Method for measuring thickness by pulse infrared thermal wave technology

Abstract

The invention provides a method for measuring thickness or defect depth by a pulse infrared thermal wave technology, comprising the following steps of (1) heating an object to be measured by pulse heating equipment; obtaining a thermographic sequence on the surface of the object to be measured by an infrared thermal imaging device; memorizing the thermographic sequence in a general memory; (2) multiplying a temperature-time curve of each point in the thermaographic sequence with corresponding time, thus obtaining a new curve f; (3) working out first-order differential on the f; and obtaining a peak time tapst; (4) working out L by a formula, wherein Alpha is thermal diffusion coefficient and L is the thickness or the defect depth of the object to be measured. By adopting the technical scheme, the thickness or detect depth of a part to be measured can be measured, a reference curve is not needed, and only one-order differential treatment is needed for the measurement, so that the processing method is simpler.

Description

technical field [0001] The invention relates to the technical field of non-destructive flaw detection, in particular to an infrared thermal wave technology, a method for measuring the thickness of a test piece or the depth of a defect by using the pulsed infrared thermal wave technology. Background technique [0002] Pulse infrared thermal wave non-destructive testing technology is a non-destructive testing technology developed after the 1980s. This method is based on thermal wave theory, by actively applying pulse thermal excitation to the measured object, and using infrared thermal imager to continuously observe and record the temperature field changes on the surface of the object, and through modern computer technology and image information processing technology. Detection, acquisition, data processing and analysis of time-series thermal wave signals to realize quantitative diagnosis of internal defects or damages of objects. [0003] The measurement of defect depth or t...

AI Technical Summary

Problems solved by technology

US5711603 uses the differential peak time of the defect area minus the reference area temperature curve as the characteristic time. This patent needs to select a reference area first, which is difficult to achieve in some applications and introduces errors

The contrast peak method uses the peak time of the temperature curve of the defect area minus the reference area as the characteristic time, but the peak time is greatly affected by factors such as the size of the defect, and the reference area is also required

S.M.Shepard uses the peak time of the second-order temperature-time logarithmic curve as the characteristic time. Its advantage is that its corresponding peak time is relatively early, and it is relatively less affected by three-dimensional thermal diffusion, but its disadvantage is that the second-order differential peak time is affected by noise. Greater impact

The logarithmic separation point method uses the separation time of the defect and non-defect areas in the temperature-time logarithmic curve as the characteristic time. This method also needs a reference curve, and it is difficult to accurately determine the separation point.

Images