arXiv subjects

Frank Schubert

Publications and source records attributed to Frank Schubert.

3 recordsLinked to original sources

arXiv2026

Generation, Annihilation and Flow of Structural Information in Ultrasonic Nondestructive Evaluation

Non-destructive testing using ultrasound is based on the interaction of sound waves with the object being tested and any defects it may contain. The aim is to extract as much information as possible about the object and its defects from the scattered wave field. In this paper, the concept of information in the context of ultrasonic testing is formalized and quantified physically for the first time. To this end, a balance equation for information is derived, analogous to Poynting's theorem for elastic energy. Various examples demonstrate how structural information is generated and annihilated within a component and along which pathways it travels from the defect to the sensor. Subsequently, the significance and potential of this new information concept for practical ultrasonic testing, structural health monitoring, numerical simulation, and machine learning are discussed. Finally, similarities and differences to mathematical Shannon information and statistical Fisher information are highlighted.

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arXiv2025

A critical note on the sideband peak count-index technique: failure for nonlinear damage characterization of impacted CFRP plates

It is widely accepted, that nonlinear elastodynamic methods are superior to linear methods in detecting early stages of material deterioration. A number of recently developed methods are reported to be particularly sensitive to nonlinearities and thus appropriate to indicate early damage. We applied systematically one of the methods, the sideband peak count index (SPC-I), to a series of increasingly damaged carbon fiber reinforced plastic (CFRP) plates. Our data leads to different conclusions. The SPC-I values are influenced by (usually undocumented) variations in the index calculation procedure, which is not acceptable for a robust method. Moreover, the behavior of the index when the ultrasound amplitude is varied contradicts material nonlinearity as a direct and significant contributor to the index value. To clarify the apparent contradiction of our results with the previously published statements, it is recommended that (a) our data are re-evaluated by independent researchers and (b) the experiments already published are repeated or (if sufficient data is availThe paper has been updated for submission to NDT&E.able) also re-evaluated.

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arXiv2023

Application of reciprocity for facilitation of wave field visualization and defect detection

The motion visualization in a structural component was studied for defect detection. Elastic motions were excited by hammer impacts at multiple points and received by an accelerometer at a fixed point. Reciprocity in elastodynamics is only valid under certain conditions. Its validity under given experimental conditions was derived from the elastodynamic reciprocity theorem. Based on this, the dynamic motion of the structural component was obtained for fixed-point excitation from measurements performed using multipoint excitations. In the visualized eigenmodes, significant additional deformation was observed at the wall thinning inserted as an artificial defect. To prevent the dependence of defect detection on its position within the mode shape, another approach was proposed based on the extraction of guided wave modes immediately after impact excitation. It is shown that this maximum intensity projection method works well in detecting defects.

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