Standards for the application of flash thermography as well as of lock-in thermography are urgently required.
Both methods are applied more and more often in research and industry, but still extensive validation procedures are required for each individual application. In this paper, the results of two research projects concerning the validation and standardisation of both methods are presented. This includes results of a detailed study of the influence of measurements parameters on flash thermography, of the comparison of the lateral resolution obtained with flash and lock-in thermography and the description of a draft standard for flash thermography.
Ever larger high pressure die castings (HPDC) with ever thinner walls raise the issue of casting defects. Properties of components are often strongly influenced by inner porosity. In the case of high pressure die castings, shrinkage and gas porosity occur. Two possibilities of characterizing porosity - by microscopy and acitve thermography - are dealt with in two articles. In the previous article, the microscopic investigations are presented. In this article, first the feasibility of thermographic detection will be discussed based on simulations and, thereafter, the experimental determination of porosity with active thermography will be described.
Lockin thermography as well as flash thermography are very well suited for non-destructive testing and characterisation of inhomogeneities and damage in CFRP structures. Both methods are applied more and more in research and industry, but until know it is not clear which are the advantages of one method against the other. In
this paper, results of two research projects concerning the validation and standardisation of both methods are presented. Three different types of CFRP test specimens consisting of well-defined flat bottom holes, of artificial delaminations made of PTFE plates embedded in CFRP and of real impact damage have been investigated systematically with flash and lockin excitation. Here, the phase images of both methods are compared qualitatively as well as quantitatively.