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Simulation Analysis and Verification of Temperature and Stress of Wheel-Mounted Brake Disc of a High-Speed Train

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Chinese Journal of Mechanical Engineering 2022年第4期35卷 347-355页

作者： Junsheng Qu Wenjing Wang Ziyu Dong Wei Shan School of Mechanical Electronic and Control EngineeringBeijing Jiaotong University Department of Locomotive&Vehicle China National Railway Group Co.Ltd

During the braking process, a large amount of heat energy is generated at the friction surfaces between the brake disc and pads and rapidly dissipates into the disc volume. In this paper, a three-dimensional thermo-mechanical coupling model of high-speed wheel-mounted brake discs containing bolted joints and contact relationships is established. The direct coupling method is used to analyze the temperature and stress of the brake discs during an emergency braking event with an initial speed of 300 km/h. A full-scale bench test is also conducted to monitor the temperatures of the friction ring and bolted joints. The simulation result shows that the surface temperature of the friction ring reaches its peak value of 414 ℃ after 102 s of braking, which agrees well with the bench test result. The maximum alternating thermal stress occurs in the bolt hole where the maximum circumferential compressive stress is-658 MPa and the maximum circumferential tensile stress is 134 MPa. During the braking process, the out-of-plane deformation of the middle part of the friction ring is larger than that of the edge, which increases the axial tensile load of the connecting bolt. This work provides support for the design of brake discs and connecting bolts.

关键词： High speed train Wheel-mounted brake disc Temperature field Stress field Thermo-mechanical coupling model bolt

Development and evaluation of corrosion resistant coating for expandable rock bolt against highly corrosive ground conditions

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International Journal of Mining Science and Technology 2018年第1期28卷 145-151页

作者： Kevin Jinrong Ma John Stankus Dakota Faulkner Keystone Mining Services LLC of Jennmar Corporation Inc

Expandable rock bolts are widely used in hard rock mines as an efficient ground control product.However, capacity and service life can be significantly reduced if the metallic body is subjected to corrosion.In some hard rock mines in the U.S., highly corrosive ground conditions exist, and it has been reported that inflatable rock bolts have corroded within a few months after installation.To provide mining industry a cost-effective inflatable bolt and combat the corrosion issues, Jennmar Corporation, Inc.,and its subsidiary Keystone Mining Services, LLC(KMS), analyzed corroded bolt samples, identified root causes, evaluated properties of various coating materials, and developed a new inflatable rock bolt,Python M3^(TM), that is protected with an innovative PyFlexU2^(TM)coating.The new generation Python M3^(TM) features improved steel chemistry for reliable performance, modified profile for better inflation, and surface preparation and coating application.The PyFlexU2^(TM)is impervious to liquid and air, durable, and UV resistant.With a flexible, adhesive, and highly corrosion-resistant undercoating, and a very hard sacrificial surface coating, the PyFlexU2^(TM)coating system provides the Python M3^(TM)superior protection against chemical corrosion and physical scratch damage.The under-coating has exceptional flexibility and adhesion to prevent coating micro-cracks or fractures after bolt inflation and possesses excellent corrosion resistance to acids(pH 11), fuels, and salt solvents.The corrosion and scratch resistant PyFlexU2^(TM)coating offers very effective bolt protection for extra longevity in highly corrosive environments.The Python M3^(TM)coated with PyFlexU2^(TM)has been tested in the most challenging conditions,including laboratory corrosion tests in extreme acidic and basic solvents, rock slurry, and borehole scratch insertion tests.With demonstrated corrosion and scratch resistance, the product has been greatly welcomed by hard rock mines in the West and is currently installed in lar

关键词： Rock bolt Hard rock Corrosive ground condition bolt corrosion

Simulation Analysis and Verifcation of Temperature and Stress of Wheel-Mounted Brake Disc of a High-Speed Train

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Chinese Journal of Mechanical Engineering 2022年第4期35卷 331-339页

作者： Junsheng Qu Wenjing Wang Ziyu Dong Wei Shan School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China Department of Locomotive&Vehicle China National Railway Group Co.LtdBeijing 100844China

During the braking process,a large amount of heat energy is generated at the friction surfaces between the brake disc and pads and rapidly dissipates into the disc volume.In this paper,a three-dimensional thermo-mechanical coupling model of high-speed wheel-mounted brake discs containing bolted joints and contact relationships is established.The direct coupling method is used to analyze the temperature and stress of the brake discs during an emergency braking event with an initial speed of 300 km/h.A full-scale bench test is also conducted to monitor the temperatures of the friction ring and bolted joints.The simulation result shows that the surface temperature of the friction ring reaches its peak value of 414°C after 102 s of braking,which agrees well with the bench test result.The maximum alternating thermal stress occurs in the bolt hole where the maximum circumferential compressive stress is−658 MPa and the maximum circumferential tensile stress is 134 MPa.During the braking process,the out-of-plane deformation of the middle part of the friction ring is larger than that of the edge,which increases the axial tensile load of the connecting bolt.This work provides support for the design of brake discs and connecting bolts.

