履帶車輛負重輪結構強度有限元分析

1、1998 No 3中國北方車輛研究所 （北京100072）1998 No 31998 No 3點.2342個單元.如圖1.© 1994-2008 China Academic Journal Electronic Publishing House. All rights resented, 本文應用有限單元法對某些履帶車輛的負重輪 分兩種工況進行了強度分析計算校核了其剛強度并提出了 改進建議。0引言負重輪是履帶車輛行動部分的關犍零部件之一 其結構 和強度對救車的性能與質量有至關重要的影響。針對目前所進行的屜帶車輛負重輪的新材料和新型結 構的研究為給這種優(yōu):化設計方案提供理論依據并為今

2、后進 一步的可靠性研究及實測試驗奠定基礎我們應用I'D EaS CAE輔助軟件結合部分自編的程序對這新方案進行了硏 種工況的有限元靜強度分析計算了其應力分布和位移。1建模及計算壞覽硬件:m icro VAX- Il工作站軟件：i-DEAS Cm版CAD/tAD/fcAE軟件.部分自編 的程序2實體建模2 1我們采用笛卡兒右手坐標系建立負重輪模型。坐標原點 定義為車輪的重心處。其x軸正向定義為負重輪軸線指向車 號外面方面軸止向定義為與堇瑩相反方向.乙軸由右手法 則確定。2 2為了建模的方便我們采用mm作為長度單位栽荷的 單位為N （牛頓幾這樣在計算結果中位移的單位將是mm 應力的單位則是

3、MPao2 3實體建模應以盡可能真實的反映零部件的實際幾何形 狀并能作合理的簡化來建立符合直實情況力學性質的有限 元模型為原則?；诖宋覀儾捎脤嶓w模型完成負重輪的構 型.其中作了如下簡化：（1）將幅板和輪緣及與安裝配合軸承的部位視為一 體忽略焊接影響區(qū)的作用。在設計及實際便用中是不允許 幅板與焊接雲部件有任何相對移動的另外按設計要求焊 接也具有一定的深度.因此我們認為作這樣的簡化是合理 的。（2）忽略負重輪中心部位的螺孔.因為在便用中裝有 緊固螺栓而且承擔看栽荷。根據我們的經驗這樣的簡化不 令對應力大小及分布產生較大影響。（3）因只作靜態(tài)線性分析計算中不孝慮棟膠戻。 負瑩輪是一個圓形盤狀的對稱

4、結構它承受的栽荷和約束也 關于ry平面對稱所以實體建模和作有限元分析只需考慮 一個對稱部分即可。3有限元網格模型有限元網格剖分主要依據于單元類型的選取及結構的 幾何形狀栽荷和約束條件。系統因未提供過渡單元便得亮 單元與實體單元不能耦合。鑒干此.我們全部選用八節(jié)點實 體單元和六節(jié)點鍥形單元來劃分負重輪有限元網格。在承栽 不大的部位.劃分得粗一些.對曲率變化較大的地方劃分較 細以保證形狀的直實性及力學計算的精度總計4211個節(jié)4材料模型該負重輪由防馬鋁合金材料 構成設定該介質各處均勻且各向 同性c其機械和物理性能參數如 下：材料密度A 2 7g/m3; 彈性模量E：70GPa;泊松比“：Q 3:

5、屈服極限：22（X1 Pa： 抗彎強度：42（M Pa;5邊界條件根據屜帶車輛的行駛情況.我 們選擇兩種工況進行強度分析計 算。車輛直線行進時的栽荷和約東條件作為工況1,車輛彎 道行駛時的栽荷和約東條件作工況II。這兩種工況均不考慮 動栽，下面我們分別分析和計算這兩種工況的邊界條件。工況I:（a）栽荷車輛直線行進時.負重輪的主要栽荷來源于車體本身1： 量參照靜強度設計原則每個車輪栽荷按車重的72%計 算.即：W = 133OOCN；P= W * Q 72:式中W車體總重量P單個負重輪承受的栽荷因車體是通過軸承施栽于負重輪上面的所以實際上負重輪 承受的是分布栽荷我們這些栽荷以集中力的形式施加于相

