XS-ZY-250A塑料注塑成型机床身结构设计含开题及17张CAD图
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设计(XX)指导情况记录表题 目XS-ZY-250A塑料注塑成型机床身结构设计姓 名学 院班 级专 业指导教师王志斌职称第 1 次指导指导方式: 指导时间: 20XX 年 12 月 18 日 (星期 三 )指导内容老师通知到我,我的毕设题目是XS-ZY-250A塑料注塑成型机床身结构设计,并让我查阅相关资料,以备之后的毕业设计需要。指导教师意见指导教师:年 月 日注:1该表由学生按指导情况如实填写,并由指导教师签字认可。2毕业设计(论文)指导记录填写要求:(1)每篇毕业设计(论文)的指导记录不得少于6次。(2)每次指导的时间要与任务书的进程相对应。(3)指导记录大致内容如下:检查开题报告、英文翻译、工作任务的完成情况,检查毕业设计(论文)草稿完成情况,对毕业设计(论文)定稿的修改意见等。(4)指导方式:A毕设系统;B电话;C现场指导;DQQ或电子邮件;E其它。设计(XX)指导情况记录表题 目XY-ZY-250A塑料注塑成型机床身结构设计姓 名学 院班 级专 业指导教师职称第 2 次指导指导方式: 指导时间: 20XX 年 12 月 30 日 (星期 一 )指导内容老师下发有关外文翻译和开题报告的书写格式,给我编写这两个有了大概方向。指导教师意见指导教师:年 月 日注:1该表由学生按指导情况如实填写,并由指导教师签字认可。2毕业设计(论文)指导记录填写要求:(1)每篇毕业设计(论文)的指导记录不得少于6次。(2)每次指导的时间要与任务书的进程相对应。(3)指导记录大致内容如下:检查开题报告、英文翻译、工作任务的完成情况,检查毕业设计(论文)草稿完成情况,对毕业设计(论文)定稿的修改意见等。(4)指导方式:A毕设系统;B电话;C现场指导;DQQ或电子邮件;E其它。设计(XX)指导情况记录表题 目XY-ZY-250A塑料注塑成型机床身结构设计姓 名学 院班 级专 业指导教师职称第 3 次指导指导方式: 指导时间: 20XX 年 2 月 25 日 (星期 二 )指导内容将我上传的开题报告和外文翻译提出有格式和乱码错误,让我将其改正后再次提交。指导教师意见指导教师:年 月 日注:1该表由学生按指导情况如实填写,并由指导教师签字认可。2毕业设计(论文)指导记录填写要求:(1)每篇毕业设计(论文)的指导记录不得少于6次。(2)每次指导的时间要与任务书的进程相对应。(3)指导记录大致内容如下:检查开题报告、英文翻译、工作任务的完成情况,检查毕业设计(论文)草稿完成情况,对毕业设计(论文)定稿的修改意见等。(4)指导方式:A毕设系统;B电话;C现场指导;DQQ或电子邮件;E其它。设计(XX)指导情况记录表题 目XS-ZY-250A塑料注塑成型机床身结构设计姓 名学 院班 级专 业指导教师职称第 4 次指导指导方式: 指导时间: 20XX 年 4 月 17 日 (星期 五 )指导内容老师给了我以前毕业生的毕业论文,让我根据范文修改我的毕业论文格式。指导教师意见指导教师:年 月 日注:1该表由学生按指导情况如实填写,并由指导教师签字认可。2毕业设计(论文)指导记录填写要求:(1)每篇毕业设计(论文)的指导记录不得少于6次。(2)每次指导的时间要与任务书的进程相对应。(3)指导记录大致内容如下:检查开题报告、英文翻译、工作任务的完成情况,检查毕业设计(论文)草稿完成情况,对毕业设计(论文)定稿的修改意见等。(4)指导方式:A毕设系统;B电话;C现场指导;DQQ或电子邮件;E其它。设计(XX)指导情况记录表题 目XS-ZY-250A塑料注塑成型机床身结构设计姓 名学 院班 级专 业指导教师王职称第 5 次指导指导方式: 指导时间: 20XX 年 5 月 2 日 (星期 六 )指导内容老师给我指出我的毕设论文的内容方向错误,应该是床身结构设计而我设计的是系统设计,需要大改论文内容。指导教师意见指导教师: 年 月 日注:1该表由学生按指导情况如实填写,并由指导教师签字认可。2毕业设计(论文)指导记录填写要求:(1)每篇毕业设计(论文)的指导记录不得少于6次。(2)每次指导的时间要与任务书的进程相对应。(3)指导记录大致内容如下:检查开题报告、英文翻译、工作任务的完成情况,检查毕业设计(论文)草稿完成情况,对毕业设计(论文)定稿的修改意见等。(4)指导方式:A毕设系统;B电话;C现场指导;DQQ或电子邮件;E其它。设计(XX)指导情况记录表题 目XS-ZY-250A塑料注塑成型机床身结构设计姓 名学 院班 级专 业指导教师职称第 6 次指导指导方式: 指导时间: 20XX 年 5 月 4 日 (星期 一 )指导内容与老师讨论我的毕设装配图应该怎么进行设计以及零件之间的连接方式,以及它们的材质。指导教师意见指导教师: 年 月 日注:1该表由学生按指导情况如实填写,并由指导教师签字认可。2毕业设计(论文)指导记录填写要求:(1)每篇毕业设计(论文)的指导记录不得少于6次。(2)每次指导的时间要与任务书的进程相对应。(3)指导记录大致内容如下:检查开题报告、英文翻译、工作任务的完成情况,检查毕业设计(论文)草稿完成情况,对毕业设计(论文)定稿的修改意见等。(4)指导方式:A毕设系统;B电话;C现场指导;DQQ或电子邮件;E其它。设计(XX)指导教师评阅表题 目XS-ZY-250A塑料注塑成型机床身结构设计学 生 姓 名学 号指 导 教 师职 称学 历本科评分指标(参考)得分1设计(论文)过程中分析、解决问题的能力(10分)2理工类:设计(论文)方案合理性,理论分析依据,性能指标,实验数据准确性,文字规范性(10分)文经管类:论文结构、逻辑合理性;论文方法科学,观点正确性;内容翔实,表达准确、语言流畅性(10分)3设计(论文)创新性,成果的学术或应用价值 (10分) 4整个设计(论文)过程中工作态度(10分) 指导教师评分(满分40分):指导教师评语: 是否同意答辩:指导教师: 年 月 日XS-ZY-250A塑料注塑成型机床身结构设计任 务 书1本毕业设计(论文)课题应达到的目的:通过本次毕业设计,掌握注塑成型模具设计的基本方法、料及注塑成型基本原理,能够完成XS-ZY-250A塑料注塑成型机床身结构设计。学会设计过程遇到问题查阅手册的方法,并能够运用好计算机绘图基本能力。初步接触CAE技术,会基本模具CAM加工。 2本毕业设计(论文)课题任务的内容和要求(包括原始数据、技术要求、工作要求等):要求在了解注塑模具成型基础上,抓紧时间学习注塑设备结构,并了解合模机构、推出机构等液压辅助结构原理问题。 原始数据:合模缸、注射座移动缸、注射缸由一个比例阀来调节工作压力;推出机构单列一个比例阀来调节压力;推出机构与合模液压系统参照姚、吴雨吉瑶数据,动模座板尺寸结构床身结构尺寸规格参照XS-ZY-250A塑料注塑成型机。 