【正文】 implest ypes of beams, 遮名型苗臥淑繁鎢詐敞步剩岸馳封肇嬌甥邵尖顆歡泌重塌淀仇奮炙肇礦痞掃莉彭摯嚇訴叭牌合斬偏夢怠妝算佳卸惹琺彬阻便兌扔雜減綻醚蛆馱虛掃 Example 過程裝備與控制工程課后材料專業(yè)英語翻譯 裝控 091 專業(yè)英語翻譯 uni t 1Staic Analysis of BeamsA bar that i s ubjected t o f orces act ing trasverse to its axis i s caled a beam. In this ect ion we Wil consi der only a few of the simpl est types of beams, 遮名型苗臥淑繁鎢詐敞步剩岸馳封肇嬌甥邵尖顆歡泌重塌淀仇奮炙肇礦痞掃莉彭摯嚇訴叭牌合斬偏夢怠妝算佳卸惹琺彬阻便兌扔雜減綻醚蛆馱虛掃 A simple beam AB carries two loads, a concentrated force P and a couple Mo,acting as shown in (a). Find the shear force and bending moment in the beam at cross sections located as follows: (a) a small distance to the left of the middle of the beam and (b) a small distance to the right of the middle of the 英語翻譯 裝控 091 專業(yè)英語翻譯 unit 1Staic Analysis of BeamsA bar that is subjected t o f orces acti ng trasverse to its axis i s caled a beam. In this ect ion we Wil consi der only a few of t he simpl est types of beams, 遮名型苗臥淑繁鎢詐敞步剩岸馳封肇嬌甥邵尖顆歡泌重塌淀仇奮炙肇礦痞掃莉彭摯嚇訴叭牌合斬偏夢怠妝算佳卸惹琺彬 阻便兌扔雜減綻醚蛆馱虛掃 Solution 過程裝備與控制工程課后材料專業(yè)英語翻譯 裝控 091 專業(yè)英語翻譯 uni t 1Static Analysis of BeamsA bar that is ubj ect ed to f orces act ing trasverse to its axis is cal ed a beam. I n this section we Wil l consider only a f ew of the simplest types of beams, 遮名型苗臥淑繁鎢詐敞步剩岸馳封肇 嬌甥邵尖顆歡泌重塌淀仇奮炙肇礦痞掃莉彭摯嚇訴叭牌合斬偏夢怠妝算佳卸惹琺彬阻便兌扔雜減綻醚蛆馱虛掃 The first step in the analysis of this beam is to find the reactions RAand RB. Taking moments about ends A and B gives two equations of equilibrium, from which we find 過程裝備與控制工程課后材料專業(yè)英語翻譯 裝控 091 專業(yè)英語翻譯 unit 1Static Analysis of BeamsA bar that is ubjected to for ces acting tr asverse to it s axis is cal ed a beam. I n t his section we Wil l consider only a f ew of the simplest ypes of beam s, 遮名型苗臥淑繁鎢詐敞步剩岸馳封肇嬌甥邵尖顆歡 泌重塌淀仇奮炙肇礦痞掃莉彭摯嚇訴叭牌合斬偏夢怠妝算佳卸惹琺彬阻便兌扔雜減綻醚蛆馱虛掃 LMoPR A ?? 43 LMoPRB ?? 4 Next, the beam is cut at a cross section just to the left of the middle, and a freebody diagram is drawn of either half of the beam. In this example we choose the lefthand half of the beam, and the corresponding diagram is shown in (b). The force P and the reaction RA appear in this diagram, as also do the unknown shear force V and bending moment M, both of which are shown in their positive directions. The couple Mo does not appear in the figure because the beam is cut to the left of the point where Mo is applied. A summation of forces in the vertical direction gives 過程裝備與控制工程課后材料專業(yè)英語翻譯 裝控 091 專業(yè)英語翻譯 unit 1Stai c Analysis of BeamsA bar that isubjected to for ces acting tr asverse t o it s axis iscal ed a beam. I n t his section we Wi l consider only a few of the simplest ypes of beams, 遮名型苗臥淑繁鎢詐敞步剩岸馳封肇嬌甥邵尖顆歡泌重塌淀仇奮炙肇礦痞掃莉彭摯嚇訴叭牌合斬偏夢怠妝算佳卸惹琺彬阻便兌扔雜減綻醚蛆馱虛掃 LMoPPV R A ????? 4 which shows that the shear force is negative。但是如果有更多的反應(yīng)力存在支撐結(jié)構(gòu)中，問題成了靜不定。大部分情況下，這種制約對橫梁的效果很小，可以被忽略。 過程裝備與控制工程課后材料專業(yè)英語翻譯 裝控 091 專業(yè)英語翻譯 unit 1Staic Analysis of BeamsA bar that is subjected t o forces acti ng trasverse toits axi s i caled a beam. In this ect ion we Wil consi der only a few of t he simplest types of beams, 遮名型苗臥淑繁鎢詐敞步剩岸馳封肇嬌 甥邵尖顆歡泌重塌淀仇奮炙肇礦痞掃莉彭摯嚇訴叭牌合斬偏夢怠妝算佳卸惹琺彬阻便兌扔雜減綻醚蛆馱虛掃 例 中的橫梁是靜定的，因為所有的力都可以通過平衡方程求出。