英漢雙語材料力學(xué)

1、 151 SUMMARY 152 PRINCIPLE AND APPLICATION OF THE STRAINOMETER OF THE RESISTANCE 153 PRINCIPLE AND APPLICATION OF THE PHOTOELASTICITY 151 概概 述述 152 電阻應(yīng)變計(jì)法的原理及應(yīng)用電阻應(yīng)變計(jì)法的原理及應(yīng)用 153 光彈性法的原理及應(yīng)用光彈性法的原理及應(yīng)用 15 SummarySummary 一、一、Function of the stress analysis method in experiments ： 1. Determine the reasona

2、ble dimension and the structureal form of a memberaccording to the tested stress or strain of the model in designing. 2. Test the true stress or strain of a member in work and find out the position and the value of the maximum stress in order to evaluate the safty and reliability of the engineering

3、structure and to provide the basis of improving working ability for the equipment. 3. Analyze the destroyed or failed member and propose the measures of improvement in order to prevent it from destroying again. 4. Test the magnitude,derection and all kinds of dynamic responses of the external load.

4、5. Explore the new rule from tests and check the theory of stress analysis and the calculation method. 15 概概 述述 一、實(shí)驗(yàn)應(yīng)力分析方法的作用：一、實(shí)驗(yàn)應(yīng)力分析方法的作用： 1.設(shè)計(jì)時(shí)，測定模型的應(yīng)力或變形，依此來確定構(gòu)件的合理尺 寸和結(jié)構(gòu)形式。 2.工作中，測定構(gòu)件的真實(shí)應(yīng)力或變形，找出最大應(yīng)力的位置 和數(shù)值，以評(píng)價(jià)工程結(jié)構(gòu)的安全可靠性，并為提高設(shè)備的 工作能力提供依據(jù)。 3.對(duì)破壞或失效構(gòu)件進(jìn)行分析，提出改進(jìn)措施，防止再次破壞。 4.測定外載的大小、方向以及各種動(dòng)響應(yīng)。 5.從試驗(yàn)中

5、探索新的規(guī)律，并對(duì)應(yīng)力分析理論和計(jì)算方法進(jìn)行 校核。 二、二、Brief introduction of methods in the stress analysis of experiments 1.The machinery measuring method. The figure of measuring deformations in the book annotated by Zheng Xuan(127-200)in the east Han dynasty. 二、實(shí)驗(yàn)應(yīng)力分析方法簡介：二、實(shí)驗(yàn)應(yīng)力分析方法簡介： 1. 機(jī) 械 量 測 法 東漢鄭玄(127200)注釋的考工記弓人中

6、的測變形圖 Leonardo Da Vinci( 1452- 1519).This picture is considered to show the earliest test in Mechanics of Materials. The tensile test of an iron wire designed by Leonardo Da Vinci. 里奧納多達(dá)芬奇(14521519) 此圖被認(rèn)為是最早的材力試驗(yàn) 里奧納多達(dá)芬奇設(shè)計(jì)的鐵絲受 拉試驗(yàn) tensile Galileo (15641642) Fig.14 Sketch of the tensile test of Galil

7、eo Fig.15 Sketch of the bending test of Galileo 伽利略伽利略 (15641642) Fig.37 Tensile-test machine of Mushenbluic Fig.38 Method to clamp two ends of a tensile specimen Mushenbluic (16921761) 穆申布洛依克穆申布洛依克 (16921761) Hydraulic verstile testing machine controlled by the computer 2. Other methods： Since the

8、early 20th century,the developments of electricity,optics acousics and materials science have provided conditions for the productionof other measurement methods of the stress analysis in experiments.Then the resistance- strain method,ordinary photoelasticity method,hologram photoelasticity method,so

