Microcracks in Carbon/Carbon Composites: A Microtomography Investigation using Synchrotron Radiation

2001 ◽  
Vol 678 ◽  
Author(s):  
Oskar Paris ◽  
Herwig Peterlik ◽  
Dieter Loidl ◽  
Christoph Rau ◽  
Timm Weitkamp
Keyword(s):  
Mechanical Properties ◽  
Synchrotron Radiation ◽  
Phase Contrast ◽  
Three Dimensional ◽  
Carbon Composites ◽  
Matrix Composites ◽  
Crack Network ◽  
Brittle Matrix Composites ◽  
3D Information

AbstractThe mechanical properties of brittle matrix composites such as carbon/carbon (C/C) are closely related to the generation and propagation of microcracks. A better understanding of the role of microcracking requires a quantification of the three-dimensional morphology of the crack network. In this study we demonstrate that phase contrast microtomography using synchrotron radiation is a unique tool to get 3D information about cracks in C/C. This is shown for three different C/C specimens subjected to different final heat treatment temperatures (HTT). The results are discussed qualitatively with respect to the influence of HTT on the distribution of microcracks and their relevance for the mechanical properties of C/C.

Stochastic Aspects of Matrix Cracking in Brittle Matrix Composites

1993 ◽  
Vol 115 (3) ◽  
pp. 314-318 ◽  
Author(s):  
S. M. Spearing ◽  
F. W. Zok
Keyword(s):  
Matrix Cracking ◽  
Matrix Composites ◽  
Brittle Matrix ◽  
Tensile Response ◽  
Brittle Matrix Composites ◽  
Crack Interactions ◽  
The Matrix ◽  
Interface Slip ◽  
Bridging Fibers

A computer simulation of multiple cracking in fiber-reinforced brittle matrix composites has been conducted, with emphasis on the role of the matrix flaw distribution. The simulations incorporate the effect of bridging fibers on the stress required for cracking. Both short and long (steady-state) flaws are considered. Furthermore, the effects of crack interactions (through the overlap of interface slip lengths) are incorporated. The influence of the crack distribution on the tensile response of such composites is also examined.

Conserving the Coherence and Uniformity of Third-Generation Synchrotron Radiation Beams: the Case of ID19, a `Long' Beamline at the ESRF

1998 ◽  
Vol 5 (5) ◽  
pp. 1243-1249 ◽  
Author(s):  
José I. Espeso ◽  
Peter Cloetens ◽  
José Baruchel ◽  
Jürgen Härtwig ◽  
Trevor Mairs ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Phase Contrast ◽  
Angular Size ◽  
Third Generation ◽  
Optical Elements ◽  
X Ray ◽  
Front End ◽  
Ray Path ◽  
Radiation Beams

The lateral coherence length is of the order of 100 µm at the `long' (145 m) ID19 beamline of the ESRF, which is mainly devoted to imaging. Most of the optical elements located along the X-ray path can thus act as `phase objects', and lead to spurious contrast and/or to coherence degradation, which shows up as an enhanced effective angular size of the source. Both the spurious contrast and the coherence degradation are detrimental for the images (diffraction topographs, tomographs, phase-contrast images) produced at this beamline. The problems identified and the way they were solved during the commissioning of ID19 are reported. More particularly, the role of the protection foils located in the front end, the beryllium windows, the filters and the monochromator defects (scratches, dust, small vibrations) is discussed.

Role of interface properties on the toughness of brittle matrix composites reinforced with ductile fibers

1992 ◽  
Vol 7 (11) ◽  
pp. 3132-3138 ◽  
Author(s):  
H.E. Dève ◽  
S. Schmauder
Keyword(s):  
Fracture Resistance ◽  
Crack Opening ◽  
Geometrical Model ◽  
Interface Properties ◽  
Matrix Composites ◽  
Brittle Matrix Composites ◽  
The Matrix ◽  
Interface Sliding ◽  
Brittle Composites

The incorporation of ductile fibers in brittle matrices can lead to a significant increase in fracture resistance. The increase in toughness that derives from crack bridging is governed by the properties of the matrix/fiber interface and the ductility of the fibers. The current study addresses the role of interface sliding stress on the toughness of brittle composites reinforced with ductile fibers. The debond length is explicitly related to the interface sliding stress and the properties of the fiber. It is then incorporated into a geometrical model to simulate the bridging tractions versus crack opening under condition of continuous debonding. The implications on the effect of interfaces on the resistance curve are discussed.