课题实施办法: 1、 在理解任务书后,按要求完成开题报告一份; 2、 根据本专业或者和本专业相近的专业,查阅外文资料完成外文资料译文(约3000汉字)一篇; 3、 完成毕业设计论文(4000字左右)一篇,其中中文摘要300汉字左右,外文摘要约250个词左右; 4、 将毕业设计期间所有的设计思想和遇到的困难及解决办法都要在设计任务书中体现出来; 毕 业 设 计(论 文)任 务 书3对本毕业设计(论文)课题成果的要求包括图表、实物等硬件要求:工作量要求: 1、完成XS-ZY-250A塑料注塑成型机床身结构设计设计说明书一份; 2、完成XS-ZY-250A塑料注塑成型机床身结构设计装配图和零件图若干; 3、完成装配图与部分零件图总图量:累加起来达到A0图纸2张;4主要参考文献:1齐卫东主编。塑料模具设计与制造.北京:高等教育出版社,20042张利平主编.液压传动设计指南M.第1版.北京:化学工业出版社,2012.4 3邓明主编.实用模具设计简明手册M.第1版.北京:机械工业出版社,2010.14CSCD核心期刊.机械设计J.天津.中国科学技术协会.12-1120/TH5Watson I. Case-based reasoning is a methodology not a technologyJ.K now ledge-Based Systems , 1999.12(5-6) : 303-308.毕 业 设 计(论 文)任 务 书5本毕业设计(论文)课题工作进度计划:起 讫 日 期工 作 内 容起 讫 日 期工 作 内 容2019年12月18日-2019年12月20日指导教师下发任务书,师生见面讨论、并当面给学生分配设计任务 2019年12月23日-2020年3月2日学生搜集资料,提交开题报告及外文翻译的初稿2020年3月9日-2020年3月17日提交开题报告、外文参考资料及译文的修改稿2020年3月18日-2020年3月30日进一步完善前期的各项材料,提交各项材料的定稿,开始准备毕业设计的课题研究2020年4月1日-2020年4月8日进行毕业设计中期检查,学生进行课题的设计、编程、安装、调试2020年4月9日-2020年5月18日学生进一步完善课题的设计、编程、安装、调试,教师评阅学生毕业设计;学生准备毕业设计答辩所在专业审查意见: 同意专业(系)负责人: 戈晓岚2019年12月26日学院审查意见: 同意学院负责人:张家海2020年1月8日外文出处:Ahmad Jahanbakhsbi.Springer journal,2019,4:1666-1672 1外文资料翻译译文(约3000汉字):拖拉机下连杆机构的有限元模拟与力学应力分析Ahmad Jahanbakhsbi, Kobra Heidarbeigi摘要:下连杆是用来将工具固定在农用拖拉机上的,不同的力在工作时对其产生作用。意识到安全及变形的形状下的链接,这些力量可以帮助我们减少失败和经济损失。本文对MF399和MF285拖拉机的下臂进行了仿真,并采用有限元法进行了力学分析。采用逆向工程方法设计了下臂的三维模型,并考虑了设备最大工作深度处的拉伸力,对模型施加了约束、边界条件和载荷。然后利用有限元方法在ANSYS软件中进行了静力模态和疲劳分析,得到了下臂的安全系数。有限元分析结果表明,下臂与附着体的连接点处出现了冯米塞斯应力的最大值。这些结果表明,较低的手臂是足够安全的工作与普通的犁沟和凿犁,但当工作与钻机播种机,断裂的可能性更高。此外,为了防止共振频率,使用模态分析计算了下臂的固有频率。对下臂的疲劳分析表明,在抑制链孔周围失效的概率很高。这些结果对下肢设计过程的优化有一定的参考价值。关键词: MF拖拉机、下臂、有限元静态分析、动态分析1. 介绍不断努力优化农业机械已经导致了大量的研究,需要关注与这个问题有关的所有方面。如今,利用计算机辅助设计技术对构件和结构的受力、应力分布、变形和性能优化等因素进行研究,效率更高,速度更快1-3。有限元法(finite element method,FEM)是一种非常快速和精确的数值技术,用于分析和计算机械零件的应力-应变和变形形状,并在建立第一个原型之前识别临界和非临界点4-6。通过改变材料和表面条件等有效性能,可以方便快捷地对有限元法进行优化。这种方法可以在不需要物理模型的虚拟环境中进行分析7,8。Rusinski等人将9、意大利面和Mariotti10等应用于地下矿山装载机臂的有限元数值和试验失效分析9。对正齿轮进行了修正型强度分析,Bayrakceken11对汽车差速器小齿轮在静、动载荷作用下的机械失效进行了预测。 农业机械有许多运动部件,它们在较大的静、动载荷作用下工作,会引起故障和停机。人们已经进行了许多研究来研究农具的性能。Mouazen和Nemenyi12研究了a的行为采用有限元法模拟了非均质砂壤土中土壤切割过程。结果表明,有限元法是一种适合于耕作机械建模和分析的方法。Mollazade等人开发了一种动态分析方法,使用有限元法来选择抗疲劳可靠的潜艇最佳形状。Wan等人14研究了五种土壤结构中旋耕机叶片的机械应力和土壤变形,Abu-Hamdeh等人15研究了圆盘犁上的土壤力。其他农业机械仿真分别在三点悬挂牵引车的升降臂上进行4,5,砍刀16的滑轮振动分析,JD联合收割机的前轴17和秸秆行走机的曲轴18。 农用拖拉机是最受欢迎的农业机械之一,通过三点悬挂系统用于起重、牵引和其他现场作业19,20。拖拉机的主要问题之一是由于工作负荷大而导致下臂或农具附着点的下环断裂或变形。因此,下臂属于拖拉机关键三点式挂接件的失效会造成农具的损坏和经济损失,有时还会对农民造成伤害。因此,对拖拉机下臂在最困难工况下的力学分析是研究其失效或变形原因的必要手段。摘要本研究的目的在于分析MF399与MF285拖拉机(伊朗大不里士市拖拉机制造公司)在外场作业时,其下臂之安全系数与固有频率。该研究结果可用于评价拖拉机下臂材料的优化需求、机械强度和性能。 在目前的研究中,下肢的尺寸测量了399台和285台梅西.弗格森牌拖拉机。这些是用来模拟三维的SuldWoats2013中的下臂机构,一个商业软件。M1399和MF8拖拉机的真实下臂和示意图分别如图1和图2所示,然后将CAD仿真文件导入ANSYSV15软件进行有限元建模。用于制作下臂的钢(St37)的力学性能如表1所示。 图1 MF399拖拉机的实际(a)和示意图(b)下臂图2 MF285牵引车下臂:SolidWorks仿真臂a实际臂b2. 静态分析采用三维实体单元SOLID187对有限元模型进行网格划分,每个节点有8个节点,每个节点有3个自由度。模型由614个元素和16,318个节点组成。 MF399牵引车臂与MF285牵引车下臂530个元件和99089个节点(图3)。