人人文库网 > 图纸下载 > 毕业设计 > ZL15装载机总体及定轴变速箱的设计【word+3张CAD图纸全套】【优秀毕业设计】

2sdarticle20.pdf

ZL15装载机总体及定轴变速箱的设计【word+3张CAD图纸全套】【优秀毕业设计】

资源目录

ZL15装载机总体及定轴变速箱的设计【word+3张CAD图纸全套】【优秀毕业设计】.rar

第四章东胜总体布置.docx---(点击预览)

第六章东胜毕业设计小结.docx---(点击预览)

第五章东胜定轴式动力换挡变速箱设计..doc---(点击预览)

第二章东胜总体设计.doc---(点击预览)

第三章东胜牵引计算.docx---(点击预览)

ZL15装载机总体及变速箱设计任务书（3轴及齿轮）.doc---(点击预览)

4.目录.doc---(点击预览)

毕业设计规定格式要求

毕业设计计算书格式及内容要求.doc---(点击预览)

毕业设计的有关规定（学生）.doc---(点击预览)

毕业设计成果装订顺序.doc---(点击预览)

毕业设计成果盒统一粘贴封面.doc---(点击预览)

毕业设计开题报告样表.doc---(点击预览)

毕业设计任务书封面.doc---(点击预览)

毕业实习报告及封面格式要求.doc---(点击预览)

有关毕业设计的表格（教师需填）.doc---(点击预览)

外文资料翻译封面及格式要求.doc---(点击预览)

毕业设计相关表格表格

毕业答辩评分表.doc---(点击预览)

本科毕业设计（论文）阶段批阅单.doc---(点击预览)

本科毕业设计（论文）评阅人评阅表.doc---(点击预览)

本科毕业设计（论文）答辩委员会评定表.doc---(点击预览)

本科毕业设计（论文）指导教师评阅表.doc---(点击预览)

本科毕业设计（论文）成绩评定表.doc---(点击预览)

本科毕业设计(论文)答辩记录表.doc---(点击预览)

年毕业设计（论文）基本情况汇总表.doc---(点击预览)

200 年本科毕业设计（论文）中期检查表.doc---(点击预览)

英文翻译

翻译1.doc---(点击预览)

封皮.doc---(点击预览)

3翻译.doc---(点击预览)

2sdarticle20.pdf---(点击预览)

说明书备份

英文摘要.docx---(点击预览)

第四章东胜总体布置.docx---(点击预览)

第六章东胜毕业设计小结.docx---(点击预览)

第五章东胜定轴式动力换挡变速箱设计..doc---(点击预览)

第二章东胜总体设计.doc---(点击预览)

第三章东胜牵引计算.docx---(点击预览)

第一章东胜前言.doc---(点击预览)

实习报告.doc---(点击预览)

参考文献(完成).doc---(点击预览)

中文摘要.docx---(点击预览)

4.目录.doc---(点击预览)

计算说明书

第四章东胜总体布置.docx---(点击预览)

第六章东胜毕业设计小结.docx---(点击预览)

第五章东胜定轴式动力换挡变速箱设计..doc---(点击预览)

第二章东胜总体设计.doc---(点击预览)

第三章东胜牵引计算.docx---(点击预览)

第一章东胜前言.doc---(点击预览)

开题报告样表1.doc---(点击预览)

dongsheng实习报告正文.doc---(点击预览)

压缩包内文档预览：

编号：295084 类型：共享资源大小：18.30MB 格式：RAR 上传时间：2014-07-06 上传人：QQ14****9609 IP属地：陕西

25
积分

版权申诉 word格式文档无特别注明外均可编辑修改；预览文档经过压缩，下载后原文更清晰！ 立即下载

关键词：: zl15 装载总体整体变速箱设计 word cad 图纸全套优秀优良毕业设计

资源描述：

ZL15装载机总体及定轴变速箱的设计（3轴及齿轮）【word+3张CAD图纸全套】【优秀机械毕业设计】

【带任务书+开题报告+外文翻译+实习报告】【77页@正文33300字】【详情如下】【全套设计需要咨询请加QQ1459919609】

4.目录.doc

ZL15装载机总体及变速箱设计任务书（3轴及齿轮）.doc

中文摘要.docx

参考文献.docx

实习报告.doc

开题报告.doc

正文.doc

毕业设计规定格式要求

第一章东胜前言.doc

第三章东胜牵引计算.docx

第二章东胜总体设计.doc

第五章东胜定轴式动力换挡变速箱设计..doc

第六章东胜毕业设计小结.docx

第四章东胜总体布置.docx

英文摘要.docx

英文翻译

装配图.dwg

说明书备份

轴.dwg

齿轮.dwg

毕业设计（论文）任务书

ZL15装载机总体及定轴变速箱设计（3轴及齿轮）

发任务书日期： 2013年 3月7日

1、本毕业设计（论文）课题应达到的目的：

本毕业设计是对机械专业学生在毕业前的一次全面训练，目的在于巩固和扩大学生在校期间所学的基础知识和专业知识，训练学生综合运用所学知识分析和解决问题的能力。是培养、锻炼学生独立工作能力和创新精神之最佳手段。毕业设计要求每个学生在工作过程中，要独立思考，刻苦钻研，有所创造的分析、解决技术问题。通过毕业设计，使学生掌握装载机的总体设计、变速箱设计、牵引计算等技术工作的实现方法，为今后步入工作岗位打下良好的基础。

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）：

（1）设计任务：

①总体参数选择：

1）总体方案及总体参数的确定；

2）牵引计算；

3）变速箱档位、速比的确定，动力换档变速箱型式的选定，学生要进行充分论证。

②变速箱设计（3轴及齿轮）：

1）方案设计，确定传动简图；

2）技术设计；

3）强度、刚度计算。

③变速箱操纵液压系统原理图设计。

（2）技术参数

①额定载重量：1.5T

②工作重量：≯5.5T

③最高车速：≮20km/h

④空载牵引力：3.5～4.4T

⑤爬坡能力：≮20°

⑥最大卸载高度：≮2.35m；最小卸载距离：≮0.75m

⑦掘起力：≮4T

（3）设计要求：

①主要任务：学生应在指导教师指导下独立完成一项给定的设计任务，编写符合要求的设计说明书，并正确绘制机械与电气工程图纸或独立撰写一份毕业论文，并绘制有关图表。

②知识要求：学生在毕业设计工作中，应综合运用多学科的理论、知识与技能，分析与解决工程问题。通过学习、研究与实践，使得理论认识深化、知识领域扩展、专业技能延伸。

③能力培养要求：学生应学会依据技术课题任务，进行资料的调研、收集、加工与整理和正确使用工具书；培养学生掌握有关工程设计的程序、方法与技术规范，提高工程设计计算、图纸绘制、编写技术文件的能力；培养学生掌握实验、测试等科学研究的基本方法；锻炼学生分析与解决工程实际问题的能力。

