基于全寿命分析方法的挖掘机结构改进研究
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摘要
在众多工程机械产品中,挖掘机占有重要的一席之地,被广泛的应用于道路施工等领域。从功能角度来说挖掘机一般被划分成三部分,即工作装置、回转机构和行走装置。工作装置(斗杆、动臂和铲斗)直接完成挖掘等任务,各部件的运动分别通过各自的油缸驱动来实现,姿态多样而灵活。行走装置能够保证整机的稳定性。
由于挖掘机具有功能多等特点,同时能够实现灵活多样的工作姿态,其作业的复杂性主要体现在：(1)复杂的作业对象,由于挖掘的物料多种多样,如不同密度、不同硬度的土质、岩石等,导致挖掘机的受力情况复杂多变,实际挖掘力更是难以确定。(2)工作姿态的多样性,挖掘机的工作姿态是由工作装置的相对位置确定的,挖掘机属于多自由度系统,因此挖掘机能够实现多种姿态。
疲劳破坏是机械结构主要的失效方式。小吨位的挖掘机由于使用量大,工作频次高,引起破坏的现象多而严重。因此针对以上问题,主要做了以下工作：
(1)现场应力测试试验。通过测试挖掘机各个结构典型位置的应力应变,了解整车结构的应力分布状态,确定关键点的应力水平与变化规律,评价结构强度。同时获取实测载荷谱,作为疲劳分析的基础。
(2)有限元分析。通过分析挖掘机的危险工况,了解结构的应力水平及状态分布,从而从强度角度判断结构的应力情况,同时ANSYS分析的结果文件作为疲劳寿命分析的输入文件输入到疲劳寿命分析软件中。
(3)在疲劳寿命分析专业软件MSC.Fatigue2005中,通过加载实测载荷谱以及材料的S-N曲线,对原有结构进行寿命分析,据此结果改进挖掘机原有结构,与此同时,分析在相同工况、相同载荷谱、相同S-N曲线情况下改进后挖掘机的寿命。
(4)对比ANSYS静力学分析结果和寿命分析结果,得出新的设计方案,并进行可行性分析,对今后挖掘机结构设计及改进提供了参考。
Excavator, as a kind of important engineer machinery, is widely used in road engineering and other fields. It has three parts:working device, rotary device and running gear. For the working device, being articulated by arm、boom and bucket, it can complete mining tasks directly. All various and flexible movements are achieved by the relevant hydraulic cylinders. The running gear is used to ensure the stability of the whole machine.
The versatility function is the typical characterization of an excavator, the complex are reflected in the following aspects:(1) the complexity of working objects. Various mining materials, such as soil and rock in different densities, lead to complicated force and elusive actual digging force of an excavator.(2) the diversity of working positions. The working position of excavator is determined by the relative position of the inclusive working device; importantly, excavator operating belongs to a multiple-degree-of-freedom system.
Fatigue failure is the principle failure of mechanical structure. On account of being used extensively and frequently, excavators with small tonnage tend to damaged easily and seriously. In order to solve the problems aforementioned, this paper investigated the following questions:
(1) Stress test. By testing the strain of typical positions for the structures, the stress distribution of vehicle structure is achieved. Then the stress levels and changing regularities of critical points can be determined further. In this way structural strength is evaluated and the actual load spectrum being treated as the basis of the fatigue analysis is obtained finally.
(2) Finite element analysis. The stress levels and distribution of the structures are labeled by analyzing dangerous working conditions of excavator. To determine the stress of the structures from the perspective of strength, files for fatigue life analysis with results from finite element analysis are input into MSC.Fatigue2005.
(3) Life calculation for excavator structure by loading actual load spectrum and the S-N curve of materials is analyzed by MSC.Fatigue. Then the original structures will be improved according to analytical results. Meanwhile, the improvement scheme life will be analyzed again to ensure the same condition, same load spectrum and same S-N curve.
