小型油动无人直升机机架振动特性与试验研究
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摘要
农用油动植保无人直升机在航空作业时因受到发动机、旋翼、传动箱动力载荷激励作用与无人机表面附面层紊流强度的影响,导致机身及相连施药关键部件的振动。若机架与喷杆连接点的激励频率与喷杆固有频率接近或相等,则会引起两者共振,强烈的振动甚至会影响无人机的飞行姿态。因此,为了保证植保无人机的安全飞行,获得机架的振动特性是研究的首要任务。为此,以小型油动无人直升机为研究对象,建立无人机机架的有限元模型,应用ANSYS Workbench对模型进行自由振动状态下的模态分析,获得前8阶非刚体模态固有频率和振型,通过模态试验验证模型的准确性。试验中,试验模态与解析模态模态频率差均小于10%,模态置信准则均大于0.8,试验结果表明:有限元模型能够反映机架振动特性,随着机架固有频率的增长,振型变化越来越复杂,由机体单向摆动向机体多向同时扭摆转变,变形最大部位在喷杆、起落架、尾管处。该研究为后续展开谐响应分析与喷杆结构优化研究提供了理论依据,旨在避免喷杆与机体产生共振。
The agricultural plant protection engine driving unmanned helicopter is excited by the dynamic loading from the engine,rotor and transmission case,as well as the effect of surface layer turbulence intensity on the surface of unmanned aerial vehicle when the unmanned helicopter is in the air,leading to the vibration of fuselage and lance. If the frequency of the connection point between the rack and the spray lance is close or equal to the nature frequency of the spray lance,it will be going to resonate,strong vibrations can even affect the flight stance of unmanned aerial vehicle,so in order to ensure the safe flight of the unmanned helicopter,the primary task of the study is to obtain the vibration characteristics of the frame. This paper focus on the small engine driving agricultural plant protection unmanned helicopter frame,establishing finite element model of unmanned helicopter frame,applying on ANSYS Workbench to analyze the modal of the finite element model under free vibration condition,obtaining the natural frequencies and modes of the first eight non-rigid modes. The accuracy of the model is verified by modal test and the results are analyzed. The result showed that the unmanned helicopter frame finite element model is correct and it can be used to reflect the vibration characteristics of the frame,with the increase of the natural frequency of the frame,the change of frame vibration is more and more complicated,and the most deformed parts are in the spray,landing gear and stern tube,so to enhance stability,it is very important to avoid the resonance of the spray and the body. This paper provide theoretical basis for subsequent research work,based on this,the study of harmonic response analysis and structure optimization can be carried out,thereby solving the optimization problem of spray structure which cannot be easy to achieve under test conditions,to avoid resonance of spray and unmanned helicopter frame.
The agricultural plant protection engine driving unmanned helicopter is excited by the dynamic loading from the engine,rotor and transmission case,as well as the effect of surface layer turbulence intensity on the surface of unmanned aerial vehicle when the unmanned helicopter is in the air,leading to the vibration of fuselage and lance. If the frequency of the connection point between the rack and the spray lance is close or equal to the nature frequency of the spray lance,it will be going to resonate,strong vibrations can even affect the flight stance of unmanned aerial vehicle,so in order to ensure the safe flight of the unmanned helicopter,the primary task of the study is to obtain the vibration characteristics of the frame. This paper focus on the small engine driving agricultural plant protection unmanned helicopter frame,establishing finite element model of unmanned helicopter frame,applying on ANSYS Workbench to analyze the modal of the finite element model under free vibration condition,obtaining the natural frequencies and modes of the first eight non-rigid modes. The accuracy of the model is verified by modal test and the results are analyzed. The result showed that the unmanned helicopter frame finite element model is correct and it can be used to reflect the vibration characteristics of the frame,with the increase of the natural frequency of the frame,the change of frame vibration is more and more complicated,and the most deformed parts are in the spray,landing gear and stern tube,so to enhance stability,it is very important to avoid the resonance of the spray and the body. This paper provide theoretical basis for subsequent research work,based on this,the study of harmonic response analysis and structure optimization can be carried out,thereby solving the optimization problem of spray structure which cannot be easy to achieve under test conditions,to avoid resonance of spray and unmanned helicopter frame.
引文
[1]薛新宇,兰玉彬.美国农业航空技术现状和发展趋势分析[J].农业机械学报,2013,44(5):194-201.
[2]陈盛德,兰玉彬,周志艳,等.小型植保无人机喷雾参数对橘树冠层雾滴沉积分布的影响[J].华南农业大学学报,2017,38(5):97-102.
