基于反向步长递减算法铝厚板预拉伸夹持区的预测方法
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摘要
预拉伸是消除铝合金板材内淬火残余应力的主要方法,但拉伸机夹钳对板材两端的夹持不仅影响着板材端部残余应力的消除效果,而且还涉及到拉伸后板材的锯切量、成材率等问题。因此,通过研究铝合金板材预拉伸本构模型、边界条件、失效准则等关键技术,建立了极限下压量和滑移因子的有限元分析方法。其次,通过构造初始夹持长度的计算函数,以一定步长正向从初始夹持长度继续取值,根据当前值与上一次取值之间滑移因子的差异,确定下一次取值的步长及其方向;若滑移因子相同则以相同步长继续正向取值,否则以递减的步长反向取值,直至步长的绝对值在阈值范围之内,构建最小夹持长度反向步长递减的确定算法,以此获得板材厚度、伸长率为输入的神经网络训练样本。借助神经网络的非线性映射能力,通过有限组的训练样本,构建了最小夹持长度的神经网络预测模型。将预测值与相应的有限元仿真值进行比较,结果表明预测误差在5%以内,进一步验证建立的工件变形预测模型具有合理性。
Pre-stretching is the main method to eliminate the residual stress in aluminum alloy plate. But the holding of stretching machine clampers on the two ends of the plate can affect the cutting volume and yield of prestretched plate, as well as the elimination of residual stresses in end of plate. Therefore, by investigating the crucial technologies for the pre-stretching of aluminum alloy plate, including the constitutive model, boundary condition, failure criterion, as so on, the finite element analysis method is established for the limited pressure and slip factor. And then, while the function of initial holding length is constructed properly, the sum of the current holding length with a certain step can be taken as the next holding length. Thus, when the slip factors between the current holding length and the last one are calculated, the difference of the two can be judged. If the two is the same, the next holding length increases with the same step along the same direction. Otherwise, the next holding length decreases with the diminishing step along the opposite direction. The difference of the slip factor of current holding length with last holding length is iteratively validated until the absolute value of the step is not more than the given threshold value. Thus, the diminishing step algorithm with opposite direction of the minimum holding length can be suggested to obtain the neural network training samples with the thickness of the plate and the stretch rate as input. With the nonlinear mapping of neural network, a neural network prediction model of the minimum holding length is established by the finite groups of training samples. By comparing the predicted value with the corresponding finite element simulation, it shows that the prediction error is less than 5%. Obviously, the proposed diminishing step algorithm with opposite direction is reasonable to holding area prediction of aluminum alloy thick plate for pre-stretching processes.
Pre-stretching is the main method to eliminate the residual stress in aluminum alloy plate. But the holding of stretching machine clampers on the two ends of the plate can affect the cutting volume and yield of prestretched plate, as well as the elimination of residual stresses in end of plate. Therefore, by investigating the crucial technologies for the pre-stretching of aluminum alloy plate, including the constitutive model, boundary condition, failure criterion, as so on, the finite element analysis method is established for the limited pressure and slip factor. And then, while the function of initial holding length is constructed properly, the sum of the current holding length with a certain step can be taken as the next holding length. Thus, when the slip factors between the current holding length and the last one are calculated, the difference of the two can be judged. If the two is the same, the next holding length increases with the same step along the same direction. Otherwise, the next holding length decreases with the diminishing step along the opposite direction. The difference of the slip factor of current holding length with last holding length is iteratively validated until the absolute value of the step is not more than the given threshold value. Thus, the diminishing step algorithm with opposite direction of the minimum holding length can be suggested to obtain the neural network training samples with the thickness of the plate and the stretch rate as input. With the nonlinear mapping of neural network, a neural network prediction model of the minimum holding length is established by the finite groups of training samples. By comparing the predicted value with the corresponding finite element simulation, it shows that the prediction error is less than 5%. Obviously, the proposed diminishing step algorithm with opposite direction is reasonable to holding area prediction of aluminum alloy thick plate for pre-stretching processes.
引文
[1]韩念梅,张新明,刘胜胆,宋丰轩.预拉伸对7050铝合金断裂韧性的影响[J].中国有色金属学报,2010,20(11):2088-2093.HAN Nian-mei,ZHANG Xin-ming,LIU Sheng-dan,SONG Feng-xuan.Effect of prestretching on fracture toughness of 7050aluminum alloy[J].The Chinese Journal of Nonferrous Metals,2010,20(11):2088-2093.