(4) The novel design scheme can be drawn out by comparing the static analysis of ANSYS and the results of fatigue life. Through the available structure improvements, to pave a reliable way for further structure design of excavators.
由于挖掘机具有功能多等特点,同时能够实现灵活多样的工作姿态,其作业的复杂性主要体现在：(1)复杂的作业对象,由于挖掘的物料多种多样,如不同密度、不同硬度的土质、岩石等,导致挖掘机的受力情况复杂多变,实际挖掘力更是难以确定。(2)工作姿态的多样性,挖掘机的工作姿态是由工作装置的相对位置确定的,挖掘机属于多自由度系统,因此挖掘机能够实现多种姿态。
疲劳破坏是机械结构主要的失效方式。小吨位的挖掘机由于使用量大,工作频次高,引起破坏的现象多而严重。因此针对以上问题,主要做了以下工作：
(1)现场应力测试试验。通过测试挖掘机各个结构典型位置的应力应变,了解整车结构的应力分布状态,确定关键点的应力水平与变化规律,评价结构强度。同时获取实测载荷谱,作为疲劳分析的基础。
(2)有限元分析。通过分析挖掘机的危险工况,了解结构的应力水平及状态分布,从而从强度角度判断结构的应力情况,同时ANSYS分析的结果文件作为疲劳寿命分析的输入文件输入到疲劳寿命分析软件中。
(3)在疲劳寿命分析专业软件MSC.Fatigue2005中,通过加载实测载荷谱以及材料的S-N曲线,对原有结构进行寿命分析,据此结果改进挖掘机原有结构,与此同时,分析在相同工况、相同载荷谱、相同S-N曲线情况下改进后挖掘机的寿命。
(4)对比ANSYS静力学分析结果和寿命分析结果,得出新的设计方案,并进行可行性分析,对今后挖掘机结构设计及改进提供了参考。
Excavator, as a kind of important engineer machinery, is widely used in road engineering and other fields. It has three parts:working device, rotary device and running gear. For the working device, being articulated by arm、boom and bucket, it can complete mining tasks directly. All various and flexible movements are achieved by the relevant hydraulic cylinders. The running gear is used to ensure the stability of the whole machine.
The versatility function is the typical characterization of an excavator, the complex are reflected in the following aspects:(1) the complexity of working objects. Various mining materials, such as soil and rock in different densities, lead to complicated force and elusive actual digging force of an excavator.(2) the diversity of working positions. The working position of excavator is determined by the relative position of the inclusive working device; importantly, excavator operating belongs to a multiple-degree-of-freedom system.
Fatigue failure is the principle failure of mechanical structure. On account of being used extensively and frequently, excavators with small tonnage tend to damaged easily and seriously. In order to solve the problems aforementioned, this paper investigated the following questions:
(1) Stress test. By testing the strain of typical positions for the structures, the stress distribution of vehicle structure is achieved. Then the stress levels and changing regularities of critical points can be determined further. In this way structural strength is evaluated and the actual load spectrum being treated as the basis of the fatigue analysis is obtained finally.
(2) Finite element analysis. The stress levels and distribution of the structures are labeled by analyzing dangerous working conditions of excavator. To determine the stress of the structures from the perspective of strength, files for fatigue life analysis with results from finite element analysis are input into MSC.Fatigue2005.
(3) Life calculation for excavator structure by loading actual load spectrum and the S-N curve of materials is analyzed by MSC.Fatigue. Then the original structures will be improved according to analytical results. Meanwhile, the improvement scheme life will be analyzed again to ensure the same condition, same load spectrum and same S-N curve.
(4) The novel design scheme can be drawn out by comparing the static analysis of ANSYS and the results of fatigue life. Through the available structure improvements, to pave a reliable way for further structure design of excavators.
引文
[1]同济大学.单斗液压挖掘机[M].北京：中国建筑工业出版社,1986.
[2]李宏宝.2011国挖掘机市场分析[J].建筑机械,2011,12(上)：42-45.
