Article
Materials Science, Composites
Mahoor Mehdikhani, Christian Breite, Yentl Swolfs, Jeroen Soete, Martine Wevers, Stepan V. Lomov, Larissa Gorbatikh
Summary: This study explores the potential of Digital Volume Correlation (DVC) in detecting and characterizing damage in fiber-reinforced composites using in-situ X-ray Computed Tomography. Through preliminary analysis of digital deformation images and real-deformation images acquired during in-situ tensile loading, DVC proves to be a promising tool for quantification of deformation and damage at both mesoscale and microscale levels. Damage mechanisms in fiber-reinforced composites are successfully detected and characterized using DVC, showing the limitations of traditional methods like grayscale thresholding.
COMPOSITES SCIENCE AND TECHNOLOGY
(2021)
Article
Thermodynamics
Haizhou Liu, Lingtao Mao, Yang Ju, Francois Hild
Summary: In order to investigate the damage development of coal under different loading conditions, in-situ tests in uniaxial and triaxial compression were conducted. Advanced digital volume correlation based on finite element discretization was used to quantify the three-dimensional initial and newborn fractures. The experiments revealed that the damage growth in coal was substantially affected by randomly distributed initial defects, and prior to a macroscopic failure, the coal samples generally experienced pre-existing fracture closure, newborn fracture initiation, interaction and propagation of the two fracture types. The study aimed to gain in-depth insights into the bulk fracture of coal and provide quantitative evidence for further understanding the damage mechanisms from the microscale to the macroscale.
Article
Materials Science, Multidisciplinary
Xianzheng Lu, Chiping Lai, Luenchow Chan
Summary: This study employed high-resolution micro-focus X-ray Computed Tomography (CT) system and loading-unloading tensile test to quantify the 3D interactions of micro-voids evolution in biocompatible alloy stainless steel 316L (SS316L). The dynamic evolution mechanism of ductile damage involving the nucleation, growth, and coalescence of micro-voids was revealed, and an improved micromechanics-based damage model considering large deformation condition was implemented for damage prediction.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2023)
Article
Multidisciplinary Sciences
Martina Mambrini, Laura Mecozzi, Erica Ferrini, Ludovica Leo, Davide Bernardi, Grandi Andrea, Nicola Sverzellati, Livia Ruffini, Mario Silva, Franco Stellari
Summary: This study proposed a routine QC protocol for in vivo micro-CT based on commercial phantoms, and found significant differences in lung density parameters before and after scanner drift, highlighting the importance of the designed QC procedure for reliable longitudinal quantification of disease progression and drug efficacy evaluation.
SCIENTIFIC REPORTS
(2022)
Review
Radiology, Nuclear Medicine & Medical Imaging
Panagiota Berta Panagiotopoulou, Nikos Courcoutsakis, Apostolos Tentes, Panos Prassopoulos
Summary: Cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy has revolutionized survival and quality of life in peritoneal carcinomatosis patients. Preoperative CT is crucial for patient selection and surgical planning. Radiologists play a key role in describing cancerous implants, analyzing involvement patterns, and estimating disease burden during CT interpretation, enhancing disease understanding and communication between radiologists and surgeons.
INSIGHTS INTO IMAGING
(2021)
Article
Chemistry, Physical
Jakub Kowalski, Adam K. Puszkarz, Mateusz Radwanski, Jerzy Sokolowski, Michal Cichomski, Rim Bourgi, Louis Hardan, Salvatore Sauro, Monika Lukomska-Szymanska
Summary: The aim of this study was to evaluate the size of microgaps between prefabricated and customised abutments (Astra Tech, Dentsply, York, PA, USA; Apollo Implants Components, Pabianice, Poland) mounted on a standard implant. The measurement of the microgap was performed using micro-computed tomography (MCT). The results showed that most samples did not exhibit any microgaps, and the microgap size of the Apollo abutment was higher and more variable than that of the Astra one.
Article
Engineering, Multidisciplinary
Cristofaro S. Timpano, Garrett W. Melenka
Summary: This study introduces a methodology for obtaining optimal DVC image datasets for composite materials by adding contrast particles to an epoxy resin. The 25 μm copper particles were found to provide the greatest accuracy. Comparison between downsampled ?-CT and full-resolution datasets demonstrated processing strategies for DVC analysis.
