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B4C particle-reinforced Al matrix composite (B4Cp/Al) has excellent properties and is expected to become the mainstream of composites in the future. Due to the complex meso-structure of B4Cp/Al, this increases the difficulty of material precision machining. In addition, the current research on the PRMMCs generally focuses on SiCp/Al and the effects of machining parameters on cutting force and temperature, while the research on the effects of tool geometry parameters on material cutting is relatively rare. Therefore, the cutting mechanism of B4Cp/Al is studied by finite element simulation. Firstly, based on the meso-structure of B4Cp/Al, a three-dimensional (3D) model of the material is established. Then the mechanism of surface formation of B4Cp/Al was studied by combining cutting simulation and turning experiment. Use the simulation to study the effect of tool rake angle on material cutting surface quality. It was found that the removal mode of B4C particles, the residual stress in Al matrix after cutting, and the plastic deformation would be affected by the tool rake angle, thus affecting the cutting surface quality. After a comprehensive comparison, it is found that when the rake angle is − 5°, the cutting quality is the best. [ABSTRACT FROM AUTHOR]

Unlike synthetic elastomers, the structure of natural rubber (NR) evolves (dynamic structuring) and so do its properties during the storage before reaching an industrial mixer. In the rubber industry this is known as storage hardening. NR samples from three genotypes (GT1, RRIM600 and PB235) were subjected to different levels of structuring by varying the structuring time (t) on phosphorus pentoxide (0 12 h). An A4F analysis of the samples was used to quantify the fraction of microaggregates smaller than 1 μm (microgel

To essentially explore and quantitatively clarify the mesoscopic failure mechanism of deep weak interlayer zone (WIZ) induced by complex stress levels and stress paths (i.e., particle breakage and orientation, pore morphology, etc.), a semi-quantitative mesoscopic structural damage analysis methodology has been proposed, by involving SEM-MATLAB image processing technique with representative meso-structural parameters after sufficient analysis of basic geotechnical properties of WIZ. Results show that the natural WIZ exhibiting a flocculated structure could be characterized as a well-graded geotechnical material forming main clay minerals, in which most pores are intergranular, with the pore size distribution concentrated in 0.007–200 μm. Higher initial confining pressure and axial loading tend to intensify the particle breakage degree and particle size distribution characteristics of WIZ more than that of axial and circumferential unloading, in which the stress path II of axial pressure loading and confining pressure unloading under the initial confining pressure of 25 MPa is the most severe with average particle area reduced by 56% and particle Korcak fractal dimension increased by 36%. The broken particles undergoing a series of irreversible dislocation, tumbling and rotation under the action of shear and tensile stress, tend to orient in the direction of 0°–15°, in which particles in stress path IV aggregate in two directions of 0–15° and 60–90° due to the bidirectional unloading. The unloading stress path IV shows the most distinct directional orientation and orderliness, with particle anisotropy increased by 267% and directional probability entropy reduced by 13%. Particle breakage and orientation in WIZ are accompanied by obvious filling, expansion and propagation of the meso-pores and meso-cracks, in which stress path IV under lower confining pressure most affects the morphological complexity of pore and crack boundaries with the pore morphology fraction dimension increased by 13.5%. The quantitative theoretical correlation of macro-meso parameters has been established by the stepwise regression analysis of two most relevant and representative correlation indexes (i.e., Korcak fractal dimension and pore morphology fractal dimension) with the ultimate bearing strength of WIZ, which has been proved to have high fitting accuracy by comparing the regression results with the test measured values. The meso-structural damage mechanism of WIZ under stress paths II and IV could, respectively, match the failure law of structural stress-induced collapse in the spandrel and the plastic squeezing-out failure of WIZ on the high sidewall of underground excavations. Research could provide feasible ideas for the relationship between macroscopic failure and mesoscopic damage of WIZ, as well as the effective basis for the further discussion of macro-meso constitutive model establishment. Highlights: A semi-quantitative method by SEM-MATLAB image processing technique was proposed to explore the mesoscopic failure mechanism of weak interlayer zone. The particle breakage, particle orientation, pore morphology and crack evolution induced by complex stress paths were quantitatively explored. The quantitative theoretical correlation of macro-meso parameters was established by stepwise regression analysis. The correlation between meso-structural variation and engineering failure mechanism of weak interlayer zone was discussed. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aggregate shape is essential for evaluating concrete properties. Most of the existing literature utilizes X-ray computed tomography (X-CT) to assess the morphological characteristics of 2D/3D aggregates. However, the obtainment of a large number of aggregates by X-CT is a tedious, time-consuming and costly task. In this study, a framework combined concrete modeling and the numerical slicing method was developed, which simulated the process for obtaining 3D models of concrete and the corresponding 2D cross-sectional concrete models in the laboratory using X-CT. This was simpler, more efficient, and less costly than the X-CT method. Based on this framework, 3D concrete models with four different aggregate shape types and corresponding 2D cross-sectional concrete models were generated. The influences of 3D aggregate shape types on the roundness, aspect ratio, packing density, and grading curves of 2D cross-sectional aggregates were statistically analyzed and the correlation between the morphological descriptors of 2D/3D aggregates was investigated. The differences between 2D meso-concrete models generated based on the numerical slicing and the random placement methods were compared. The results showed that the 3D aggregate shape type had significant effects on the meso-structure of 2D sectional concrete. Unlike the projection image method, the morphological descriptors of 2D cross-sectional aggregates obtained based on the slicing method were poorly correlated with the morphological characteristics of 3D aggregates. This study laid the foundation for the study of the qualitative and quantitative relationships between the shape index and mechanical properties of aggregates. [ABSTRACT FROM AUTHOR]

