基于直角切削的高温合金John-Cook本构参数逆向识别
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摘要
随着计算机技术的发展,有限元仿真越来越广泛应用于切削加工中参数优化、切削机理研究等领域。John-Cook(J-C)本构模型是高温合金切削仿真的基础,关系到仿真结果的准确性与可靠性。针对传统的霍普金森杆试验(SplitHopkinson pressure bar, SHPB)获得的材料流动特性不能准确描述切削加工中材料的热塑性变形,其参数辨识的结果与实际切削状况有较大偏差的问题。提出了一种基于OXLEY切削理论和直角切削试验相结合的高温合金J-C本构参数逆向辨识方法。首先,基于不等分剪切区模型,给出了切削过程中应变、应变率、剪切区温度的分布规律;然后,针对传统车削与二维仿真模型无法直接比较的问题,设计并搭建了直角切削试验平台;最后,基于不等分剪切区模型与直角切削试验,分别计算了主剪切面流动应力的理论值和试验值,在给定本构参数约束条件下,以理论值与试验值差距最小为目标函数,通过遗传算法搜索本构参数的最优组合,实现了5个J-C本构参数(初始屈服应力A,应变强化系数B,应变率强化系数C,热软化系数m,加工硬化指数n)的最小二乘辨识。最后,将获得J-C本构参数的仿真值与试验结果进行对比,验证了逆向辨识方法的可行性与本构模型的准确性。
With the development of computer technology, finite element simulation is increasingly used in the fields of parameter optimization, cutting mechanism research etc. John-Cook(J-C) constitutive model,the foundation of superalloy cutting simulation, is immediately related to the accuracy and reliability of simulation results. Centring on the problem that the material flow characteristics obtained by traditional Split Hopkinson pressure bar(SHPB) test cannot accurately describe the thermoplastic deformation of materials in cutting process and the results of parameter identification are quite different from the actual cutting conditions, a reverse identification method for J-C constitutive parameters of superalloy based on OXLEY cutting theory and orthogonal cutting test is put forward. Firstly, considering the model of unequal shear zone, the distribution regularity of strain, strain rate and shear temperature in cutting process is brought out; secondly, in view of the impossibility about directly comparing traditional turning with its two-dimensional simulation model, an orthogonal cutting experimental platform is designed and built; thirdly, based on the unequal shear zone model and the orthogonal cutting test, the theoretical and experimental values of the flow stress on the main shear plane are calculated respectively, and the least square identification of the five J-C constitutive parameters(initial yield stress A, strain strengthening coefficient B, strain rate strengthening coefficient C, thermal softening coefficient m, work hardening index n) is realized by searching the optimal combination of constitutive parameters with genetic algorithm by setting the minimum gap between the theoretical value and the experimental value as the objective function under the constraint condition of the constitutive parameters to search for its optimal combination. Eventually, the comparison between the simulation results of J-C constitutive parameters and the experimental ones is made to verify the feasibility of the reverse identification method and the accuracy of the constitutive model.
With the development of computer technology, finite element simulation is increasingly used in the fields of parameter optimization, cutting mechanism research etc. John-Cook(J-C) constitutive model,the foundation of superalloy cutting simulation, is immediately related to the accuracy and reliability of simulation results. Centring on the problem that the material flow characteristics obtained by traditional Split Hopkinson pressure bar(SHPB) test cannot accurately describe the thermoplastic deformation of materials in cutting process and the results of parameter identification are quite different from the actual cutting conditions, a reverse identification method for J-C constitutive parameters of superalloy based on OXLEY cutting theory and orthogonal cutting test is put forward. Firstly, considering the model of unequal shear zone, the distribution regularity of strain, strain rate and shear temperature in cutting process is brought out; secondly, in view of the impossibility about directly comparing traditional turning with its two-dimensional simulation model, an orthogonal cutting experimental platform is designed and built; thirdly, based on the unequal shear zone model and the orthogonal cutting test, the theoretical and experimental values of the flow stress on the main shear plane are calculated respectively, and the least square identification of the five J-C constitutive parameters(initial yield stress A, strain strengthening coefficient B, strain rate strengthening coefficient C, thermal softening coefficient m, work hardening index n) is realized by searching the optimal combination of constitutive parameters with genetic algorithm by setting the minimum gap between the theoretical value and the experimental value as the objective function under the constraint condition of the constitutive parameters to search for its optimal combination. Eventually, the comparison between the simulation results of J-C constitutive parameters and the experimental ones is made to verify the feasibility of the reverse identification method and the accuracy of the constitutive model.
引文
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[18]MALAKIZADI A,CEDERGREN S,SURREDDI K B,et al.A methodology to evaluate the machinability of Alloy 718 by means of FE simulation[C]//International Conference on Advanced Manufacturing Engineering and Technologies,2013,95-106.
