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About this book

This book introduces the engineering application of the discrete element method (DEM), especially the simulation analysis of the typical equipment (scraper conveyor, coal silos, subsoiler) in the coal and agricultural machinery. In this book, the DEM is applied to build rigid and loose coupling model, and the kinematic effect of the bulk materials, the mechanical effect of the interaction between the bulk materials, and the mechanical equipment in the operation process of the relevant equipment are studied. On this basis, the optimization design strategy of the relevant structure is proposed. This book effectively promotes the application of DEM in engineering, analyzes the operation state, failure mechanism, and operation effect of related equipment in operation, and provides theoretical basis for the optimal design of equipment. The book is intended for undergraduate and graduate students who are interested in mechanical engineering, researchers investigating coal and agricultural machinery, and engineers working on designing related equipments.

Table of Contents

Frontmatter

Chapter 1. Introduction

Abstract
Discrete element method (DEM), as a numerical simulation method for non-continuous medium, has been widely used to simulate particle flow in particle system and dust. It can effectively analyze the movement and force of particles, and extract the flow information of particles which cannot be obtained in experiments. In this chapter, the basic theory and development trend of DEM were introduced in detail, and the current calibration methods of DEM were summarized.
Xuewen Wang, Bo Li, Rui Xia, Haozhou Ma

Chapter 2. Application of DEM in Coal and Agricultural Machinery

Abstract
DEM has been widely used in geotechnical engineering, agricultural engineering, mining engineering, mechanical engineering and other fields. It can better simulate mechanical problems and movement problems such as coal and rock mining, coal and rock transportation, soil excavation, crop transportation, and can also be used to simulate and analyze the force problems of rock and soil, crops and related machinery. This chapter mainly introduced the application of DEM in main coal machinery equipment and agricultural equipment.
Xuewen Wang, Bo Li, Rui Xia, Haozhou Ma

Chapter 3. Analysis of the Coal Bulk Transport State Based on DEM

Abstract
DEM has great advantages in the field of bulk material analysis, and has been widely used in the study of coal bulk transportation. It can obtain a large number of complex behavior information and difficult to measure particle size behavior information of coal bulk, so as to further reveal the transport state of coal bulk in the middle through. This chapter established the scraper conveyor analysis model based on EDEM, simulated the scraper conveyor under different transport conditions, and analyzed the transport status of coal bulk according to the simulation results.
Xuewen Wang, Bo Li, Rui Xia, Haozhou Ma

Chapter 4. Mechanical Effect of Scraper Conveyor Based on DEM

Abstract
In the process of transportation in the middle trough, the coal bulk acts as the load of the scraper conveyor, and the force on the related parts affects their normal work, may cause malfunctions and the scraper conveyor cannot work normally. Moreover, its load characteristics have a significant impact on the normal operation and service life of related components. In previous studies, load of coal bulk was often regarded as a concentrated load acting at a certain point, ignoring the time variability of load of coal bulk and its related load caused by the interaction of components. In this chapter, EDEM was used to simulate the distribution and flow characteristics of coal in the middle trough under different conditions, as well as the load distribution characteristics of coal and the force characteristics of affected parts. Based on the simulation results, the distribution of wear area of the middle plate, the size of wear and the wear reason of the middle plate were analyzed.
Xuewen Wang, Bo Li, Rui Xia, Haozhou Ma

Chapter 5. Application of DEM on the Design of Wear-Resistant Bionic Chute of Scraper Conveyor

Abstract
In order to solve or alleviate the failure of the middle plate due to excessive wear, the wear-resistant geometric structure or characteristic law of organism surface was studied, to some extent, the biological characteristic wear-resistant geometry or physical mechanism of natural action was designed to the middle plate of scraper conveyor. This chapter studies the layout of the pit on the middle plate surface under the dry friction condition in order to obtain the most wear-resistant pit structure, which provides a reference for the wear-resistant design of the scraper conveyor. And the single factor and response surface method (RSM) was used to optimize the structural parameters of the pit, and the interaction law of the factors was studied.
Xuewen Wang, Bo Li, Rui Xia, Haozhou Ma

Chapter 6. Flowing State Analysis of Coal Bulk in Silos Using DEM

Abstract
In coal mine production, coal silos are used for temporary coal storage by transferring coal materials at the bottom or wellhead, and also for coal storage in thermal power generation, coal preparation, coking, smelting and other industries. This chapter simulated silo unloading based on DEM, analyzed the influence of different factors on unloading, optimized the structure of silo hopper and analyzed the advantages and disadvantages of three hopper structures.
Xuewen Wang, Bo Li, Rui Xia, Haozhou Ma

Chapter 7. Stress Analysis of Silos Using DEM

Abstract
The coal silos are typical kind in silo applications filed, its storage and throughput is one of the most important aspects of coal production in mining areas, directly decide the productive capacity of coal. Considering the change of the flowing state of coal powder and mechanical behavior of its influence on silo, this chapter simulated the whole process of loading and unloading materials in the straight coal silo based on DEM, analyzed the side pressure distribution of coal silos and discharged, the overpressure distribution when unloading, and carried on the test and verification.
Xuewen Wang, Bo Li, Rui Xia, Haozhou Ma

Chapter 8. Application of DEM on the Design and Performance Analysis of Bionic Subsoiler

Abstract
Soil working machines are very important for farmland operation. Although each machine has its specific use, the most basic function is to work on the land [1]. The effect of soil working tools depends on the interaction between soil and machinery, and the cultivation resistance is a very important evaluation index in the effect, especially for the subsoiler, the resistance is directly related to the power consumption of power machinery. Many scholars have used bionic methods to improve farming components, but these studies only extract the structure simply, and do not analyze the animal structure itself. In this chapter, the claw of black bear was taken as the research object, and its real model was established by three-dimensional scanning. The claw–soil interaction model was constructed by DEM, the loosening process of the claw of black bear was studied and the bionics method was used to improve the subsoiler.
Xuewen Wang, Bo Li, Rui Xia, Haozhou Ma

Chapter 9. The Effect of Two Wings of Subsoiler on Tillage Based on DEM

Abstract
The performance of subsoiling tools is primarily affected by the rake angle and working depth of the tool. Therefore, different rake angles and working depths should be evaluated for all design alternatives. In this chapter, PFC3D was used to model soil-tool interaction. The model was used to evaluate two design alternatives of subsoiling tool. This virtual test eliminated the cost and time of fabricating and testing the prototypes under various operational parameters.
Xuewen Wang, Bo Li, Rui Xia, Haozhou Ma

Chapter 10. Conclusion and Prospect

Abstract
This book introduces the simulation analysis of DEM in engineering, especially for the typical equipment (scraper conveyor, coal bunker and subsoiler) in coal and agricultural machinery. The rigid-discrete coupling model is established by using the discrete element software, and the motion effect of the bulk material and the mechanical effect of the interaction between the bulk material and the mechanical equipment in the operation process of the relevant equipment are studied. On this basis, the optimization design strategy of related structures is proposed. This chapter summarized the work and main conclusions of the book, and put forward the prospect of future research.
Xuewen Wang, Bo Li, Rui Xia, Haozhou Ma
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