The realistic particles in lithium batteries have unique microstructures, which should be determined in the analysis of chemo-mechanical behaviors during charge/discharge cycles. In this paper, an image-basedfinite e...
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The realistic particles in lithium batteries have unique microstructures, which should be determined in the analysis of chemo-mechanical behaviors during charge/discharge cycles. In this paper, an image-based finite element method (IBFEM) is developed to investigate the volume expansion, Li-ion distribution, and diffusioninduced stress (DIS) of a realistic particle. A threshold-based segmentation method is proposed to improve the segmentation accuracy based on the improved threshold of each phase. based on the IBFEM, the active material phase, conductive additive and binder phase, and pore space are segmented and reconstructed using microstructural images. The volume expansion, Li-ion distribution, and DIS of an image-based SnO2 nanoparticle are simulated under galvanostatic/potentiostatic charging process. The predicted lithiation that induced the volume expansion of the SnO2 nanoparticle is approximately coincided with the experiment result observed by TEM. The realistic particle shape and size have a significant impact on the Li-ion distribution and DIS. The concentration profile is analogous to the boundary of the realistic particle at the early stage of lithiation and gradually disappears with further lithiation. The von Mises stress near a concave region is higher than that near a convex region. The maximum von Mises stress in the realistic particle with a larger equivalent radius is higher than that in the smaller particle with the same state of charge. By considering the comprehensive effect of particle shape and size, the size can be increased appropriately while guaranteeing the particle mechanical integrity. These results will contribute to understanding DIS evolution in a realistic particle and can be used to guide the selection of active particles for electrode preparation.
Carbon fiber reinforced silicon carbide matrix composites(C/SiC)have emerged as key materials for ther-mal protection systems owing to their high strength-to-weight ratio,high-temperature durability,resis-tance to oxi...
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Carbon fiber reinforced silicon carbide matrix composites(C/SiC)have emerged as key materials for ther-mal protection systems owing to their high strength-to-weight ratio,high-temperature durability,resis-tance to oxidation,and outstanding ***,manufacturing defects deteriorate the mechani-cal response of these composites under extreme thermal-force coupling conditions,prompting significant research *** study demonstrates a customized in situ loading device compatible with syn-chrotron radiation facilities,enabling high spatial and temporal resolution recording of internal material damage evolution and failure behavior under thermal-force coupling *** thermal radia-tion units in a confocal configuration were used to create ultra-high-temperature environments,offering advantages of compactness,rapid heating,and *** situ tensile tests were conducted on C/SiC samples in a nitrogen atmosphere at both room temperature and 1200℃.The high-resolution image data demonstrate various failure phenomena,such as matrix cracking and pore ***-based fi-nite element simulations indicate that the temperature-dependent variation of the failure mechanism is attributable to thermal residual stresses and defect-induced stress *** work seamlessly integrates extreme mechanical testing methods with in situ observation techniques,providing a compre-hensive solution for accurately quantifying crack initiation,pore connection,and failure behavior of C/SiC composites.
In this paper, the morphology and distribution of yarn imperfections induced by the fabrication process in C/SiC composites were captured and statistically analyzed by X-ray computed tomography using deep learning met...
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In this paper, the morphology and distribution of yarn imperfections induced by the fabrication process in C/SiC composites were captured and statistically analyzed by X-ray computed tomography using deep learning methods for image processing. Subsequently, these imperfections were decoupled into four typical characteristic imperfections: fiber cross-sectional shape, under-sized (over-sized) yarn cross-section, yarn cross-section variation, and yarn waviness. High-fidelity image-based finite element method (IB-FEM) model was generated from CT images, which considered the mesoscopic geometric morphology. The tensile response and failure mechanism of the as-designed model, IB-FEM model, and statistical models were established and verified by experimental results. The impact of yarn geometric imperfections on tensile properties was systematically discussed and elucidated. The results indicate that the intensification of yarn geometric imperfections (yarn cross-section variation and yarn waviness) significantly weakened the ultimate bearing capacity and failure strain of composites under tension, which have greater impacts than other geometric imperfections.
The construction and examination of meso-structural finiteelement models of a Chemical-Vapor-Infiltrated (CVI) C/SiC composite is carried out based on X-ray microtomography digital images (IB-FEM). The accurate mesos...
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The construction and examination of meso-structural finiteelement models of a Chemical-Vapor-Infiltrated (CVI) C/SiC composite is carried out based on X-ray microtomography digital images (IB-FEM). The accurate mesostructural features of the C/SiC composites, which are consisted of carbon fiber tows and CVI-SiC matrix, in particular the cavity defects, are reconstructed. With the IB-FEM, the damage evolution and fracture behaviors of the C/SiC composite are investigated. At the same time, an in situ tensile test is applied to the C/SiC composite under a CT real-time quantitative imaging system, aiming to investigate the damage and failure features of the material as well as to verify the IB-FEM. The IB-FEM results indicate that material damage initially occur at the defects, followed by propagating toward the fiber-tow/SiC-matrix interfaces, ultimately, combined into macrocracks, which is in good agreement with the in situ CT experiment results.
Manufacturing defects in ceramic matrix composites (CMCs), such as voids, microcracks, etc., significantly affect the damage events and strength of the materials. This study aims to reveal the effect of void defects o...
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Manufacturing defects in ceramic matrix composites (CMCs), such as voids, microcracks, etc., significantly affect the damage events and strength of the materials. This study aims to reveal the effect of void defects on the failure behavior and tensile strength of a plain-woven C/SiC composite. The mesoscopic architectures of the C/SiC composites are tested by micro-computed tomography. based on the mu-CT images of the material, finiteelement models (IB-FEM) of the C/SiC composite are established with different void volume fractions and different void geometry. The tensile strength and fracture features of the C/SiC composites are calculated by using the IB-FEM. The effects of void volume fraction and geometry on failure behaviors and tensile strength of the C/SiC composites are investigated and discussed. This study is of great significance for further understanding the influence of defects on the mechanical behavior of CMCs.
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