④综合素质要求：通过毕业设计，学生应能树立正确的设计思想；培养学生严肃认真的科学态度和严谨求实的工作作风；在工程设计中，应能树立正确的生产观点、经济观点与全局观点。

⑤设计成果要求：

1）凡给定的设计内容，包括说明书、计算书、图纸等必须完整，不得有未完成的部分，不应出现缺页、少图纸现象。

2）对设计的全部内容，包括设计计算、机械构造、工作原理、液压系统、整机布置等，均应有清晰的了解。对设计过程、设计步骤有明确的概念，能用图纸完整地表达机械结构与工艺要求，有比较熟练的认识图纸能力。对运输、安装、使用等亦应有一般了解。

3）说明书、计算书内容要精炼，表述要清楚，取材合理，取值合适，设计计算步骤正确，数字计算准确，各项说明要有依据，插图、表格及字迹均应工整、清楚、不得随意涂改。制图要符合机械制图标准，且清洁整齐。

4）对国内外装载机情况有一般的了解，对各种装载机有一定的分析、比较能力。

5）其它各项应符合本资料有关部分提出的要求。

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）：

①计算说明书一份

内容包括：设计任务要求的选型论证、设计计算内容，毕业实习报告等。做到内容完整，论证充分（包括经济性论证），字迹清楚，插图和表格正规（分别进行统一编号）、准确，字数要求不少于2万字。查阅文献15篇以上，翻译机械类外文资料，译文字数不少于3000字；撰写中英文摘要；并引导学生应用计算机进行设计、计算与绘图。

②图纸一套（折合不少于3张0号图）

1）总体布置图一张（0号）；

2）变速箱传动简图一张（1号）；

3）变速箱装配图二张（两个视图）（0号二张）；

4）变速箱操纵液压系统原理图一张（1号）；

5）零件图二张（2号二张）；

4、主要参考文献：

要求按国标GB 7714—87《文后参考文献著录规则》书写。

【1】同济大学主编. 铲土运输机械. 北京: 中国建筑工业出版社，1987

【2】吉林工业大学主编. 轮式装载机设计. 北京: 中国建筑工业出版社，1989

【3】杨晋生主编. 铲土运输机械. 北京: 机械工业出版社, 1987

【4】同济大学主编. 工程机械底盘构造与设计. 北京: 中国建筑工业出版社, 1987

【5】诸文农主编. 底盘设计（上、下）. 机械工业出版社，1981年7月

【6】许镇宇，邱宣怀主编.机械零件(修订版)[M] .北京：人民教育出版社，1981

【7】吉林工业大学主编. 工程机械液压与液力传动. 机械工业出版社，1979

【8】东北工学院主编. 机械零件设计手册. 冶金工业出版社，1997

【9】黄谊主编. 液压与气压传动（第一版）. 北京：机械工业出版社, 2000年5月

【10】成大光主编. 机械设计手册（第一卷）. 北京：化学工业出版社, 2003年9月

成大光主编. 机械设计手册（第二卷）. 北京：化学工业出版社, 2003年9月

成大光主编. 机械设计手册（第三卷）. 北京：化学工业出版社, 2003年9月

成大光主编. 机械设计手册（第四卷）. 北京：化学工业出版社, 2003年9月

成大光主编. 机械设计手册（第五卷）. 北京：化学工业出版社, 2003年9月

【11】董刚, 李建功, 潘凤章主编. 机械设计.北京：机械工业出版社, 1998年7月

【12】刘鸿文主编. 材料力学（第四版）. 高等教育出版社, 2004年1月

【13】路凤仪主编. 机械原理课程设计. 北京：机械工业出版社, 2002年6月

5、本毕业设计（论文）课题工作进度计划：

起迄日期工作内容

2013.2.25-2013.3.4

2013.3.5-2013.3.16

2013.3.17-2013.4.9

2013.4.10-2013.4.16

2013.4.17-2013.5.1

2013.5.2-2013.5.11

2013.5.12-2013.5.19

2013.5.20-2013.5.26

2013.5.27-2013.6.2

2013.6.3-2013.6.16

2013.6.17-2013.6.28

毕业实习及熟悉整理资料并写开题报告

总体方案选择及总体设计

牵引计算

进行总体布置并绘制总体布置图

变速箱设计

绘制传动简图、液压系统图

绘制变速箱装配图

典型零件设计及有限元分析

完善计算书、图纸准备和进行答辩

修改设计图、计算书完善设计成果

教研室审查意见：

摘要

我所设计的ZL15装载机既保留了传统装载机的优点，而且具有新的性能和优点。

本次设计主要进行的是变速箱的设计。ZL15装载机属于小型土方机械，广泛应用于城市建设工地及货场、煤场、仓库等装载及堆放松散货料的场所，并且可以用来完成轻度的挖掘及平整场地作业。

ZL15型装载机属于ZL系列，采用轮式行走系，液力机械传动系，铰接式车架,所以该机具有机动性好、转向灵活、生产率高、操纵轻便等优点。另外，该机后桥布置为摆动桥，增加了整机的稳定性，所以该机的安全性好。

ZL15型装载机采用定轴式变速箱，结构简单，制造成本较低，维修方便，特别是采用离合器外置式时，变速箱体尺寸小，便于总体布置。本机在设计中，参考同类机型，选用最佳传动方案，使机构简单，操作方便，并满足作业要求。定轴式变速箱采用动力换挡，使驾驶室操作便捷，减少劳动强度。

变速箱设计包括：变速箱型式的选择、传动比最终的确定、传动简图设计（前三后三档位）、所有齿轮的配齿计算、Ⅰ轴和Ⅱ轴离合器设计、结构设计（包括轴、轴承以及齿轮的选择校核计算）。最后还运用有CATIA对输出轴的受力情况进行了有限元分析。

【关键词】轮式装载机定轴式变速箱换挡离合器有限元分析

ABSTRACT

This type of ZL15 loader that I have designed has the common virtues of the traditional loaders.And it has some new-improved virtues and function.

In my design progress,I put emphasis on the gearbox design. The ZL15 loader belongs to pint-size earthmoving machine.It is suitable for the construction site, the freight yard and so on, where the bulk materials are placed. Other more, it can dig and level lightly.

