Simulation of Cobalt-Rich Crust''s Crushing Process Based on ANSYS

It is a great concern in international oceanology to mine cobalt-rich crust. At present, spiral mining head is regarded as the best crushing scheme. Based on the dynamic model of spiral mining head, the of cobalt crust's crushing process was simulated with the ANSYS software. The material model of Johnson and Cook Plasticity, maximal principal stress failure criterion, and eroding contact arithmetic were selected. At the same time, the influence of cutting depth, feed speed, rotational speed of mining head on torque and force subjected by mining head was taken into account. At last a computer simulation model of crushing process of cobalt crust was established. By analyzing simulation results, the relationships among these controllable process parameters, torque and force can be obtained, which will provide a technical reference for practical mining system.     

Obstacle performance of cobalt-enriching crust wheeled mining vehicle

1 INTRODUCTIONDeep-sea cobalt-enriching crust is a kind ofvery i mportant seabed mineral resources , whichwidely distributes over seamount slopes in the wa-ter-depth of 500 3000 m, with cover degree up to70 % 100 %and abundance up to 30 70 kg/m2.The crust is richin many metal elements includingcobalt ,nickel ,copper ,platinum,gold and manga-nese[1 7]. Plenty of investigations show that thecobalt-enriching crust with commercial mining val-ueis the cobalt crust withlarge area ,whose areaisup…     

Optimization methods of cutting depth in mining Co-rich crusts

For optimizing the cutting depth of spiral drum type cutting head,the relations among collecting ratio,interfusing ratio of mullock and cutting depth of the mining cobalt-rich crusts in ocean were discussed.Furthermore,the multi-extremum problem about cutting depth was analyzed in mining at a certain interfusing ratio of mullock.Through introducing genetic algorithm(GA),the cutting depth-control problem when the collecting ratio is maximized by controlling the interfusing ratio of mullock was solved with global-optimization-search algorithms.Then optimization theory for cutting depth in mining cobalt-rich crusts by GA,and computer programming were given to realize the algorithm.The computation result of actual data proves the validity of this method.     

Die wall lubricated warm compaction behavior of non-lubricant admixed iron powder

The phenomena of die wall lubricated warm compaction of non-lubricant admixed iron powders were researched, and its mechanism of densification was discussed. Water atomized powder obtained from the Wuhan Iron and Steel Corporation was used. With compacting and sintering, compared with cold compaction, the density of warm compacted samples increases by 0.07 - 0. 22 g/cm^3 at the same pressed pressure. The maximum achievable green density of warm compacted samples is 7.12 g/cm^3 at 120℃, and the maximum sintered density is 7.18 g/cm^3 at 80℃. Compared with cold compaction, the ejection force of warm compaction is smaller; the maximum discrep- ancy is about 7 kN. The warm compacted mechanism of densification of iron powders can be obtained： heating the powder contributes to improving plastic deformation of powder particles, and accelerating the mutual filling and rearrangement of powder particles.     

Dynamic impedance of piles in visco-elastic material considering axial loads

The dynamic impedance function of pile in visco-elastic material considering axial loads under lateral dynamic force was analyzed, and the beam dynamic differential equation was used to induce the dynamic impedance function. After analyzing the edge conditions, the dynamic impedance functions were deduced. Contrasted with the result that does not consider axial loads, the axial loads have obvious influence on the dynamic impedance function. And the results show that the dimensionless parameter of the dynamic impedance will change from 6% to 9% when considering axial loads, and dimensionless parameter of the dynamic impedance of the coupling horizontal-sway will increase by 31%. Foundation item: Project(50078021) supported by the National Natural Science Foundation of China     

Ground pressure and overlying strata structure for a repeated mining face of residual coal after room and pillar mining

To investigate the abnormal ground pressures and roof control problem in fully mechanized repeated mining of residual coal after room and pillar mining,the roof fracture structural model and mechanical model were developed using numerical simulation and theoretical analysis.The roof fracture characteristics of a repeated mining face were revealed and the ground pressure law and roof supporting conditions of the repeated mining face were obtained.The results indicate that when the repeated mining face passes the residual pillars,the sudden instability causes fracturing in the main roof above the old goaf and forms an extra-large rock block above the mining face.A relatively stable ‘‘Voussoir beam" structure is formed after the advance fracturing of the main roof.When the repeated mining face passes the old goaf,as the large rock block revolves and touches gangue,the rock block will break secondarily under overburden rock loads.An example calculation was performed involving an integrated mine in Shanxi province,results showed that minimum working resistance values of support determined to be reasonable were respectively 11,412 kN and 10,743 kN when repeated mining face passed through residual pillar and goaf.On-site ground pressure monitoring results indicated that the mechanical model and support resistance calculation were reasonable.     