[2]秦国华,林锋,左敦稳.基于材料非均匀性的铝厚板预拉伸残余应力的预测方法[J].中国有色金属学报,2015,25(3):1-8.QIN Guo-hua,LIN Feng,ZUO Dun-wen.Prediction approach to residual stresses distribution in aluminum alloy pre-stretched thick plate based on material non-uniformity[J].The Chinese Journal of Nonferrous Metals,2015,25(3):1-8.
[3]林高用.高性能7x75系铝合金厚板加工技术相关基础研究[M].长沙:中南大学,2006.LIN Gao-yong.Effect of pre-ageing temperature and retrogression heating rate on microstructure and properties of7055 aluminium alloy[M].Changsha:Central South University,2006.
[4]王祝堂.对当前铝厚板热轧与大挤压型材项目投资热的分析[J].世界有色金属,2012(1):58-60.WANG Zhu-tang.Analysis of current investment boom for hot rolling and large extrusion of aluminum alloy thick plates[J].World Nonferrous Metals,2012(1):58-60.
[5]ZHANG S Y,WU Y X,GONG H.A modeling of residual stress in stretched aluminum alloy plate[J].Journal of Materials Processing Technology,2012,212(11):2463-2473.
[6]王中秋.航空整体结构件加工变形滚压校正理论及方法研究[D].济南:山东大学,2009.WANG Zhong-qiu.Study on theory and approach for correcting aerospace monolithic component due to machining distortion using rolling method[D].Jinan:Shandong University,2009.
[7]宋寒,杨吟飞,陈波,郑晓伟.7055-T7751铝合金预拉伸板内部残余应力分布评估[J].机械制造与自动化,2016,45(1):18-21.SONG Han,YANG Yin-fei,CHEN Bo,ZHENG Xiao-wei.Evaluation of residual stress in depth profile of 7055-T7751pre-stretched aluminum alloy plate[J].Machine Building&Automation,2016,45(1):18-21.
[8]郑林,车路长,张津,张鹏程,何长光,彭正坤,肖勇,封先河,朱蕾.预拉伸厚铝板内部残余应力与晶粒取向均匀性的研究[J].精密成形工程,2014,6(5):50-58.ZHANG Lin,CHE Lu-chang,ZHANG Jin,ZHANG Peng-cheng,HE Chang-guang,PENG Zheng-kun,XIAO Yong,FENG Xian-he,ZHU Lei.Internal residual stress and texture homogenization in pre-stretched aluminum alloy plate[J].Journal of Netshape Forming Engineering,2014,6(5):50-58.
[9]龚海,吴运新,廖凯.预拉伸对7075铝合金厚板残余应力分布的影响[J].材料热处理学报,2009,30(6):202-205.GONG Hai,WU Yun-xin,LIAO Kai.Influence of pre-stretching on residual stress distribution in 7075 aluminum alloy thick plates[J].Transactions of Materials and Heat Treatment,2009,30(6):202-205.
[10]袁望姣,吴运新.基于预拉伸工艺的铝合金厚板残余应力消除机理[J].中南大学学报(自然科学版),2011,42(8):2303-2308.YUAN Wang-jiao,WU Yun-xin.Mechanics about eliminating residual stress of aluminum alloy thicken-plates based on pre-stretching technology[J].Journal of Central South University(Science and Technology),2011,42(8):2303-2308.
[11]朱才朝,罗家元,李大峰,丁华峰,钟渝.7075铝合金板预拉伸工艺研究[J].机械工程学报,2011,47(24):57-62.ZHU Cai-chao,LUO Jia-yuan,LI Da-feng,DING Hua-feng,ZHONG Yu.Numerical simulation and experimental investigation of the aluminum alloy quenching process by considering the flow stress characteristic[J].Journal of Mechanical Engineering,2011,47(24):57-62.
[12]TANNER D A,ROBINSON J S.Modelling stress reduction techniques of cold compression and stretching in wrought aluminum alloy products[J].Finite Elements in Analysis and Design,2003,39(5/6):369-386.
[13]朱才朝,罗家元,钟渝.考虑夹持影响的铝合金拉伸模拟及试验[J].材料科学与工艺,2011,19(6):16-20.ZHU Cai-chao,LUO Jia-yuan,ZHONG Yu.Stretching simulation and experiment of aluminum alloy sheet with clamping[J].Materials Science&Technology,2011,19(6):16-20.
[14]李淑明,刘贤锋,胡永会.铝合金厚板淬火-预拉伸残余应力的有限元仿真[J].热加工工艺,2012,41(14):209-211.LI Shu-ming,LIU Xian-feng,HU Yong-hui.FEM simulation of quenching-prestretching residual stress for aluminum alloy thick plate[J].Hot Working Technology,2012,41(14):209-211.