[3]李宏宝.2011国挖掘机市场分析及2012展望[J].CMTM,2012,01：75-82.
[4]陈能诵.挖掘机械：在危机中稳步前进[J].建筑机械技术与管理,2009,11：27-33.
[5]徐灏.疲劳强度[M].高等教育出版社,1998.
[6]赵振华,陈伟,吴铁鹰.高低周复合载荷下的钛合金疲劳寿命估算[J].机械强度,2011,33(4)：629-632.
[7]颜伟泽,郝艳华,黄致建,蒋万标.车轮径向疲劳试验有限元仿真与疲劳寿命估算[J].机械设计与制造,2011(6)：27-29.
[8]范小宁,徐格宁,杨瑞刚.基于损伤—断裂力学理论的起重机疲劳寿命估算方法[J].中国安全科学学报,2011,21(6)：58-63.
[9]高清振,王耀华,张晓南.基于样本法的某型飞机救生机构振动疲劳寿命估算[J].中国机械工程,2011,22(2)：162-165.
[10]王振亚,刘道新,张晓化.基于有限元分析的断裂比拟法估算寿命疲劳寿命[J].机械强度,2011,33(5)：729-734.
[11]朱永梅,王明强,刘艳梨.曲轴轴系的结构强度分析与疲劳寿命估算[J].机械强度,2011,32(6)：1018-1021.
[12]任旭东,姜大伟,张永康,张田,罗新民.7050-T7451铝合金试件的疲劳安全寿命估算[J].航空动力学报,2011,26(1)：185-190.
[13]孟彩茹,卢博友.基于PSD的随机载荷下振动疲劳寿命估算[J].机械设计,2009,26(5)：73-75.
[14]陈吉平,丁智平,尹泽勇.面心立方体单晶材料多轴低周疲劳寿命的估算方法[J].机械工程学报,2008,44(2)：213-218.
[15]曾宪任.对DS60挖掘机工作装置开裂的研究[D].四川：西华大学.2010.
[16]张卫国,权龙,程珩,杨敬.真实载荷驱动下挖掘机工作装置疲劳寿命研究[J].农业机械学报,2011,38(5)：35-38.
[17]陈东升.挖掘机结构件焊接工艺及变形研究[D].长春：吉林大学.2009.
[18]周家付.基于ANSYS的挖掘机连杆螺栓的疲劳寿命预测[J].设备管理&维修技术,2010：77-82.
[19]Frimpong, Hu, Y. Parametric simulation of shovel-oil sands interactions during excavation [J]. International Journal of Surface Mining, Reclamation and Environment, 2004,18(3):205-219.
[20]Eugeniusz Rusinski, Piotr Harnatkiewicz, Marcin Kowalczyk, Przemyslaw Moczko. Examination of the causes of a bucket wheel fracture in a bucket wheel excavator [J]. Engineering Failure Analysis,2010,17:1300-1312.
[21]Srdan Bonjak, Zoran Petkovic, Nenad Zrnic, Milorad Pantelic, Aleksandar Obradovic. Failure analysis and redesign of the bucket wheel excavator two-wheel bogie [J]. Engineering Failure Analysis,2010,17:473-485.
[22]Predrag D. Jovancic, Dragan Ignjatovic, Milo Tanasijevic, Tako Maneski. Load-bearing steel structure diagnostics on bucket wheel excavator, for the purpose of failure prevention [J]. Engineering Failure Analysis,2011,18:1203-1211.
[23]Luca Susmel, David Taylor. A critical distance/plane method to estimate finite life of notched components under variable amplitude uniaxial/multiaxial fatigue loading [J]. International Journal of Fatigue,2012,38:7-24.
[24]Chang Yeol Jeong, Jung-Chan Bae, Chang-Seog Kang, Jae-IK Cho, Hyeon-Taek Son. Normalized creep-fatigue life prediction model based on the energy dissipation during hold time [J]. Materials Science and Engineering,2007,460-461:195-203.