Nondestructive imaging of the internal microstructure of vessels and nerve fibers in rat spinal cord using phase-contrast synchrotron radiation microtomography

2017 ◽  
Vol 24 (2) ◽  
pp. 482-489 ◽  
Author(s):  
Jianzhong Hu ◽  
Ping Li ◽  
Xianzhen Yin ◽  
Tianding Wu ◽  
Yong Cao ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Synchrotron Radiation ◽  
Phase Contrast ◽  
Three Dimensional ◽  
Nerve Fibers ◽  
The Body ◽  
Rat Spinal Cord ◽  
Nondestructive Imaging ◽  
Synchrotron Radiation Microtomography ◽  
The Brain

The spinal cord is the primary neurological link between the brain and other parts of the body, but unlike those of the brain, advances in spinal cord imaging have been challenged by the more complicated and inhomogeneous anatomy of the spine. Fortunately with the advancement of high technology, phase-contrast synchrotron radiation microtomography has become widespread in scientific research because of its ability to generate high-quality and high-resolution images. In this study, this method has been employed for nondestructive imaging of the internal microstructure of rat spinal cord. Furthermore, digital virtual slices based on phase-contrast synchrotron radiation were compared with conventional histological sections. The three-dimensional internal microstructure of the intramedullary arteries and nerve fibers was vividly detected within the same spinal cord specimen without the application of a stain or contrast agent or sectioning. With the aid of image post-processing, an optimization of vessel and nerve fiber images was obtained. The findings indicated that phase-contrast synchrotron radiation microtomography is unique in the field of three-dimensional imaging and sets novel standards for pathophysiological investigations in various neurovascular diseases.

scholarly journals Three-dimensional virtual histology of human cerebellum by X-ray phase-contrast tomography

2018 ◽  
Vol 115 (27) ◽  
pp. 6940-6945 ◽  
Author(s):  
Mareike Töpperwien ◽  
Franziska van der Meer ◽  
Christine Stadelmann ◽  
Tim Salditt
Keyword(s):  
Phase Contrast ◽  
Spatial Organization ◽  
Granular Layer ◽  
Three Dimensional ◽  
Cell Segmentation ◽  
X Ray ◽  
Human Cerebellum ◽  
Conventional Histology ◽  
3D Information ◽  
Phase Contrast Tomography

To quantitatively evaluate brain tissue and its corresponding function, knowledge of the 3D cellular distribution is essential. The gold standard to obtain this information is histology, a destructive and labor-intensive technique where the specimen is sliced and examined under a light microscope, providing 3D information at nonisotropic resolution. To overcome the limitations of conventional histology, we use phase-contrast X-ray tomography with optimized optics, reconstruction, and image analysis, both at a dedicated synchrotron radiation endstation, which we have equipped with X-ray waveguide optics for coherence and wavefront filtering, and at a compact laboratory source. As a proof-of-concept demonstration we probe the 3D cytoarchitecture in millimeter-sized punches of unstained human cerebellum embedded in paraffin and show that isotropic subcellular resolution can be reached at both setups throughout the specimen. To enable a quantitative analysis of the reconstructed data, we demonstrate automatic cell segmentation and localization of over 1 million neurons within the cerebellar cortex. This allows for the analysis of the spatial organization and correlation of cells in all dimensions by borrowing concepts from condensed-matter physics, indicating a strong short-range order and local clustering of the cells in the granular layer. By quantification of 3D neuronal “packing,” we can hence shed light on how the human cerebellum accommodates 80% of the total neurons in the brain in only 10% of its volume. In addition, we show that the distribution of neighboring neurons in the granular layer is anisotropic with respect to the Purkinje cell dendrites.

Matrix cracking and the mechanical behaviour of SiC─CAS composites

1992 ◽  
Vol 437 (1899) ◽  
pp. 109-131 ◽  
Keyword(s):  
Elastic Properties ◽  
Three Dimensional ◽  
Matrix Cracking ◽  
Repeated Loading ◽  
Matrix Composites ◽  
Pull Out ◽  
Matrix Cracks ◽  
Brittle Matrix Composites ◽  
Dimensional Network ◽  
The Matrix

An experimental investigation has been carried out on the mechanical properties of unidirectional (0) 12 , (0, 90) 3S , (±45, 0 2 ) S , and (±45) 3S composites consisting of CAS glass ceramic reinforced with Nicalon SiC fibres. Measurements have been made of the elastic properties and of the tensile, compression and shear strengths of the composites, and these have been supported by a detailed study of the damage which occurs during monotonic and repeated loading. These damage studies have been carried out by means of edge replication microscopy and acoustic emission monitoring. The elastic properties of the composites are, by and large, close to the values that would be predicted from the constituent properties and lay-up sequences, but their strengths are lower than expected, and it appears that the Nicalon reinforcing fibre has been seriously degraded during manufacture. The fracture energy is much higher than predicted from observations of fibre pull-out, and it is suggested that the energy required to form a close three-dimensional network of matrix cracks could account for the high apparent toughness. The matrix cracking stress can be predicted reasonably closely by the Aveston, Cooper and Kelly model of cracking in brittle matrix composites, but it is shown that subcritical microcracks can form and/or grow at stresses well below the predicted critical values without affecting composite properties.