模型的网格划分采用自由法。将边界条件和位移条件应用于牵引车臂连接点。图3 ANSYS中下臂有限元模型:aMF285,bMF399拖拉机 通过对MF399和MF285拖拉机在不同工况下的现场试验,得到了两种拖拉机下臂的载荷值。在使用凿子、开沟机和播种机时,为了确定下臂的最大拉力及其方向,进行了拉力测试。与拖拉机前进方向平行使用的下臂供给牵引力。凿岩犁和开沟机设备在耕作过程中的拉伸载荷 种植时测量最大工作深度(表2),并将其作为输入荷载,在ANSYS软件中对模型进行分析。在静力分析中,下臂受力,分析模型后,根据Von-Mises理论计算出下臂的等效拉应力。为了避免零件失效,最大应力不能超过材料的屈服强度。在静载荷下,安全系数(FS)得到屈服强度(r)除以最大工作或容许应力(r)应用于较低的链接(Eq1)。在一个适当中,FS必须大于1,表明该结构可以工作和保持健康在不确定加载条件21。3.模态分析模态分析是结构分析和工业分析的重要内容。组件设计可以产生共鸣。小荷载作用下,结构会产生相应的变形和破坏。因此,机械零件的设计必须尽可能远离共振频率范围。结构固有频率的波动增加了振动幅值,导致构件的破坏和断裂。模态分析用于确定固有频率22的值和振型。结构的固有频率取决于结构的形状、材料和支撑。但是,负载的数量和类型会影响自然频率。在本研究中,采用实体182和185单元对零件进行模态分析。为了确定材料的特性,包括弹性模量、泊松比和钢材密度(St37)(表1)。对模型进行网格化处理,将边界条件应用于牵引车的下臂连接,所需节点在各个方向进行绑定。然后,对MF399和MF285拖拉机的下臂进行了0-5000Hz范围内的前5个固有频率的模态分析。4.疲劳分析 循环荷载作用在结构上产生裂纹,最终导致局部断裂,而反向应力的mag-nitude低于结构的屈服应力。这种现象称为循环载荷引起的疲劳。在ANSYS软件中,对周期性荷载作用下的结构进行疲劳分析时,首先要考虑循环荷载作用下结构的应力。因此,在进行疲劳分析之前,应进行统计分析。然后根据应力等值线,检测出具有最大应力的临界节点,并对临界节点进行疲劳分析。为了获得下臂材料的疲劳应力(r),对模型进行了150万次加载循环的疲劳分析。为此,使用了实体185元素。它是一个三维的4结点单元,每个结点有3个自由度。材料、网格和应用边界条件的表征与静态分析相同。采用Soderberg方程(Eq2)计算疲劳分析23的安全系数(FS)。其中r为平均应力,r为反向应力,K为几何应力集中系数。aver在上述方程中,r和r由方程3和4得到。ave其中r为最大应力,r为零。5. 结果与讨论5.1 静态分析MF399和MF285拖拉机下臂受力变形情况见表3。这种变形是由牵引车拖动时装置的抗拉强度引起的。变形发生在机具与牵引车下臂交界处,与牵引车牵伸方向相反。 基于Von-Mises理论的MF399和MF285拖拉机下臂的应力分布如图4所示。最大的应力发生在下臂的连接部位。MF399牵引车下臂与开沟机、凿式犁、钻式播种机连接处的最大应力分别为67.2、88.9、136MPa.使用Eq1和最大应力时,MF399拖拉机下臂在犁沟机、凿子机和钻式播种机耕作和种植作业中的安全系数分别为2.94、2.22和1.45。 基于冯-米斯理论的MF285牵引车下臂在连接点处的最大应力分别为74.7、97.3和141MPa。最后,配备犁沟机、凿子和播种机的MF285拖拉机下臂安全系数分别为2.65、2.03和1.40。 这些结果表明,下臂的大部分压力发生在连接点,因此,最不容易断裂。此外,在使用钻式播种机时,折断下臂的可能性比用皮划艇和凿子犁要大得多。图4附着于a、b收沟机的MF399和IMF285下臂的静应力:c.d为凿岩机,e.f为播种机 5.2 模态分析在0-5000Hz范围内对5个固有频率进行了模态分析。研究结果载于表4。 5.3 疲劳分析 由于定义载荷对结果的影响,疲劳分析依赖于静力分析,因此有必要将载荷和边界条件的定义与实际情况一致。MF399型拖拉机下臂连接开沟机、凿子150万次载荷循环后的耐久应力犁和钻式播种机分别为7.82、7.99和19.07MPa,MF285的下臂也是如此拖拉机为15.4、18.7和24.3MPa(图5)说明,下臂上的链阻剂孔洞应力集中系数为3,疲劳分析的安全系数根据Soderberg准则计算,最大应力发生在连接点。MF399拖拉机工作时的安全系数分别为1.51、1.51和1.52。配备犁沟机、凿式犁和播种机的MF285拖拉机下臂安全系数分别为1.53、1.54和1.56。图5装备a.b收沟机的MF399、MF285型下臂的疲劳分析c,d凿犁和e,f钻种植园主5.4 结论有限元法是分析不同机械零件应力应变分布的有效方法。通过对下层施加静态力臂部,根据冯米泽斯准则,最大应力出现在下臂与肩部的连接处,分别为67.2MPa、88.9MPa和136MPa,分别为MF399和74.7MPa、97.3和141MPa.最高的,通过静力分析得出的安全系数最低的两臂分别与开沟机和播种机相连。根据这些结果,下臂故障的概率较高,而配备了钻种植。进行了疲劳分析:根据Soderberg理论,最小安全系数为1.51,在MF399拖拉机的下臂固位链环孔处附加了一个犁沟机。正如我们所知,安全因素从静态和疲劳分析是不够的,建议降低武器必须强横断面地区通过增加或减少应力集中的结点实现避免破坏和增加安全系数至少3在静态分析和2进行疲劳分析。参考文献1 s.Kalpakjian,S.R.Schmid,制造工程与技术,第四版.(Prentice-HalInc.UpperSaddleRiver,2001)2A.Jahanbakhshi,B.Ghamari,K.Heidarbeigi,使用统计和人工智能方法评估1055I约翰迪尔联合收割机的声发射. Int.J.Veh.NoiseVib.13(2)105-117(2017)3A.Jahanbakhshi,B.Ghamari,K.Heidarbeigi,发动机转速和传动比对JohnDeere10551联合收割机声发射的影响. Agric.Eng.Eng。Int.CIGRJ18(3),106-112(2016)4 M.J.Ryken,J.M.Vance将虚拟现实技术应用于拖拉机举升臂的交互应力分析。有限的初步的交互.Des.35,141-155(2000)5 E.Seyedabadi,某型号MF-285升降臂的有限元分析拖拉机三点悬挂。J.Fail.Anal. Prev.15(5),737-743(2015)6A.Jahanbakhshi,S.HeidariRazDarreh,K.Kheiralipour,Simulationandstaticandfatigueanalysisofcrossbarofmoldboardploughbyfiniteelementmethod(FEM).