The cumulative deformation properties of subgrade soil under cyclic traffic loads are critical for optimizing pavement structure design and ensuring long-term highway structural performance. This study aims to investigate the coupling effect of freeze-thaw cycles and cyclic loads on the cumulative deformation behaviors and meso-structure of coarse-grained saline soil (CGSS) subgrade filling in high-cold areas. Dynamic triaxial tests and computed tomography (CT) scanning were conducted to analyze the CGSS under different working conditions. The research focused on the dynamic deformation development and damage evolution under varying freeze-thaw cycles and load amplitudes. The research results show that the cumulative deformation behavior of CGSS under cyclic loading is relatively sensitive to the freeze-thaw process. The cumulative dynamic strain increases as the freeze-thaw cycles, with a critical freeze-thaw cycle number of five. The stable cumulative dynamic strain curve exhibits clear three-stage characteristics when plotted in semi-log coordination, with critical loading cycles at 20 and 1,000. After 10-100 loading cycles, the cumulative strain curve quickly shows failure. The CGSS's low density and pore regions greatly increase after a freeze-thaw cycle. The rise in dynamic stress amplitude notably affects the bonding between soil particles and crystalline salts. The coupling effect of the freeze-thaw cycle and dynamic activity exacerbates the deterioration of soil structure, resulting in variations in CT values within the scanning layer in the final state. [ABSTRACT FROM AUTHOR]

High-alumina cement has an important position in refractory materials with its good performance at high temperatures, but its disadvantages such as strength inversion and unstable transformation of hydration products have always limited its development. To clarify the working mechanism of high-alumina cement and improve its high temperature resistance, MgO and Al2O3 were added to the high-alumina cement paste. The optimal design method was used to determine the influence of each factor on the high temperature stability of the cement paste. The mix ratio of raw materials was optimized and the strength change patterns of the specimens under the optimal ratio were verified. From a microstructure perspective, the high temperature evolution of the hardened paste of high-alumina cement was explored using X-ray diffraction, scanning electron microscopy, thermogravimetry, and differential scanning calorimetry. The results show that the introduction of refractory powders, especially Al2O3, can significantly improve the volumetric stability of the cement paste at high temperatures. When the water-cement ratio is 0.20, the admixture of MgO is 5 % or 10 %, and Al2O3 is 20 %, the high temperature volume stability of the cement paste is the best. However, its corresponding mechanical strength is weakened to some extent with an increase in calcinating temperature. Moreover, the structure-property evolution process of cementite under high temperature calcinating conditions was verified by microstructural characterization, especially the influence of the powder on the volume and strength of the cement block at high temperatures. The results of this study can serve as a guide for the development of high-alumina cement and its cementing materials, as well as for the improvement of their properties.

Copyright of Journal of Tiangong University is the property of Journal of Tianjin Polytechnic University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The cumulative deformation properties of subgrade soil under cyclic traffic loads are critical for optimizing pavement structure design and ensuring long-term highway structural performance. This study aims to investigate the coupling effect of freeze-thaw cycles and cyclic loads on the cumulative deformation behaviors and meso-structure of coarse-grained saline soil (CGSS) subgrade filling in high-cold areas. Dynamic triaxial tests and computed tomography (CT) scanning were conducted to analyze the CGSS under different working conditions. The research focused on the dynamic deformation development and damage evolution under varying freeze-thaw cycles and load amplitudes. The research results show that the cumulative deformation behavior of CGSS under cyclic loading is relatively sensitive to the freeze-thaw process. The cumulative dynamic strain increases as the freeze-thaw cycles, with a critical freeze-thaw cycle number of five. The stable cumulative dynamic strain curve exhibits clear three-stage characteristics when plotted in semi-log coordination, with critical loading cycles at 20 and 1,000. After 10–100 loading cycles, the cumulative strain curve quickly shows failure. The CGSS’s low density and pore regions greatly increase after a freeze-thaw cycle. The rise in dynamic stress amplitude notably affects the bonding between soil particles and crystalline salts. The coupling effect of the freeze-thaw cycle and dynamic activity exacerbates the deterioration of soil structure, resulting in variations in CT values within the scanning layer in the final state.