scholarly journals Role of Wood Flour on Physical and Mechanical Properties in Polymer Matrix Composites-A Critical Review

2021 ◽  
Vol 31 (2) ◽  
pp. 81-92
Author(s):  
Lalit Ranakoti ◽  
Pawan Kumar Rakesh ◽  
Brijesh Gangil
Keyword(s):  
Mechanical Properties ◽  
Polymer Composite ◽  
Material Science ◽  
Polymer Matrix Composites ◽  
Wood Flour ◽  
Natural Fibers ◽  
Physical And Mechanical Properties ◽  
Critical Parameters ◽  
Matrix Composites

Green and sustainable material is the utmost prerequisite for the advancement of a healthy society and fulfilling the necessary for the improvement in material science. Naturally obtaining wood flour has the competence to be reinforced as a filler substance in the polymer composite. The present article deals with the usage of wood flour as a filler in the polymer composite. The article comprises properties, characteristics, occurrence, the structure of wood, and the techniques implemented in the manufacturing of wood flour polymer composites. In addition, critical parameters and causes that can bring changes in the properties like tensile, flexural, impact and hardness of polymers are also discussed with the addition of wood flour alone and with nanoparticles. The advantages of using wood flour as a filler in the thermoset and thermoplastic polymers discussed, and its hybridization with various natural fibers was also discussed in the present study.

scholarly journals Three-dimensional Construction of Micrometer Level in Rat Stomach by Synchrotron RadiationThree-dimensional Construction of Micrometer Level in Rat Stomach by Synchrotron Radiation

2020 ◽  
Author(s):  
Qiang Tao ◽  
Chen-Chen Gao ◽  
Xue-Hong Tong ◽  
Shizhen Yuan ◽  
Tian-tian Wang ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Phase Contrast ◽  
Three Dimensional ◽  
Image Resolution ◽  
Phase Contrast Imaging ◽  
Imaging Method ◽  
Rat Stomach ◽  
Contrast Imaging ◽  
X Ray ◽  
3 Dimensional

Abstract Objectives This article shows an imaging method of the stomach that does not use imaging agents. X-ray phase-contrast images of different stages of gastric development were taken using X-ray in-line phase-contrast imaging (XILPCI). The aim of the study was to demonstrate that XILPCI is a micron imaging method for gastric structures. Methods The stomachs of 4-, 6- and 12-week-old rats were removed and cleaned. XILPCI has 1000 times greater soft tissue contrast than that of X-ray traditional absorption radiography. The projection images of the rats’ stomachs were recorded by an XILPCI charge coupled device (CCD) at 9 μm image resolution. Results The X-ray in-line phase-contrast images of the different stages of rat gastric specimens clearly showed the gastric architectures and the details of the gastroduodenal region. 3-dimensional stomach anatomical structure images were reconstruction. Conclusion The reconstructed gastric 3D images can clearly display the internal structure of the stomach. XILPCI may be a useful method for medical research in the future. Keywords: Synchrotron radiation phase-contrast imaging, 3-dimensional gastric structure images

Effect of Silicon Carbide Interlayers on the Mechanical Behavior of T800-HB-Fiber-Reinforced Silicon Carbide-Matrix Composites

2008 ◽  
Vol 368-372 ◽  
pp. 1844-1846 ◽  
Author(s):  
Xin Gui Zhou ◽  
Hai Jiao Yu ◽  
Bo Yun Huang ◽  
Jian Gao Yang ◽  
Ze Lan Huang
Keyword(s):  
Mechanical Properties ◽  
Silicon Carbide ◽  
Three Dimensional ◽  
Bending Test ◽  
Matrix Composites ◽  
High Mechanical Strength ◽  
Three Point Bending ◽  
Carbide Matrix ◽  
Fiber Matrix ◽  
Sic Composites

The influence of the fiber/matrix interlayers on the mechanical properties of T800-HB fiber (a kind of carbon fiber) (the fibrous is three-dimensional four-directional braided) reinforced silicon carbide (SiC) matrix composites has been evaluated in this paper. The composites were fabricated through PIP process, and SiC layers were deposited as fiber/matrix interlayers by the isothermal CVD process. Fiber/matrix debonding and relatively long fiber pullouts were observed on the fracture surfaces. The mechanical properties were investigated using three-point bending test and single-edge notched beam test. The T800-HB/SiC composites exhibited high mechanical strength, and the flexural strength and fracture toughness were 511.5MPa and 20.8MPa•m1/2, respectively.

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