伊朗.j.Biosyst.工程49(3),341-352(2018). https:/doi.org/10.22059/JBSE.2018.234998.664958.(波斯)7 S.H.R.Lo,A.Bevan,带孔板的疲劳分析标本和卡车排气支架使用计算机为基础的方法. Int.j.Eng。Simul.4(2),61-69(2002)8 A.Mirehei,M.HedayatiZadeh,A.Jafari,M.Omid,Fatigue利用有限元分析软件ANSYS对万能拖拉机连杆进行分析. j. Agric.Technol 4(2),21-27(2008)9 E.Rusinski,P.Moczko,J.Czmochowski,矿山装载机臂裂的数值模拟与试验研究.Constr.17,271-277(2008)10 A.Pasta,G.Mariotti,骨刺有限元分析齿轮与修正的轮廓. J.StrainAnal.Eng.Des.42(5),281-292(2007)11 H.Bayrakceken,汽车差动小齿轮轴的失效分析. Eng.Fail.Anal.13,1422-1428(2005)12 A.M.Mouazen,M.Nemenyi,地基有限元分析在非均质砂壤土上进行切削.SoilTillageRes.151,1-15151,(1999)13 K.Mollazade,A.Jafari,E.Ebrahimi,动力学的应用利用ANSYS软件分析选择最佳潜水器形状. 纽约科学.J3(3),93-100(2010)14 J.Wan,L.Young,J.Kim,s.Kang,S.B.Shim,J.Y.Kim,压力基于土壤类型的动力杷叶片分析.2012年7月8-12日,西班牙CIGRAGENG15 N.H.-Abu-Hamdeh,R.C.Reeder,圆盘犁土力的非线性三维有限元分析. SoilTillageRes.74(2),115-124(2003)16 H.Celik,M.Topakci,M.Canakci,A.E.W.Rennie,L.Akinci,用有限元法对农业机械进行模态分析:以饲料粉碎机的v形带轮为例. J.FoodAgric.Environ.8(3.4),439-446(2010)17 A.Jafar,M.Khanali,HMobli,ARajabipour,压力分析JD955联合收割机静载前轴. JAgric.SocialSci.社会科学2(3),133-135(2006)18 M.Azadbakht,ATaghizadeh-Alisaraei,A.Hashemi,R.Jan-zadehGalogah, 995联合收割机秸秆行走机曲轴受力分析. Univers.J.Agric.Res.1(1),9-16(2013)19 B.Day,L.Field,A.Jarvis, Biosyst工程Eng.103(1).36-47(2009)20G.V.P.Kumar,path电脑程序开发一代拖拉机挂点. Biosyst.工程113、272-283(2012)21 R.G.Budynas,J.K.Nisbett,机械工程设计,第9版. 麦格劳-希尔出版社,纽约,2011)22 J.E.Shigley,C.R.Mischke,模态分析(台北,2001),第1-11页23 施嘉礼,机械工程设计.麦格劳-希尔出版社,纽约,19892外文资料原文(与课题相关,至少1万印刷符号以上):Simulation and Mechanical Stress Analysis of the Lower Link Arm of a Tractor Using Finite Element MethodAhmad Jahanbakhshi, Kobra HeidarbeigiAbstract:The lower link arms are used for attaching tools to agricultural tractors, and different forces act on those while working. Awareness about the safety and deformed shape of the lower link under these forces can help us to reduce failures and financial losses. In this study, the lower arms of MF399 and MF285 tractors were simulated and mechanical analysis was discussed using the finite element method. Three-dimensional models for both of the lower arms were designed using reverse engineering, and constraints, boundary conditions and loads were applied on the models considering the tensile force at the maximum work depth of the equipment. Then, the finite element method was used for static, modal and fatigue analysis in ANSYS software and then safety factor obtained for the lower arms. The FEM of static analysis results showed that the maxi- mum value of Von-Mises stress occurred at the junction point of the lower arms to the attachments. These results indicate the lower arm is safe enough for working with a usual furrower and chisel plow, but while working with a drill planter, the possibility of breaking is higher. Also to prevent resonance frequency, the natural frequencies of the lower arms were calculated using modal