Multimodal Imaging for Characterisation and Testing of Composite Materials

Carbon fibre reinforced polymers (CFRP) are widely used across several industries, including aerospace, as they are lightweight and offer superior mechanical properties. Barely Visible Impact Damage (BVID), including cracks, delaminations, fibre debonding, as well as manufacturing defects such as porosity, are detrimental to CFRP structural integrity and detection of such faults is important. Different non-destructive evaluation (NDE) methods exist, including ultrasound, X-ray computed tomography (X-ray CT), infrared, and liquid penetrant testing. Edge Illumination X-ray Phase Contrast imaging (EI XPCi) was benchmarked as a viable NDE method for damage detection in CFRP, as it offers additional information through multimodal imaging. With the acquisition of at least three images, EI XPCi allows for the retrieval of the attenuation, differential phase, and dark field signals, using a pair of apertured masks. EI XPCi CT was compared with ultrasonic immersion C-scan imaging and high-resolution X-ray CT for the detection of severe impact damage in a composite plate (visible indent damage on surface of plate and protrusion on the back). The full extent and scale of the different defects were observed in the phase-based signals to a better standard than ultrasonic immersion imaging, with observations confirmed using high resolution X-ray CT. Planar EI XPCi was then compared to contrast agent X-ray imaging and ultrasonic immersion C-scan imaging on a different, less damaged specimen (only small crack visible on surface), showing that planar EI XPCi can detect a network of cracks across the specimen and overcame some of the limitations of contrast agent X-ray imaging. However, in the planar imaging, delamination damage was only detected by the ultrasonic measurement, showing the necessity of using both ultrasonic imaging and EI XPCi for a complete understanding of the damage in the plate. EI XPCi was used for the quantification of porosity for woven composite plates with varying porosity (0.7% to 10.7%), compared to ultrasonic through transmission imaging and destructive matrix digestion. The introduction of the standard deviation of the differential phase (STDP) showed excellent correlation with the porosity calculated from matrix digestion. The STDP signal quantifies the variation of the distribution of inhomogeneities for features of a scale equal to or above the system resolution (in this case, 12µm along the direction of phase sensitivity), which was advantageous for the investigated set of specimens with larger porosity

Close-Range Sensing and Data Fusion for Built Heritage Inspection and Monitoring - A Review

Built cultural heritage is under constant threat due to environmental pressures, anthropogenic damages, and interventions. Understanding the preservation state of monuments and historical structures, and the factors that alter their architectural and structural characteristics through time, is crucial for ensuring their protection. Therefore, inspection and monitoring techniques are essential for heritage preservation, as they enable knowledge about the altering factors that put built cultural heritage at risk, by recording their immediate effects on monuments and historic structures. Nondestructive evaluations with close-range sensing techniques play a crucial role in monitoring. However, data recorded by different sensors are frequently processed separately, which hinders integrated use, visualization, and interpretation. This article’s aim is twofold: i) to present an overview of close-range sensing techniques frequently applied to evaluate built heritage conditions, and ii) to review the progress made regarding the fusion of multi-sensor data recorded by them. Particular emphasis is given to the integration of data from metric surveying and from recording techniques that are traditionally non-metric. The article attempts to shed light on the problems of the individual and integrated use of image-based modeling, laser scanning, thermography, multispectral imaging, ground penetrating radar, and ultrasonic testing, giving heritage practitioners a point of reference for the successful implementation of multidisciplinary approaches for built cultural heritage scientific investigations

Self-Evaluation Applied Mathematics 2003-2008 University of Twente

This report contains the self-study for the research assessment of the Department of Applied Mathematics (AM) of the Faculty of Electrical Engineering, Mathematics and Computer Science (EEMCS) at the University of Twente (UT). The report provides the information for the Research Assessment Committee for Applied Mathematics, dealing with mathematical sciences at the three universities of technology in the Netherlands. It describes the state of affairs pertaining to the period 1 January 2003 to 31 December 2008

Selected Papers from the 9th World Congress on Industrial Process Tomography

Industrial process tomography (IPT) is becoming an important tool for Industry 4.0. It consists of multidimensional sensor technologies and methods that aim to provide unparalleled internal information on industrial processes used in many sectors. This book showcases a selection of papers at the forefront of the latest developments in such technologies

6th International Probabilistic Workshop - 32. Darmstädter Massivbauseminar: 26-27 November 2008 ; Darmstadt, Germany 2008 ; Technische Universität Darmstadt

These are the proceedings of the 6th International Probabilistic Workshop, formerly known as Dresden Probabilistic Symposium or International Probabilistic Symposium. The workshop was held twice in Dresden, then it moved to Vienna, Berlin, Ghent and finally to Darmstadt in 2008. All of the conference cities feature some specialities. However, Darmstadt features a very special property: The element number 110 was named Darmstadtium after Darmstadt: There are only very few cities worldwide after which a chemical element is named. The high element number 110 of Darmstadtium indicates, that much research is still required and carried out. This is also true for the issue of probabilistic safety concepts in engineering. Although the history of probabilistic safety concepts can be traced back nearly 90 years, for the practical applications a long way to go still remains. This is not a disadvantage. Just as research chemists strive to discover new element properties, with the application of new probabilistic techniques we may advance the properties of structures substantially. (Auszug aus Vorwort