履帶車輛負(fù)重輪結(jié)構(gòu)強(qiáng)度有限元分析

1、1998 No 3中國(guó)北方車輛研究所 （北京100072）1998 No 31998 No 3點(diǎn).2342個(gè)單元.如圖1.© 1994-2008 China Academic Journal Electronic Publishing House. All rights resented, 本文應(yīng)用有限單元法對(duì)某些履帶車輛的負(fù)重輪 分兩種工況進(jìn)行了強(qiáng)度分析計(jì)算校核了其剛強(qiáng)度并提出了 改進(jìn)建議。0引言負(fù)重輪是履帶車輛行動(dòng)部分的關(guān)犍零部件之一 其結(jié)構(gòu) 和強(qiáng)度對(duì)救車的性能與質(zhì)量有至關(guān)重要的影響。針對(duì)目前所進(jìn)行的屜帶車輛負(fù)重輪的新材料和新型結(jié) 構(gòu)的研究為給這種優(yōu):化設(shè)計(jì)方案提供理論依據(jù)并為今

2、后進(jìn) 一步的可靠性研究及實(shí)測(cè)試驗(yàn)奠定基礎(chǔ)我們應(yīng)用I'D EaS CAE輔助軟件結(jié)合部分自編的程序?qū)@新方案進(jìn)行了硏 種工況的有限元靜強(qiáng)度分析計(jì)算了其應(yīng)力分布和位移。1建模及計(jì)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(shí)體建模2 1我們采用笛卡兒右手坐標(biāo)系建立負(fù)重輪模型。坐標(biāo)原點(diǎn) 定義為車輪的重心處。其x軸正向定義為負(fù)重輪軸線指向車 號(hào)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(zhǎng)度單位栽荷的 單位為N （牛頓幾這樣在計(jì)算結(jié)果中位移的單位將是mm 應(yīng)力的單位則是

3、MPao2 3實(shí)體建模應(yīng)以盡可能真實(shí)的反映零部件的實(shí)際幾何形 狀并能作合理的簡(jiǎn)化來建立符合直實(shí)情況力學(xué)性質(zhì)的有限 元模型為原則?；诖宋覀儾捎脤?shí)體模型完成負(fù)重輪的構(gòu) 型.其中作了如下簡(jiǎn)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(shè)計(jì)及實(shí)際便用中是不允許 幅板與焊接雲(yún)部件有任何相對(duì)移動(dòng)的另外按設(shè)計(jì)要求焊 接也具有一定的深度.因此我們認(rèn)為作這樣的簡(jiǎn)化是合理 的。（2）忽略負(fù)重輪中心部位的螺孔.因?yàn)樵诒阌弥醒b有 緊固螺栓而且承擔(dān)看栽荷。根據(jù)我們的經(jīng)驗(yàn)這樣的簡(jiǎn)化不 令對(duì)應(yīng)力大小及分布產(chǎn)生較大影響。（3）因只作靜態(tài)線性分析計(jì)算中不孝慮棟膠戻。 負(fù)瑩輪是一個(gè)圓形盤狀的對(duì)稱

4、結(jié)構(gòu)它承受的栽荷和約束也 關(guān)于ry平面對(duì)稱所以實(shí)體建模和作有限元分析只需考慮 一個(gè)對(duì)稱部分即可。3有限元網(wǎng)格模型有限元網(wǎng)格剖分主要依據(jù)于單元類型的選取及結(jié)構(gòu)的 幾何形狀栽荷和約束條件。系統(tǒng)因未提供過渡單元便得亮 單元與實(shí)體單元不能耦合。鑒干此.我們?nèi)窟x用八節(jié)點(diǎn)實(shí) 體單元和六節(jié)點(diǎn)鍥形單元來劃分負(fù)重輪有限元網(wǎng)格。在承栽 不大的部位.劃分得粗一些.對(duì)曲率變化較大的地方劃分較 細(xì)以保證形狀的直實(shí)性及力學(xué)計(jì)算的精度總計(jì)4211個(gè)節(jié)4材料模型該負(fù)重輪由防馬鋁合金材料 構(gòu)成設(shè)定該介質(zhì)各處均勻且各向 同性c其機(jī)械和物理性能參數(shù)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(qiáng)度：42（M Pa;5邊界條件根據(jù)屜帶車輛的行駛情況.我 們選擇兩種工況進(jìn)行強(qiáng)度分析計(jì) 算。車輛直線行進(jìn)時(shí)的栽荷和約東條件作為工況1,車輛彎 道行駛時(shí)的栽荷和約東條件作工況II。這兩種工況均不考慮 動(dòng)栽，下面我們分別分析和計(jì)算這兩種工況的邊界條件。工況I:（a）栽荷車輛直線行進(jìn)時(shí).負(fù)重輪的主要栽荷來源于車體本身1： 量參照靜強(qiáng)度設(shè)計(jì)原則每個(gè)車輪栽荷按車重的72%計(jì) 算.即：W = 133OOCN；P= W * Q 72:式中W車體總重量P單個(gè)負(fù)重輪承受的栽荷因車體是通過軸承施栽于負(fù)重輪上面的所以實(shí)際上負(fù)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(guān)節(jié)點(diǎn)上.各節(jié)點(diǎn)栽荷按如下公式計(jì)算：Q. = COSi/2ptQmai p/(1+ 2£cOS 兩式中6第，節(jié)點(diǎn)和坐標(biāo)原點(diǎn)的連線與y軸負(fù)向之間夾 甬Q.第i節(jié)點(diǎn)栽荷(b)約束因我們貝考慮半個(gè)負(fù)重 輪所以將人了平面上的所有 節(jié)點(diǎn)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(chǎn)生剛體移動(dòng)將 位于對(duì)稱面下輪緣邊上外側(cè) 的一個(gè)節(jié)點(diǎn)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(jìn)入彎道后除了承 受工況I的栽荷外還受到側(cè) 向力的作用其大小按車重的圖228%計(jì)算.并將這些分布力轉(zhuǎn)化成集中力后施加到負(fù)重輪上 下輪緣的相關(guān)節(jié)點(diǎn)上。(b)