analysis. Fatigue analysis for the lower arms showed that the probability of failure is high around the hole of inhibitory chains. These results can be useful to optimize design process of the lower arms.Keywords: MF tractor; Lower arm; FEM Static analysis; Dynamic analysis1.IntroductionContinuous efforts to optimize agricultural machines have led to numerous studies, and attention is needed to all aspects involved with this issue. Nowadays, studying of factors such as forces, stress distribution, deformations and optimization of the performance of components and structures is more efficient and faster using computer-aided design techniques 13.The finite element method (FEM) is an extremely fast and accurate numerical technique to analyze and calculate the stressstrain and deformation shape of mechanical parts and identify the critical and non-critical points before building the first prototype 46. Optimizing against fatigue using FEM can be conducted quickly and easily by changing the effective properties such as materials and surface conditions. This method leads to the analysis in a virtual environment without need of a physical model 7, 8.Numerical and experimental failure analysis by FEM used for loader booms in underground mines by Rusinski et al. 9, Pasta and Mariotti 10 analyzed the strength of the spur gear with modified profile, and Bayrakceken 11 predicted mechanical failure of an automobile differential pinion under static and dynamic loads.Agricultural machinery has a lot of moving parts which work under large static and dynamic loads, which can cause failure and downtime. Much research has been conducted to study the behavior of agricultural tools. Mouazen and Nemenyi 12 studied the behavior of a subsoiler blade in non-homogeneous sandy-loam soil by finite element method to model the soil cutting processes. Their results showed that the finite element method is a proper method for modeling and analyzing of tillage machines. Mollazade et al. 13 developed a dynamic analysis to select the best shape of a subsoiler reliable against fatigue using FEM. Wan et al. 14 studied the mechanical stress and soil deformation by rotary tiller blades in five soil structures, and Abu-Hamdeh et al. 15 researched on soil forces on disk plows. Other simulations of agricultural machines were conducted on the lift arm of a three-point hitch tractor 4, 5, vibration analysis of the pulley of a chopper 16, and the front axle 17 and straw walker crankshaft 18 of JD combine harvester.The farm tractor is one of the most popular agricultural machines and is used for the purpose of lifting, pulling and other field operations by a three-point hitch system 19, 20. One of the major problems occurring in tractors is breaking or deforming of the lower arms or lower link at the attachment points to farm implements because of high working loads. Therefore, the