ZL15 loader belongs to ZL series, using wheeled walking system, hydro mechanical drive, articulated car frame, so the loader has many advantages, such as good maneuverability、turning agility、high productivity、operate portability, and so on. In addition, setting the latter bridge as Swing Bridge increases the overall stability and the safety of the machine.

The ZL15 loader is adopted fixed-axis gear-box, which can simplifies the structure of the whole machine, lowers production costs and make it easier for general service. In the design, after referring to the same type machine, the best transmission scheme is adopted finally, which can minimize the number of the parts and makes the machine has reasonable transmission ratio, so as to satisfy the demand of operation. The fixed-axis gear-box adopts dynamic gear-shifting, which makes the operation of the cab handier, and reduces the intensity of labor.

Gearbox design, including: the choice of transmission type, to determine the final drive ratio, transmission schematic design (three after three stalls), all gears with teeth, Ⅰaxis and Ⅱaxis clutch design, structural design (including the axis , the choice of bearings and gears check prices). Finally I use CATIA to analyze the stress situation of the output axis.

【KEY WORDS】 wheeled loader fixed-axis gear-box Gear-shifting sleeve

Finite element

第1章前言1

第2章总体设计2

2.1 概述2

2.2 选择确定总体参数2

2.3 装载机底盘部件型式选择12

第3章牵引计算20

3.1 柴油机与变矩器联合工作的输入与输出特性曲线20

3.2 确定档位及各档传动比24

3.3 运输工况牵引特性曲线27

3.4 求出各档最高车速并分析牵引特性29

第4章总体布置35

4.1 估计各部件重量（可根据样机定），并确定部件位置坐标35

4.2 各部件布置35

4.3平衡重计算39

4.4 验算轮胎载荷40

第5章定轴式动力换档变速箱设计42

5.1 传动比的确定43

5.2 传动简图设计45

5.3 配齿计算48

5.4 离合器设计50

5.5 结构设计53

第6章毕业设计小结70

参考文献72

第一章前言

装载机属于铲土运输机械类，是一种通过安装在前端一个完整的铲斗支撑结构和连杆，随机器向前运动进行装载或挖掘，以及提升、运输和卸载的自行式履带或轮胎机械，它广泛应用于公路、铁路、建筑和矿山等工程建设。装载机具有作业速度快、效率高、机动性好、操作轻便等优点，因此成为工程建设中土石方施工的主要机种之一，对于加快工程建设速度，减轻劳动强度，提高工程质量，降低工程成本都发挥着重要的作用，是现代机械化施工中不可缺少的装备之一。

ZL15装载机是小型土力机械，广泛应用于城市建设工地及货场、煤场、仓库等装载及堆放松散物料的场所，工作在密实的土壤,并且可以用来完成轻度挖掘及平整场地的作业。

ZL15装载机属于ZL系列，采用轮式行走系；液力机械传动系；铰接式车架；工作装置采用液压操纵，所以该机具有机动性好，转向灵活、生产率高、操纵轻便等优点。另外，该机后桥布置为摆动桥，增加了整车的稳定性，所以，该机安全性好。

ZL15装载机现在普遍采用的设计是分动装置、变矩器和变速箱“三合一”布置。变速箱采用定轴式动力换挡变速箱，动力装置采用高速柴油机。驱动桥为一级减速主传动，轮边行星减速，且采用双桥驱动，采用钳盘式制动器，工作装置采用反转连杆机构。为了适应工作要求，适应生产要求，并尽力向ZL标准系列靠拢，我们在设计过程中，将采用最先进的型式和技术。

第2章总体设计

2.1 概述

总体设计是机械设计中极为关键的环节，它是对所设计机械的总的设想。总体设计的成败，关系到整部机械的经济技术指标，直接决定了机械设计的成败。

总体设计指导机构设计和部件设计的进行，一般由主任工程师（或总工程师）主持进行。在接受设计任务以后，应进行深入细致的调查研究，收集国内外同类机械的有关资料。了解当前国内外装载机的使用、生产、设计和科研情况，并进行分析比较，制定总的设计原则。设计原则应当保证所设计机型符合有关的方针、政策。在满足使用要求的基础上，力求结构合理，技术先进，经济性好，寿命长。

总体设计原则：

1.遵循三化：零件标准化、产品系列化、部件通用化。

2.采用四新：新技术、新结构、新材料、新工艺。

3.满足三好：好制造、好使用、好维修。

4.对零部件设计负责。

制定设计总则以后，便可以编写设计任务书，在调研的基础上，运用所学知识，从优选择确定总体方案，保证设计的成功。

2.2 选择确定总体参数

目前，装载机的总体设计中有计算法、类比法及综合运用计算法和类比等三种设计方法。限于我们的条件，我们的设计采用计算法和类比法综合运用的方法。

总体参数的确定包括以下内容（其余见任务书）：

2.2.1轴距及轮距

轴距和轮距的大小可以影响装载机的使用性能，因此总体设计中的参数，一般是参考同类机型初选，然后通过绘制总体布置图才能准确地选定轴距。

1.轴距L—它的改变会影响以下几个方面的整机性能：

A：影响前后桥轴荷的分配。当各总成（除后桥外）相对于前桥的前后位置不变时，轴距的改变会使前后轴的载荷发生变化。如图2-1所示，后桥载荷，如保持整车重心位置G不变，则增大L，后桥载荷必减小，反之，则增大。因此，改变轴距可调整轴荷分配。

B：影响装载机的纵向稳定性。轴距增大，有利于提高整车的纵向稳定性，如图（2）所示，取临界平衡状态（前桥为支点），如保持前后桥轴荷不变，则增大轴距L值，必增大值，即增加抗整机绕前轴倾翻的力矩(G)。轴距增大还可以减少装载机在行驶中的前后颠簸，提高行驶平稳性，减少司机疲劳。

C：影响最小转弯半径。轴距增大，最小转弯半径增大。

此外，轴距的改变，还会影响车架受力和整机通透性。考虑以上因素，参考天津市政工程机械厂和江西工程机械厂生产的ZL15同类机型。初选轴距L=2050mm。

2.轮距B：

大部分装载机前后轮距相同，且前后轮使用相同轮胎。

A：轮距增加，提高装载机的横向稳定性，但最小转弯半径增加。

B：轮距增大会造成铲斗宽度增加，这样将降低单位斗刃长度上的插入力。

设计中尽可能希望轮距小些。

参考同类机型，选取轮距W=1440mm

2.2.2初选轮胎

轮胎是行走系的主要部件，承担着繁重而复杂的载荷，它对装载机的技术性能和工作指标影响很大，并且还直接影响装载机的安全行驶；从经济指标上看，轮式装载机的轮胎费用占整机购置费的10-15%，占装载机使用费用的25-50%，因此，合理而正确的选择轮胎对扩大装载机的使用范围、降低装载机的使用成本具有很大的意义。