COMPOSITES PART B-ENGINEERING
(2021)
Article
Multidisciplinary Sciences
Hirotsugu Sakamoto, Makoto Nishimura, Alexei Teplov, Galen Leung, Peter Ntiamoah, Emine Cesmecioglu, Noboru Kawata, Takashi Ohnishi, Ibrahim Kareem, Jinru Shia, Yukako Yagi
Summary: Endoscopic submucosal dissection is an effective method for treating large superficial gastrointestinal lesions. This study successfully generated three-dimensional images of nine samples using a micro-CT imaging system, which can provide valuable information for evaluating the extent of the lesion and surgical margins.
SCIENTIFIC REPORTS
(2022)
Article
Engineering, Multidisciplinary
Xuanhao Zhang, Lijuan Sun, Bo Wang, Bing Pan
Summary: Digital volume correlation (DVC) is a method to quantify internal 3D displacement and strain fields by correlating volume images acquired from a tested object at different states. This study experimentally investigated the effect of the number of projections on DVC measurements with X-ray CT. The results showed that increasing the number of projections can improve the accuracy and quality of DVC measurements, but it also increases the imaging time.
Article
Multidisciplinary Sciences
Brent van der Heyden, Stijn Roden, Rueveyda Dok, Sandra Nuyts, Edmond Sterpin
Summary: The study developed a vMonoCT model based on a seven-layer U-Net architecture to predict virtual monoenergetic X-ray projections for reducing imaging artifacts in micro cone-beam computed tomography (mu CBCT). The model achieved a low percentage error and effectively minimized pixel reduction artifacts in the projection dataset.
SCIENTIFIC REPORTS
(2022)
Article
Orthopedics
Amelie Poilliot, Max Hans-Peter Gay-Dujak, Magdalena Muller-Gerbl
Summary: This study assessed the mineralization and microstructure of the subchondral endplates and trabecular bone in the cervical vertebrae using computed tomography osteoabsorptiometry and micro-computed tomography. The results showed that the highest mineralization was found in the dorsal-caudal region of the C4 vertebra. Based on these findings, it is recommended to position orthopedic implants dorsally with screws anchored in the dorsal-caudal region.
JOURNAL OF ORTHOPAEDIC SURGERY AND RESEARCH
(2023)
Article
Engineering, Geological
Rizwan Khan, Gali Madhavi Latha
Summary: To understand the process of mobilisation of shear strength in sand-geosynthetic interfaces at a fundamental level, the size and shape of the grains and the shear-induced surface changes in geosynthetics need to be precisely characterized. In this study, shear behavior of dilative and non-dilative geosynthetics interfacing with sands of different morphological characteristics was analyzed through interface shear tests and digital imaging techniques. The shape parameters of sands and surface changes in geosynthetic surfaces were quantified using X-ray micro computed tomography (mu CT), optical profilometry, and laser profilometry. Interface shear tests revealed the effects of irregularity, angularity, and surface texture of particles on the peak and residual friction angles. The surface texture of geotextile surfaces resulted in higher interface friction and displacement compared to geomembrane surfaces, which showed non-dilative behavior. The shear zone thickness and microscopic shearing mechanisms were quantified using digital image correlation (DIC) analysis.
GEOTEXTILES AND GEOMEMBRANES
(2023)
Article
Cardiac & Cardiovascular Systems
Kenji Kawai, Yu Sato, Jason Y. Hokama, Rika Kawakami, Takao Konishi, Saikat Kumar B. Ghosh, Renu Virmani, Aloke Finn
Summary: In this study, the histologic effects of intravascular lithotripsy (IVL) on coronary calcified lesions were examined. IVL demonstrated a superior fracturing effect on coronary calcified lesions compared with plain old balloon angioplasty (POBA). Optical coherence tomography (OCT) failed to identify the presence of some calcium fractures and underestimated the depth of fracture when compared with micro-computed tomography (CT).
JACC-CARDIOVASCULAR INTERVENTIONS
(2023)
Article
Optics
V. Di Trapani, L. Brombal, F. Brun
Summary: This study presents a cone-beam micro-CT setup with a photon counting detector and an innovative image processing pipeline to address the issues of limited energy resolution and noise amplification. Experimental results demonstrate the ability of the combined hardware and software tools to effectively discriminate materials with a few key separation.