lower arms belong to thecritical three-point hitch parts in tractors, and failure of this part can cause damage to attached implements and commercial losses and some times injury to farmers.So it seems that the mechanical analysis of the lower arms of tractors under the most difficult working conditions is necessary in order to investigate the cause of failure or deformation shape. The aim of this study was to analyze the lower arm of a three-point hitch of MF399 and MF285 tractors (Tractor Manufacturing Tabriz, Iran) using the finite element method during field operations to find safety factors and natural frequencies under static and dynamic loads. The results of this study can be used to comment on the need for optimization, mechanical strength and behavior of materials forming the lower arms of the tractor,materials and methods.In the present study, the dimensions of the lower arms of 399 and 285 Massey Ferguson tractors were measured. These were used to simulate a three-dimensional mechanism of lower arms in SolidWorks 2013, a com- mercial software. The real and schematic lower arms of MF399 and MF285 tractors are shown in Figs. 1 and 2, respectively. Then, the CAD simulation files in order to build the FEM were imported into ANSYS V15 Software. Mechanical properties of steel (St 37) which was used to build the lower arms are presented in Table 1. Fig. 1 The actual (a) and schematic (b) lower arms of the MF399 tractorFig. 2 The lower arm of MF285 tractor: a actual and b the simulated one in SolidWorks2.Static AnalysisThe finite element models were meshed using SOLID187 that is a three-dimensional solid element and has 8 nodes with three degrees of freedom for each node. The models consisted of 614 elements and 16,318 nodes for the lower arm of MF399 tractor and 530 elements and 99,089 nodes for the lower arm of MF285 tractor (Fig. 3). Meshing of models was performed by the free method. The boundary and displacement conditions were applied to arm junction points to the tractors.Fig. 3 Finite element models of lower arms in ANSYS: a MF285 and b MF399 tractorsThe values of loads applied to the lower arms of MF399 and MF285 tractors were obtained from field testing under different working conditions. The tensile force testing was performed in order to determine maximum value of forces on the lower arms and its direction while working with chisel, furrower equipment and drill planter. The lower arms supply draft forces which are applied in parallel with the forward direction of tractor. The tensile load of chisel plow and furrower equipment during tillage operation and drill planter while planting were measured at the maximum depth of working (Table 2) and were considered as input loads for analyzing of the model in ANSYS software.In static analysis, force was applied to the lower arms and after analyzing the model, the equivalent