High-alumina cement has an important position in refractory materials with its good performance at high temperatures, but its disadvantages such as strength inversion and unstable transformation of hydration products have always limited its development. To clarify the working mechanism of high-alumina cement and improve its high temperature resistance, MgO and Al2O3 were added to the high-alumina cement paste. The optimal design method was used to determine the influence of each factor on the high temperature stability of the cement paste. The mix ratio of raw materials was optimized and the strength change patterns of the specimens under the optimal ratio were verified. From a microstructure perspective, the high temperature evolution of the hardened paste of high-alumina cement was explored using X-ray diffraction, scanning electron microscopy, thermogravimetry, and differential scanning calorimetry. The results show that the introduction of refractory powders, especially Al2O3, can significantly improve the volumetric stability of the cement paste at high temperatures. When the water-cement ratio is 0.20, the admixture of MgO is 5 % or 10 %, and Al2O3 is 20 %, the high temperature volume stability of the cement paste is the best. However, its corresponding mechanical strength is weakened to some extent with an increase in calcinating temperature. Moreover, the structureproperty evolution process of cementite under high temperature calcinating conditions was verified by microstructural characterization, especially the influence of the powder on the volume and strength of the cement block at high temperatures. The results of this study can serve as a guide for the development of high-alumina cement and its cementing materials, as well as for the improvement of their properties. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of Nanjing University of Aeronautics & Astronautics is the property of Editorial Department of Journal of Nanjing University of Aeronautics & Astronautics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As a basic method to quantify the scale effect of porous media materials, representative elementary volume (REV) is an effective means to construct the macro-meso structure of coal. In order to improve the accuracy of REV results of coal meso-structure, a quantitative characterization method of coal meso-structure was proposed based on the study of pore-fracture structure characteristics at meso-scale of coal samples. Based on the binary images of pore-fracture at 423 scales at different positions and different fracture directions of coal samples, the geometric characteristics of coal meso-structure were analyzed from three aspects: pore-fracture distribution density, geometric shape and orientation. Based on the sampling method considering the heterogeneity and anisotropy of coal, the spatial effect and directional effect of REV size are analyzed. Finally, the reasonable microscopic REV size of coal sample is determined by the coefficient of variation method. The results show that: ① A method for accurate identification and quantitative analysis of pore fracture structure is proposed for SEM images of coal samples with uneven gray level, blurred boundary and low contrast. ② A quantitative characterization system of meso-structure reflecting the anisotropy of coal samples was established, including porosity, overall shape factor, fractal dimension and directional distribution coefficient. ③ Compared with the parallel bedding, the micro-fractures in the vertical bedding direction are more developed, the porosity is 2 times that of the parallel bedding, the contribution rate of large aperture pores is 85%, and it has strong spatial filling ability. The overall morphology of pores and fractures is poor, but the edge morphology is smooth and the directional distribution tends to be simpler. ④ Based on the acceptable value of the coefficient of variation of 10%, the size of the coal meso-structure characterization unit is determined to be 200 μm × 200 μm.

Abstract This study addresses the meso-structure of recycled aggregate concrete with different admixture and c;uring condition. The RCA (Recycled concrete aggregate) with admixture of slag power and fly ash and curing condition of steam was casted. X-ray CT (Computed tomography) was used to obtain meso-structure of RCA, and the pore structure, aggregate, and interface traction zone were analyzed. The results show that steam curing not only increases the pore volume but also makes the pore morphology more complex, the fractal dimension increases, the proportion of spherical pores decreases, and the pores develop from spherical to flat and slender with the increase of steam curing temperature. The porosity of micron pores in recycled aggregate concrete is about 2.3%, in which the pores with aperture less than 300 μm accounts for more than 85%. The thickness of the interface area between recycled aggregate and new mortar is about 200 μm, and the crack width in recycled aggregate is about 300– 400 μm.