7、約束除工況I的約東外.還須將車輪與螺拴聯(lián)結(jié)的螺孔處的 節(jié)點(diǎn)在z方向的位移約東為零.同時(shí)還得解除工況I中在 方向被限死的節(jié)點(diǎn)的約束。6計(jì)算結(jié)果與分析我們分別就上面兩種工況進(jìn)行了有限元計(jì)算C為了能反 映該負(fù)重輪結(jié)構(gòu)的剛度和強(qiáng)度待性計(jì)算結(jié)果分別以位移和 應(yīng)力的方式給出其中應(yīng)力用三個(gè)方向的主應(yīng)力最大剪應(yīng) 力.等效應(yīng)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(jì)算的結(jié)果表明在這兩種工況中結(jié)構(gòu)的位移在三個(gè) 方向上均在1mm之內(nèi).平均位移在a知m以內(nèi).這說明負(fù) 重輪的變形很小其剛度性能是良好的。6 2從應(yīng)力結(jié)果可以看出.車輛直線行進(jìn)時(shí)負(fù)重輪所承受 的最大拉應(yīng)力為51M Pa.

8、最大壓應(yīng)力為11-M Pa.最大等效 應(yīng)力為I1L Pa.均小干屈服強(qiáng)度.滿足強(qiáng)度要求。最大壓 應(yīng)力和最大剪應(yīng)力的幾何位直正是位干幅板曲率方向變化 的地方.且在對(duì)稱面上.廿點(diǎn)號(hào)是1398.如圖3中標(biāo)號(hào)所示。 這點(diǎn)是結(jié)構(gòu)和強(qiáng)度設(shè)計(jì)時(shí)應(yīng)重點(diǎn)考慮的部位之一。當(dāng)車輛彎道行駛時(shí).最大拉應(yīng)力為82 (M Pa.最大壓應(yīng) 力等干146 NPa.對(duì)應(yīng)的節(jié)點(diǎn)號(hào)是2341(如圖4中所標(biāo)).S 3圖4最大等效應(yīng)力為136 M Pa.對(duì)應(yīng)的節(jié)點(diǎn)號(hào)是2407(示于圖4 中)，這些值都小于屈月艮強(qiáng)度滿足設(shè)計(jì)要求它們的幾何位 直在負(fù)車輪靠車體一側(cè)的左下處并靠近對(duì)稱面顯然這也 應(yīng)是設(shè)計(jì)時(shí)重點(diǎn)考慮的部位之一。而兩種工況的應(yīng)力分

9、布均 表明負(fù)重輪的一些較厚實(shí)的部位.例如輪緣部分.其剰余強(qiáng) 度較多就輪重優(yōu)化而言還有考慮的余地。參考文獻(xiàn)I楊海元張敬宇趙志崗編酋固體力學(xué)的敎值方法天津大學(xué)出 版社2許懊宇邱宜懷主編機(jī)械誓件高等教育出版社3 I-DEAS用戶手冊(cè)趙華 男.65年6月出生.工學(xué)碩士近年來主要從事機(jī)械疲勞 強(qiáng)度及可靠性分析與研究'CAD/tAH/CAE應(yīng)用與開發(fā)等工作.承 擔(dān)國(guó)家預(yù)研課題多頊發(fā)表論文數(shù)篇曽獲部料技進(jìn)步三等獎(jiǎng)。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