[19]PRETE A D,FILICE L,UMBRELLO D.Numerical simulation of machining nickel-based alloys[J].Procedia CIRP,2013,8:540-545.
[20]HE X,CHEN G,WANG T.Analysis of the temperature and residual stress field in the turning cutting of superalloy GH4169[J].Mechanical Science&Technology for Aerospace Engineering,2011,30(12):2116-2115.
[2]OXLEY P L B.The mechanics of machining:An analytical approach to assessing machinability[M].Chichester:Ellis Horwood Publisher,1989
[3]彭鸿博,张宏建.金属材料本构模型的研究进展[J].机械工程材料,2012,36(3):5-11.PENG Hongbo,ZHANG Hongjian.Research development of the constitutive models of metal materials[J].Materials for Mechanical Engineering,2012,36(3):5-11.
[4]孔金星,陈辉,何宁,等.纯铁材料动态力学性能测试及本构模型[J].航空学报,2014,35(7):2063-2071.KONG Jinxing,CHEN Hui,HE Ning,et al.Dynamic mechanical property tests and constitutive model of pure iron material[J].Acta Aeronautica Et Astronautica Sinica,2014,35(7):2063-2071.
[5]SHROT A.,B?KER M.Determination of Johnson-Cook parameters from machining simulations[J].Computational Materials Science,2012,52(1):298-304.
[6]PUJANA J,ARRAZOLA P J,M’SAOUBI R,et al.Analysis of the inverse identification of constitutive equations applied in orthogonal cutting process[J].International Journal of Machine Tools&Manufacture,2007,47(14):2153-2161.
[7]GR?ZKA M,JANISZEWSKI J,KRUSZKA L,et al.Identification methods of parameters for Johnson-Cook constitutive equation-comparison[J].Applied Mechanics&Materials,2014,566:97-103.
[8]DAOUD M,JOMAA W,CHATELAIN J F,et al.Amachining-based methodology to identify material constitutive law for finite element simulation[J].International Journal of Advanced Manufacturing Technology,2015,77(9-12):2019-2033.
[9]KLOCKE F,LUNG D,BUCHKREMER S.Inverse identification of the constitutive equation of inconel 718and AISI 1045 from FE machining simulations[C]//14th CIRP Conference on Modeling of Machining Operations,2013:212-217.
[10]SHI B,ATTIA H,TOUNSI N.Identification of material constitutive laws for machining-Part II:Generation of the constitutive data and validation of the constitutive law[J].Journal of Manufacturing Science&Engineering,2010,132(5):1009-1017.
[11]MOUFKI A,DUDZINSKI D,MOLINARI A,et al.Thermoviscoplastic modelling of oblique cutting:Forces and chip flow predictions[J].International Journal of Mechanical Sciences,2000,42(6):1205-1232.
[12]SHI B,ATTIA H,TOUNSI N.Identification of material constitutive laws for machining-part I:An analytical model describing the stress,strain,strain rate,and temperature fields in the primary shear zone in orthogonal metal cutting[J].Journal of Manufacturing Science&Engineering,2010,132(5):998-1008.
[13]TOUNSI N,VINCENTI J,OTHO A,et al.From the basic mechanics of orthogonal metal cutting toward the identification of the constitutive equation[J].International Journal of Machine Tools&Manufacture,2002,42(12):1373-1383.
[14]DEMANGE J J,PRAKASH V,PEREIRA J M.Effects of material microstructure on blunt projectile penetration of a nickel-based super alloy[J].International Journal of Impact Engineering,2009,36(8):1027-1043.
[15]WANG X,HUANG C,ZOU B,et al.Dynamic behavior and a modified Johnson-Cook constitutive model of Inconel 718at high strain rate and elevated temperature[J].Materials Science&Engineering A,2013,580(37):385-390.
[16]LORENTZON J,J?RVSTR?T N,JOSEFSON B L.Modelling chip formation of alloy 718[J].Journal of Materials Processing Technology,2009,209(10):4645-4653.
[17]OZEL T,LLANOS I,SORIANO J,et al.3D finite element modelling of chip formation process for machining inconel 718:Comparison of FE software predictions[J].Machining Science&Technology,2011,15(1):21-46.
[18]MALAKIZADI A,CEDERGREN S,SURREDDI K B,et al.A methodology to evaluate the machinability of Alloy 718 by means of FE simulation[C]//International Conference on Advanced Manufacturing Engineering and Technologies,2013,95-106.
[19]PRETE A D,FILICE L,UMBRELLO D.Numerical simulation of machining nickel-based alloys[J].Procedia CIRP,2013,8:540-545.
[20]HE X,CHEN G,WANG T.Analysis of the temperature and residual stress field in the turning cutting of superalloy GH4169[J].Mechanical Science&Technology for Aerospace Engineering,2011,30(12):2116-2115.