This work presents a new approach to investigating water conduction properties in real three-dimensional (3D) voids of asphalt mixtures. Three different molding methods were employed for the same grade of asphalt mixture, and the three asphalt mixture specimens were scanned using X-ray Computerized Tomography (CT) to identify the real 3D void structure distribution inside the mixture. The real 3D behavior of void moisture conduction inside the mixture was simulated using the discrete lattice Boltzmann method and the BGK collision model. Three different molding methods were used to study the behavior of mesoscopic seepage inside the specimen. The results show that water conduction varies substantially in real 3D voids inside diverse molded objects. Regardless of flow and flow velocity, the Superpave Gyratory Compactor (SGC) method is extraordinarily close to the conduction qualities of the actual field core material. It shows that the Marshall molding method is inconsistent with the actual pavement molding method, and the SGC method can not only ensure that the reasonable void ratio is conducive to the thermal expansion and cold shrinkage space of the asphalt mixture but also prevents rainwater from entering the asphalt mixture. This work provides a new perspective for the study of water damage resistance and medium transmission characteristics of asphalt mixtures. [ABSTRACT FROM AUTHOR]

Periodic fluctuations of reservoir water level lead to the variations in seepage stress inside landslide bodies. Dynamic seepage pressures can lead to deterioration in the structure and strength of the slide zone, which affects the stability of the landslide. To identify the effect of seepage on the pore structure of the slip zone, the seepage tests were performed. First, a seepage test apparatus was developed and combined with CT scanning technology to obtain the meso-structure of the sliding zone under different seepage conditions. Then, the changes in the structural parameters of the slip zone soils were quantified by Avizo software. Finally, the mechanism of the meso-structural evolution of the sliding zone under seepage was analyzed. The results show that the permeability coefficient of the sliding zone decreases exponentially with time, and a higher seepage pressure will lead to a smaller permeability coefficient of the sliding zone. Statistical data show that the apparent porosity of sliding zone soil decreases from 5% to 1%. The proportion of pores with an equivalent spherical diameter of less than 80 μm increases with seepage time, while the proportion of pores with an equivalent spherical diameter greater than 80 μm decreases with seepage time. The above results indicate that the large pores in the slip zone soils are filled with small particles during the seepage.Hence, the seepage channels become elongated and curved, and the effective connectivity of the pores is weakened.

Surface emissivity is an essential parameter for thermal radiation, which greatly influences thermal protection materials (TPMs) under high temperature. In the present study, dual‐scale models of 2.5D woven carbon fiber fabric reinforced resin‐based composites are built with different weaving parameters of fabric, to investigate the meso‐structure influence on the surface emissivity, and the surface emissivity for different composites is calculated based on discrete ordinate method (DOM). Two morphological indexes are proposed to further analyze the effect of meso‐structure characteristics on emissivity. The results show that the surface emissivity is mainly determined by the ablated woven composite within a certain depth. More compact in‐plain weaving architecture improves surface emissivity, while more compact through‐the‐thickness weaving architecture reduces the surface emissivity of 2.5D woven ablative composites. The meso‐structure with a lower roughness factor and a higher specific surface area leads to intense surface radiation. This study can provide scientific guidance for the design of 2.5D woven ablative composite for thermal protection. [ABSTRACT FROM AUTHOR]

In order to investigate the mesoscopic mechanism of thaw settlement for soft soil, freeze-thaw (F-T) test and X-ray computed tomography (X-CT), combined with image processing technology and fractal theory, were adopted to study the changes of meso-structure for silty clay in Shanghai before and after F-T with or without water supply during freezing. Results showed that, the freeze-necking phenomenon was observed in soil specimen without water supply, but it did not happen in soil specimen with water supply. There was a good linear relationship between the change of the average CT gray intensity after F-T and the changes in soil moisture content, porosity, and dry density. Based on the proposed soil mesopore recognition method, it was found that freeze-thaw significantly changed the transverse-sectional porosity and average mesopore size, and the biggest change happened in unfrozen area with water supply, but happened near the final freezing front without water supply. Fractal dimensions had better linear relation with transverse-sectional porosity and average mesopore size, respectively. The study showed that the change in soil meso-structure with water supply during freezing differed significantly from that without water supply during F-T, and F-T altered soil mesopore structure obviously under water-supply condition. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study addresses the meso-structure of recycled aggregate concrete with different admixture and c;uring condition. The RCA (Recycled concrete aggregate) with admixture of slag power and fly ash and curing condition of steam was casted. X-ray CT (Computed tomography) was used to obtain meso-structure of RCA, and the pore structure, aggregate, and interface traction zone were analyzed. The results show that steam curing not only increases the pore volume but also makes the pore morphology more complex, the fractal dimension increases, the proportion of spherical pores decreases, and the pores develop from spherical to flat and slender with the increase of steam curing temperature. The porosity of micron pores in recycled aggregate concrete is about 2.3%, in which the pores with aperture less than 300 μm accounts for more than 85%. The thickness of the interface area between recycled aggregate and new mortar is about 200 μm, and the crack width in recycled aggregate is about 300– 400 μm. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering Geology / Gongcheng Dizhi Xuebao is the property of Journal of Engineering Geology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This work presents a new approach to investigating water conduction properties in real three-dimensional (3D) voids of asphalt mixtures. Three different molding methods were employed for the same grade of asphalt mixture, and the three asphalt mixture specimens were scanned using X-ray Computerized Tomography (CT) to identify the real 3D void structure distribution inside the mixture. The real 3D behavior of void moisture conduction inside the mixture was simulated using the discrete lattice Boltzmann method and the BGK collision model. Three different molding methods were used to study the behavior of mesoscopic seepage inside the specimen. The results show that water conduction varies substantially in real 3D voids inside diverse molded objects. Regardless of flow and flow velocity, the Superpave Gyratory Compactor (SGC) method is extraordinarily close to the conduction qualities of the actual field core material. It shows that the Marshall molding method is inconsistent with the actual pavement molding method, and the SGC method can not only ensure that the reasonable void ratio is conducive to the thermal expansion and cold shrinkage space of the asphalt mixture but also prevents rainwater from entering the asphalt mixture. This work provides a new perspective for the study of water damage resistance and medium transmission characteristics of asphalt mixtures.