关键词： High speed train Wheel-mounted brake disc Temperature feld Stress feld Thermo-mechanical coupling model bolt

Loading characteristics of mechanical rib bolts determined through testing and numerical modeling

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International Journal of Mining Science and Technology 2020年第1期30卷 17-24页

作者： Khaled Mohamed Gamal Rashed Zorica Radakovic-Guzina Centers for Disease Control National Institute for Occupational Safety and HealthPittsburghPA 15236USA ITASCA Consulting Group MinneapolisMN 55401USA

Underground coal mines use mechanical bolts in addition to other types of bolts to control the rib deformation and to stabilize the yielded coal ribs.Limited research has been conducted to understand the performance of the mechanical bolts in coal ribs.Researchers from the National Institute for Occupational Safety and Health(NIOSH)conducted this work to understand the loading characteristics of mechanical bolts(stiffness and capacity)installed in coal ribs at five underground coal mines.Standard pull-out tests were performed in this study to define the loading characteristics of mechanical rib bolts.Different installation torques were applied to the tested bolts based on the strength of the coal seam.A typical tri-linear load-deformation response for mechanical bolts was obtained from these tests.It was found that the anchorage capacity depended mainly on the coal strength.Guidelines for modeling mechanical bolts have been developed using the tri-linear load-deformation response.The outcome of this research provides essential data for rib support design.

关键词： Coal rib Mechanical bolt Conventional bolt Tension bolt Point-anchored bolt Rib support Pull-out test Numerical modeling FLAC3D

Numerical simulation and analysis of drill rods vibration during roof bolt hole drilling in underground mines

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International Journal of Mining Science and Technology 2018年第6期28卷 877-884页

作者： Shaowei Liu Mengxiong Fu Housheng Jia Wenbin Li Yafei Luo School of Energy Science and Engineering Henan Polytechnic UniversityJiaozuo 454000China The Safety of Coal Production Collaborative Innovation Center Jiaozuo 454000China

Structural deterioration in the roof in an underground mine can easily cause roof fall, and deterioration is difficult to detect. When drilling holes for roof bolts, there is a relationship between the vibration of the drill rod and the properties of the rock being drilled. This paper analyzes transverse, longitudinal, and torsional vibrations in the drill rod by using vibration theory. Characteristic indexes for three kinds of vibration are determined. Using the finite element analysis software ABAQUS, a model for drill rod vibration during the drilling of roof bolt holes was established based on the geological and mining conditions in the Guyuan Coal Mine, northern China. Results from the model determined that the transverse and the longitudinal vibration decrease as the rock hardness decreases. In descending order, sandstone,sandy mudstone, mudstone, and weak interbeds cause progressively less vibration when being drilled.The ranking for strata that cause decreasing torsional vibration is slightly different, being, in descending order, mudstone, sandstone, sandy mudstone, and weak interbeds. These results provide a theoretical basis for predicting dangerous roof conditions and the presence of weak interbeds to allow for adjusting bolt support schemes.

关键词： Roof bolt holedrilling Drill rod vibration Vibration radius Vibration point amplitude Negative angular acceleration

Non-destructive testing and pre-warning analysis on the quality of bolt support in deep roadways of mining districts

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International Journal of Mining Science and Technology 2017年第6期27卷 989-998页

作者： Zhang Houquan Miao Xiexing Zhang Guimin Wu Yu Chen Yanlong State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and Technology Xuzhou 221116 China School of Mechanics and Civil Engineering China University of Mining and Technology Xuzhou 221116 China

The bolt support quality of coal roadways is one of the important factors for the efficiency and security of coal production. By means of a self-developed technique and equipment of random non-destructive testing, non-destructive detection and pre-warning analysis on the quality of bolt support in deep roadways of mining districts were performed in a number of mining areas. The measured data were obtained in the detection instances of abnormal in-situ stress and support invalidation etc. The corresponding relation between axial bolt load variation and roadway surrounding rock deformation and stability was summarized in different mining service stages. Pre-warning technology of roadway surrounding rock stability is proposed based on the detection of axial bolt load. Meanwhile, pre-warning indicators of axial bolt load in different mining service stages are offered and some successful pre-warning cases are also illustrated.The research results show that the change rules of axial bolt load in different mining service stages are quite similar in different mining areas. The change of axial bolt load is in accord with the adjustment of surrounding rock stress, which can consequently reflect the deformation and stability state of roadway surrounding rock. Through the detection of axial bolt load in different sections of roadways, the status of real-time bolt support quality can be reflected; meanwhile, the rationality of bolt support design can be evaluated which provides reference for bolting parameters optimization.