Article
Materials Science, Characterization & Testing
Wei Zhou, Reng Qin, Kang-ning Han, Zhi-yuan Wei, Lian-Hua Ma
Summary: Tensile failure and damage visualization of three-dimensional braided composites were investigated using progressive damage mechanics. Results show that progressive damage affects specimen's load carrying capacity, stability, and damage evolution. Longitudinal and transverse cracks are the main forms of specimen failure under different tensile stresses.
Article
Engineering, Mechanical
Maxwell Hein, Nelson Filipe Lopes Dias, David Kokalj, Dominic Stangier, Kay-Peter Hoyer, Wolfgang Tillmann, Mirko Schaper
Summary: The tensile and fatigue properties of Ti-6Al-7Nb alloy processed by laser powder bed fusion can be improved by depositing thin coatings of TiN, TiCN, and a-C:Ag using physical vapor deposition (PVD) technique. These coatings enhance the tensile strength and fatigue resistance, except for the a-C:Ag coating, due to their high residual compressive stresses and increased surface hardness.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Article
Metallurgy & Metallurgical Engineering
Hong Li, Bo-jin Li, Zeng-cheng Xing, Erika Hodulova, Yi-peng Wang, Benjamin Lehmert, Zhuo-xin Li, Wolfgang Tillmann
Summary: This article proposes a novel Cu/W nano-multilayer film as filler material for pulsed pressure diffusion bonding of Ti-6Al-4 V alloy. By increasing the rate of heating, Cu diffused into the Ti-6Al-4 V base metal, reducing the formation of brittle compounds in the bonding and enhancing the tensile strength of the joint.
WELDING IN THE WORLD
(2023)
Article
Metallurgy & Metallurgical Engineering
W. Tillmann, T. Ulitzka, L. Dahl, L. Wojarski, H. Ulitzka, M. Koymatli
Summary: Recently, a successful integration of maraging steel heat treatment into vacuum brazing has led to the manufacture of high-strength cemented carbide-steel joints. The low wettability of the maraging steel was overcome by applying a nickel layer through arc-PVD, although this method is not suitable for industrial applications. This study evaluates the use of chemical plating and electroplating as alternative nickel-coating methods, and found that electroplating with a 20.0-mu m-thick nickel layer resulted in the highest shear strength of 344.8 MPa.
WELDING IN THE WORLD
(2023)
Article
Materials Science, Coatings & Films
W. Tillmann, O. Khalil, I. Baumann, J. Zajaczkowski
Summary: In this study, titanium coatings were deposited on top of plasma-sprayed stabilized-zirconia coatings by the high-pressure cold spray process. The effects of cold spray process parameters and ceramic substrate roughness on the properties of the metallic layer were investigated. It was found that the deformation of titanium splats plays a crucial role in the bonding with the ceramic substrate, and increasing the propellant gas temperature and pressure improves the bonding strength and hardness of the metallic layer while reducing its porosity. Additionally, the roughness of the ceramic substrate affects the thickness of the metallic layer but not its roughness.
SURFACE & COATINGS TECHNOLOGY
(2023)
Article
Metallurgy & Metallurgical Engineering
A. Joeckel, J. Baumgartner, W. Tillmann, J. Bueltena, K. Bobzin, H. Heinemann, M. Erck
Summary: In this study, induction-brazed, vacuum-brazed, and continuous furnace-brazed joints were used to assess the fatigue life. It was found that the local brazing geometry in conjunction with the surface condition had the most influence on the failure behavior and fatigue strength.
WELDING IN THE WORLD
(2023)
Article
Polymer Science
Yanling Schneider, Vinzenz Guski, Siegfried Schmauder, Javad Kadkhodapour, Jonas Hufert, Axel Grebhardt, Christian Bonten
Summary: This work presents a general process to simulate the deformation behavior of auxetic structures made of various polymers. It discusses the challenges and provides suggestions for calculating the Poisson's ratio of auxetic structures. The finite element simulation results match the testing results well and provide insights into the stress distribution and local topology.
Article
Environmental Sciences
Kevin Hoppe, Lukas Wischemann, Gerhard Schaldach, Reiner Zielke, Wolfgang Tillmann, Markus Thommes, Damian Pieloth
Summary: Depth filtration is a widespread technique used in separating airborne particles. Simulations are crucial to optimize the filter structure and develop filter materials with high efficiency and low pressure differences. A one-dimensional model combined with microstructural data of filter materials is presented in this work, enabling more realistic modeling of the filtration process.