Modeling and simulation of ocean mining subsystem based on virtual prototyping technology

1　INTRODUCTIONThe study of ocean mining system is a greatconcern in international ocean resources research.The system is related to many subjects, such as o cean re connoitering, mining, mechatronics, mate rial, environment and so on . It is considered thatthe first commercial mining system will be possiblymade up of mining subsystem, lifting subsystem,remote measuring and controlling subsystem andsurface supporting system. The mining subsystemis used to crush and collec…     

Mechanism of zonal disintegration phenomenon in enclosing rock mass around deep tunnels

In order to study the mechanism of the zonal disintegration phenomenon (ZDP), both experimental and theoretical investigations were carried out. Firstly, based on the similarity law, gypsum was chosen as equivalent material to simulate the deep rock mass, the excavation of deep tunnel was modeled by drilling a hole in the gypsum models, two circular cracked zones were measured in the model, and ZDP in the enclosing rock mass around deep tunnel was simulated in 3D gypsum model tests. Secondly, based on the elasto-plastic analysis of the stressed-strained state of the surrounding rock mass with the improved Hoek-Brown strength criterion and the bilinear constitutive model, the maximum stress zone occurred in vicinity of the elastic-plastic interface due to the excavation of the deep tunnel, rock material in maximum stress zone is in the approximate uniaxial loading state owing to the larger tangential force and smaller radial force, the mechanism of ZDP was explained, which lay in the creep instability failure of rock mass due to the development of plastic zone and transfer of the maximum stress zone within the rock mass. Thirdly, the analytical critical depth for the occurrence of ZDP was obtained, which depended on the mechanical indices and stress concentration coefficient of rock mass. Foundation item: Projects(50525825, 90815010) supported by the National Natural Science Foundation of China; Project(2009CB724608) supported by the Major state Basic Research Development Program of China     

Dynamics of vertical pipe in deep-ocean mining system

A 3-D geometrical nonlinear model for the entire lift system of 1000-m sea trial system of China Ocean Mineral Resources R＆D Association was established with finite element method. The model was utilized to analyze the dynamic characteristics of the vertical pipe under the influence of moving velocity, current direction and wave. The simulation results show that the axial stress is dominant on the vertical pipe, its maximum is located at the pipe top, all stresses are much less than the allowable value of the vertical pipe and joint; the heave motion leads to violent fluctuation of the force and stress, but a period of 8 s is not likely to resonate the present pipe; against the current, 0.50 m/s is the suggested moving velocity of the ship and miner, while along the current, the moving velocity can be slightly higher than 0.75 m/s.     

Stability and nonlinear dynamic behavior of drilling shaft system in copper stave deep hole drilling

The stability and nonlinear dynamic behavior of drilling shaft system in copper stave deep hole drilling were analyzed. The effects of the fluctuation of the cutting force, the mass eccentricity and the hydrodynamic forces of cutting fluid could be taken into consideration in the model of drilling shaft system. Based on the isoparametric finite element method, the variational form of Reynolds equation in hydrodynamic fluid was used to calculate nonlinear hydrodynamic forces and their Jacobian matrices simultaneously. In the stability analysis, a new shooting method for rapidly determining the periodic orbit of the nonlinear drilling shaft system and its period was presented by rebuilding the traditional shooting method and changing the time scale. Through the combination of theories with experiment, the correctness and effectiveness of the above methods are verified by using the Floquet theory. The results show that the mass eccentricity can inhibit the whirling motion of drilling shaft to some extent. Foundation item: Project(2007CB707706) supported by the Major State Basic Research Development Program of China; Projects(2007E213, 2007E203) supported by the Natural Science Foundation of Shaanxi Province, China     