Composed of large rock blocks and fine soil particles, the physical and mechanical behaviors of soil–rock mixtures (S–RMs) are quite complex. To develop insight into the S–RM deformation and failure mechanisms on the macro and mesoscales, CT image sequences of the samples were obtained on different stages of the S–RM triaxial test. Then, the 3D mesostructures of the samples were reconstructed based on the developed 3D Meso-Structure Reconstruction and Analysis System (MSRAS3D), and the algorithms required for quantitative analysis of the S–RM mesostructure were provided. The fracture and motion processes of the rock blocks in the S–RM sample were tracked based on the reconstructed 3D models. Because of the influence of the sample preparation method, the primary axes of the rock blocks trended toward the horizontal direction. This led to the initial anisotropy of the S–RM's mesoscale structure. To compare reconstructed 3D models of the samples from different test stages, three types of the rock-block breakage modes were analyzed: disintegration, fracturing, and edge-corner breakage. The tests results indicated that the influence of the rock blocks makes the S–RM stronger than soil, The S–RM p–q curve was not a straight line due to the rock block breakage. As a result, a modified Mohr–Coulomb strength relationship in the form of a power function was suggested. [ABSTRACT FROM AUTHOR]

The way of modeling the contact phenomena of two bodies -- with a finite and infinite radius of curvature -- is presented in the paper. The basic method used in the research was the finite element method. A model to simulate deformations occurring during rotational and translational movement of a wheel on a flat surface was developed. The research was based on the own design solution of the mobile platform's running gear. The model takes into account all geometrical parameters, the flexibility of the contact zone loaded, and orthotropic material properties of the analyzed meso-structural bodies. The work contains the values of all parameters of the material model that were obtained experimentally. The final result of the study was to determine the relationship between rolling resistance and external loads. [ABSTRACT FROM AUTHOR]

In order to study the effects of different forming methods on road performance and void structure of asphalt mixtures, the specimens of AC-16 (Medium grained asphalt concrete with coarse aggregate of maximum nominal particle size 16 mm crushed stone, with continuous gradation), SUP-16(Medium grained asphalt concrete with coarse aggregate of maximum nominal particle size of 16 mm crushed stone, continuously graded but with prohibited areas) and PAC-13(Asphalt concrete with a maximum nominal particle size of 13 mm crushed stone in coarse aggregate, open graded) were fabricated by using Marshall compaction and gyratory compaction instruments. The dynamic stability, flexural tensile strength and freeze-thaw splitting strength ratio were used as evaluation indexes to compare and analyze the effects of different forming methods on their road performance. Meanwhile, section scanning and void image recognition (PCAS) were used for image processing of specimen sections, the change laws of structural parameters such as void ratio, void number and void analysis dimension of different mix types under two compaction conditions were analyzed. The results showed that the asphalt mixes obtained by gyratory compaction molding method had better road properties. At the same time, the void parameters in the cross-section of the specimens obtained by gyratory compaction were smaller than those of Marshall compaction, which indicated that gyratory compaction can effectively improve the structural distribution of the internal voids in asphalt mixture, resulting in better uniformity of the specimens and better road performance. Therefore, the road performance of the rotary compaction specimen was better than that of the compaction specimen. [ABSTRACT FROM AUTHOR]