[15]辜蕾钢,汪凌云,刘晓川.铝合金厚板预拉伸过程分析[J].轻合金加工技术,2014,32(4):27-29.GU Lei-gang,WANG Ling-yun,LIU Xiao-chuan.Prestretch process analysis of aluminum alloy thick plates[J].Light Alloy Fabrication Technology,2014,32(4):27-29.
[16]董辉跃.航空整体结构件加工过程的数值仿真[D].杭州:浙江大学,2004.Dong Hui-yue.Machining process simulation of aerospace monolithic component[D].Hangzhou:Zhejiang University,2004.
[17]秦国华,王华敏,叶海潮,吴竹溪.基于力的存在性与可行性的夹紧力变向增量递减规划算法[J].机械工程学报,2016,52(11):72-79.QIN Guo-hua,WANG Hua-min,YE Hai-chao,WU Zhu-xi.A planning algorithm of clamping forces for workpiece fixturing scheme based on existence and feasibility of forces[J].Journal of Mechanical Engineering,2016,52(11):72-79.
[18]秦国华,孙烁,王华敏,左敦稳,吴铁军,鲁宇明.基于工件稳定性的全区域夹紧力变向迭代规划算法[J].兵工学报,2016,37(9):1700-1707.QIN Guo-hua,SUN Shuo,WANG Hua-min,ZUO Dun-wen,WU Tie-jun,LU Yu-ming.A reverse direction iterative planning algorithm of clamping forces in entire region based on workpiece stability[J].Acta Armamentarii,2016,37(9):1700-1707.
[19]ANDONIE R.The psychological limits of neural computation[C]//Dealing with Complexity:A Neural Network Approach.KARNY M,WARWICK K,KURKOVA V.London:Springer-Verlag,1997:252-263.
[20]张园园,吴运新,李丽敏,张明容.7075铝合金预拉伸板淬火后残余应力的有限元模拟[J].热加工工艺,2008,37(14):88-91.ZHANG Yuan-yuan,WU Yun-xin,LI Li-min,ZHANG Ming-rong.Finite element simulation of residual stress in pre-stretching thick-plates of 7075 aluminum alloy after quenching[J].Hot Working Technology,2008,37(14):88-91.
[2]秦国华,林锋,左敦稳.基于材料非均匀性的铝厚板预拉伸残余应力的预测方法[J].中国有色金属学报,2015,25(3):1-8.QIN Guo-hua,LIN Feng,ZUO Dun-wen.Prediction approach to residual stresses distribution in aluminum alloy pre-stretched thick plate based on material non-uniformity[J].The Chinese Journal of Nonferrous Metals,2015,25(3):1-8.
[3]林高用.高性能7x75系铝合金厚板加工技术相关基础研究[M].长沙:中南大学,2006.LIN Gao-yong.Effect of pre-ageing temperature and retrogression heating rate on microstructure and properties of7055 aluminium alloy[M].Changsha:Central South University,2006.
[4]王祝堂.对当前铝厚板热轧与大挤压型材项目投资热的分析[J].世界有色金属,2012(1):58-60.WANG Zhu-tang.Analysis of current investment boom for hot rolling and large extrusion of aluminum alloy thick plates[J].World Nonferrous Metals,2012(1):58-60.
[5]ZHANG S Y,WU Y X,GONG H.A modeling of residual stress in stretched aluminum alloy plate[J].Journal of Materials Processing Technology,2012,212(11):2463-2473.
[6]王中秋.航空整体结构件加工变形滚压校正理论及方法研究[D].济南:山东大学,2009.WANG Zhong-qiu.Study on theory and approach for correcting aerospace monolithic component due to machining distortion using rolling method[D].Jinan:Shandong University,2009.
[7]宋寒,杨吟飞,陈波,郑晓伟.7055-T7751铝合金预拉伸板内部残余应力分布评估[J].机械制造与自动化,2016,45(1):18-21.SONG Han,YANG Yin-fei,CHEN Bo,ZHENG Xiao-wei.Evaluation of residual stress in depth profile of 7055-T7751pre-stretched aluminum alloy plate[J].Machine Building&Automation,2016,45(1):18-21.
[8]郑林,车路长,张津,张鹏程,何长光,彭正坤,肖勇,封先河,朱蕾.预拉伸厚铝板内部残余应力与晶粒取向均匀性的研究[J].精密成形工程,2014,6(5):50-58.ZHANG Lin,CHE Lu-chang,ZHANG Jin,ZHANG Peng-cheng,HE Chang-guang,PENG Zheng-kun,XIAO Yong,FENG Xian-he,ZHU Lei.Internal residual stress and texture homogenization in pre-stretched aluminum alloy plate[J].Journal of Netshape Forming Engineering,2014,6(5):50-58.