6、39 關節(jié)點上.各節(jié)點栽荷按如下公式計算：Q. = COSi/2ptQmai p/(1+ 2£cOS 兩式中6第，節(jié)點和坐標原點的連線與y軸負向之間夾 甬Q.第i節(jié)點栽荷(b)約束因我們貝考慮半個負重 輪所以將人了平面上的所有 節(jié)點在x方向的位移自由度 匚約束為零.其它方向自由另 外以防止產生剛體移動將 位于對稱面下輪緣邊上外側 的一個節(jié)點在x.v.z方向的 位移約東為零"該工況的約東 如圖2所示。工況II：(a)栽荷車輛進入彎道后除了承 受工況I的栽荷外還受到側 向力的作用其大小按車重的圖228%計算.并將這些分布力轉化成集中力后施加到負重輪上 下輪緣的相關節(jié)點上。(b)

7、約束除工況I的約東外.還須將車輪與螺拴聯結的螺孔處的 節(jié)點在z方向的位移約東為零.同時還得解除工況I中在 方向被限死的節(jié)點的約束。6計算結果與分析我們分別就上面兩種工況進行了有限元計算C為了能反 映該負重輪結構的剛度和強度待性計算結果分別以位移和 應力的方式給出其中應力用三個方向的主應力最大剪應 力.等效應力VON M ISS的形式給出.位移則給出在X. V.Z 方向的大小。6 1計算的結果表明在這兩種工況中結構的位移在三個 方向上均在1mm之內.平均位移在a知m以內.這說明負 重輪的變形很小其剛度性能是良好的。6 2從應力結果可以看出.車輛直線行進時負重輪所承受 的最大拉應力為51M Pa.

8、最大壓應力為11-M Pa.最大等效 應力為I1L Pa.均小干屈服強度.滿足強度要求。最大壓 應力和最大剪應力的幾何位直正是位干幅板曲率方向變化 的地方.且在對稱面上.廿點號是1398.如圖3中標號所示。 這點是結構和強度設計時應重點考慮的部位之一。當車輛彎道行駛時.最大拉應力為82 (M Pa.最大壓應 力等干146 NPa.對應的節(jié)點號是2341(如圖4中所標).S 3圖4最大等效應力為136 M Pa.對應的節(jié)點號是2407(示于圖4 中)，這些值都小于屈月艮強度滿足設計要求它們的幾何位 直在負車輪靠車體一側的左下處并靠近對稱面顯然這也 應是設計時重點考慮的部位之一。而兩種工況的應力分

9、布均 表明負重輪的一些較厚實的部位.例如輪緣部分.其剰余強 度較多就輪重優(yōu)化而言還有考慮的余地。參考文獻I楊海元張敬宇趙志崗編酋固體力學的敎值方法天津大學出 版社2許懊宇邱宜懷主編機械誓件高等教育出版社3 I-DEAS用戶手冊趙華 男.65年6月出生.工學碩士近年來主要從事機械疲勞 強度及可靠性分析與研究'CAD/tAH/CAE應用與開發(fā)等工作.承 擔國家預研課題多頊發(fā)表論文數篇曽獲部料技進步三等獎。1998 No 31998 No 340 © 1994-2008 China Academic Journal Electronic Publishing House. All

10、rights resented, 1998 No 3tal principles Applicatbn project7 1998 No 3Quadratic RckitMiShof M ulti|)lc Critcrii for Redundant Robots and It s Opt in izationTang Sh mang et al(Beijing U niversity of Aeronautics and A stronautics. Beijing.China)P27Abstract In this paper it is drawn that the mu It pie

11、criteria for redundant robots bear a quadratic relatbnship to the joint accelerations Then a new sin pie opt hi izatbn method based on parabolic interpolatbn is discussed It can solve a variety of optmal problem s of kinematics, dynam ics etc for redundant robots in an unified pattern M eanu hilc it