装载机的作业条件是选择其轮胎的重要依据，用于土方工程的装载机常在比压小的软基路面和凹凸不平的路面上行驶作业。另外，装载机的行走装置一般都是与车架刚性连接。所以，在选择轮胎时，除了满足一定的承载能力外，还需要有好的耐磨性、牵引性、通过性及缓冲性能。

1.机构形式的选择

目前装载机广泛采用低压、宽基系列轮胎。

低压轮胎的外形尺寸较大，弹性较好，能增大接

地面积，减少接地比压，所以它能在比压小的软基路面上行驶，下陷小，降低滚动阻力，通过性好；在凹凸路面或碎石路面行驶时，能很好地吸收冲击与振动，缓冲性能好。

宽基轮胎比标准轮胎宽度大，从而接地比压小，在软基路面上通过性能好，牵引力也大。另外具有在同样载荷下使用较低气压的优点。同时又能改善驾驶性能及行驶的稳定性，所以为轮式装载机所广泛采用。

2.轮胎花纹的选用

轮胎胎面上有不同形状的花纹，轮胎花纹的主要作用是保证轮胎和道路之间的良好附着性，传递机械的牵引力与制动力。在本设计中采用混合花纹：中间部分是纵向而两臂部分是横向花纹，其花纹占接地面积的30%，中间纵向花纹可保证纵向稳定，而两臂花纹可提供驱动力与制动力，并且有较好的耐磨性。

3.轮胎尺寸对装载机性能有很大影响，它影响传动系传动比的选择，整机重心高度、离地间隙以及各部件的总体布置等。轮胎尺寸增加，可以增加轮胎的承载能力，能有效地改善附着性能，但它引起机器成本的增加和整机重心的提高。

综合考虑以上因素，参考同类机型，由《工程机

械轮胎手册》表2-3-6和表1-1-5查得：

轮胎型号最大负荷充气压力外直径断面宽度

11.00-202945Kgf7.0

Kg/cm2 1090mm2875mm

2.2.3初定斗宽和斗型

1.斗宽的确定

斗宽B=轮距+轮胎宽+2a （参见设计指导书）

由以上设计知轮距为1440mm，轮胎宽为290mm，取a=50～100mm，则斗宽

B=1440＋290＋2×(50～100)=1830～1930mm

取斗宽B=1900mm。

2.斗型的确定

铲斗是铲装物料的工具,它的斗型与结构是否合理,直接影响装载机的生产率。在设计工作装置连杆机构之前，首先要确定铲斗的几何形状和尺寸，因为它与连杆机构的设计有密切联系。

铲斗首先要有合理的斗型，减少切削和装料阻力，提高作业生产年率，其次是在保证铲斗具有足够强度和刚度的前提下，尽量减少自重；同时也应考虑到更换工作装置和修复易损零件的方便。

铲斗有普通形式的铲斗、蛙式、侧卸式和强制卸料等。普通铲斗有直刀刃、V形刀刃、带斗齿和V形刀刃带斗齿铲斗。直线型斗刃适于装载轻质和松散小颗粒物料，并可利用刀刃作刮平、清理场地工作；V形刀刃便于插入物料堆，有利于改善作业装置的偏载，适宜铲装较密实物料；带斗齿铲斗具有较大的插入料堆的能力，适宜于铲装矿石和坚实物料。齿型的选择应考虑插入阻力和耐磨两个因素，并且要便于更换。尖齿插入力较强，但不耐磨，纯齿则较耐磨，然而插入阻力大，一般轮式装载机多用于前者，大型装载机则常用分体式。这种连接方式便于更换。

ZL15装载机属于中小型装载机，据作业要求，并参考一些同类产品，本机选用直刀刃尖齿铲斗。

参考文献

【1】同济大学主编.铲土运输机械. 北京:中国建筑工业出版社,1987.

【2】吉林工业大学编.轮式装载机设计. 北京:中国建筑工业出版社,1989.

【3】杨晋生主编.铲土运输机械. 北京:机械工业出版社,1987.

【4】同济大学主编.工程机械底盘构造与设计. 北京:中国建筑工业出版社,1987.

【5】诸文农编.底盘设计(上下). 北京:机械工业出版社,1981.