9、und launching method and so on are made fast developments and wide applications. 2.其它方法： 20世紀(jì)初至今，電學(xué)、光學(xué)、聲學(xué)和材料科學(xué)的發(fā)展， 為試驗(yàn)應(yīng)力分析其它測量方法的產(chǎn)生創(chuàng)造了條件。于是，電 阻應(yīng)變法、普通光彈法、全息光彈法、散斑法、聲發(fā)射法等 方法都有了快速發(fā)展和廣泛應(yīng)用。 152 Principle and application of the strainometer of the resistance 1 1、Resistance law :Resisance of a conductor A

10、L R 2、Elastic law: Land A will change after the cinductor is subjected to forces or changes in temperatures. T E 3、Strain foil of resistance K L L K R R Sensitive coefficient 1 2 3 4 5 Wire-coiled strain foil 1Overburden 2Fundus 3Drawn line 4Binder 5Sensitive bar 152 電阻應(yīng)變計(jì)法的原理及應(yīng)用電阻應(yīng)變計(jì)法的原理及應(yīng)用 一、電阻定律一

11、、電阻定律：導(dǎo)體電阻 A L R 二、彈性定律：二、彈性定律：導(dǎo)體受力或變溫后，L、A都將發(fā)生改變。 T E 三、三、電阻應(yīng)變片：電阻應(yīng)變片： K L L K R R 靈敏系數(shù)： 1 2 3 4 5 絲繞式應(yīng)變片 1覆蓋層 2基底 3引出線 4粘結(jié)劑 5敏感柵 4、Balance principle of the electric bridge 3 4 2 1 R R R R when 0U After the resistance changes： )( 4 4 4 3 3 2 2 1 1 R R R R R R R RE U )( 4 4321 KE U R1 R2 R4 I1,2 I3,

12、4 A B C D Bridge with the output voltage R3 四、電橋平衡原理四、電橋平衡原理 : 3 4 2 1 時(shí) R R R R 0U 電阻變化后： )( 4 4 4 3 3 2 2 1 1 R R R R R R R RE U )( 4 4321 KE U R1 R2 R4 I1,2 I3,4 A B C D 電壓輸出橋 R3 5、Strainometer of resistance 4321 measured Transform to output voltage into the magnitude of strain. 五、電阻應(yīng)變儀五、電阻應(yīng)變儀 43

13、21 讀數(shù) 將輸出電壓轉(zhuǎn)變?yōu)閼?yīng)變讀數(shù)。將輸出電壓轉(zhuǎn)變?yōu)閼?yīng)變讀數(shù)。 6、Arrange foils ：Make the directions of foils coincide with those of principal stresses as much as possible. When the directions of principal stresses are un-known, the stress state of a point must be determined by three independent quantities. Three strain foils of

14、45 0 45 90 Three strain foils of 60 0 60120 六、布片：六、布片：盡可能使片子的方向與主應(yīng)力方向一致。盡可能使片子的方向與主應(yīng)力方向一致。 主應(yīng)力方向未知時(shí)，必須由三個(gè)獨(dú)立量才能確定一點(diǎn)的 應(yīng)力狀態(tài)。 三片45應(yīng)變花 0 45 90 三片60應(yīng)變花 0 60120 yx xy 0 2tg 7、Relations between the principal strains and the measured strains. 2cos 2 1 2sin 22 2sin 2 1 2cos 22 xy yx xy yxyx 22 min max )()( 2

15、1 xyyxyx yx xy 0 2tg 七、主應(yīng)變與測量應(yīng)變之間的關(guān)系：七、主應(yīng)變與測量應(yīng)變之間的關(guān)系： 2cos 2 1 2sin 22 2sin 2 1 2cos 22 xy yx xy yxyx 22 min max )()( 2 1 xyyxyx Example 1 Three linear strains of a point are tested by the strain foil 45.Try to determine the principal strain of this point. 2)( 2 1 22 max ）（）（ yuuxyx 2)( 2 1 22 min ）