12、 can transfbrm the kinem atics and dynam ics calculation of re- duntant robots into that of non-redundant robots Then many efficient caleulatbn methods for nonredundant robots can be used in this methodKey words Redundant robots M ultiple criteria Op- tm izatbnA Stiidv of the Basic Pattem and Its Ev

13、olution of the P&ral- lelM ove GcarM echan ianZhang Chuilh et al(Beijing U niversity of Science and Techno fogy. Beijing, China)P29Abstract On the basisof the princple of combinatbn> deduction and the variation of the isomoiphian w ith distinct properties, the evolution and m u tat bn of the

14、basic pattern of the parallel move gear m echan isn is studied In th is thesis, we firstly discuss the basic pattern of outer parallel move gear mechanisn and its evolution and point out that the problem of the size and the overweight of the outer parallel move gear is not easily solvcd by mcans of

15、the theory of mechanian evolutbn According to the above-mentbned princplcs<we discuss the evolutbn and mu tat bn of the basic pattern of the in te ma 1 p ara lie I m o ve gear m echan isn and design a kind of new pattern parallel move gear mechanisn w hich has large 甲eed ratb, compact structure,

16、high efficiency and balanced bad It provides theoretic fundament for designing internal parallel move gear reductor and accelera- torKey words Parallel move Basic pattern Evolutbn V ariatbnEnvelope Cyclo id M eclian mi and Its Applicatbn Prospect Wang Jii et al (Xuzhou PetroleunM achinery Factory.Xu

17、zhoiiChina)P31Abstnict The article describes one kind of envebpe cycloid m echan iaii il can be designed into new eye bid lathe boring.m illiiig grinding machines, etc or their accessories. they have to lbw ing advantages in comparison w ith the machincsof same kind： (1 )Rake and relief angles remai

18、n unchanged in process of turning and boring; (2)No lin it for diameters of m illmg cutter and grinder: (3)Cyctoid and its e- quklistant cu rve can be turned, bored .milled and ground The applicatbn foreground of the mechanisn/machine is very broa d e g fine cutting of wheel hole of ellipse and ap p

19、roxinate regular polygon and cycloid wheel, and fine grinding of the configuratbn of plate cam as wellKey words Envebpe cycloid mechanise FundamenA Sin pie M ethod of Opthi izatirm for GcariJr heHong Jii di et al (East China Jab tong U niversity, N anchang ch ina)P33Abstract In this paper. On the ba

20、sis of the theory of the equabstreugth opthi iz<itbn by analyzed rehtbn between gear contact strength and gear bend strength, the conccptbn of the combined gear fonn factor and numeric nit of teeth was intruduced. a new metod was proposed that used to acquire the op tin al result of the gear driv

21、e directly W hile optm izing two and more grade gear assembly, this method is more direct and clean and the process is more s hi pie and rapidKey word Gear drive Equal strength op tin izatbn Com bined gear fbmi factor N umeric unit of teethFatigue Crack Propagation h VVelded Johts of Structural Stee

22、lHe Bo et al(Shanghai J uio Tong U niversity, Shanghai.China)P35Abstract The propagatbn of fatigue crack in welds of two kinds of joints was studkled experinentally tor a structural steel (Q235a )w ith constant bad of R = Q 2 applied la It was found that the fatigue crack propagatbn resistance of we

23、ld metals w ith high yield strength is higher than that of base metals Above the Ihreshold region, a da/dn v AK relatonsh p of weld metal can be epressed snip led by Paris law. A nd also the effect of m icrostructurc on the crack propagatbn rate was analizedKey words Structural steel W elded pint Fa

24、tigue crack propagatbnThe Three-1hie Desipi of Helical Sprhg RigidityW u HiKizhi (Changzhou bidustrical Technobgy College. Changzhou China)P37Abstract The three-tine design methed of Dr Genichi Taguchi is applied to the design of helical spring rigidity The optinun level component of design panimeter was defined by means of the analysis of sig