【正文】 n equivalent load must be considered which takes into account both torsion and bending . also the allowable stress must contain a factor of safety which includes fatigue, since torsional and bending stress reversals occur. Many shafts are supported by three or more bearings, which means that the problem is Stacically indeterminate text on strench of matenals give methods of solving such probIems. The design effort should be in keeping with the economics of a given situation , for example , if one line shaft supported by three or more bearings id needed , it probably would be cheaper to make conservative assumptions to moments and design it as though it were determinate . the extra cost of an oversize shaft may be less than the extra cost of an claboratc design analysis There are several types of shaft couplings, their charactcristics depend on the purposc for which they are used. If an exceptionally long shaft is required in a manufacturing plant or apropeller shaft on a ship , it is made in sections that are coupled together with rigid couplings.A mon type of rigid coupling consists of two mating radial flanges that are attached by key driven hubs to the ends of adjacent shaft sections and bolted together through the flanges to form a rigid connection. Alignment of the connected shafts in usually effected by means of a rabbet joint on the face of the flanges.In connecting shafts belonging to separate device such as an electric motor and a gearbox),precise aligning of the shafts is difficult and a fkexible coupling is used . this coupling connects the shafts in such a way as to minimize the harmful effects of shafts misalignment of loads and to move freely float in the axial direction without interfering with one another ,flexiable couplings can also serve to reduce the intensity of shock loads and vibrations transrrutted from one shaft to another .機械運動和動力學運動學的基本目是去設計一個機械零件的理想運動，然后再用數學的方法去描繪該零件的位置，速度和加速度，再運用這些參數來設計零件。我們設計小組內諸位同學熱烈的交流氛圍和嚴謹的治學態(tài)度為本設計的順利完成提供了非常優(yōu)秀的客觀條件，衷心感謝本小組的各位同學的幫助、支持和啟發(fā)，與他們在一起是快樂和充實的。除此之外，對于偏軌箱形梁來說，主腹板與上翼緣板連接處的應力是比較復雜的，在一些大型企業(yè)中為了避免此處的應力驗算采用進口的T型鋼，但是對于大多數企業(yè)來說只能用增加主腹板板厚來解決這一問題，但同時帶來了自重大，應力集中等問題。 連接計算=式中 為桿件驗算截面上的高強螺栓數目；n為桿件一邊的高強螺栓數目；； 故合格第六章 副端梁計算 內力分析自重產生的內力（垂直）:根據前述假定條件，副端梁按兩端固定考慮 副端梁自重載荷圖副主梁產生的內力（垂直） 副端梁外加載荷圖當副小車滿載且在近極限位置時有：同時，根據結構力學知識有： 當副小車空載且位于遠極限位置時有： 主梁扭矩產生的彎矩： 扭矩： 綜上所述，副端梁在C截面受力最嚴重，C截面（均忽略自重）：； ；水平慣性力：鑒于副框架的水平慣性力對副端梁的影響很小，而且其計算又很煩瑣，這里忽略不計，其誤差不超過5%。翼緣板縱向加勁肋選用角鋼， 縱向加勁肋對翼緣板與加勁肋接觸面的慣性矩為 （合格）主、副腹板采用相同的縱向加勁肋 縱向加勁肋對腹板板厚中心線的慣性矩為 綜上所述，選擇的加勁肋合格。 