【6】许镇宇，邱宣怀主编.机械零件(修订版)[M] .北京：人民教育出版社，1981

【7】吉林工业大学主编. 工程机械液压与液力传动. 机械工业出版社，1979

【8】东北工学院主编. 机械零件设计手册. 冶金工业出版社，1997

【9】黄谊主编. 液压与气压传动（第一版）. 北京：机械工业出版社, 2000年5月

【10】成大光主编. 机械设计手册（第一卷）. 北京：化学工业出版社, 2003年9月

成大光主编. 机械设计手册（第二卷）. 北京：化学工业出版社, 2003年9月

成大光主编. 机械设计手册（第三卷）. 北京：化学工业出版社, 2003年9月

成大光主编. 机械设计手册（第四卷）. 北京：化学工业出版社, 2003年9月

成大光主编. 机械设计手册（第五卷）. 北京：化学工业出版社, 2003年9月

【11】董刚, 李建功, 潘凤章主编. 机械设计. 北京：机械工业出版社, 1998年7月

【12】刘鸿文主编. 材料力学（第四版）. 高等教育出版社, 2004年1月

【13】路凤仪主编. 机械原理课程设计. 北京：机械工业出版社, 2002年6月

【14】青风，国内轮式装载机的现状和发展趋势，机电信息，2004年第八期

360桌面截图20140706150626.gif

360桌面截图20140706151142.gif

齿轮.gif

轴.gif

装配图.gif

内容简介：: The numerical modelling of excavator bucket filling using DEMC.J. Coetzee*, D.N.J. ElsDepartment of Mechanical and Mechatronic Engineering, University of Stellenbosch, Private Bag X1, Matieland 7602, South AfricaReceived 15 February 2007; received in revised form 25 February 2009; accepted 28 May 2009Available online 25 June 2009AbstractThe filling of an excavator bucket is a complex granular flow problem. In order to optimize the filling process, it is important to under-stand the different mechanisms involved. The discrete element method (DEM) is a promising approach to model soil-implement inter-actions and it was used in this study to model the filling process of an excavator bucket. Model validation was based on the accuracy withwhich the model predicted the bucket drag force and the development of the different flow regions. Compared to experimental measure-ments, DEM predicted lower bucket drag forces, but the general trend was accurately modelled. At the end of the filling process the errorin predicted drag force was 20%. Qualitatively, there was a good agreement between the observed and the modelled flow regions in termsof position and transition from one stage to the other. During all stages of filling, DEM was able to predict the volume of material insidethe bucket accurately to within 6%.? 2009 ISTVS. Published by Elsevier Ltd. All rights reserved.1. IntroductionEarthmoving equipment plays an important role in theagricultural, earthmoving and mining industries. Theequipment is highly diverse in shape and function, but mostof the soil cutting machines can be categorised into one ofthree principal classes, namely blades, rippers and buckets(shovels). This paper focuses on the numerical modelling ofexcavator bucket filling using the discrete element method(DEM).Buckets are found on a number of earthmoving machin-ery. Draglines are used to remove blasted overburden fromopen cut mines. Its removal exposes the coal depositsbeneath for mining. A dragline is a crane-like structurewith a huge bucket of up to 100 m3in volume suspendedby steel ropes. Draglines are an expensive and essential partof mine operations and play an important role in the com-petitiveness of South African mines. In the coal miningindustry it is generally accepted that a 1% improvementin the efficiency of a dragline will result in an R1 millionincrease in annual production per dragline 1. Bucketsare also found on hydraulic excavators, loaders and shovelexcavators.The filling of a bucket is a complex granular flow prob-lem. Instrumentation of field equipment for measuringbucket filling is difficult and expensive. It is possible touse small-scale (usually 1/10th scale) experimental rigs toevaluate bucket designs 1,2 but they are expensive andthere are questions regarding the validity of scaling 3,4.To scale-up results from model experiments is problematicsince there are no general scaling laws for granular flows asthere are for fluid dynamics 5.According to Cleary 5 the filling of buckets, in theabsence of very large rocks, is observed to be relativelytwo-dimensional with little motion in the transverse direc-tion. The flow pattern along a cross-section of the bucket inthe drag direction is the most important aspect of fillingand can be analysed satisfactorily using two-dimensionalmodels. Rowlands 2 made similar observations based ondragline bucket filling experiments.According to Maciejewski et al. 6, in practical caseswhen the motion of a bucket or bulldozer blade is dis-cussed, plane strain conditions apply only in some defor-mation regions. The plane strain solution for such toolscan be assumed only with limited accuracy. Maciejewski0022-4898/$36.00 ? 2009 ISTVS. Published by Elsevier Ltd. All rights reserved.doi:10.1016/j.jterra.2009.05.003*Corresponding author. Tel.: +27 21 808 4239; fax: +27 21 808 4958.E-mail address: ccoetzeesun.ac.za (C.J. Coetzee)./locate/jterraAvailable online at Journal of Terramechanics 46 (2009) 217227JournalofTerramechanicset al. 6 also investigated the assumption of plane strainconditions in soil bins where the soil and tool motion isconstrained between two transparent walls. For measure-ments in such a bin, the force acting on the tool due tothe friction between the soil and the sidewalls has to be esti-mated or neglected. They have shown that for a high num-ber of teeth on the bucket, the teeth do not act as separatethree-dimensional objects but as one wide tool built upfrom several modules. The deformation pattern in frontof such an assembly of teeth was found to be plane straindeformation. The authors, however, concluded that thiswas true for the particular cohesive soil (sandy clay) andmay not apply to other (especially rocky and brittle) mate-rials. In this study the bucket had a full-width lip with noteeth and based on the findings by Maciejewski et al. 6,the assumption of plane strain was made and two-dimen-sional DEM models were used.Analytical methods 711 used to model soiltool inter-action are limited to infinitesimal motion of the tool andthe given geometry of the problem. These methods werenot expected to be valid for the analysis of the subsequentstages of advanced earth digging problems 12. The analyt-ical methods are based on Terzaghis passive earth pressuretheory and assumptions of a preliminary soil failure pattern13. Complicated tool geometry (such as buckets) and largedeformations cannot be modelled using these methods 14.The discrete element method is a promising approach tomodel soil-implement interaction and can be used to over-come some of the difficulties encountered by analyticalmethods 15. In DEM, the failure patterns and materialdeformation are not needed in advance. The tools are mod-elled using a number of flat walls and the complexity of thetool geometry does not complicate the DEM model. Largedeformation in the granular material and the developmentof the granular material free surface are automatically han-dled by the method.Cleary 5 modelled dragline bucket filling using DEM.Trends were shown and qualitative comparisons made, butno experimental results were presented. The process ofhydraulic excavator bucket filling was investigated experi-mentally by Maciejewski and Jarzebowski 12. The aim oftheir research was optimization of the digging process andbucket trajectories. It is shown that the most energy efficientbucket is the one where the pushing effect of the back wall isminimized.Owenetal.21modelled3Ddraglinebucketfill-ing. In there approach, the bucket was modelled with thefinite element method and the soil with DEM. Ellipsoidsand clumped spheres were used to approximate the particleangularity. The bucket followed a prescribed path.Esterhuyse 1 and Rowlands 2 investigated the fillingbehaviour of scaled dragline buckets experimentally withthe focus on rigging configuration, bucket shape and teethspacing. They have shown that the aspect ratio of thebucket (width to depth) plays and important role in thedrag distance needed to fill a bucket. The bucket with theshortest fill distance was found to produce the highest peakdrag force.The main objective of this study was to