非标准凸台小试样高温蠕变伸长率光学测试

Optical Testing of Creep Elongation of Non-Standard Small Specimens at High Temperature

为了测量高温条件下非标准凸台试样的蠕变伸长率,研制了高温蠕变光学测试系统。设计了带观察窗的高温炉,使用窄带光源与滤光片获取清晰高温图像。在获取的高温图像上使用轮廓识别、凸台定位、亚像素边缘检测、灰度预测等算法对试样的凸台中心线进行检测、定位。通过实验给出了高温光学引伸计的测量结果以及由灰度预测算法去除异常波动值后的结果。实验证明:光学引伸计能够测量高温蠕变伸长率;同时经灰度预测算法平滑后的数据,平均相对误差由1. 234%降至0. 966%,伸长率曲线更加平滑。所采用的方法为非标准小试样的高温蠕变测试提供了一种新的途径。

In order to measure the tensile creep elongation of non-standard specimens with bosses at high temperature,a high temperature creep optical extensometers system is developed. The high temperature furnace with an observation window was designed. The narrowband light source and a matched light filter were used to obtain the clear high temperature images. On these acquired images,contour recognition,boss location,sub-pixel edge detection,gray prediction and other algorithms were used to detect and locate the boss center lines. The measurement results of the high temperature optical extensometer and the results of removing the abnormal fluctuation values were given in experiments by using gray prediction algorithm. Experiment results show that the optical extensometer can measure creep elongation at high temperature. The average relative error of creep rate data predicted by gray level decreases from 1. 234% to 0. 966%. The adopted method provides a new way for creep testing of non-standard small specimens at high temperature.