Article
Nanoscience & Nanotechnology
Carl Arne Thomann, Adrian Wittrock, Alexandra Wittig, Nelson Filipe Lopes Dias, Dominic Stangier, Wolfgang Tillmann, Joerg Debus
Summary: Amorphous carbon (a-C) is widely studied in tribology and thin film technologies for its versatile properties. This study presents an optical method to induce structural ordering and investigate solid-to-solid structural transitions of element modified a-C films. By using a pump laser to control heat introduction and a second laser to probe Raman scattering signatures, the research reveals the reduction of defects and non-sixfold aromatic rings with low pump power, a transition to defected graphite and hydrogen effusion with increased laser power, and progressive graphitization with rising laser power. Chemical modification of the films with Si or Cu enhances thermal stability, while a-C:W film shows efficient enrichment of nanocrystalline graphitic clusters.
Article
Materials Science, Multidisciplinary
Xiang Xu, Xi Zhang, Andrei Ruban, Siegfried Schmauder, Blazej Grabowski
Summary: APBs are important for understanding the temperature dependence of the yield stress of Ni3Al. Accurate prediction of temperature-dependent APB energies has been lacking, and the impact of magnetism at elevated temperatures has been neglected. We show that thermally-induced magnetic spin fluctuations significantly affect the APB energies, especially for the (100)APB. Our results highlight the need to consider these spin fluctuations even for weak ferromagnetic materials like Ni3Al and the potential consequences for large-scale modeling in Ni-based superalloys.
Article
Automation & Control Systems
Wolfgang Tillmann, Tim Henning, Lukas Wojarski, Christian Timmer, Finn Ontrup
Summary: A novel FE-model was developed in ANSYS Workbench to calculate the time and location resolved component deformation of AISI 316L/B-Ni2 brazing assemblies. The results showed that the component deformation during heating can be easily kept in the elastic range and can be almost completely eliminated by using a geometry-dependent soaking time. High cooling rates were found to result in significant component deformation. A fixture for vertical positioning was designed based on the simulation results, which successfully reduced the distortion of the brazing assembly.
INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
(2023)
Article
Metallurgy & Metallurgical Engineering
Wolfgang Tillmann, Tim Henning, Lukas Wojarski, Julia Bueltena
Summary: Laser powder bed fusion (LPBF) processes provide excellent design options for complex components. However, the economic production of high-volume components is still challenging. Vacuum brazing is a promising technology for joining LPBF components with conventionally manufactured parts. This study investigates the brazeability and joint properties of a specific steel alloy, and the results show that nickel-plated surfaces are crucial for achieving sufficient process control and enhancing joint strength.
STEEL RESEARCH INTERNATIONAL
(2023)
Article
Metallurgy & Metallurgical Engineering
L. Wojarski, W. Tillmann, H. Ulitzka, T. Ulitzka
Summary: The poor wettability of cemented carbides by molten metals and the different material properties compared to steel pose challenges in thermal joining process. However, the innovative ultrasonic-assisted induction brazing can quickly and cost-effectively join the materials without the use of environmentally hazardous fluxes. The use of ultrasound can break up oxide scales and promote wetting in the joining process.
WELDING IN THE WORLD
(2023)
Article
Chemistry, Physical
Galina Lasko, Siegfried Schmauder, Yitong Yang, Sabine Weiss, Kiarash Dogahe
Summary: Vascular stents have been used to treat clogged vessels for over two decades, but they can cause serious adverse effects. Therefore, it is important to study the mechanical properties and predict the lifespan of stents.
Article
Materials Science, Multidisciplinary
Christian Timmer, Wolfgang Tillmann, Lukas Wojarski, Manuel Pinho Ferreira
Summary: In response to the increasing demand and carcinogenic effect of cobalt, alternative metal matrixes without cobalt are developed for hot-pressed diamond tools. Through experimentation, Cr5Cu20Fe25Mn25Ni25 alloy is identified as a promising cobalt-free metal matrix material.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2023)
Article
Materials Science, Ceramics
Vera Petrova, Siegfried Schmauder, Alexandros Georgiadis
Summary: This paper investigates the thermal fracture problem of a functionally graded coating (FGC) on a homogeneous substrate (H), referred to as the FGC/H structure. The FGC/H structure is subject to thermo-mechanical loadings, and systems of interacting cracks are present in the FGC. The material properties and fracture toughness of the FGC are modeled using a rule of mixtures approach.
CERAMICS-SWITZERLAND
(2023)