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A New Approach to Guided Wave Ray Tomography for Temperature-Robust Damage Detection Using Piezoelectric Sensors
摘要： In this paper, a new approach to guided wave ray tomography for temperature-robust damage detection with time-of-flight (TOF) temperature compensation is developed. Based on the linear relationship between the TOF of a guided wave and temperature, analyses show that the TOF of the baseline signal can be compensated by the temperature measurement of the inspected materials without estimating the temperature compensation parameters. The inversion is based on the optimization of the TOF misfit function between the inspected and compensated baseline TOFs of the guided waves, and is applied by the elastic net penalty approach to perform thickness change mapping in a structural health monitoring (SHM) application. Experiments that are conducted in isotropic plates by piezoelectric sensors demonstrate the effectiveness of the proposed method. According to the results, our approach not only eliminates the artefacts that are caused by a temperature variation from 25 ?C to 70 ?C but also provides more accurate and clearer imaging of damage than conventional ray tomography methods.
关键词： TOF,ray tomography,piezoelectric sensors,guided wave,structural health monitoring,temperature compensation
更新于2025-09-23 15:21:21
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Influence of manufacturing orientations on the morphology of alloy 718 single struts manufactured by selective laser melting
摘要： Selective laser melting (SLM) is of great interest for manufacturing lightweight structures such as lattices. It allows a broad range of lattice topologies to be created. However, when manufacturing small struts, roughness, lack of dimensional accuracy, and porosity level can decrease their mechanical properties and thus affect the mechanical response of the entire structure. This study focuses on the high-resolution characterization of alloy 718 (UNS N07718) single struts (constitutive elements of the lattice) manufactured by SLM. Process parameters, strategy, and post-treatments remain constant while varying strut positions on the build plate and orientations. A methodology for the systematic characterization of 19 struts with high-resolution X-ray tomography has been developed. Different features related to the strut size, shape, waviness, roughness, and porosity are extracted. The analysis of those features when varying strut positions and orientations highlights the influence of each parameter. The build orientation is a first-order parameter influencing strut morphology as already referenced in the literature. This systematic study reveals also the influence of the in-plane orientation for inclined struts that alters their roughness, shape, and size.
关键词： Selective Laser Melting,Build orientation,X-ray tomography,Lattice structures,Single struts,In-plane orientation
更新于2025-09-19 17:13:59
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Pore Closure Effect of Laser Shock Peening of Additively Manufactured AlSi10Mg
摘要： This article reports on an exceptional insight provided by nondestructive X-ray tomography of the same samples before and after laser shock peening (LSP). The porosity in two additively manufactured aluminum alloy (AlSi10Mg) tensile samples before and after LSP was imaged using identical X-ray tomography settings and overlap of the data was performed for direct comparison. The results indicate clearly that near-surface pores are closed by the process, while internal pores remain unaffected. LSP has become well known as a method to improve the fatigue properties of materials, including those of additively manufactured aluminum alloys. This improvement is usually attributed to the compressive residual stress induced by the process. The additional effect of closure of near-surface pores that is illustrated in this work is of interest for additive manufacturing because additive manufacturing is not yet able to produce completely pore-free components. Since the critical pore initiating fatigue cracks are always attributed to surface or subsurface pores, the closure of these pores may play an additional role in improving the fatigue properties. While more work remains to unravel the relative importance of near-surface porosity compared to the compressive residual stress effect, this work clearly shows the effect of LSP—closing of pores near the surface. For the processing conditions demonstrated here, all pores up to 0.7 mm from the surface are closed without damaging the surface, while higher peening power results in surface damage.
关键词： additive manufacturing,laser shock peening,X-ray tomography,aluminum alloys,laser powder bed fusion
更新于2025-09-11 14:15:04
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On-the-Fly Fast X-Ray Tomography Using a CdTe Pixelated Detector – Application in Mechanical Testing
摘要： Fast tomography measurements are still done almost exclusively within the domain of synchrotrons. However, recent progress in X-ray imaging instrumentation has enabled researchers to perform time-lapse computed tomography (4D-CT) even under laboratory conditions with standard X-Ray sources. Thus, fast time-dependent processes within materials with relatively high X-Ray attenuation can be monitored. The article describes the in-situ tomographic monitoring of crack formation and propagation in a quasi-brittle silicate matrix composite subjected to three point bending. A three-dimensional CT volume containing the region of interest (ROI) in the specimen is imaged over a period of time while the continuously increasing load causes crack initiation and propagation, creating a dynamic volume dataset. An acquisition time of 50 seconds for one full angle tomography with 400 projections makes this tomographic system one of the fastest systems in the world. The resulting visualizations provide qualitative information concerning progressive crack propagation within areas of lower material density. Differential images then allow displaying the spatial orientation of the crack over time. The results were further processed for a quantitative analysis of image quality using various methods of beam hardening correction.
关键词： X-ray imaging techniques,X-ray tomography,Materials characterization,Mechanical testing,Quasi-brittle material,Fracture mechanics,CdTe detectors
更新于2025-09-10 09:29:36
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Use of iodine for improving phase quantification using x-ray tomography
摘要： X-ray computed tomography (CT) has been used to quantify pore structure and crack characterization in cementitious materials. However, similar contrast (greyscale values) of the hydration products in the reconstructed image volume has limited the ability to quantify these phases, and this remains a significant need to further the impact of this experimental method. The goal of this research was to improve the ability to quantify synthesized hydration products by incorporating a contrast agent to improve segmentation between the four main hydration products in portland cement; C-S-H, calcium hydroxide (CH), monosulfate (AFm), and ettringite (AFt). Pure C-S-H, CH, and AFt, and a pure and modified AFm, with iodine as a contrast agent, were synthesized for investigation by x-ray CT. Multi-energy scans were used to isolate individual phases using a synchrotron radiation facility. Using iodine as a contrast agent resulted in accurate quantification of the four main hydration products.
关键词： Composite (E),Hydration products (B),Image analysis (B),X-ray tomography,Cement (D)
更新于2025-09-10 09:29:36
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[Fundamental Biomedical Technologies] Advanced High-Resolution Tomography in Regenerative Medicine (Three-Dimensional Exploration into the Interactions between Tissues, Cells, and Biomaterials) || In-Line X-Ray Phase Tomography of Bone and Biomaterials for Regenerative Medicine
摘要： The aim of this chapter is to present recent developments in X-ray tomography using in-line phase contrast and their applications to mineralised tissue, whether bone or artificial biomaterials, at micro- and nanoscale. Recently, the main efforts in reconstruction algorithms for in-line X-ray phase contrast imaging have been to push resolution towards the nanoscale and extend the possibilities for quantitative imaging to more general objects. The first is made possible by the use of X-ray optics and the second by the introduction of more advanced priors in the reconstruction. We summarise here these developments and outline recent applications of these techniques, namely, nano-tomography of the ultrastructure of bone and micro-tomography of bone formation in artificial bone grafts as well as in healthy growing mice. While still relatively little used in the field of regenerative medicine, we hope that these examples will stimulate further studies in this field.
关键词： mineralised tissue,regenerative medicine,biomaterials,bone,X-ray tomography,micro-tomography,in-line phase contrast,nano-tomography
更新于2025-09-09 09:28:46