基于光弹性贴片法的材料表面应变场测量研究

 针对常用电阻应变片法的点测结果不易反映构件表面应变场分布的问题，将光弹性贴片方法应用于材料表面应变场测量。制作了光弹性贴片，并标定光弹性贴片的材料条纹值，通过几种典型形状光弹性贴片试件的加载实验掌握应力场分布的条纹图像判读方法。开展光弹性贴片在简支钢梁的应变场测量应用，在薄弱点位置光弹性贴片法相比电阻应变片法应变值偏差在5%以内。对C30混凝土试块进行4.4 MPa～39.6 MPa的应力加载过程中，有效监测到混凝土表面裂缝产生、稳定扩展及失稳破坏过程中的条纹图像变化过程。实验表明，光弹性贴片方法可以直观可靠地测量金属及混凝土的表面应力场变化。

Research and measurement of material surface's strain field based on photoelastic coating

Strain gauge can measure the strain of one point, but it cannot measure the strain field of material surface. To solve this problem, photoelastic coatings were adopted to measure the material surface-s strain field. Photoelastic coatings were casted, and the strain fringe constant of the photoelastic coatings was calibrated. Experiments loading photoelastic coatings with special shapes were carried out, and the strain fringe interpretation method was studied. Photoelastic coatings were applied to measure the strain field of simply supported beam. Comparing with strain gauge, the strain value on weak spots obtained by photoelastic coatings is less than 5% on the high side. In experiments that concrete specimens were under loading of 4.4 MPa to 39.6 MPa, the variation of strain fringe in the process, of which the surface crack of the concrete specimen appeared, propagated and finally was fractured, was obtained. It is proved that photoelastic coatings can measure the variation of surface-s strain field of metal and concrete visually and credibly.