The widespread utilisation of tunnel boring machines(TBMs)in underground construction engineering requires a detailed investigation of the cutter-rock interaction.In this paper,we conduct a series of largescale standi...The widespread utilisation of tunnel boring machines(TBMs)in underground construction engineering requires a detailed investigation of the cutter-rock interaction.In this paper,we conduct a series of largescale standing rotary cutting tests on granite in conjunction with high-fidelity numerical simulations based on a particle-type discrete element method(DEM)to explore the effects of key cutting parameters on the TBM cutter performance and the distribution of cutter-rock contact stresses.The assessment results of cutter performance obtained from the cutting tests and numerical simulations reveal similar dependencies on the key cutting parameters.More specifically,the normal and rolling forces exhibit a positive correlation with penetration but are slightly influenced by the cutting radius.In contrast,the side force decreases as the cutting radius increases.Additionally,the side force shows a positive relationship with the penetration for smaller cutting radii but tends to become negative as the cutting radius increases.The cutter's relative effectiveness in rock breaking is significantly impacted by the penetration but shows little dependency on the cutting radius.Consequently,an optimal penetration is identified,leading to a low boreability index and specific energy.A combined Hertz-Weibull function is developed to fit the cutter-rock contact stress distribution obtained in DEM simulations,whereby an improved CSM(Colorado School of Mines)model is proposed by replacing the original monotonic cutting force distribution with this combined Hertz-Weibull model.The proposed model outperforms the original CSM model as demonstrated by a comparison of the estimated cutting forces with those from the tests/simulations.The findings from this work that advance our understanding of TBM cutter performance have important implications for improving the efficiency and reliability of TBM tunnelling in granite.展开更多
In order to improve the efficiency of gas drainage before and during longwall extraction,a waterjet rotary cutting system has been developed for in-seam cross panel methane drainage.The purpose of the water rotary cut...In order to improve the efficiency of gas drainage before and during longwall extraction,a waterjet rotary cutting system has been developed for in-seam cross panel methane drainage.The purpose of the water rotary cutting system developed was to create artificial fractures along the gas drainage boreholes.During the design of the system,it was perceived that the nozzle geometry is one of the key factors,affecting cutting capacity.Therefore,we studied the structural and geometric parameters of the nozzle and optimized its performance during laboratory tests and numerical simulation.Underground trials conducted in a coal mine,indicate that production of gas drainage before and after cutting significantly increased by up to three times.The advantages of waterjet assisted gas drainage method has been identified as:1) increasing gas drainage efficiency,2) a possible development of a gas drainage fractured network within coal seams associated with panel extraction,and 3) reducing the risk of exceeding gas limits during longwalling.展开更多
An experimental programm of investigating the cutting capacity of PDC flat cutters in very hard rock has been performed. Experiments include both the cutting of PDC fixed at different angles on the granite core or bar...An experimental programm of investigating the cutting capacity of PDC flat cutters in very hard rock has been performed. Experiments include both the cutting of PDC fixed at different angles on the granite core or bar and linear cutting with different static thrust on the block of granite. The effects of the rough degree of rock surface, cutting angles, and static thrust on the cutting capacity of PDC in very hard rock were investigated and analyzed. The results show that the single mode of rotary drilling using PDC cutters is not applied for very hard rocks.展开更多