Analyzing the change in the roughness of the shear failure surface under different particle composition is important to reveal the mesoscopic mechanism of strength change of coarse-grained slip zone soil. Slip zone soils were grouped according to different particle gradations and coarse particle contents for experiments. To collect shear surface coordinate data points, the customized shear surface measurement mold was examined to measure the shear surface. Then, the measured 3D elevation data are drawn into a 3D surface map by using the Surfer software to show the actual situation of the shear surface. The shear surfaces were analyzed by using box plots and ice crystal flower plots. Finally, the roughness of the shear surface was quantified by the root mean square of the relative undulation (Z2). Findings indicate that the shear surface undulation characteristics of coarse-grained slip zone soil are obviously correlated with the proportion of particles with a size between 5--20 mm. Moreover, whether the gradation is good or poor has a significant effect on the shear surface characteristics. The well-graded shear surface is rougher and more undulated, whereas the poorly graded shear surface is the opposite. As the normal pressure increases, the roughness of the shear surface decrease. As the content of coarse particles increases, the roughness of the shear surface increases, and Z2 has a highly positive linear correlation with the coarse particle content. [ABSTRACT FROM AUTHOR]

SiCf/SiC textile composites have enormous development potentials in the field of aerospace hot-end component owing to their strong structural design, low density, excellent mechanical properties, high-temperature resistance and oxidation resistance. However, there are few researches on the preparation technology, performance and meso-structure of SiCf/SiC textile composites. In the long run, it is still the research direction that must be carried out in country’s aviation engine manufacturing. In this paper, the research status of SiCf/SiC textile composites in recent years is introduced from three aspects: meso-scale structure, mechanical properties and numerical simulation. The research status of SiCf/SiC textile composites in recent years is summarized, and the basic research of domestic and foreign applications is comprehensively compared. Although the domestic preparation technology has made great progress and reached the international advanced level, it is still in its infancy in terms of component assessment and verification and application. Only by optimizing on the basis of the comprehensive balance of reliability, durability, process and performance, and realizing the synergy of materials and processes, structure and design, can breakthroughs be made in the future development of aeroengines.

Glacial till is a special soil in alpine mountainous areas, which often induces geohazards such as debris flows and landslides due to the influence of special geological environmental conditions in alpine mountainous areas. The change in the structure of glacial till is the main cause of geohazards. Glacial till structure is one of the important factors affecting the mechanical properties of soil. It can explain the mechanical phenomena of soil engineering and establish the quantitative relationship between soil structure and macro–mechanical properties. However, there are few systematic research results on its structure. For this reason, the intact glacial till in the Moxi River Basin, South of Kangding City, Tibetan Autonomous Prefecture of Garzê, Sichuan Province was taken as the research object, and the meso-structure and micro-structure of intact glacial till were studied using CT scanning and scanning electron microscopy (SEM). The meso-structure and micro-structure images of the interior of intact glacial till were obtained and the porosity, particle shape, directivity and structural unit were analyzed. The results show that: (1) the average porosity of longitudinal and transverse sections of intact glacial till are 24.92% and 24.35%, respectively, and the difference is not significant; (2) the average circularity of the particles in the longitudinal and transverse sections is 0.836 and 0.802, respectively, and the average aspect ratio is 2.5 and 3.7, respectively. The shape of the particles in the longitudinal section is more circular than in the transverse section, and the orientation of the particles in the transverse sectional direction is more obvious; (3) the main mineral components of the glacial till sample are mica, feldspar and quartz. In the process of transportation and deposition, the mineral particles undergo different degrees of grinding, crushing and dissolution. The particles are mainly formed by calcareous cementation, and the cementation is dense. The structure is mainly a skeleton structure composed of fine particles that are wrapped or filled. These findings provide the scientific basis for highway-, railway- and hydro-power-station construction and disaster prevention and mitigation in the alpine mountainous area. [ABSTRACT FROM AUTHOR]