焊縫受力跨中；跨端跨中： 跨端： 焊縫驗算合格由于采用的焊縫厚度同板厚的強度相同，焊縫可不驗算，下同。水平方向:跨端水平彎矩很小（按鉸支處理），忽略不計，主梁自重 q 產生的水平彎矩（跨中）為，集中載荷P產生的水平跨中彎矩為 ，式中，圖33 主梁自重產生的水平彎矩圖同理，當滿載動作用于跨中時，有水平最大彎矩：=式中當在左極限空載時，有同種工況下的最小水平彎矩= 剪力當滿載作用于跨中或空載作用于跨端時，在跨中截面產生的垂直、水平剪力很小，因而對跨中截面校核產生的影響可忽略不計，這里著重求跨端的最大剪力。設使副端梁產生的轉角為，則可得 ………(1) 同理 ………(2) 因為副端梁距主主梁支點的距離與跨度相比非常小(,所以取主主梁支點的轉角與副端梁兩端產生的轉角、分別相等。，水平剛度則考慮全部水平載荷作用。 橋架假定 為了簡化八梁橋架的計算，特作如下假定 1. 以主、副小車單獨工作為最不利載荷情況。上下翼緣板外伸部分長不相同。為了省去走臺，對寬型偏軌箱型梁H1/B1=~，主主梁腹板內側間距取B1=2800mmL/50=630mm,上下翼緣板厚度δ0=24mm，上翼緣板寬為2930mm，下翼緣板寬為2626mm,主腹板厚度δ1=14mm，副腹板厚度δ2=12mm。由以上計算知最大，按組合考慮由代替計算小車自重的動載荷，可不計算偏斜側向力，這樣計算偏安全。、副端梁認為在同一平面內。 副主梁載荷圖 副端梁受扭圖 主主梁載荷圖以上三圖中,、分別為副端梁對副主梁的約束彎矩，、分別為副端梁對主主梁的約束彎矩，、分別為副主梁在A、B支點的轉角， 、分別為主主梁在C、D支點的轉角。由內力圖可知: 代入典型方程得：； ………… (*)總彎矩圖為 總彎矩圖圖中:(*)式中,為主主梁的扭矩： ；10；當小車在左極限（即滿載時：主、副端梁上受到主梁扭矩的作用最大：主端梁上分到的彎矩：副端梁上分到的彎矩：當小車在右極限時（空載）有，此時，= 主端梁上分到的彎矩：副端梁上分到的彎矩：第三章 主主梁計算 內力分析 彎矩垂直方向: 主主梁受力圖查文獻知：司機室重；運行機構重； 電氣設備重固定載荷產生的彎矩（跨中）:取而主主梁兩端鉸支，跨端彎矩為：集中載荷:當滿載動作用于跨中時，產生跨中最大彎矩 主主梁跨中彎矩示意圖當滿載靜作用于左極限位置時，產生跨中最小彎矩分析：根據橋架分析，副端梁對主梁作用的彎矩最大，其占主梁的百分比：，可見、 對主梁影響很小，可忽略不計。 焊縫驗算如前所述，主腹板與上蓋板之間的焊縫所受應力最復雜，這里只驗算此處焊縫強度。2) 加勁肋的確定橫隔板厚度 ，板中開孔尺寸為 。注： 計算中用到的、為主端梁端部的外力，實際連接處的外力比計算值要小，所以連接計算偏安全。現在工廠里多用雙梁橋式起重機，因此我們所能接觸到的關于此類設計方面的資料較多，而本次設計的八梁橋式鑄造起重機，其設計過程則主要是先估算各截面的尺寸，然后再對其進行強度、剛度、穩(wěn)定性以及疲勞強度的驗算，通過反復修改，直至滿足為止，但是，通過本次設計我對此類起重機設計時各梁截面尺寸的選取有了一個大的范圍，希望對大家以后的設計能有所幫助。在此，謹向他的辛勤培養(yǎng)和悉心關懷表示衷心的感謝。 or the design must be pleted so rapidlly that there is not enough time for testing.(4) The part has already been designed, manufactured. and tested and found to be unsatisfactory. Analysis is required to understand why the part is unsatisfactory and what to do to improve it. It is with the last three categories that we shall be mostly means that the dcsigner will usually have only published values of yicld sirth . ultimatc strgth,and percentage clongation with this meager information the engiccr is expected to design against static and dynamic loads. biaxiaL and triaxial stress states , high and Low temperatures, and large and small parts! The data usually available for design have been obtained from the simple tension test ,where the load was applied gradually and the strain given time to develop.Yet these same data must be used in designing parts with plicated dynamic loads applied thousands of times per minute. No wonder machine parts sometimes fail. To sum up, the fundamental problem of the designer is to use the simple tension test data and relate them to the strength of the part .re