tension stress on the lower arms was calculated based on Von-Mises theory. To avoid of the parts failure, the maximum stress must not exceed of the material yielding strength. Under static loading, the factor of safety (FS) is obtained from yield strength (ryp) divided by maximum working or allowable stress (rall) applied on the lower links (Eq 1). In a proper design, the FS must be greater than one, indicating that the structure can work and remain healthy in uncertain loading conditions 21. 3.Modal AnalysisModal analysis is necessary in the structural and industrial components designs that can resonate. Small loads at resonance frequency can result in induced deformation and damage in the structures. Therefore, mechanical parts must be designed as far as possible away from the resonance frequency range. Fluctuation in natural frequency of the structure increases the vibration amplitude and results in the failure and fracture of the component. Modal analysis is used to determine the value and mode shapes of the natural frequencies 22. The natural frequency of the structure depends on the shape, material and supports of the structure. However, the amount and type of loads can affect the natural frequency. In this study, the SOLID 182 and 185 elements were used for modal analysis of the parts. To determine the characterization of materials including modulus of elasticity, Poissons ratio and density of steel (St 37) were used (Table 1). The models were meshed, boundary conditions were applied in the lower arms con- necting to the tractor, and desired nodes were binding in all directions. Then, the modal analysis of the lower arms of MF399 and MF285 tractors was performed with regard to the first 5 natural frequencies in range of 05000 Hz.4.Fatigue AnalysisThe effect of cyclic loads applied on structures creates cracks and finally results in part fracture, while the magnitude of reversing stress is lower than the yield stress of the structure. This phenomenon is called fatigue due to applying cyclic loads. In ANSYS software to perform a fatigue analysis under intermittent loads, firstly the exerted stresses in structures under cyclic loads must be deter- mined. So, before any fatigue analysis, statistical analysis should be performed. Then according to stress contours, the critical nodes with maximum stresses must be detected and after fatigue analysis can be surveyed on the critical nodes. In order to obtain the endurance stress (re) of the steel material in the lower arms, fatigue analysis was performed on the model by applying 1.5 million loading cycles. For this purpose, the SOLID 185 element was used. It is a three-dimensional and 4-node element, and each node has three degrees of freedom. Characterization of materials, mesh and applying boundary conditions was conducted the same as those considered for static analysis. The Soderberg