demonstrate theability of DEM to predict the drag force on the bucket andthe material flow patterns that develop as the bucket fillsup. The DEM results were compared to experiments per-formed in a soil bin.2. The discrete element methodDiscrete element methods are based on the simulation ofthe motion of granular material as separate particles. DEMwas first applied to rock mechanics by Cundall and Strack16. In this study, all the simulations were two-dimensionalandperformedusingcommercialDEMsoftwarePFC2D17.A linear contact model was used with a spring stiffness knin the normal direction and a spring stiffness ksin the sheardirection (Fig. 1). Frictional slip is allowed in the tangentialdirectionwithafrictioncoefficientl.Thedampingforceactson a particle in the opposite direction to the particle velocityand is proportional to the resultant force acting on the par-ticle with a proportionality constant (damping coefficient)C 17. For a detailed description of DEM, the reader isreferred to Cleary and Sawley 18, Cundall and Strack16, Hogue 19 and Zhang and Whiten 20.3. ExperimentalTwo parallel glass panels were fixed 200 mm apart toform the soil bin. The bucket profile was fixed to a trolleywhich was driven by a ball screw and stepper motor. TheFrictionknksFig. 1. DEM contact model.218C.J. Coetzee, D.N.J. Els/Journal of Terramechanics 46 (2009) 217227complete rig could be set at an angle h to the horizontal asshown in Fig. 2a. The first arm was then rotated and fixedsuch that both arms remained vertical. The second armremained free to move in the vertical direction. First, coun-terweights were added at position A (Fig. 2a) to balancethe combined weight of the bucket profile and the secondarm assembly. This resulted in a weightless” bucket.Counterweights were then added at position B to set theeffective” bucket weight. Since arm 2 was always verticaleven for rig angles other then zero, the effective bucketweight always acted vertically downwards (Fig. 2c). Bucketweights of 49.1 N, 93.2 N, 138.3 N and 202.1 N were used.When the bucket was dragged in the direction as indi-cated, it was also free to move in the vertical direction asa result of the effective bucket weight and the force of thegrains acting on it. The bottom edge of the bucket wasalways set to be parallel to the drag direction and the mate-rial free surface. This type of motion resembles that of adragline bucket which is dragged in the drag direction bya set of ropes, but with freedom of motion in all otherdirections 2.Spring loaded Teflon wipers were used to seal the smallopening between the bucket profile and the glass panels. Aforce transducer was designed and built to measure the dragforce on the bucket. A set of strain gauges was bonded to asteel beam of which the position is shown in Fig. 2a. Theset of four strain gauges was used to measure the force inthe drag direction. Other force components were notmeasured. The force transducer was calibrated and thecalibration checked regularly to avoid drift in the measure-ments. For rig angles other than zero, the force transducerwas zeroed before the drag commenced. This compensatedforthecomponentofthebucketweightthatactedinthedragdirection. The vertical displacement of the bucket was mea-sured with a linear variable differential transformer (LVDT)andusedasinputtotheDEMsimulation. Inboththeexper-imentsandtheDEMsimulationsthebucketwasgivenadragvelocity of 10 mm s?1. The dimensions of the bucket profileare shown in Fig. 2b.In this study corn grains were used. Although the corngrains are not real soil, Rowlands 2 observed that seedgrains are suitable for experimental testing and closelyresemble natural soil flow into dragline buckets.4. DEM parameters and numerical modelFig. 3 shows the range of measured grain dimensionsand the equivalent DEM grain. A normal distributionwithin the range of dimensions given was used to createthe clumped particles. Clumps can be formed by addingtwo or more particles (discs in 2D and spheres in 3D)together to form one rigid particle, i.e. particles includedin the clump remain at a fixed distance from each other17. Particles within a clump can overlap to any extentand contact forces are not generated between these parti-cles. Clumps cannot break up during simulations regardlessof the forces acting upon them. In the model 20,00030,000clumped particles were used.A calibration process, presented in another paper, wasdeveloped for cohesionless material. The particle size, shapeand density were determined from physical measurements.The laboratory shear tests and compressions tests were usedto determine the material internalfriction angleandstiffnessrespectively. These tests were repeated numerically usingDEM models with different sets of particle friction coeffi-cientsandparticle stiffness values.Thecombinationofsheartestandcompressiontestresultscouldbeusedtodetermineaunique set of particle friction and particle stiffness values,Table 1.ADirection of drag Direction of vertical motion 2nd Arm1st ArmBForce transducer 100 mm200 mm150 mm Max volume 35 mm45WbcosWbCounter weights abcFig. 2. Experimental setup.5 - 98 - 125 - 64 - 53 - 6R 2.5 - 4.5 R 1.5 - 3.0 3.0 - 5.0 abFig. 3. (a) Physical grain dimensions and (b) DEM grain model.Dimensions in (mm).C.J. Coetzee, D.N.J. Els/Journal of Terramechanics 46 (2009) 217227219In the software used, PFC2D, so-called walls are used tobuild structures. The test rig and the bucket, with the samedimensions as in the experiment, were built from walls. Thewalls are rigid and move according to prescribed transla-tional and rotational velocities. The forces and momentsacting on the walls do not influence the motion of the wall.During the experiments a constant drag velocity of10 mm s?1was applied while the vertical displacementwas measured. The vertical displacement was influencedby both the rig angle and the effective bucket weight. A typ-ical result is shown in Fig. 4. Except for the initial transi-tion, the vertical velocity was nearly constant, for a givensetup, and increased with an increase in bucket weight. Inthe DEM model, the drag velocity was set to 10 mm s?1and the measured vertical displacement was read from adata file and applied to the bucket.Standard functions build into PFC2Dwere used toobtain the forces and moments acting on individual wallsand on the bucket as a whole. For rig angles other thanzero, the rig was kept horizontal but the gravity compo-nents were set accordingly.5. Results and discussionIt is difficult to make quantitative comparisons regard-ing flow patterns. When comparing the material freesurface, some comparisons could however be made. Figs.5 and 6 show how the material flowed into the bucket forrig angles of h = 0? and h = 20?, respectively. When com-paring the shape of the material free surface, the simula-tions were able to predict the general shape during theinitial stages of filling. The simulations however failed toaccurately predict the material free surface during the finalstages of filling.Curves were fitted to the experimental free surface andoverlaid on the numerical results in Figs. 5 and 6. The max-imum difference between the two free surfaces (heapheight) was measured along the direction perpendicularto the drag direction. Two measurements were made, onewhere DEM predicted a higher heap height, and onemeasurement where DEM predicted a lower heap height.The values and the positions where they were measuredare indicated in the figures. Taking the nominal particlesize as 10 mm, DEM predicted the heap height accuratelywithin 1.54.5 particle diameters.Fig. 7 shows typical drag forces obtained from experi-ments and simulations. The large jump in the drag forceat the beginning of the experiment was observed in mostof the runs and could not