NDE of microstructured materials by x-ray diffraction and refraction topography
For the purpose of micro structural characterization X-ray topography reveals the spatially resolved scattering of materials and small components. It combines the advantages of radiographic imaging and the analytical information of wide and small angle X-ray scattering like phase distribution, texture, micro cracks, interfaces and pores. Scanning techniques at selected scattering conditions permit the topographic characterization of any crystalline or amorphous solid or liquid. Topographic methods and applications for the purposes of research, quality control and damage evaluation are presented.
Röntgenkleinwinkelbrechung an Metalldrähten, Glasfäden und hartelastischem Polyproplen
Very thin equatorial small-angle scattering of Cu Kα radiation is observed from metallic wires, glass fibres and hard elastic polypropylene which can be explained quantitatively as a refraction phenomenon if the excess refractive indices n = 1 - ∊ of the samples are smaller than unity. For Cu Kα radiation and SiO2 glass ∊ has a value of 7.2 × 10-6. The intensity Is of reflection within a total reflection angle δ = 3.8 × 10-3 = 13' is negligibly small compared with the intensity of refraction IB. In addition to refraction, diffraction by gaps and holes in strained polypropylene was observed. The scattering of 60 μm particles of Li-Ba silicate glass powders [Nau & Bruckner (1971). Kolloid Z. Z. Polym. 244, 223-233] can be explained by transforming the observed scattering of spheres to cylinders yielding the refraction IB as calculated.
Robust solutions of inverse problems in electromagnetic non-destructive evaluation
Non-destructive testing (NDT) is the application of physical measurement technology based on energy interaction with the material and its nonconformities. The material's response is sensed by transducers and sensors which?in most cases?scan the component and document the results in inspection images. However, NDT measures a physically defined quantity or even an intrinsic property. The difference between non-destructive evaluation (NDE) and NDT is in the interpretation of the inspection data. NDE has to discuss the inspection results in terms of quality elements and characteristics which are relevant to describe the fitness of the material for use. In the case of macroscopic defects these are the kind of defect (cracklike, globular) and its size and orientation to the main stress directions; in the case of material property determination the parameters are mainly mechanical properties. Therefore, in NDE one has to solve inverse problems. The solution of inverse problems based on mathematical procedures such as integral equations is a strong developing discipline and most of the articles prepared for this special issue of the journal have the objective of discussing the latest state of the art in that field. However, practical NDE needs robust and quick solutions which are to be applied mainly online. Therefore, we present here inversion procedures based on multiple linear regression algorithms applied to inspection data. We describe the calibration procedure to fit the free parameters of the model functions and give examples of practical applications in industry.