[25]Carole Erny, David Thevenet, Jean-Yves Cognard, Manuel Korner. Fatigue life prediction of welded ship details [J]. Marine Structures,2012,25:13-32.
[26]Y. S. Upadhyaya, B. K. Sridhara. Fatigue life prediction:A Continuum Damage Mechanics and Fracture Mechanics approach [J]. Materials and Design,2012,35:220-224.
[27]Yan-Hui Zhang, Stephen J. Maddox. Fatigue life prediction for toe ground welded joints [J]. International Journal of Fatigue,2009,31:1124-1136.
[28]Luca Susmel. Estimating fatigue lifetime of steel weldments locally damaged by variable amplitude multiaxial stress fields [J]. International Journal of fatigue 2010,32: 1057-1080.
[29]杨莹,陈进,张石强,白玉琳.正铲液压挖掘机工作装置优化设计[J].工程机械,2008,7：40-44.
[30]刘迎春.传感器原理设计与应用[M].国防科技大学出版社,2000.
[31]GB/T7586-2008液压挖掘机试验方法[S].北京：中国标准出版社,2009.
[32]GB/T13332-2008土方机械液压挖掘机和挖掘装载机挖掘力的测定方法[S].北京：中国标准出版社,2009.
[33]尚晓江,邱峰,赵海峰ANSYS结构有限元高级分析方法与范例应用[M].中国水利水电出版社(第二版),2008.
[34]龚曙光,谢桂兰,黄云清ANSYS参数化编程与命令手册[M].机械工程出版社,2009.
[35]王国军MSC. Fatigue疲劳分析实例与指导教程[M].机械工程出版社,2009.
[36]周传月,郑红霞,罗志强等.MSC. Fatigue疲劳分析应用与实例[M].科学工程出版社,2005.
[37]付荣柏.起重机钢结构焊接制造技术[M].机械工业出版社,2008.
[38]张彦华.焊接强度分析[M].西北工业大学出版社,2011.
[2]李宏宝.2011国挖掘机市场分析[J].建筑机械,2011,12(上)：42-45.
[3]李宏宝.2011国挖掘机市场分析及2012展望[J].CMTM,2012,01：75-82.
[4]陈能诵.挖掘机械：在危机中稳步前进[J].建筑机械技术与管理,2009,11：27-33.
[5]徐灏.疲劳强度[M].高等教育出版社,1998.
[6]赵振华,陈伟,吴铁鹰.高低周复合载荷下的钛合金疲劳寿命估算[J].机械强度,2011,33(4)：629-632.
[7]颜伟泽,郝艳华,黄致建,蒋万标.车轮径向疲劳试验有限元仿真与疲劳寿命估算[J].机械设计与制造,2011(6)：27-29.
[8]范小宁,徐格宁,杨瑞刚.基于损伤—断裂力学理论的起重机疲劳寿命估算方法[J].中国安全科学学报,2011,21(6)：58-63.
[9]高清振,王耀华,张晓南.基于样本法的某型飞机救生机构振动疲劳寿命估算[J].中国机械工程,2011,22(2)：162-165.
[10]王振亚,刘道新,张晓化.基于有限元分析的断裂比拟法估算寿命疲劳寿命[J].机械强度,2011,33(5)：729-734.
[11]朱永梅,王明强,刘艳梨.曲轴轴系的结构强度分析与疲劳寿命估算[J].机械强度,2011,32(6)：1018-1021.
[12]任旭东,姜大伟,张永康,张田,罗新民.7050-T7451铝合金试件的疲劳安全寿命估算[J].航空动力学报,2011,26(1)：185-190.
[13]孟彩茹,卢博友.基于PSD的随机载荷下振动疲劳寿命估算[J].机械设计,2009,26(5)：73-75.
[14]陈吉平,丁智平,尹泽勇.面心立方体单晶材料多轴低周疲劳寿命的估算方法[J].机械工程学报,2008,44(2)：213-218.
[15]曾宪任.对DS60挖掘机工作装置开裂的研究[D].四川：西华大学.2010.