A mathematic model is established using infinitesimal geometry for the cutting edge design of special milling cutters which use equal lead helix as cutting edges; equations are given for front-end and proclitic surfac...A mathematic model is established using infinitesimal geometry for the cutting edge design of special milling cutters which use equal lead helix as cutting edges; equations are given for front-end and proclitic surface of revolution of ball pillar milling cutters, ball taper milling cutters and angularly conical milling cutters; and corresponding models are established for the continuity cutting edge curves of milling cutters. Typical examples are given to illustrate the applications of mathematic models, which prove the correctness and applicability of these geometric models.展开更多
This article deals with the use of an interdisciplinary approach to modelling and creation of a complex technical system of different physical nature in relation to the kinematics of cutting and shaping. The professor...This article deals with the use of an interdisciplinary approach to modelling and creation of a complex technical system of different physical nature in relation to the kinematics of cutting and shaping. The professor of the National Technical University of Ukraine, Kuznetcov Iu. N., proposed the approach based on generalization of knowledge, methodological basis of which is the theory of evolution of the systems and methods of genetic analysis and synthesis. For generalization of the knowledge in the fundamental sciences is based on the principles of a limited number of elementary generic structures with the introduction of the gene concept. The modelling and synthesis of kinematic cutting schemes are providing the efficiency and viability of genetic and morphological approach. The material point, which can interact with other ma-terial points in space and time, simulating anthropogenic system of different origin, is introduced as a material object.展开更多
针对秸秆还田机具关键部件设计优化过程中秸秆-刀具互作关系分析缺乏准确秸秆离散元模型的问题,本文以水稻秸秆为研究对象,基于Hertz-Mindlin with Bonding接触模型,采用颗粒替换方式构建水稻秸秆离散元柔性模型,开展了离散元接触模型...针对秸秆还田机具关键部件设计优化过程中秸秆-刀具互作关系分析缺乏准确秸秆离散元模型的问题,本文以水稻秸秆为研究对象,基于Hertz-Mindlin with Bonding接触模型,采用颗粒替换方式构建水稻秸秆离散元柔性模型,开展了离散元接触模型参数标定与多工况试验验证。通过物理试验测定了水稻秸秆摩擦因数,以秸秆弯曲试验测得最大载荷作为参数标定试验指标,通过Plackett-Burman试验和最陡爬坡试验筛选柔性模型显著性因素及其最优值范围,并由Central-Composite试验确定了显著性因素的最优值组合为:法向接触刚度3.040×10^(10)N/m^(3)、切向接触刚度2.296×10^(10)N/m^(3),该标定参数值所得最大载荷仿真值与实测值相对误差为1.82%,表明标定参数有效。通过刀具弯曲试验和旋耕刀旋转切割试验验证上述标定方法在不同工况下的有效性,刀具弯曲试验中仿真所得最大载荷与实测最大载荷相对误差不大于4.55%,旋耕刀旋转切割试验中仿真所得最大扭矩与实测最大扭矩相对误差不大于7.95%,研究结果表明,以弯曲试验参数标定法构建的水稻秸秆柔性模型在秸秆弯曲试验和旋耕刀旋转切割过程仿真中均准确有效,适用于旋耕作业条件下仿真分析,可为秸秆还田机具旋耕部件优化设计提供参考。展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.52278407 and 52378407)the China Postdoctoral Science Foundation(Grant No.2023M732670)the support by the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation.
文摘The widespread utilisation of tunnel boring machines(TBMs)in underground construction engineering requires a detailed investigation of the cutter-rock interaction.In this paper,we conduct a series of largescale standing rotary cutting tests on granite in conjunction with high-fidelity numerical simulations based on a particle-type discrete element method(DEM)to explore the effects of key cutting parameters on the TBM cutter performance and the distribution of cutter-rock contact stresses.The assessment results of cutter performance obtained from the cutting tests and numerical simulations reveal similar dependencies on the key cutting parameters.More specifically,the normal and rolling forces exhibit a positive correlation with penetration but are slightly influenced by the cutting radius.In contrast,the side force decreases as the cutting radius increases.Additionally,the side force shows a positive relationship with the penetration for smaller cutting radii but tends to become negative as the cutting radius increases.The cutter's relative effectiveness in rock breaking is significantly impacted by the penetration but shows little dependency on the cutting radius.Consequently,an optimal penetration is identified,leading to a low boreability index and specific energy.A combined Hertz-Weibull function is developed to fit the cutter-rock contact stress distribution obtained in DEM simulations,whereby an improved CSM(Colorado School of Mines)model is proposed by replacing the original monotonic cutting force distribution with this combined Hertz-Weibull model.The proposed model outperforms the original CSM model as demonstrated by a comparison of the estimated cutting forces with those from the tests/simulations.The findings from this work that advance our understanding of TBM cutter performance have important implications for improving the efficiency and reliability of TBM tunnelling in granite.
基金support provided by the Shenhua Ningxia Coal Group Without this assistance,the project would have been difficult to carry out.