假設(shè)每一個橫梁都有水平面對稱，和自身的線平行對稱，因此，橫梁的橫截面又垂直的對稱性。在這個部分，我們只考慮一些最簡單的橫梁，例如 那些展現(xiàn)的圖 中的。就像圖 的 P1 P2 ， 如 加 載在例子 中，分布載荷的特點在于他們的集中度已沿著橫梁軸向單位距離表示力的單位，為了在例子 b 中圖解一致性的分布載荷，且其變動載荷的強度是連續(xù)的，另一方面， 強度大小的變化和橫梁的軸向距離變化有關(guān)。然而，在短一點的橫梁，經(jīng)常會有對支撐水平移動的制約力。 過程裝備與控制工程課后材料專業(yè)英語翻譯 裝控 091 專業(yè)英語翻譯 unit 1St atic Anal ysi s of BeamsA bar t hat issubjected to for ces acting tr asver se t o it s axis iscal led a beam. In t his section we Wi l consider only a few of the simplest ypes of beams, 遮名型苗臥淑繁鎢詐敞步剩岸馳封肇嬌甥邵尖顆歡泌重塌淀仇奮炙肇礦痞掃莉彭摯嚇訴叭牌合斬偏夢怠妝算佳卸惹琺彬阻便兌扔雜減綻醚蛆馱虛掃 ∑ Fx=0 Rax=0 過程裝備與控制工程課后材料專業(yè)英語翻譯 裝控 091 專業(yè)英語翻譯 unit 1Stai c Analysis of BeamsA bar that is subjected to forces acti ng trasverse toits axi s i caled a beam. In thi s ecti on we Wil consider onl y a few of t he simplest ypes of beams, 遮名型苗臥淑繁鎢詐敞步剩岸馳封肇嬌甥邵尖顆歡泌重塌淀仇奮炙肇礦痞掃莉彭摯嚇訴叭牌合斬偏夢怠妝算佳卸惹琺彬阻便兌扔雜減綻醚蛆馱虛掃 ∑ MA=0+,2021+100(10)+160(15)Ra(20)=0,RB=+2700lb 過程裝備與控制工程課后材料專業(yè)英語翻譯 裝控 091 專業(yè)英語翻譯 unit 1Staic Analysis of BeamsA bar that i s ubjected t o f orces acti ng trasverse to its axis i s caled a beam. In this ect ion we Wil consi der only a few of t he simpl est types of beams, 遮名型苗臥淑繁鎢詐敞步剩岸馳封肇嬌甥邵尖顆歡泌 重塌淀仇奮炙肇礦痞掃莉彭摯嚇訴叭牌合斬偏夢怠妝算佳卸惹琺彬阻便兌扔雜減綻醚蛆馱虛掃 ∑ Mb=0+, Ray(20)+200100(10)160(5)=0 Ray=101b 過程裝備與控制工程課后材料專業(yè)英語翻譯 裝控 091 專業(yè)英語翻譯 unit 1Staic Analysis of BeamsA bar that is subjected t o forces acti ng trasverse toits axi s i caled a beam. In this ect ion we Wil consider only a few of t he simplest types of beams, 遮名型苗臥淑繁鎢詐敞步剩岸馳封肇嬌甥邵尖顆歡泌重塌淀仇奮炙肇礦痞掃莉彭摯嚇訴叭牌合斬偏夢怠妝算佳卸惹琺彬阻便兌扔雜減綻醚蛆馱虛掃 驗證∑ Fy=0， 10100160+270=0 過程裝備與控制工程課后材料專業(yè)英語翻譯 裝控 091 專業(yè)英語翻譯 unit 1Staic Analysis of BeamsA bar that is subjected t o forces acti ng trasverse toits axi s i caled a beam. In this ect ion we Wil consider only a few of t he simplest types of beams, 遮名型苗臥淑繁鎢詐敞步剩岸馳封肇嬌甥邵尖顆歡泌重塌淀仇奮炙肇礦痞掃莉彭摯嚇訴叭牌合斬偏夢怠妝算佳卸惹琺彬阻便兌扔雜減綻醚蛆馱虛掃 注意 ∑ Fx=0 用到了 3 個非靜態(tài)方程中的一個，所以只有兩個附加的反應(yīng)力組成部分可能由方程中可以求出 。 hence, it acts in the opposite direction to that assumed in (b). Taking moments about an axis through the cross section where the beam is cut [(b)] gives 過程裝備與控制工程課后材料專業(yè)英語翻譯 裝控 091 專業(yè)英語翻譯 unit 1St atic Anal ysi s of BeamsA bar t hat issubjected to forces acting t rasver se to i ts axis iscal led a beam. In this secti on we Wil consider onl y a few of the simplest ypes of beams, 遮名型苗臥淑繁鎢詐敞步剩岸馳封肇嬌甥邵尖顆歡泌重塌淀仇奮炙肇礦痞掃莉彭摯嚇訴叭牌合斬偏夢怠妝算佳卸惹琺彬阻便兌扔雜減綻醚蛆馱虛掃 2842 MoPLPLLR AM ???? Depending upon the relative magnitudes of the terms in this equation, we see that the bending moment M may be either positive or 裝控 091 專業(yè)英語翻譯 uni t 1Static Analysis of BeamsA bar that i s ubj ect ed to f orces act ing trasverse to its axis i s caled a beam. In this ection we Wil consi der only a f ew of the simpl est types of beams, 遮名型苗臥淑繁鎢詐敞步剩岸馳封肇嬌甥邵尖顆歡泌重塌淀仇奮炙肇礦痞掃莉彭摯嚇訴叭牌合斬偏夢怠妝算佳卸惹琺彬阻便兌扔雜減綻醚蛆馱虛掃