions for modelling moving heat sources in a semi-infinite medium and applications to laser material processing[J].International Journal of Heat and Mass Transfer.50(2007).pp.4872--4882
[49]X.P.Lin,X.F.Peng,B.X.Wang and D.M.Christopher,Influence of Marangoni flow on the melting process[J].Porg.Nat.Sci.7(1997),pp.616-623.
[50]M.Van Elsen,M.Baelmans Solutions for modelling moving heat sources in a semi-infinite medium and applications to laser material processing[j].International Journal of Heat and Mass Transfer,2007,pp.4872-4882
[51]X.P.Lin,X.F.Peng,B.X.Wang and D.M.Christopher,Influence of Marangoni flow on the melting process[J].Porg.Nat.Sci.7(1997),pp.616-623.
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[53]李俊昌 激光衍射及热作用计算[M]北京:科学出版社,1991
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[2]Rappaz M,.Carrupt B,Zimmermann M,et al.Eutectic solidification in the laser treatment of materials[J].Helv Phys ACTA,1987,60:924-936
[3]Xie,Kar.Mathematical modeling of melting during laser materials processing[J].AppLPhys,1997,81(7):3015-3022
[4]Allan H.Clauer,David F.Lahrman.Laser shock processing as a surface enhancement process[J].Key Engineering Materials,2001,197:121-144
[5]鲁金忠,张永康,孔德军等.激光冲击强化对TC4电子束焊缝机械性能的影响[J].江苏大学学报(自然科学版),2006,27(3):207-210.
[6]时党勇,李裕春,张胜明.基于ANSYS/LS-DYNA8.1进行显式动力分析[M].北京:清华大学出版社,2005.
[7]R.Schroder.Influences on development of thermal and residual stresses in quenched steel cylinders of different dimensions[J].Materials Science and Technology,1985,1:p754
[8]J.B.Leblond,G:Mottet,J.Devaux.Mathematical models of anisothermal phase transformations in steels and predicted plastic behaviour[j].Materials Science and Technology,1985,1:p815
[10]T.Inoue,Zhigang.Coupling between stress,temperature,and metallic structures during processes involving phase transformations[J].Materials Science and Technology,1985,1:p845
[11]D.Y.Ju et al,Simulation of quenching-tempering process based on metallo-thermo-mechanics [J].Soc.Mater.Sci.Jpn.1996,45(6):p643
[12]S.Sjostrom,Interactionsand constitutive models for calculating quench stress in steel[J],Mater.Sci.Tech.1985,1:p823
[13]A.J.Fletcher,C.Lewis.Effect of free edge on thermal stresses in quenched steel plates[J].Materials Science and Technology,1985,1:p780
[14]Y.Nagasaka,J.K.Brimacombe,E.B.Hawbolt,LV.Samarasekera.Mathematical model of phasetransformations and elasto-plastic stress in the water spray quenching of steel bars[J].Metallurgical Transactions A,1993,24:p795
[15]T.Reti,Z.Fried,LFelde,Computer simulation of steel quenching process using a multi-phase transformation model[J].Computational Materals Science,2001,22:p261
[16]袁文庆,潘健生等,工件加热三维非稳态温度场的计算机模拟[J],金属热处理学报,1991,11(6):p35
[17]田东,胡明娟,潘健生等,T8钢淬火过程三维温度场计算及实验[J],上海交通大学学报1998,32(2):p109
[18]张永康,周立春,任旭东,李扬,鲁金忠.激光冲击TC4残余应力场的试验及有限元分析[J].江苏大学学报(自然科学版),2009,30(1):10-13
[19]张永康,戴希敏,蔡兰.激光冲击强化力学效应的数学模型[J].应用激光,1999,19(3):67-73
[20]任旭东,张永康,周建忠等.航空钛合金的激光冲击研究[J].华中科技大学学报,2007,35:150-152
[21]胡永祥,姚振强 胡俊.激光冲击强化残余应力场的数值仿真分析[J].中国激光,2006,33(6):846-851
[22]C.Hu and T.N.Baker,Prediction of laser transformation model[J].Acta metal.mater,1995,43:p3563
[23]姚善长.圆柱体工件激光相变硬化过程的理论研究[J],中国激光,1987 14(6):p321
[24]周南,乔登江.脉冲束辐照材料动力学[M].北京:国防工业出版社.2002.
[25]M.Davis et al.Heat Hardening of Metal Surface with A Scanning Laser Beam[J].Beamed.GRA.1984,84:19
[26]刘江龙等.高能束热处理[J].机械工业出版社,1997.8
[27]曾大文,谢长生.激光熔覆温度场和流场数值模拟研究现状和发展趋势[J],材料科学与工程,Vol.15,No.41997
[28]Y.K.Zhang,Y.Y.Gu,X.Q.Zhang et al.Study of the mechanism of overlays acting on laser shock waves[J].J.Appl.Phys,2006,10:161
[29]姚国凤.激光熔凝加工中温度场的数值模拟.博士学位论文.中国科学院力学研究所.
[30]王既成,邵敏.有限单元法基本原理和数值方法[M].清华大学出版社,1997.3
[31]聂铁军等,数值计算方法[M],西北工业大学出版社,1990.6
[32]C.L.Chan,J.Mazumder and M.M.Chen,Effect of surface tension gradient driven convection [J].Appl.Phys.1988,pp.6166-6174
[33]O.Manca,B.Morrone,and V.Naso,Quasi-steady-state three-dimensional temperature distribution induced by a moving circular Gaussian heat source in finite depth solid[J],Int.J.Heat mass trasfer 1995,Vol.38,No.7,pp.1305-1315.
[34]A.F.A.Hoaldley et al,Int.J.Meth.Heat Fluid Flow,1994;4:61
[35]X.P.Lin,X.F.Peng,B.X.Wang and D.M.Christopher,Influence of Marangoni flow on the melting process[J].Porg.Nat.Sci.7(1997),pp.616-623.
[36]Reed N H,Hill T R.Triangle mesh methods for Neutron transport equation[R].Los Alamos Scientific Laboratory,Report LAUR-73-497,1973
[37]Cockburn B,Shu C W.The Runge-Kutta local projection P-discontinuous Galerkin method for scalar comservation law[J].MAN1991,337:337-361
[38]R.C.Reed,Z.Shen,J.M.Robinson,et al..Laser transformation hardening of steel:effects of beam mode,beam size,and composition.Materials Science and Technology,1999,v15:109-118
[39]李俊昌,R.谢瓦利埃,J.M.兰热.激光热处理温度场及相变硬化带的快速计算[J].中国激光,1997,VolA24,No.7
[40]管一弘等.激光淬火温度场及材料性能的数值模拟[J].中国激光,1999年3月,第26卷,第三期.
[41]M.Davis et al.Heat Hardening of Metal Surface with A Scanning.Laser Beam[J].Beamed.GRA.1984,84:19
[42]陈继明 许向阳 肖荣诗.激光现代制造技术[M].北京:国防工业出版社,2007
[43]E.M.Sparrow,S.V.Patankar,S.Ramadhyni,Analysis of melting in the presence of natural convection in the melted region[J].ASME J.Heat Transfer 99(1977) 520-526
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