关键词： Deep roadways bolt support quality Random nondestructive testing Surrounding rock stability Prediction and pre-warning

Experimental and theoretical investigation on mechanisms performance of the rock-coal-bolt(RCB)composite system

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International Journal of Mining Science and Technology 2020年第6期30卷 759-768页

作者： Genshui Wu Weijian Yu Jianping Zuo Shaohua Du School of Mechanics and Civil Engineering China University of Mining and Technology-BeijingBeijing 100083China State Key Laboratory of Coal Resources and Safe Mining China University of Mining and Technology-BeijingBeijing 100083China School of Resource&Environment and Safety Engineering Hunan University of Science and TechnologyXiangtan 411201China School of Resources and Safety Engineering Central South UniversityChangsha 410083China

For coal mines,rock,coal,and rock bolt are the critical constituent materials for surrounding rock in the underground engineering.The stability of the“rock-coal-bolt”(RCB)composite system is affected by the structure and fracture of the coal-rock mass.More rock bolts installed on the rock,more complex condition of the engineering stress environment will be(tensile-shear composite stress is principal).In this paper,experimental analysis and theoretical verification were performed on the RCB composite system with different angles.The results revealed that the failure of the rock-coal(RC)composite specimen was caused by tensile and shear cracks.After anchoring,the reinforcement body formed inside the composite system limits the area where the crack could occur in the specimen.Specifically,shearing damage occurred only around the bolt,and the stress-strain curve presented a better post-peak mechanical property.The mechanical mechanism of the bolt under the combined action of tension and shear stress was analyzed.Additionally,a rock-coal-bolt tensile-shear mechanical(RCBTSM)model was established.The relationship(similar to the exponential function)between the bolt tensile-shear stress and the angle was obtained.Moreover,the influences of the dilatancy angle and bolt diameter of the RCB composite system were also considered and analyzed.Most of the bolts are subjected to the tensile-shearing action in the post-peak stage.The implications of these results for engineering practice indicated that the bolts of the RCB composite system should be prevented from entering the limit shearing state early.

关键词： Thin coal seam Coal and rock roadway bolt Tension-shear failure “Rock-coal-bolt”composite system

Rockburst mechanism research and its control

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International Journal of Mining Science and Technology 2018年第5期28卷 829-837页

作者： Manchao He Fuqiang Ren Dongqiao Liu State Key Laboratory for Geomechanics & Deep Underground Engineering School of Mechanics and Civil Engineering China University of Mining & TechnologyBeijing

A new rockburst classification, innovative works in developing a ‘‘strainburst test machine" and an‘‘impact-induced rockburst test machine" that can reproduce rockbursts in laboratory were researched.New concepts were proposed regarding the stress paths that take into account both the static and dynamic stresses analogous to that at excavation boundaries for generating artificially-induced strainburst and impact-induced rockburst. As an important method for rockburst control, a novel energyabsorbing bolt was developed, which has a constant-resistance under both static and impact loadings and a large-elongation capacity for containing large deformations of rock masses under burst-prone conditions.

关键词： Rockburst Stress paths Energy-absorbing bolt Rockburst control

Competitive Failure of bolt Loosening and Fatigue under Different Preloads

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Chinese Journal of Mechanical Engineering 2021年第6期34卷 417-427页

作者： Guangwu Yang Long Yang Jingsong Chen Shoune Xiao Shilin Jiang State Key Laboratory of Traction Power Southwest Jiaotong UniversityChengdu 610031China

Existing research on the competitive failure relationship,failure mechanism,and influencing factors of bolt loosening and fatigue under different preloads is insufficient.This study analyzes the competitive failure relationship between bolt loosening and fatigue under composite excitation through competitive failure tests of bolt loosening and fatigue under different preloads.The results indicated that the failure mode of the bolt is only related to the load ratio(R)and is unrelated to the initial preload and excitation amplitude,which only determine the failure life of the bolt.The small axial loads of composite excitation can restrain bolt failure,and the significant degree of this restraining effect is differ-ent for different preloads.Subsequently,a fracture analysis of the bolt was performed to verify the competitive failure relationship of the bolt from a microscopic perspective,and the competitive failure mechanism of the bolt was deter-mined.Based on the findings,we propose a calculation equation for the optimal preload of 8.8 grade high-strength bolts that can serve as a reference for engineering applications.

关键词： bolt Preload Loosening Fatigue Competitive failure