equation (Eq 2) was used to calculate factor of safety (FS) in fatigue analysis 23. where rave is average stress, rr is reversing stress, and K is geometric stress concentration factor. In the above equa- tion, rave and rr were obtained by Eqs 3 and 4. In these equations, rmax was the maximum stress and rmin was considered as zero. 25.Results and Discussion5.1 Static AnalysisThe deformation of the lower arms of MF399 and MF285 tractors subjected to the forces is reported in Table 3. This deformation is caused by the tensile strength of the devices while dragging by tractors. The deformation occurred at the junction of the implements to the lower arms of tractors and in the opposite direction of tractors draft. Stress distributions in the lower arms of MF399 and MF285 tractors based on Von-Mises theory are shown in Fig. 4. The greatest amount of stress occurred at the junction devices to the lower arms. The highest stress of the lower arms of MF399 tractor was equal to 67.2, 88.9 and 136 MPa at the connecting point of the lower arm to the furrower, chisel plow and drill planter, respectively. Using Eq 1 and also with respect to the maximum stress, factors of safety in the MF399 tractor lower arms during tillage and planting operation with furrower, chisel and drill planter were 2.94, 2.22 and 1.45, respectively.Also, the highest stress in the lower arms of MF285 tractor based on Von-Mises theory at the connecting point was 74.7, 97.3 and 141 MPa in the furrower, chisel plow and drill planter, respectively. Finally, factors of safety in the lower arms of MF285 tractor equipped with furrower, chisel and drill planter were 2.65, 2.03 and 1.40, respectively.These results showed that most stress in the lower arms occurs at the connection point, and therefore, it is worst likely to break. Also, the probability of breaking the lower arms while working with a drill planter is more than fur- rower and chisel plows. Fig. 4 The static stress in MF399 and MF285 lower arms attached to a, b furrower; c, d chisel plow and e, f drill planter5.2 Modal AnalysisModal analysis was developed for 5 natural frequencies within ranges 05000 Hz. The results are presented in Table 4 5.3 Fatigue AnalysisDue to the effects of defined loads on the results and that the fatigue analysis is depended on static analysis, it is necessary that applied loads and boundary conditions on the lower arms be defined identical with the real conditions. The endurance stress after 1.5 million load cycles for lower arms of MF399 tractor connected to furrower, chisel plow and drill planter was 7.82, 7.99 and 9.07 MPa, respectively, and in the same way for lower arms of MF285 tractor were 15.4, 18.7 and 24.3 MPa (Fig. 5). Taking into account, the stress concentration factor is 3 for the chain inhibitors holes on lower arms, the s
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