Machining process model based on virtual reality environment

Virtual manufacturing is fast becoming an affordable technology with wide-ranging applications in modern manufacturing. Its advantages over existing technology are primarily that users can visualize, feel involvement and interact with virtual representations of real world activities in real time. In this paper, a virtual cutting system is built which can simulate turning process, estimate tool wear and cutting force using artificial neural network etc. Using the simulated machining environment in virtual reality (VR), the user can practise and preview the operations for possible problems that might occur during implementation. This approach enables designers to evaluate and design feasible machining processes in a consistent manner as early as possible during the development process. Foundation item: Projects (50475117, 50175081) supported by the National Natural Science Foundation of China; project (033181611) supported by the Science and Technology Commission of Tianjin Municipal     

Dynamic modeling and simulation for nonholonomic welding mobile robot

Based on the Newton-Euler method, the dynamic behaviors of the left and right driving wheels and the robot body for the welding mobile robot were derived. In order to realize the combination control of body turning and slider adjustment, the dynamic behaviors of sliders were also investigated. As a result, a systematic and complete dynamic model for the welding mobile robot was constructed. In order to verify the effectiveness of the above model, a sliding mode tracking control method was proposed and simulated, the lateral error stabilizes between ?0.2 mm and 0.2 mm, and the total distance of travel for the slider is consistently within ±2 mm. The simulation results verify the effectiveness of the established dynamic model and also show that the seam tracking controller based on the dynamic model has excellent performance in terms of stability and robustness. Furthermore, the model is found to be very suitable for practical applications of the welding mobile robot.     

Failure analysis of polycrystalline diamond compact cutters for breaking rock by bending waves theory

The breakage mechanism of the polycrystalline diamond compact（PDC） cutters was analyzed by the energy theory of bending waves. The cutting tests of granite block were conducted on a multifunctional testing device by using the cutter at three kinds of negative fore angles of 30°, 45°and 60°. The results show that, when the edge of the PDC layer is broken, the layer of tungsten cobalt is broken a little under the angle of 30°, while the layer of tungsten cobalt is broken continuously under the angle of 60°, their maximum depths are about 2 and 7 mm respectively in the two cases. The eccentric distance mainly depends on the negative fore angle of the cutter. When the cutter thrusts into the rock under an attack angle of 60°, the energy of bending waves reaches the maximum since the eccentric distance is the maximum. So the damage of cutter is the most serious. This test result is consistent with the conclusion of theoretical analysis well. The eccentric distance from the axial line of cutter to the point of action between the rock and cutter has great effect on the breakage of the cutter. Thus during the process of cutting, the eccentric distance should be reduced to improve the service life of PDC cutters.     

一种包含内摩擦的输送带动态特性研究

带式输送机输送带内部填充物产生的内摩擦对输送带的动态特性有着重要的影响.考虑输送带的内部摩擦力,以BERG模型为基础,提出了一种包含内摩擦元件的输送带动力学模型,给出了模型内部参数的识别方法,并进行了模型仿真与验证试验,进而推导出了基于该模型的带式输送机系统动力学方程.在AMEsim软件环境下将复杂的输送带力学模型转化为超级元件,建立带式输送机系统仿真模型,并对带式输送机可控软起动过程进行了仿真.结果表明:仿真速度曲线与起动工况相符,由于输送带较长,张力传递需要时间,并且要克服沿程阻力,机头部与机尾部分别在0s和5s时开始起动加速,经过约10s的爬行段后,速度曲线趋于平滑;系统于80s时达到运行带速2.5m/s;机头部和机尾部输送带张力值最大值分别为238.8kN和59.6kN,与实际张力分布规律一致,证明了包含内摩擦的输送带模型的正确性与可行性.     

Contact pressure distribution and support angle optimization of kiln tyre

Rotary kiln is the key equipment in many in-dustrial depart ments ,such as metallurgical indus-try ,building materialsindustry ,etc . Kilntyreis aloose ferrule on the shell ,supported by two roll-ers . The angle between the vertical line and theline linking roller center and tyre center is definedas tyre support angle . Accordingtothe postulationthat kiln load was transformed to the shell at thestation of tyre as uniformly distributed verticalforces ,and Alan et al[1 3]deduced the formula ofty…     

Measurements of in situ stress and mining-induced stress in Beiminghe Iron Mine of China