16、（）（ yuuxyx yx yxu 2 2tg 0 0 max 45 x y u 例例1 1 用用4545應(yīng)變花測得一點(diǎn)的三個(gè)線應(yīng)變后，求該點(diǎn)的主應(yīng)變花測得一點(diǎn)的三個(gè)線應(yīng)變后，求該點(diǎn)的主 應(yīng)變。應(yīng)變。 0 max 2)( 2 1 22 max ）（）（ yuuxyx 2)( 2 1 22 min ）（）（ yuuxyx yx yxu 2 2tg 0 45 x y u Example 2 Try to determine the principal strain of a point after the three linear strains of this point are tested

17、by the strain foil of 60。 2 12060 2 120600 0 120600 max 3 1 33 ）（）（ 120600 12060 0 2 )(3 2tg 2 12060 2 120600 0 120600 min 3 1 33 ）（）（ Three strain foils of 60 0 60120 例例2 用60應(yīng)變花測得一點(diǎn)的三 個(gè)線應(yīng)變后，求該點(diǎn)的主應(yīng)變。 2 12060 2 120600 0 120600 max 3 1 33 ）（）（ 120600 12060 0 2 )(3 2tg 2 12060 2 120600 0 120600 min 3 1

18、 33 ）（）（ 三片60應(yīng)變花 0 60120 8 8、Connect the bridge： Make the stress distribute alternately;make the total bridge have a high precision and the half bridge a low precision .The half bridhe with two arms is often used. 9、Temperature compensation： T E It is better to realize the compensation by itself; ot

19、herwise we should use the temperature compensator that is without any forces.We must make the working foil and the compensation foil in the same temperature field. 八、接橋：八、接橋： 要使應(yīng)力正負(fù)相間；全橋精度高，半橋精度低。常用半橋 雙臂式橋路。 九、溫度補(bǔ)償：九、溫度補(bǔ)償： T E 最好能在橋路中自補(bǔ)償；否則，要用絕對(duì)不受力的溫度補(bǔ)償片。 工作片與補(bǔ)償片要始終處于同一溫度場中。 153 Principle and applic

20、ation of the photoelasticity 1、Principle of the photoelasticity: . Permanent double refraction： . Temporary(artificial)double refraction: Double refraction in the anisotropic body due to the entering of light e o 153 光彈性法的原理及應(yīng)用光彈性法的原理及應(yīng)用 一、光測原理：一、光測原理： 1.永久雙折射： 2.暫時(shí)（人工）雙折射： 光射入各向異性體產(chǎn)生的雙折射 e o 2、Plan

21、e stress -optics law： 2101 BAnn 1202 BAnn )( 2121 Cnn .Refractive index： CStress optical coefficient of the model material 1 1 1 1 2 2 2 2 Plane polarized light The plane polarized light passes through the model subjected to forces. So 二、平面應(yīng)力二、平面應(yīng)力光學(xué)定律：光學(xué)定律： 2101 BAnn 1202 BAnn )( 2121 Cnn 1.折射率： C模

22、型材料的應(yīng)力光學(xué)系數(shù)。 1 1 1 1 2 2 2 2 平 面 偏 振 光 平面偏振光通過受力模型 )( 21 Ch . Optical path difference： .The light intensity in the plane polarization field: The model subjected to forces is in the cross plane polarization field . P 1 1 2 2 A O f Light source Model Analyzer Polarizer )( 21 Ch 2.光程差： 3.平面偏振場中的光強(qiáng)： 受力模型

23、在正交平面偏振布置中 P 1 1 2 2 A O f 光源光源 模型模型 檢偏鏡檢偏鏡 起偏鏡起偏鏡 2 )sin2sin( :intensityight aKI l , 0I 02sin Equal inclination lines As a black point occurs behind the analyzer. The interference fringes formed in the locus of the black points are called equal inclination lines. On the equal inclination lines,the

24、directions of the pricipal stresses are same and they coincide with the polarization axle. Pictures of the plane polarization field taken every 150.The position of the colored equal color lines is not changed, but the position of the black equal inclinnation lines is changed when the polaroid rotate