[3]秦维彩,薛新宇,周立新,等.无人直升机喷雾参数对玉米冠层雾滴沉积分布的影响[J].农业工程学报,2014,30(5):50-56.
[4]吕晓兰,傅锡敏,吴萍,等.喷雾技术参数对雾滴沉积分布影响试验[J].农业机械学报,2011,42(6):70-75.
[5]张京,何雄奎,宋利坚,等.无人驾驶直升机航空喷雾参数对雾滴沉积的影响[J].农业机械学报,2012,43(12):94-96.
[6]傅泽田,祁力钧,王俊红.精准施药技术研究进展与对策[J].农业机械学报,2007,38(1):189-192.
[7]刘剑君,贾世通,杜新武,等.无人机低空施药技术发展现状与趋势[J].农业工程,2014,4(5):10-14.
[8]张宋超,薛新宇,秦维彩,等.N-3型农用无人直升机航空施药飘移模拟与试验[J].农业工程学报,2015,31(3):87-93.
[9]王玲,兰玉彬,W Clint Hoffmann,等.微型无人机低空变量喷药系统设计与雾滴沉积规律研究[J].农业机械学报,2016,47(1):15-22.
[10]刘伟,汪小旵,丁为民,等.背负式喷雾器变量喷雾控制系统设计与特性分析[J].农业工程学报,2012,28(9):16-21.
[11]茹煜,金兰,周宏平,等.航空施药旋转液力雾化喷头性能试验[J].农业工程学报,2014,30(3):50-54.
[12]吕晓兰,何雄奎,宋坚利,等.标准扇形雾喷头雾化过程测试分析[J].农业工程学报,2007,23(9):95-100.
[13]周立新,薛新宇,孙竹,等.航空喷雾用电动离心喷头试验研究[J].中国农机化,2011(1):107-111.
[14]Kirk I W.Measurement and prediction of atomization parameters from fixed-wing aircraft spray nozzles[J].Transactions of the ASABE,2007,50(3):693-703.
[15]邱白晶,何耀杰,盛云辉,等.喷雾机喷杆有限元模态分析与结构优化[J].农业机械学报,2014,45(8):112-116.
[16]Roman H,Anthonis J,Moshou D,et al.Evaluation of a cascade compensator for horizontal vibration of a flexible spray boom[J].Journal of Agricultural Engineering Research,1998,71(1):81-92.
[17]张志龙,尹明德,刘进进.某轻型直升机机身模态分析[J].机械工程与自动化,2013(1):35-37.
[18]Hemez F M.Theoretical and experimental correlation between finite element models and modal tests in the context of large flexible space structures[D].Colorado:University of Colorado,1993.
[19]陈树人,韩红阳,陈刚,等.喷杆喷雾机机架动态特性分析与减振设计[J].农业机械学报,2013,44(4):50-53.
[20]袁军,王景立.基于Pro/E与ANSYS Workbench的深松铲结构分析及优化[J].中国农机化,2012(5):77.
[21]张力,林建龙,项辉宇.模态分析与实验[M].北京:清华大学出版社,2011.
[22]谭明敏,杨务滋,周立强,等.挖掘机式冲击器斗杆有限元模态分析[J].中南林业科技大学学报,2011,31(4):187-191.
[23]刘进进,尹明德,张志龙.基于ANSYS的某直升机尾梁管模态及谐响应分析[J].机械工程与自动化,2013(1):64-66.
[24]沃德·海伦,斯蒂芬·拉门兹,波尔·萨斯.模态分析理论与试验[M].白化同,郭继忠,译.北京:北京理工大学出版社,2001.
[25]徐有刚,冯加权,杜强,等.大型结构件模态试验方法[J].科学技术与工程,2007,13(7):3231-3234.
[26]苏忠亭,徐达,杨明华,等.基于模态试验的某火炮身管有限元模型修正[J].振动与冲击,2012,31(24):54-59.
[27]何耀杰,邱白晶,杨亚飞,等.基于有限元模型的喷雾机喷杆弹性变形分析与控制[J].农业工程学报,2014,30(6):28-36.
[28]丁剑平,缪增华,陈小亮.某全地形车车架模态相关性分析[J].固体力学学报,2013,33(5):193-197.
[29]王学鹏.多功能电动车车架机架结构有限元分析及优化[D].武汉:武汉理工大学,2010.