[16]张卫国,权龙,程珩,杨敬.真实载荷驱动下挖掘机工作装置疲劳寿命研究[J].农业机械学报,2011,38(5)：35-38.
[17]陈东升.挖掘机结构件焊接工艺及变形研究[D].长春：吉林大学.2009.
[18]周家付.基于ANSYS的挖掘机连杆螺栓的疲劳寿命预测[J].设备管理&维修技术,2010：77-82.
[19]Frimpong, Hu, Y. Parametric simulation of shovel-oil sands interactions during excavation [J]. International Journal of Surface Mining, Reclamation and Environment, 2004,18(3):205-219.
[20]Eugeniusz Rusinski, Piotr Harnatkiewicz, Marcin Kowalczyk, Przemyslaw Moczko. Examination of the causes of a bucket wheel fracture in a bucket wheel excavator [J]. Engineering Failure Analysis,2010,17:1300-1312.
[21]Srdan Bonjak, Zoran Petkovic, Nenad Zrnic, Milorad Pantelic, Aleksandar Obradovic. Failure analysis and redesign of the bucket wheel excavator two-wheel bogie [J]. Engineering Failure Analysis,2010,17:473-485.
[22]Predrag D. Jovancic, Dragan Ignjatovic, Milo Tanasijevic, Tako Maneski. Load-bearing steel structure diagnostics on bucket wheel excavator, for the purpose of failure prevention [J]. Engineering Failure Analysis,2011,18:1203-1211.
[23]Luca Susmel, David Taylor. A critical distance/plane method to estimate finite life of notched components under variable amplitude uniaxial/multiaxial fatigue loading [J]. International Journal of Fatigue,2012,38:7-24.
[24]Chang Yeol Jeong, Jung-Chan Bae, Chang-Seog Kang, Jae-IK Cho, Hyeon-Taek Son. Normalized creep-fatigue life prediction model based on the energy dissipation during hold time [J]. Materials Science and Engineering,2007,460-461:195-203.
[25]Carole Erny, David Thevenet, Jean-Yves Cognard, Manuel Korner. Fatigue life prediction of welded ship details [J]. Marine Structures,2012,25:13-32.
[26]Y. S. Upadhyaya, B. K. Sridhara. Fatigue life prediction:A Continuum Damage Mechanics and Fracture Mechanics approach [J]. Materials and Design,2012,35:220-224.
[27]Yan-Hui Zhang, Stephen J. Maddox. Fatigue life prediction for toe ground welded joints [J]. International Journal of Fatigue,2009,31:1124-1136.
[28]Luca Susmel. Estimating fatigue lifetime of steel weldments locally damaged by variable amplitude multiaxial stress fields [J]. International Journal of fatigue 2010,32: 1057-1080.
[29]杨莹,陈进,张石强,白玉琳.正铲液压挖掘机工作装置优化设计[J].工程机械,2008,7：40-44.
[30]刘迎春.传感器原理设计与应用[M].国防科技大学出版社,2000.
[31]GB/T7586-2008液压挖掘机试验方法[S].北京：中国标准出版社,2009.
[32]GB/T13332-2008土方机械液压挖掘机和挖掘装载机挖掘力的测定方法[S].北京：中国标准出版社,2009.
[33]尚晓江,邱峰,赵海峰ANSYS结构有限元高级分析方法与范例应用[M].中国水利水电出版社(第二版),2008.
[34]龚曙光,谢桂兰,黄云清ANSYS参数化编程与命令手册[M].机械工程出版社,2009.
[35]王国军MSC. Fatigue疲劳分析实例与指导教程[M].机械工程出版社,2009.
[36]周传月,郑红霞,罗志强等.MSC. Fatigue疲劳分析应用与实例[M].科学工程出版社,2005.
[37]付荣柏.起重机钢结构焊接制造技术[M].机械工业出版社,2008.
[38]张彦华.焊接强度分析[M].西北工业大学出版社,2011.