|
Infrared thermography as a wide-area, rapid, and noncontact nondestructive testing (NDT) method has been widely
recognized for many years. It is based on the thermal wave theory, using different heat source to heat the detected
samples, Pulsed Infrared Thermography has emerged as the most widely used form of the technique, through the
measurement of the surface temperature, the inside information of the sample can be obtained. However, the detectivity
of the Pulsed Infrared Thermography has its limitations, fundamental detectivity of a flaw will depend on its size, depth
and the distance between two adjacent flaws. In this paper, the theoretical analysis of detectivity of infrared pulsed
thermography and criteria to assess the detectivity are discussed , as well as the theoretical testing limit is given for the
Pulsed Infrared Thermography , two related experiments are done, one sample is the aluminum plate with back-drilled
rectangle flumes, having six flumes in the same size but different depths, the sample is used as the detectivity reference
sample, which is used to analysis the relationship between detectivity of the pulsed infrared system and the characters of
a flaw. Meanwhile, a second sample is the Sandwiched structures which are composed by a honeycomb core between
two multi-layer carbon fiber reinforced plastic (CFRP) facesheets, the structure is widely used in aerospace nowadays, it
has flaws in different sizes, depths and distances between two flaws, the second sample is used to study the influence
factors of the detectivity of the Pulsed Infrared Thermography. For the CFRP sample, the detectable size, depth, and
distances between the flaws are given as a result. From the two different experiments, detectivity of the Infrared Pulsed
Thermograhy has been studied.
|