be explained and needs furtherinvestigation. From this result, it is clear that the DEMmodel captured the general trend in drag force, but it pre-dicted lower values compared to the measured values. Overthe complete drag of 800 mm, the model predicted a forcewhich was 1550 N lower than the measured force. At theend of the drag the error was 20%. The frictional forcebetween the Teflon wipers and the glass panels was mea-sured in a run without grains. This frictional force was sub-tracted from the measured drag force. Frictional forcesbetween the grains and the side panels would also havean influence on the measured results. These frictional forcescould not be measured or included in the 2D DEM modeland might be the reason why the model predicts lower dragforces 6.The drag energy was defined as the area under the dragforcedisplacement curve. Making use of different rigangles h and effective bucket weights Wb, the drag energyE700up to a displacement of 700 mm is compared in Fig. 8.The first observation that could me made was that withan increase in effective bucket weight, for a given rig angleh, there was a linear increase in required drag energy. Acloser investigation showed that with an increase in bucketweight, the bucket was forced deeper into the materialwhich caused a higher drag force when compared to abucket with less weight.The second observation that can be made is that with anincrease in the rig angle, there is a decrease in drag energy.The effective bucket weight Wbalways acted verticallyTable 1Summary of corn properties and DEM parameters used.Macro propertyMeasuredDEMInternal friction angle23?24?Angle of repose25 2?24 1?Bulk density778 kg m?3778 kg m?3Confined bulk modulus1.60 MPa1.52 MPaMaterial-steel friction14?14?Calibrated DEM propertiesParticle stiffness, kn= ks450 kN/mParticle density, qp855 kg/m3Particle friction coefficient, l0.12Other propertiesDamping, C0.2Model width0.2 m0100200300400500Drag displacement mm60070020406080100Vertical displacement mm120Wb= 202.1 N138.3 N93.2 N 49.1 N Fig. 4. Measured vertical displacement of the bucket with h = 10? andfour values of effective bucket weight Wb.220C.J. Coetzee, D.N.J. Els/Journal of Terramechanics 46 (2009) 217227downward (Fig. 2c) so that the normal force pushing thebucket into the material is given by Wb? cos (h). Thus, withan increase in rig angle, there is a decrease in the normalforce pushing the bucket into the material. This caused areduction in the drag force, and hence a reduction in thedrag energy, when compared to results using a lower rigangle. The DEM simulations were able to capture the gen-eral trends, but it predicted drag energies lower than themeasured. The reason for this is that the predicted dragforces were too low due to the exclusion of the frictionforces between the grains and the glass panels. It would,however, still be possible to use the simulation results forqualitative optimization of bucket filling.Using the simulation results it was possible to identifyhow much of the total force was exerted on each of thebucket sections. In Fig. 9 the bucket was divided into sixsections. The graphs show, as a ratio of the total dragforce, the force on each of the sections. From the startup to a displacement of 200 mm (25% of total displace-ment) the total force acted mainly on the lip and the bot-tom section. As material started to flow into the bucket,the other sections came into play, first the inner curveand finally the front section. Less than 5% of the forceacted on the top section. This was far less than the bottomsection (30%). The reason for this is that the material insidethe bucket showed little movement relative to the bucketFig. 5. Bucket filling results with rig angle h = 0?.C.J. Coetzee, D.N.J. Els/Journal of Terramechanics 46 (2009) 217227221and the pressure on the top section was only due to theweight of the material inside the bucket. On the bottomsection, the pressure was due to the combined weight ofthe material inside the bucket and the weight of the bucketitself. During the complete filling process, 2030% of thedrag force acted on the lip. This shows that the design ofthe lip and teeth is important. It is well known that thelength of the lip/teeth and the angle of attack are importantfactors influencing bucket filling 2 .Rowlands 2 made use of mixtures of millet, peas andcorn in his 2D test rig. The observation of the filling behav-iour led to the development of a theory that describes theflow characteristics and patterns of material entering thebucket. Rowlands 2 named this concept the Shear ZoneTheory. He observed that definite planes of shear (rupture)formed between distinct moving material regimes. Theseshear planes changed orientation and location dependingon initial setup and during different stages of the filling pro-cess itself. The generalised theory is shown in Fig. 10. Thedifferent flow regions, as named by Rowlands 2, are indi-cated on the figure. The movements of the material relativeto the bucket are indicated by the arrows.The virgin material remains largely undisturbed until thefinal third of the drag during which bulldozing” occurs.The initial laminar layer flows into the bucket during thefirst third of the drag (Fig. 10a). After entering to a certaindistance, this layer fails at the bucket lip and subsequentlybecomes stationary with respect to the bucket for theFig. 6. Bucket filling results with rig angle h = 20?.222C.J. Coetzee, D.N.J. Els/Journal of Terramechanics 46 (2009) 217227remainder of the drag (Fig. 10b and c). At steeper dragangles, the material flows more rapidly towards the rearbecause of the added gravitational assistance. This effectcan be seen by comparing Figs. 5 and 6.With the laminar layer becoming stationary, a new zone,the active flow zone, develops (Fig. 10). In this zone, thematerial displacement is predominantly in the verticaldirection. The active dig zone is located above the teethand bucket lip. This area develops as material starts toenter the bucket and increases in size after failure of the ini-tial laminar layer. In this zone, the virgin material fails andeither flows into the bucket as part of the laminar layerduring the first part of filling or moves into the active flowzone during the latter part of filling.The dead load that has resulted from live” material inthe active flow zone ramps up and over the initial laminarlayer. Some of the material in the initial laminar layer failsand starts to form part of the dead load (Fig. 10c). Duringexperiments and while the material was flowing, a definiterupture or shear line could be observed here. With anincrease in drag angle, the active dig zone and active flowzone tended to join into one continuous band.1002003004005006007008000ExperimentSimulation250200Drag force N 15010050Displacement in drag direction mm Fig. 7. Typical bucket drag forces with rig angle h = 10? and a bucketweight Wb= 138.3 N. = 0 = 10 = 20 Experiment Simulation 40 40220200 180160140120WbN 10080 60 506070 80100 120 110 90E700 J Fig. 8. Bucket drag energy E700as a function of the bucket weight Wbfordifferent rig angles h.010020030040050060070080000.10.20.30.40.5Displacement mm Drag force ratio FrontInner curveTopLip Bottom Outer curve LipTopBottomFrontInner curveOuter curveFig. 9. Bucket drag force distribution with h = 10?.Active dig zone Initial laminar layer Active dig zone Initial laminar layerActive flow zone Virgin material Active dig zone Dead loadActive flow zone Initial laminar layer Shear lineShear line Shear line Dead load shear line Virgin material Virgin material bcaFig. 