In order to obtain the distribution rules of in situ stress and mining-induced stress of Beiminghe Iron Mine, the stress relief method by overcoring was used to measure the in situ stress, and the MC type bore-hole stress gauge was adopted to measure the mining-induced stress. In the in situ stress measuring, the technique of improved hollow inclusion cells was adopted, which can realize complete temperature compensation. Based on the measuring results, the distribution model of in situ stress was established and analyzed. The in situ stress measuring result shows that the maximum horizontal stress is 1.75–2.45 times of vertical stress and almost 1.83 times of the minimum horizontal stress in this mineral field. And the mining-induced stress measuring result shows that, according to the magnitude of front abutment pressure the stress region can be separated into stress-relaxed area, stress-concentrated area and initial stress area. At the −50 m mining level of this mine, the range of stress-relaxed area is 0–3 m before mining face; the range of stress-concentrated area is 3–55 m before mining face, and the maximum mining-induced stress is 16.5–17.5 MPa, which is 15–20 m from the mining face. The coefficient of stress concentration is 1.85. Foundation item: Projects(10702072, 10632100) supported by the National Nature Science Foundation of China     

Design and dynamic simulation of hydraulic system of a new automatic transmission

A new hydraulic system of a novel automatic transmission (AT) was designed. The dimension and structure of valves and cylinders were designed by theoretical calculation. The dynamic simulation model of hydraulic system of AT was established by ITI-SimulationX. Simulation results and theoretical design results were compared to confirm the simulation model. Based on the confirmed simulation model, the simulation results of pressure and flow of the hydraulic system were analyzed. The dynamic simulation method is very helpful for designing and analyzing the performance of hydraulic system and further optimization design. The theoretical design method and dynamic simulation model are feasible for the real industrial applications. The research results can be used in hydraulic system design and optimization. Foundation item: Project(911901204) supported by Youth Innovation Foundation of Beijing University of Aeronautics and Astronautics     

车削加工过程中切削力的试验研究

运用DEFORM仿真软件对金属切削过程进行仿真实验,以金刚石为切削刀具,AISI52100淬硬钢为工件材料,采用正交仿真实验分析切削速度、进给量、切削深度对切削力的影响规律,并给出实验范围内的最优加工参数组合,当切削速度vc=120 m/min、进给量f=0.10 mm/r、切削深度为时ap=0.1 mm,切削力达到最小。最后运用回归分析方法建立切削力的经验模型,对得到的经验公式进行显著性检验,证明经验公式的可信性。     

Control strategy for pneumatic rotary position servo systems based on feed forward compensation pole-placement self-tuning method

The pneumatic rotary position system, in which an electro-pneumatic proportional flow valve controled a rotary cylinder, was studied, and its mathematical model was built. The model indicated that the controlled pneumatic system had disadvantages such as inherent non-linearity and variations of system parameters with working points. In order to improve the dynamic performance of the system, feed forward compensation self-tuning pole-placement strategy was adopted to place the poles of the system in a desired position in real time, and a recursive least square method with fixed forgetting factors was also used in the parameter estimation. Experimental results show that the steady state error of the pneumatic rotary position system is within 3% and the identified system parameters can be converged in 5 s. Under different loads, the controlled system has an excellent tracking performance and robustness of anti-disturbance. Foundation item: Project(50375034) supported by the National Natural Science Foundation of China     

Finite element analysis on nut post structure of Three Gorges Project ship lift

A nonlinear finite element model of the nut post reinforced concrete (RC) structure of the safety mechanism in the Three Gorges Project (TGP) ship lift was built by ANSYS software. Some irregular structures such as the nut post and the rotary rod were divided by curved surface into a series of regular parts, and the structures were all meshed to hexahedron. Constraint equations were defined between two interfaces with different element sizes and mesh patterns. PRETS179 elements were used to simulate the preload in the tendons and the pre-stressed screws, and the loss of pre-stressing force was calculated. Five extreme load cases were analyzed. The stress of each part in the structure was obtained. The results indicate that the maximum compressive stress of concrete C35 is 24.13 MPa, so the concrete may be partially crushed; the maximum tensile stress of the grouting motar is 6.73 MPa, so the grouting motar may partially fracture; the maximum von Mises stress of the rotary rod is 648.70 MPa, therefore the rotary rod may partially yield. Foundation item: Project (SPKJ 016-06) supported by the Key Research Project of State Power Corporation; Project (2004AC101D31) supported the Key Scientific Research Project of Hubei Province, China