Pavement temperature field affects pavement service life and the thermal environment the near road surface; thus, is important for sustainable pavement design. This paper developed a combined prediction method for the thermal conductivity of asphalt concrete based on meso-structure and renormalization technology, which is critical for determining the pavement temperature field. The accuracy of the combined prediction method was verified by laboratory experiments. Using the tested and proven model, the effect of coarse aggregate type, shape, content, spatial orientation, air void of asphalt concrete, and steel fiber on the effective thermal conductivity was analyzed. The analysis results show that the orientation angle and aspect ratio of the aggregate have a combined effect on thermal conductivity. In general, when the aggregate orientation is parallel with the heat conduction direction, the effective thermal conductivity of asphalt concrete in that direction tends to be greater. The effective thermal conductivity of asphalt concrete decreases with the decrease of coarse aggregate content or steel fiber content or with the increase of porosity, and it increases with the increase of the effective thermal conductivity of coarse aggregate. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering Geology / Gongcheng Dizhi Xuebao is the property of Journal of Engineering Geology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Truss-like lightweight materials (TLMs) have been widely used in aeronautics and astronautics, because of excellent mechanical property and superior energy absorption capability. The design of TLMs’ meso-structures was a critical task to improve its performance. Hence, a structure design method based on the symmetric groups was proposed for TLMs, and a novel hexagonal prism TLM’s meso-structure was deduced by the symmetric and translational operations of the space group P 6 mm . To investigate the performance of the novel TLM, the mechanical analysis model was established. The predictive equations of compression performance was proposed based on Euler–Bernoulli beam theory. The stress distribution of the novel TLM’s meso-structure under compression load was discussed by the finite element analysis method, and its compression and energy absorption properties were investigated. The simulation results were in agreement with the predictive results. In addition, the common FCC and BCC TLMs were discussed using the symmetry group analysis method, and their compression properties were predicted. The results showed that the proposed novel TLM in this study had better compression property than BCC and FCC TLMs at the same relative density.

Truss-like lightweight materials (TLLMs) with superior mechanical performance and excellent energy absorption capability are extensively used in aerospace and automobile industries. The performance of TLLM was closely related to its meso-structure, but the lack of innovation and variety in the geometric configuration of TLLM’s meso-structure limits the reinforcement effect and strength enhancement. Hence, it is important to thoroughly study the theoretical design method for TLLM’s meso-structure. Inspired by the symmetric feature of TLLM’s meso-structures, the symmetric groups were applied to describe, classify and design TLLM’s meso-structures. First of all, it was found that the representative volume unit (RVU) of TLLM corresponded to point groups that contained the symmetry of TLLM’s meso-structure. Space groups, which consist of point groups and space lattices, could be used to describe the geometric configuration of TLLM’s meso-structures. Then, TLLM’s meso-structures were classified according to different types of point groups. Finally, a description and design method for TLLM’s meso-structure based on the symmetric group theory was proposed. In addition, a novel TLLM’s meso-structure was deduced through the symmetric operations of space group, which could verify the feasibility of the method. Therefore, the present study provides a basis for the design of high-performance TLLMs.

Copyright of Journal of Fuzhou University is the property of Journal of Fuzhou University, Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Cemented granular materials play an important role in both natural and engineered structures, as they are able to resist traction forces. However, modeling the mechanical behavior of such materials is still challenging, and most of existing constitutive models follow phenomenological approaches that unavoidably disregard the microstructural mechanisms taking place on the bonded grains scale. This paper presents a multiscale approach applicable to any kind of granular materials with solid bonds between particles. Inspired from the H -model, this approach allows simulating the behavior of cemented materials along various loading paths, by describing the elementary mechanisms taking place between bonded grains. In particular, the effect of local bond failure process on the macroscopic response of the whole specimen is investigated according to the bond strength characteristics. [ABSTRACT FROM AUTHOR]

Akikazu Sakudo,1,2 Risa Yamashiro,2 Makoto Haritani,3 Koichi Furusaki,4 Rumiko Onishi,5 Takashi Onodera3 1Faculty of Veterinary Medicine, Okayama University of Science, Imabari, Ehime 794-8555, Japan; 2Laboratory of Biometabolic Chemistry, School of Health Sciences, University of the Ryukyus, Nishihara, Okinawa 903-0215, Japan; 3Research Center for Food Safety, The University of Tokyo, Bunkyo-Ku, Tokyo 113-8657, Japan; 4Mineral Activation Technical Research Center, Omuta, Fukuoka 836-0041, Japan; 5Santa Mineral Co., Ltd., Minato-Ku, Tokyo 105-0013, JapanCorrespondence: Akikazu SakudoFaculty of Veterinary Medicine, Okayama University of Science, Imabari, Ehime 794-8555, JapanTel/Fax +81-898-52-9198Email akikazusakudo@gmail.comIntroduction: A previous study demonstrated the virucidal effect of an electrically charged disinfectant (CAC-717), which contains meso-structure nanoparticles, on enveloped viruses (influenza viruses). However, the effect of CAC-717 on other microorganisms and the mechanisms by which CAC-717 inactivates the microorganisms remain unclear. In this study, CAC-717 was further evaluated in terms of its biocidal and virucidal activity as well as its effect on bacterial and viral nucleic acids.Methods: The inactivation effects of CAC-717 against various microorganisms [non-enveloped virus, feline calicivirus (FCV); bacteria, Salmonella enterica and Escherichia coli] were investigated by comparing the viral titer of the medium tissue culture infectious dose (TCID50) and the D value (estimated treatment time required to reduce the number of microorganisms by 90%). Furthermore, the effects of CAC-717 on viral and bacterial genomic RNA/DNA were examined using a polymerase chain reaction (PCR).Results: Treatment of an equal volume of CAC-717 with cell lysate infected with a non-enveloped virus, feline calicivirus (FCV), reduced the TCID50. Viral titer dropped below the detection limit after 2 min of treatment. The D value of FCV was 0.256 min (average of multiple endpoint D values) and endpoint D value was 0.341 min. The D value for E. coli and S. enterica was 0.290 min and 0.080 min (average of multiple endpoint D values), respectively and the endpoint D value was 0.545 min and 0.054 min, respectively. In addition, PCR showed the inhibition of nucleic acid amplification of the RNA and DNA genome of FCV and bacteria, respectively.Conclusion: Our findings suggest that CAC-717 inactivates viruses and bacteria by modifying the viral and bacterial nucleic acids.Keywords: class I disinfectant, E. coli, feline calicivirus, food safety, meso-structure, Salmonella

