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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.)

Copyright of Journal of Materials Science & Engineering (1673-2812) is the property of Journal of Materials Science & Engineering 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.)

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.)

Flax is one of the five major oil crops in China. However, the local planting areas are mostly mountainous and hilly landform, and the harvesting process is excessively dependent on manual operation. Due to the problems of high labor intensity and low rate of mechanized equipment for harvesting operation, the development process of flax industrialization in China is seriously restricted. At present, the flax harvest process is still dominated by segmented harvest, and the threshing material formed after flax harvest needs to be separated and cleaned to remove the impurities in the grain. According to different principles, grain separated process can be divided into vibration screening and pneumatic sorting. Discrete element modeling technology is an auxiliary research method widely used in vibration screening research, which can establish various material shapes in agricultural production. However, the existing research methods use the multi-spherical aggregation method to fit the shape of grain and stalks, which is different from the real material in structure. On this basis, in order to improve the shape reality of flax threshing material and reduce the simulation modeling error, based on the open source discrete element method framework, the non-spherical particles of different components of flax threshing material were established by using the super-quadric surface element method, and the multi-stage vibration screening process was simulated and experimentally studied. In this study, the distribution of materials on the screen surface of the first screen and the second screen, the percentage passing and impurity content of different materials were analyzed, and the experimental verification was carried out. Different shapes of flax threshing could be constructed by changing the parameters of the super-quadric control equation. According to the volume fraction of different components of flax threshing, 3 148 grains, 1 728 stems and 124 fruits were generated in the simulation, respectively. In order to facilitated the analysis of simulation data, the primary screen and the secondary screen were divided into three different data statistical areas. The vibrating screening process was mainly analyzed from the material distribution on the screen surface, the screening rate of different materials and the impurity content. The results showed that the non-spherical particles of super-quadric surface could well simulate the physical properties of real materials; The percentage passing of seed and short stalks in the first screen was 99.08% and 66.49%, respectively, and the whole fruit could be sorted; In the second screen, the percentage passing of seed and short stalks were 96.38% and 4.79%, respectively, and the short stalks could be sorted. The sorted material could migrate on the corresponding screen surface under the excitation, which was conducive to screening. The impurity contents of different materials were counted, including 4.87% for seed, 21.95% for short stalks and 3.38% for whole fruit. Then the simulation process was experimented and verified. The composition and quantity of flax thresher in the test were consistent with the simulation, and the different components were mixed evenly before the experiment. In addition, the equipment must be subject to idle commissioning before the threshing material were dumped into the first screen. After the experiment, counting the quantity of different materials from the bottom collecting tank to the first screen. The experiment results showed that the relative data deviations of percentage passing and impurity content of different components of flax threshing materials were less than 10%. Although the modeling method used in the study has good shape fitting degree for non-spherical particles, it still had some limitations, which were discussed in this study. The results showed that the non-spherical particles established by the super-quadric surface method could be applied to the simulation of non-spherical materials involved in different agricultural production process. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Mine Automation is the property of Industry & Mine Automation 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.)

As a large agricultural country, China has abundant straw resources, and the annual output of corn stalks is 3 billion tons. Corn straw could be used as silage after mechanized processing, it could effectively alleviate the current shortage problem of animal feed. At present, the research on kneading and crushing of corn straw mainly focused on physical experiment, but less on numerical simulation. Therefore, the lack of effective numerical simulation method in the crushing process of corn straw and the improvement efficiency for the structure of processing equipment is reduced to some extent. Based on the above background, in this paper, a discrete element model for bimodal distribution of corn straw was established based on discrete element method, which was originally applied to the field of geotechnical mechanics. This process included setting particle size, filling geometric model, obtaining particle group coordinate information and so on. All of the numerical simulations were carried out in EDEM 2018 version, and users were allowed to customize the settings. Then the parameters calibration for the bonded particle contact model of corn straw was carried out that combined with physical experiment and virtual experiment. The mechanical parameters were obtained through compressing and shearing experiments of corn stalk samples. This parameter could provide basis for theoretical calculation of bonded particle model parameters of corn stalks. The mechanical properties of bonded particle model were determined by 5 parameters: normal stiffness coefficient, tangential stiffness coefficient, normal critical stress, shear critical stress and bonded radius which could be obtained through theoretical formula calculation. In the virtual experiment, the corn stalk model was subjected to axial compression experiment and radial shear experiment, respectively. The final BPM (bonded particle model) parameters were determined by the phenomenological simulation method which was compared physical experiment and virtual experiment. Finally, the discrete element model of corn straw was simulated and verified by physical experiment. This process involved the kneading and crushing simulation of corn straw model, classifying the types of materials and weighing the mass of materials, and using API plug-in to realize particle replacement and adding bonded particle model in the simulation process. After the simulation was completed, the change of bonded number and the shape classification of broken materials were analyzed. The whole research results showed that the maximum critical loads were 2,260 N and 110 N, respectively when the straw was compressed and sheared at a loading rate of 5 mm/min; After calibrating the parameters of bonded particle model, it was found that the normal stiffness coefficient, tangential stiffness coefficient, critical normal stress, critical tangential stress and bonded radius were 9.60×106 N/m, 6.80×106 N/m, 8.72 MPa, 7.5 MPa and 2 mm, respectively. At this time, the mechanical properties of the discrete element model were close to the harvested corn straw that had a moisture content of 87.8%. After the simulation, material could be divided into four types: short type, standard type, long type and incomplete crushing type. At the same time, the simulation mass of 4 materials were 5.2, 5.8, 8.2 and 8 g, respectively. After the physical experiment, the mass of different types of materials were respectively 4.8, 5.3, 7.6 and 9.1 g. The deviation of the mass for different materials were 8.3%, 9.4%, 7.8% and 7.7%, respectively. The mass deviation for different types of materials between the physical experiment and virtual experiment was kept within 10%. This research could not only prove that it was feasible to establish corn straw model by discrete element method and simulate the kneading and crushing process, but also provide guidance for kneading other straws. [ABSTRACT FROM AUTHOR]

Copyright of China Petroleum Machinery is the property of China Petroleum Machinery 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.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering 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 Jianzhu Cailiao Xuebao: Journal of Building Materials is the property of Journal of Building 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.)