[2]陈盛德,兰玉彬,周志艳,等.小型植保无人机喷雾参数对橘树冠层雾滴沉积分布的影响[J].华南农业大学学报,2017,38(5):97-102.
[3]秦维彩,薛新宇,周立新,等.无人直升机喷雾参数对玉米冠层雾滴沉积分布的影响[J].农业工程学报,2014,30(5):50-56.
[4]吕晓兰,傅锡敏,吴萍,等.喷雾技术参数对雾滴沉积分布影响试验[J].农业机械学报,2011,42(6):70-75.
[5]张京,何雄奎,宋利坚,等.无人驾驶直升机航空喷雾参数对雾滴沉积的影响[J].农业机械学报,2012,43(12):94-96.
[6]傅泽田,祁力钧,王俊红.精准施药技术研究进展与对策[J].农业机械学报,2007,38(1):189-192.
[7]刘剑君,贾世通,杜新武,等.无人机低空施药技术发展现状与趋势[J].农业工程,2014,4(5):10-14.
[8]张宋超,薛新宇,秦维彩,等.N-3型农用无人直升机航空施药飘移模拟与试验[J].农业工程学报,2015,31(3):87-93.
[9]王玲,兰玉彬,W Clint Hoffmann,等.微型无人机低空变量喷药系统设计与雾滴沉积规律研究[J].农业机械学报,2016,47(1):15-22.
[10]刘伟,汪小旵,丁为民,等.背负式喷雾器变量喷雾控制系统设计与特性分析[J].农业工程学报,2012,28(9):16-21.
[11]茹煜,金兰,周宏平,等.航空施药旋转液力雾化喷头性能试验[J].农业工程学报,2014,30(3):50-54.
[12]吕晓兰,何雄奎,宋坚利,等.标准扇形雾喷头雾化过程测试分析[J].农业工程学报,2007,23(9):95-100.
[13]周立新,薛新宇,孙竹,等.航空喷雾用电动离心喷头试验研究[J].中国农机化,2011(1):107-111.
[14]Kirk I W.Measurement and prediction of atomization parameters from fixed-wing aircraft spray nozzles[J].Transactions of the ASABE,2007,50(3):693-703.
[15]邱白晶,何耀杰,盛云辉,等.喷雾机喷杆有限元模态分析与结构优化[J].农业机械学报,2014,45(8):112-116.
[16]Roman H,Anthonis J,Moshou D,et al.Evaluation of a cascade compensator for horizontal vibration of a flexible spray boom[J].Journal of Agricultural Engineering Research,1998,71(1):81-92.
[17]张志龙,尹明德,刘进进.某轻型直升机机身模态分析[J].机械工程与自动化,2013(1):35-37.
[18]Hemez F M.Theoretical and experimental correlation between finite element models and modal tests in the context of large flexible space structures[D].Colorado:University of Colorado,1993.
[19]陈树人,韩红阳,陈刚,等.喷杆喷雾机机架动态特性分析与减振设计[J].农业机械学报,2013,44(4):50-53.
[20]袁军,王景立.基于Pro/E与ANSYS Workbench的深松铲结构分析及优化[J].中国农机化,2012(5):77.
[21]张力,林建龙,项辉宇.模态分析与实验[M].北京:清华大学出版社,2011.
[22]谭明敏,杨务滋,周立强,等.挖掘机式冲击器斗杆有限元模态分析[J].中南林业科技大学学报,2011,31(4):187-191.
[23]刘进进,尹明德,张志龙.基于ANSYS的某直升机尾梁管模态及谐响应分析[J].机械工程与自动化,2013(1):64-66.
[24]沃德·海伦,斯蒂芬·拉门兹,波尔·萨斯.模态分析理论与试验[M].白化同,郭继忠,译.北京:北京理工大学出版社,2001.
[25]徐有刚,冯加权,杜强,等.大型结构件模态试验方法[J].科学技术与工程,2007,13(7):3231-3234.
[26]苏忠亭,徐达,杨明华,等.基于模态试验的某火炮身管有限元模型修正[J].振动与冲击,2012,31(24):54-59.
[27]何耀杰,邱白晶,杨亚飞,等.基于有限元模型的喷雾机喷杆弹性变形分析与控制[J].农业工程学报,2014,30(6):28-36.
[28]丁剑平,缪增华,陈小亮.某全地形车车架模态相关性分析[J].固体力学学报,2013,33(5):193-197.
[29]王学鹏.多功能电动车车架机架结构有限元分析及优化[D].武汉:武汉理工大学,2010.
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