基于普通镜头与改进视场分离技术的光学引伸计

Optical extensometer based on the common lens and modified field-of-view splitting technique

虽然基于远心镜头的光学引伸计在应变测量中具有精度高的优点,但是远心镜头成本高、视场固定的不足使得引伸计灵活性较差,因此,本文提出了一种基于低成本普通镜头与改进视场分离技术的光学引伸计方法。该方法取2个独立视场中心线上的点作为标距点,既减小了离面刚体位移对测量方向应变的影响,又有效增加了引伸计标距。通过不锈钢试样的静态实验和单轴拉伸实验验证了该光学引伸计的可行性和稳定性,实验结果的均方根误差(RMSE)约为5με,表明提出的光学引伸计具有很高的应变测量精度。

Although optical extensometers based on telecentric lens have the advantages of high strain measurement accuracy,the shortcomings of high cost and fixed field of view(FOV)of telecentric lenses make the extensometer less flexible.Therefore,an optical extensometer based on a low-cost common lens and improved FOV-splitting technique was proposed.This method took the points on the centerline of two independent fields of view as the gauge points,which not only reduced the influence of the rigid-body displacement on the strain of the measurement direction,but also effectively increased the gauge length of the extensometer.Static experiments and uniaxial tensile experiments of a stainless-steel specimen were carried out to verify the feasibility and measurement accuracy of the optical extensometer,and the root mean square error(RMSE)of the experimental results was approximately 5μe,indicating that the improved optical extensometer has high strain measurement accuracy.