英汉双语材料力学.pptVIP

§15–１ Summary §15–１ 概 述 [例2 ] 用60°应变花测得一点的三个线应变后，求该点的主应变。 三片60°应变花 0° 60° 120° 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： It is better to realize the compensation by itself; otherwise 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、接桥： 要使应力正负相间；全桥精度高，半桥精度低。常用半桥双臂式桥路。 九、温度补偿： 最好能在桥路中自补偿；否则，要用绝对不受力的温度补偿片。 工作片与补偿片要始终处于同一温度场中。 §15－3 Principle and application of the photoelasticity 1、Principle of the photoelasticity: ①. Permanent double refraction： ②. Temporary(artificial)double refraction: Double refraction in the anisotropic body due to the entering of light e o §15－3 光弹性法的原理及应用 一、光测原理： 1.永久双折射： 2.暂时（人工）双折射： 光射入各向异性体产生的双折射 e o 2、Plane stress --optics law： ①.Refractive index： C——Stress optical coefficient of the model material D s1 s1 s2 s2 Plane polarized light The plane polarized light passes through the model subjected to forces. So 二、平面应力——光学定律： 1.折射率： C——模型材料的应力光学系数。 D s1 s1 s2 s2 平面偏振光 平面偏振光通过受力模型 ②. Optical path difference： ③.The light intensity in the plane polarization field: The model subjected to forces is in the cross plane polarization field . P s1 s2 A O f Light source Model Analyzer Polarizer 2.光程差： 3.平面偏振场中的光强： 受力模型在正交平面偏振布置中 P s1 s2 A O f 光源 模型 检偏镜 起偏镜 ①Equal 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 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 rotates s