25、s synchronously. 2 )sin2sin(: aKI光強(qiáng) 。時(shí)，檢偏鏡后出現(xiàn)黑點(diǎn) 0I 02sin 等傾線 引起的黑點(diǎn)的跡線形成的干 涉條紋等傾線 等傾線上，主應(yīng)力方向相同 且與偏振軸重合。 0sin Equal difference lines. The formed interference fringes-equal difference lines. N The white light is considered to be the light source and the equal difference lines aare coloured fringes, so

26、the equal difference lines are also called equal colour lines. As N=0,they are called the No.0 equal difference lines(black); as N=1,they are called the No.1 equal difference lines. Simulating the plae part connected by screws and screw caps (method of pasting foils) 0sin 等差線 形成的干涉條紋等差線 N 以白光為光源, 等差

27、線為彩色條 紋,故等差線又 稱等色線 )(0 , 0 黑色級(jí)等差線 稱為N 級(jí)等差線 稱為 1 , 1N h N f h N C )( 21 fThe value of the fringe of a material a、Under the repeated loading, the equal inclination lines are not changed, but the equal difference lines are changed Distinguish equal inclination lines and equal difference lines b、If we r

28、otate synchronously the polarizer and the analyzer, the equal inclination lines are changed and the equal difference lines are not changed. c、According to experiences,the equal inclination lines are thick(all the black) and equal difference lines are thin(a line). h N f h N C )( 21 f材料的條紋值。 a、反復(fù)加載，等

29、傾線不變，等差線改變。 區(qū)分等傾線與等差線 b、同步旋轉(zhuǎn)起偏鏡與檢偏鏡，等傾線改變，等差線不變。 c、憑經(jīng)驗(yàn)，等傾線較粗（一片黑），等差線較細(xì)（一條線）。 ,)sin( 2 aKI , 0I 0sin N There are no equal inclination lines in the cross circular polarization field.So the equal difference lines are clear. Light intensity:as Black points occur behind the analyzer. (N=0,1,2,) As As ,

30、0mThey are called the No.0.5 equal difference lines. , 1m They are called the No.1.5 equal difference lines. 2 )sin(: aKI光強(qiáng)。時(shí)，檢偏鏡后出現(xiàn)黑點(diǎn) 0I 0sin N .0.5 , 0級(jí)等差線稱為m .1.5 , 1級(jí)等差線為m 正交圓偏振場中，無等傾線。故等差線比較清晰。正交圓偏振場中，無等傾線。故等差線比較清晰。 (N=0,1,2,) . Light intensity in the cross circular polarization field. Cross ci

31、rcular polarization field 45 Fast axle Slow axle 45 Fast axle Slow axle P A S z 4.正交圓偏振場中的光強(qiáng)： 正交圓偏振場正交圓偏振場 45 快軸 慢軸 45 快軸 慢軸 P A S z Figure of the equal difference lines of a disc subjected to radial pressures Equal-colour lines of the spinning disc Interference fringes of the ring subjected to radi

32、al pressures in the plane polarization field. There are only equal-different interference fringes in the circular polarization field when the ring is subjected to radial pressures. 二、二、Brief introduction of methods in the stress analysis of experiments 1.The machinery measuring method. The figure of

33、 measuring deformations in the book annotated by Zheng Xuan(127-200)in the east Han dynasty. 里奧納多達(dá)芬奇(14521519) 此圖被認(rèn)為是最早的材力試驗(yàn) 里奧納多達(dá)芬奇設(shè)計(jì)的鐵絲受 拉試驗(yàn) 例例2 用60應(yīng)變花測得一點(diǎn)的三 個(gè)線應(yīng)變后，求該點(diǎn)的主應(yīng)變。 2 12060 2 120600 0 120600 max 3 1 33 ）（）（ 120600 12060 0 2 )(3 2tg 2 12060 2 120600 0 120600 min 3 1 33 ）（）（ 三片60應(yīng)變花 0 60120 8 8、Connect the bridge： Make the stress distribute alternately;make the total bridge have a high precision and the half bridge a low precision .The half bridhe with two arms is often used. 9、Temperature compensation： T E It is better to realiz