[9]龚海,吴运新,廖凯.预拉伸对7075铝合金厚板残余应力分布的影响[J].材料热处理学报,2009,30(6):202-205.GONG Hai,WU Yun-xin,LIAO Kai.Influence of pre-stretching on residual stress distribution in 7075 aluminum alloy thick plates[J].Transactions of Materials and Heat Treatment,2009,30(6):202-205.
[10]袁望姣,吴运新.基于预拉伸工艺的铝合金厚板残余应力消除机理[J].中南大学学报(自然科学版),2011,42(8):2303-2308.YUAN Wang-jiao,WU Yun-xin.Mechanics about eliminating residual stress of aluminum alloy thicken-plates based on pre-stretching technology[J].Journal of Central South University(Science and Technology),2011,42(8):2303-2308.
[11]朱才朝,罗家元,李大峰,丁华峰,钟渝.7075铝合金板预拉伸工艺研究[J].机械工程学报,2011,47(24):57-62.ZHU Cai-chao,LUO Jia-yuan,LI Da-feng,DING Hua-feng,ZHONG Yu.Numerical simulation and experimental investigation of the aluminum alloy quenching process by considering the flow stress characteristic[J].Journal of Mechanical Engineering,2011,47(24):57-62.
[12]TANNER D A,ROBINSON J S.Modelling stress reduction techniques of cold compression and stretching in wrought aluminum alloy products[J].Finite Elements in Analysis and Design,2003,39(5/6):369-386.
[13]朱才朝,罗家元,钟渝.考虑夹持影响的铝合金拉伸模拟及试验[J].材料科学与工艺,2011,19(6):16-20.ZHU Cai-chao,LUO Jia-yuan,ZHONG Yu.Stretching simulation and experiment of aluminum alloy sheet with clamping[J].Materials Science&Technology,2011,19(6):16-20.
[14]李淑明,刘贤锋,胡永会.铝合金厚板淬火-预拉伸残余应力的有限元仿真[J].热加工工艺,2012,41(14):209-211.LI Shu-ming,LIU Xian-feng,HU Yong-hui.FEM simulation of quenching-prestretching residual stress for aluminum alloy thick plate[J].Hot Working Technology,2012,41(14):209-211.
[15]辜蕾钢,汪凌云,刘晓川.铝合金厚板预拉伸过程分析[J].轻合金加工技术,2014,32(4):27-29.GU Lei-gang,WANG Ling-yun,LIU Xiao-chuan.Prestretch process analysis of aluminum alloy thick plates[J].Light Alloy Fabrication Technology,2014,32(4):27-29.
[16]董辉跃.航空整体结构件加工过程的数值仿真[D].杭州:浙江大学,2004.Dong Hui-yue.Machining process simulation of aerospace monolithic component[D].Hangzhou:Zhejiang University,2004.
[17]秦国华,王华敏,叶海潮,吴竹溪.基于力的存在性与可行性的夹紧力变向增量递减规划算法[J].机械工程学报,2016,52(11):72-79.QIN Guo-hua,WANG Hua-min,YE Hai-chao,WU Zhu-xi.A planning algorithm of clamping forces for workpiece fixturing scheme based on existence and feasibility of forces[J].Journal of Mechanical Engineering,2016,52(11):72-79.
[18]秦国华,孙烁,王华敏,左敦稳,吴铁军,鲁宇明.基于工件稳定性的全区域夹紧力变向迭代规划算法[J].兵工学报,2016,37(9):1700-1707.QIN Guo-hua,SUN Shuo,WANG Hua-min,ZUO Dun-wen,WU Tie-jun,LU Yu-ming.A reverse direction iterative planning algorithm of clamping forces in entire region based on workpiece stability[J].Acta Armamentarii,2016,37(9):1700-1707.
[19]ANDONIE R.The psychological limits of neural computation[C]//Dealing with Complexity:A Neural Network Approach.KARNY M,WARWICK K,KURKOVA V.London:Springer-Verlag,1997:252-263.
[20]张园园,吴运新,李丽敏,张明容.7075铝合金预拉伸板淬火后残余应力的有限元模拟[J].热加工工艺,2008,37(14):88-91.ZHANG Yuan-yuan,WU Yun-xin,LI Li-min,ZHANG Ming-rong.Finite element simulation of residual stress in pre-stretching thick-plates of 7075 aluminum alloy after quenching[J].Hot Working Technology,2008,37(14):88-91.
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