Analysis And Experimental Verification Of Influencing Factors Of High-precision Digital Image Correlation Measurement

For high stable structural components in a spacecraft,it is critical to test its deformation in a simulated space environment in a lab in order to verify rationality and validity of the design.Experiments show that the variants in lab environment,including vibration,ambient light,temperature,air pressure,etc.Seriously affect the measurement system,viz DIC(Digital Image Correlation)SYS,and result in inaccurate and unstable measurement.Therefore,researching the mechanism of how environmental variants affect the measure accuracy of component's deformation and exploring the methods of how to improve it are expected.By decoupling the variants of experimental environment based on DIC mentioned above,though respective experiments and further analyzing the testing results,the influencing mechanism for each variant is induced.based on above job,reducing or eliminating measuring errors methods are designed,and relative testing experiments are carried out.testing results implied that the eliminating error method s mentioned above is feasible and valid.The following initial results were obtained:1.Through experiments and the results analyzing,it is concluded that the influence of the laboratory environment micro vibration on the DIC cannot be ignored,so based on above results,isolating vibration is considered,and the air spring technology is applied.further testing experiments show that this isolations design is worked.2.The experiment proves that the change of light intensity in the test environment will affect the measurement results of DIC.The reason is that the change of gray scale of speckle,the extreme light intensity will makes the images collected by DIC unable to match,which leads to the measurement invalid.on DIC measurement,The environmental light filtering technology can effectively reduce the influence of light intensity change.The experimental results show that the higher the intensity(i.e.the higher the brightness of the image),the higher the measurement accuracy is in the range of the matched intensity of DIC.3.Experiments implied that the temperature change will affect the DIC measurement results.The first reason is the change of camera calibration parameters caused by the camera self heating and the camera baseline rod thermal expansion.The second reason is the distortion of the optical path caused by the air temperature change.The influence caused by the two factors above is micron level.Before the DIC measurement,preheating the camera and placing the acquisition system in the insulation device can effectively eliminate the influence of temperature changes and make the measurement results more accurate.