X-ray computed tomography of polymer composites

Generation of 3D representative volume elements for heterogeneous materials: a review

The concept of industrial computed tomography (CT) is introduced in this chapter. CT is defined, and the history of CT scanning is outlined. As part of the history, the conventional tomography technique is explained. The development of CT is documented, outlining the initial experiments that lead to the development of modern CT. An overview of the current state of CT scanning is then presented, outlining the five main generations of clinical CT scanner and the two main types of scanner used in industrial CT. The industrial requirements of CT are then discussed, and the content of the following chapters is briefly outlined. Computed tomography is defined as an imaging method in which the object is irradiated with X-rays or gamma rays and mathematical algorithms are used to create a cross-sectional image or a sequence of such images (VDI/VDE 2009). The word tomography itself comes from the Greek tomos, meaning a ‘slice’ or ‘section’, and graphien, meaning ‘to write’. In the process of tomography, X-ray radiography is used to take a large number of radiographic projections, which are then reconstructed using a mathematical algorithm to form a slice image of the object being scanned (Hsieh 2009). These reconstructed slices can then be stacked to form a three-dimensional (3D) representation of the object that can be used in a wide array of applications. The tomographic technique was originally developed as a novel method of clinical visualisation, due to the advantage presented by the technology when compared to traditional two-dimensional (2D) radiography, which compresses a 3D volume into a 2D projection. 2D radiography, therefore, carries the caveat that, due to overlapping structures, locating a feature within a wider object becomes difficult due to the ambiguity regarding the depth of the feature. It is also the case that more dense structures overlapping a feature of interest may obscure that feature entirely, for example in the case of patient jewellery (see Fig. 1.1), or when a bone lies along the same X-ray path as a cancerous tumor, the tumor can be completely obscured by the presence of the bone. A. Thompson (&) R. Leach Faculty of Engineering, University of Nottingham, NG7 2RD Nottingham, UK e-mail: Adam.Thompson@nottingham.ac.uk © Springer International Publishing AG 2018 S. Carmignato et al. (eds.), Industrial X-Ray Computed Tomography, https://doi.org/10.1007/978-3-319-59573-3_1 1 1.1 History of X-ray Computed Tomography Since the discovery of X-rays and the inception of X-ray imaging, there have been many developments in X-ray technologies that have eventually resulted in the industrial CT scanners available today. This section provides a concise history of conventional and computed tomography, and examines the progress of the technologies that have evolved into that which is seen in modern scanners. The initial experiments that defined modern CT are explored, and key developments over time are documented. 1.1.1 X-ray Tomography Prior to the invention of modern computing, there existed a version of tomographic technology that did not require the complex computation that allows today’s computed tomography (CT) scanners to function. Conventional tomography was conceived initially in 1921 by André Bocage (Bocage 1921; Hsieh 2009), in a patent describing a method of attaining slice images of an object by blurring structures above and below the plane of interest. Bocage used the simple setup of an X-ray source, an object and a detector, in this case a piece of X-ray film. For his experiment, Bocage synchronously translated the X-ray source and the detector linearly in opposite directions, in order to blur the structures that lay outside of the focal plane of the system. To understand how Bocage’s method works, two points Fig. 1.1 Left An example X-ray radiograph taken by William Röntgen of his wife’s hand, showing the finger bone concealed beneath the subject’s wedding ring (NASA 2007). Right The basic X-ray acquisition setup (Hsieh 2009) 2 A. Thompson and R. Leach

Industrial X-Ray Computed Tomography

Composite materials/structures are advancing in product efficiency, cost-effectiveness and the development of superior specific properties. There are increasing demands in their applications to loa...

/pdf/non-destructive-testing-and-evaluation-of-composite-25jy7cttmq.pdf

Non-destructive testing and evaluation of composite materials/structures: A state-of-the-art review

3D imaging has become popular for analyzing material microstructures. When time lapse series of 3D pictures are acquired during a single experiment, it is possible to measure displacement fields via digital volume correlation (DVC), thereby leading to 4D results. Such 4D analyses have been performed for almost two decades. The present paper aims at reviewing the achievements of and challenges faced by such measurement technique. Ex-situ and in-situ experiments are discussed. A general and unified DVC framework is introduced. Various sources of measurement bias and uncertainties are analyzed. The current challenges are studied and some propositions are given to address them.

/pdf/digital-volume-correlation-review-of-progress-and-challenges-24sgmjfw7w.pdf

Digital Volume Correlation: Review of Progress and Challenges

Meso-scale FE analyses of textile composite reinforcement deformation based on X-ray computed tomography

3D composite reinforcement meso F.E. analyses based on X-ray computed tomography

This study deals with the identification of macroscopic elastic parameters of a layer-to-layer interlock woven composite from a full-field measurement. As this woven composite has a coarse microstructure, the characteristic length of the weaving is not small as compared to the specimen size. A procedure based on an inverse identification method and full-field digital image correlation kinematic measurement is proposed to exploit a three-point bending test on short coupons to characterize the out-of-plane shear modulus. Each step of the proposed procedure is presented, and their respective uncertainty is characterized with the help of numerical simulations. The shear modulus is identified with an accuracy of about 1.5 % and is 15 % lower than the estimate obtained through Iosipescu tests. The proposed procedure shows a correlation between the ideal mesh size and the weaving period. It also reveals that the actual boundary conditions deviate from the ideal ones and hence a special attention is paid to their optimization.

Identification of the Out-of-Plane Shear Modulus of a 3D Woven Composite

https://hal.archives-ouvertes.fr/hal-02156832/document

Julien Schneider

Papers

Meso-scale FE analyses of textile composite reinforcement deformation based on X-ray computed tomography

3D composite reinforcement meso F.E. analyses based on X-ray computed tomography

Identification of the Out-of-Plane Shear Modulus of a 3D Woven Composite

Differentiating 3D textile composites: A novel field of application for Digital Volume Correlation

The correlation framework: Bridging the gap between modeling and analysis for 3D woven composites