文摘In order to improve the efficiency of gas drainage before and during longwall extraction,a waterjet rotary cutting system has been developed for in-seam cross panel methane drainage.The purpose of the water rotary cutting system developed was to create artificial fractures along the gas drainage boreholes.During the design of the system,it was perceived that the nozzle geometry is one of the key factors,affecting cutting capacity.Therefore,we studied the structural and geometric parameters of the nozzle and optimized its performance during laboratory tests and numerical simulation.Underground trials conducted in a coal mine,indicate that production of gas drainage before and after cutting significantly increased by up to three times.The advantages of waterjet assisted gas drainage method has been identified as:1) increasing gas drainage efficiency,2) a possible development of a gas drainage fractured network within coal seams associated with panel extraction,and 3) reducing the risk of exceeding gas limits during longwalling.
基金Project (5 0 1740 5 6)supportedbytheNationalNaturalScienceFoundationofChina project (DE -FG0 3 )supportedbytheNovatekundertheDepartmentofEnergy USA
文摘An experimental programm of investigating the cutting capacity of PDC flat cutters in very hard rock has been performed. Experiments include both the cutting of PDC fixed at different angles on the granite core or bar and linear cutting with different static thrust on the block of granite. The effects of the rough degree of rock surface, cutting angles, and static thrust on the cutting capacity of PDC in very hard rock were investigated and analyzed. The results show that the single mode of rotary drilling using PDC cutters is not applied for very hard rocks.
文摘A mathematic model is established using infinitesimal geometry for the cutting edge design of special milling cutters which use equal lead helix as cutting edges; equations are given for front-end and proclitic surface of revolution of ball pillar milling cutters, ball taper milling cutters and angularly conical milling cutters; and corresponding models are established for the continuity cutting edge curves of milling cutters. Typical examples are given to illustrate the applications of mathematic models, which prove the correctness and applicability of these geometric models.
文摘This article deals with the use of an interdisciplinary approach to modelling and creation of a complex technical system of different physical nature in relation to the kinematics of cutting and shaping. The professor of the National Technical University of Ukraine, Kuznetcov Iu. N., proposed the approach based on generalization of knowledge, methodological basis of which is the theory of evolution of the systems and methods of genetic analysis and synthesis. For generalization of the knowledge in the fundamental sciences is based on the principles of a limited number of elementary generic structures with the introduction of the gene concept. The modelling and synthesis of kinematic cutting schemes are providing the efficiency and viability of genetic and morphological approach. The material point, which can interact with other ma-terial points in space and time, simulating anthropogenic system of different origin, is introduced as a material object.
文摘针对秸秆还田机具关键部件设计优化过程中秸秆-刀具互作关系分析缺乏准确秸秆离散元模型的问题,本文以水稻秸秆为研究对象,基于Hertz-Mindlin with Bonding接触模型,采用颗粒替换方式构建水稻秸秆离散元柔性模型,开展了离散元接触模型参数标定与多工况试验验证。通过物理试验测定了水稻秸秆摩擦因数,以秸秆弯曲试验测得最大载荷作为参数标定试验指标,通过Plackett-Burman试验和最陡爬坡试验筛选柔性模型显著性因素及其最优值范围,并由Central-Composite试验确定了显著性因素的最优值组合为:法向接触刚度3.040×10^(10)N/m^(3)、切向接触刚度2.296×10^(10)N/m^(3),该标定参数值所得最大载荷仿真值与实测值相对误差为1.82%,表明标定参数有效。通过刀具弯曲试验和旋耕刀旋转切割试验验证上述标定方法在不同工况下的有效性,刀具弯曲试验中仿真所得最大载荷与实测最大载荷相对误差不大于4.55%,旋耕刀旋转切割试验中仿真所得最大扭矩与实测最大扭矩相对误差不大于7.95%,研究结果表明,以弯曲试验参数标定法构建的水稻秸秆柔性模型在秸秆弯曲试验和旋耕刀旋转切割过程仿真中均准确有效,适用于旋耕作业条件下仿真分析,可为秸秆还田机具旋耕部件优化设计提供参考。