Polarizing microscope, nuclear magnetic resonance, and thermal constant analyzer were used to test the granite samples in the depth of 1500-2000 m in Sanshandao before and after the heat treatment and be carried out to study the corresponding relationship between rock meso-structure characteristics and different geothermal temperature circumstances, and the influence of thermal cycling on rock meso-structure. Tests results present that the porosity, pore size distribution, thermal conductivity and specific heat capacity are significantly affected by the environment where the rock occurs, mineral composition and particle size, and the increase in porosity and water content will cause the thermal conductivity and specific heat capacity to decrease. [ABSTRACT FROM AUTHOR]

The deformation mechanism related to the initial relative density and uniformity of Cu W composite powders under quasi-static compression was investigated by multi-particle finite element method. The results show that under the same pressure, the relative density of powder increases with the increase of initial relative density or the uniformity of composite powders. The densification processes can be divided into three stages, namely particle rearrangement, Cu particle deformation and W particle deformation. Pores are mainly filled by the rearrangement of particles and the deformation of Cu particles. The rearrangement and deformation of particles are quantitatively characterized by introducing the mean rotation degree and the mean equivalent strain of powders. It is found that smaller voids formed in the initial denser powder are easily filled by the deformation of adjacent particles during compaction. Strong force chains formed by the contact of W particles severely hinder the compression, resulting in large porosity. Unlabelled Image • Multi-particle finite element models of Cu W composite powders are constructed. • Multi-scale analysis on the effects of initial packing structure is carried out. • Pores are mainly filled by particle rearrangement and Cu particle deformation. • Particle rotation and deformation are quantitatively characterized. • The deformation mechanisms of local packing structures are explored. [ABSTRACT FROM AUTHOR]

In this work, the influence of fiber/matrix meso-structure on the strain concentration of three-dimensional (3D) reinforced carbon-carbon composites with a drilling hole is discussed by experimental and numerical ways. The full-field digital image correlation (DIC) method is adopted to obtain the strain field of the experimental specimens, and the meso-FEM model with the consistent meso-structure of the experimental specimens is established to reveal the main deformation and damage mechanism. The results show that the strain concentration appeared off the location of ±90° hole tips, which is different with homogeneous material. Furthermore, the shear bands are observed and located on the region between the cut fiber yarn and the adjacent uncut one. The peculiarities are found connecting with the meso-structure. Moreover, the damage locations obtained from the meso-model show good agreements with the experimental fracture path, thereby, the analyses are verified.

Copyright of Journal of China University of Petroleum is the property of China University of Petroleum and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Aeronautical Materials is the property of Editorial Board of Journal of Aeronautical Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The polymer-bonded explosive (PBX) is a kind of multi-phase composite consisting of the polymeric binder and embedded energetic particles, in which the particle volume fraction (PVF) is often higher than 90%. In the present work, by using the Voronoi-polygon generation method along with the concept of gradation to generate Voronoi particles with given gradation, and with further operations including modification, shrinking, smoothing, etc. to the particles, a new meso-structure construction method for PBXs is proposed. The constructed meso-structures possess good gradation relationship and have high PVFs (94.99% in maximum) simultaneously. The strict periodicity on the boundaries of the meso-structure can also be achieved. To verify the constructed PBX meso-structures, the numerical manifold method (NMM) is used to simulate the effective modulus of the constructed meso-structures by considering different influencing factors such as the size of meso-structure, PVF, gradation, and initial defects, etc. The simulation results are analyzed qualitatively, and the causes of differences between the simulation results and available experimental results or other numerical results are discussed. The validity of the proposed method for the construction of PBX meso-structures is verified. This work also provides foundations for the further numerical studies of the mechanical and thermal behaviors of PBXs at the mesoscale. [ABSTRACT FROM AUTHOR]