10. The Shear Zone Theory according to Rowlands 2.C.J. Coetzee, D.N.J. Els/Journal of Terramechanics 46 (2009) 217227223It should be noted that Fig. 10 only shows three stagesof the filling process, but in reality there is a gradual tran-sition from one stage to the next. It should also be notedthat this is a generalised theory and there will be variationsin the results when different materials and bucket geome-tries are used. During experiments two definite shear linescould be observed. The one extended from the tip of thelip up to the free surface. This is named the cutting shearline. The second line is the one between the initial laminarlayer and the dead load, called the dead load shear line.Making use of DEM and investigating the flow regionsfurther, the following procedure was devised. The bucketwas moved through the material and paused” after each100 mm. The displacement vector of each particle was thenset to be zero after which the bucket was given a furtherdisplacement of 1015 mm (13 particle lengths). The par-ticle displacement ratio PDR was defined as the ratio of themagnitude of the particle absolute displacement vector tothe magnitude of the bucket absolute displacement vector.The particles were then coloured according to their individ-ual PDR values. A PDR equal to unity means that the par-ticle is moving with the bucket. The result is shown inFig. 11. This is in effect the average velocity ratio over ashort period.The flow regimes as predicted by the Shear Zone Theoryare indicated on the figure. The three pictures correspondFig. 11. Flow regions using the particlebucket displacement ratio.224C.J. Coetzee, D.N.J. Els/Journal of Terramechanics 46 (2009) 217227to the three pictures given in Fig. 10. After a displacementof 100 mm, the active dig zone is clearly visible with0.40 6 PDR 0.65. The initial laminar layer moves intothe bucket with 0.10 6 PDR 0.25. This corresponds wellto the flow zones shown in Fig. 10a.After 500 mm, the characteristic V” shape of the activeflow zone can be seen with 0.10 6 PDR 0.25. Althoughthe PDR is relatively low, the displacement is predomi-nantly in the vertical direction. The active dig zone is stillpresent and in the back of the bucket, the initial laminarlayer starts to become stationary relative to the bucket.This is visible by the PDR values that increase towardsthe back of the bucket. This corresponds well to the flowzones shown in Fig. 10b.After 800 mm the existence of the dead load shear line isclearly visible. When compared to Fig. 10c, the active flowzone and active dig zone cannot be distinguished from thedead load. The reason for this is that at a bucket displace-ment of 800 mm, the bulldozing effect is large and over-shadows the other flow zones.Dragline bucket optimization is very important in termsof force and energy requirements and cycle time. In someapplications it would be advantageous to fill the bucketusing the minimum amount of energy. In other applica-tions, it would be advantageous to fill the bucket as quicklyas possible to decrease cycle time 1. To investigate fillrates, images from the experiment were taken at differentstages of filling, the outline of the material digitized, andthe volume of material inside the bucket calculated andexpressed as a percentage of the maximum bucket volume.The maximum bucket volume of 0.0146 m3is defined inFig. 2b. Using the DEM results, the same procedure wasfollowed and the results compared.Fig. 12 shows the experimental results using three differ-ent rig angles. The bucket fill percentage is plotted againstbucket displacement in terms of bucket-lengths. In thedragline industry, the target is to get the bucket completelyfilled in 23 bucket-lengths. With an increase of the rigangle from 0? to 10?, there is a slight increase in fill percent-age towards the latter stages of filling. This is due to thefact that when material is disturbed, it flows more easilyinto the bucket. When the rig angle is further increasedto 20? there is, however, a decrease in fill percentage. A fur-ther investigation showed that with an increase in rig angle,the bucket displacement into the material is less. It hasbeen shown that the force perpendicular to the materialsurface is given by Wb? cos (h). Hence, with an increasein the rig angle, the force component forcing the bucketto dig in, decreases. When this force component decreases,the penetration depth of the bucket into the material isreduced and the bucket scoops up less material. Whenthe bucket scoops up less material, there is a decrease in fillpercentage.The comparison between experimental and DEM fillpercentages is summarised in Fig. 13. Using three rigangles h = 0?, 10? and 30? and two effective bucketweights Wb= 49.1 N and 138.3 N, the fill percentagewas calculated at displacements of 100, 200, 300, 400,500, 600 and 700 mm. The 42 data points were plottedand the two lines indicate that in all cases, except fortwo, the DEM results were within 6% of the experi-mental results.In practice, the bucket is rotated to prevent the majorityof the material to fall out when the bucket is disengaged.This principle is depicted in Fig. 14 where, at the end ofits displacement, the bucket was lifted out of the materialand kept at the rig angle. The effect of bucket orientationis clear on the amount of material that the bucket couldhold. Again, the experimental free surface outline is shownon the DEM results with good agreement for h = 0?. Forh = 20?, the DEM model predicts additional material inthe back of the bucket which can be explained by the differ-ence in the final fill state as seen in Fig. 6 at a displacementof 800 mm.0.511.522.50102030405060708090100Displacement bucket lengthBucket fill % = 0 = 10 = 20 Fig. 12. Bucket fill percentage as a function of bucket displacement fordifferent rig angles. = 0, Wb = 49.1 N = 10, Wb = 49.1 N = 20, Wb = 49.1 N = 0, Wb = 138.3 N = 10, Wb = 138.3 N = 20, Wb = 138.3 N102030Experimental %405060010203040Simulation %5060- 6% + 6% Fig. 13. Comparison between experimental and DEM fill percentages.C.J. Coetzee, D.N.J. Els/Journal of Terramechanics 46 (2009) 2172272256. ConclusionsThe main objective of this paper was to demonstratehow accurately the discrete element method can predictthe process of excavator bucket filling. The flow patternsof material entering the bucket, drag force acting on bucketdue to material interaction, energy requirements and thebucket fill rates were compared to experimental observa-tions and measurements. The study was limited to cohe-sionless granular material and two-dimensional models.The conclusions of the paper are:1. Comparing the material free surface, DEM can accu-rately model the flow of material into the bucket duringthe initial stages of filling. During the latter stages of fill-ing DEM, however, fails to accurately predict the mate-rial free surface.2. DEM can accurately predict the general trend in bucketdrag force. Over the complete drag of 800 mm DEMpredicts a drag force 1550 N lower than the measuredvalues. The maximum measured drag force is 250 Nwhile DEM predicts a maximum drag force of 200 N.3. DEM fails to accurately predict the drag energy. Thegeneral trends are however correct and it is shown thatthe drag energy increases linearly with an increase inbucket weight.4. Based on the DEM results, between 20% and 30% of thetotal bucket force acts on the lip. With the currentexperimental setup this cannot be validated.5. The DEM results show good agreement with

温馨提示:
1: 本站所有资源如无特殊说明，都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
2: 本站的文档不包含任何第三方提供的附件图纸等，如果需要附件，请联系上传者。文件的所有权益归上传用户所有。
3.本站RAR压缩包中若带图纸，网页内容里面会有图纸预览，若没有图纸预览就没有图纸。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 人人文库网仅提供信息存储空间，仅对用户上传内容的表现方式做保护处理，对用户上传分享的文档内容本身不做任何修改或编辑，并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容，请与我们联系，我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。

人人文库网所有资源均是用户自行上传分享，仅供网友学习交流，未经上传用户书面授权，请勿作他用。