144 results about "Discrete element method" patented technology

The present invention discloses a helicopter aerodynamic layout optimization method capable of reducing the adverse effect of aerodynamic interference. According to the method, aiming at the defects of a wind tunnel test and a CFD method and based on a discrete vortex method and a surface element method, a coupled aerodynamic interference high-precision analysis model for a helicopter is set up, so that the influence of aerodynamic interference on the helicopter can be considered only by simulating calculation without carrying out the wind tunnel test; compared with the CFD method, the method has the advantages of greatly reducing the requirements of a simulation model for computing resources and shortening computing time. In order to further reduce calculated amount and a optimization region, a helicopter fuselage shape parameter model is set up by a parametric method and a combined optimization method based on an agent model is adopted, so that the optimal helicopter aerodynamic outline and layout are obtained and the purpose of reducing aerodynamic interference to improve the flight characteristics of the helicopter is achieved. The helicopter aerodynamic layout optimization method can be applied to the conceptual design phase of the helicopter so as to improve the flight characteristics, the balancing characteristic, stability and manoeuvrability of the helicopter.

The invention discloses a bituminous mixture compaction simulation method based on discrete elements. The method comprises the steps that a prescribed space region is generated through a 'wall' command in PFC<3D> software, and the space region is randomly filled with a particle system composed of coarse aggregates and bituminous mortar; partial bituminous mortar is randomly deleted; corresponding contact types are given to the interior of the coarse aggregates, the interior of the bituminous mortar and the space between the coarse aggregates and the bituminous mortar in a bituminous mixture; a 'clump', formed by gathering basic unit particles, in the PFC<3D> software is set to serve as a rolling wheel of a road roller, and the static pressure action on the bituminous mixture is achieved through rolling wheels of the road roller under the action of gravity; excitation force is given to the 'clump', the excitation force of a 'clump' system is coupled with the gravity, and vibrating compaction action is simulated; compaction of compaction road rolling wheels to the bituminous mixture is controlled through fish language programming. The method is easy and convenient to use, economical and effective and has certain significance to construction of a bituminous mixture pavement.

The present invention provides a modeling method for 3D discrete element method numerical model of complicated terrain based on contour line, and belongs to numerical simulation research fields in geological engineering and mining engineering fields. The method comprises: firstly, acquiring a digital topographic map of a modeling area, encrypting elevation points at a boundary of the area and an area with sparse elevation points and obtaining elevation values of each encrypted elevation point, and extracting 3D spatial information of each elevation point and saving the information; then performing surface spline interpolation on the digital topographic map, and drawing a modeling area surface 3D graphics; inputting the 3D spatial information of all the elevation points after surface splineinterpolation into a final terrain data file, and establishing a 3D numerical model by 3D discrete element method software; and by comparison and verification with the surface 3D graphics, obtaininga final 3D discrete element method numerical model of the modeling area. According to the method, high-precision numerical modeling can be performed on any complicated terrain area, and the established model surface has smaller deviation than the actual terrain surface, and the method has higher application value.

The invention belongs to the research field of geological disaster mechanism, and discloses a method for simulating the catastrophic evolution of overlying karst collapse based on the discrete elementmethod. The mechanism of overlying karst collapse and the catastrophic evolution process are analyzed by using the discrete element method. The whole process of karst collapse is revealed from the microscopic angle, including: crack formation, particle spalling, soil cavity formation, soil cavity expansion, overburden collapse and so on. The displacement of overburden soil particles, the development trend of cracks and the variation of system unbalance force are analyzed in order to truly reflect the multi-field variation characteristics of the catastrophic main body (overburden soil) under the action of external forces. The invention obtains the critical soil hole equilibrium height and the critical groundwater flow velocity formed by the soil hole of the overlying karst collapse by using the discrete element numerical simulation method, and compares with the theoretical result, and the simulation result can provide a reliable basis for the exploration and treatment of the karst collapse geological disaster, the disaster prevention and mitigation work.

The invention provides a method for predicting a distribution rule of ground surface fissures induced by underground mining of a surface mine end slope. The method comprises the following steps of collecting terrain and geology data of a surface iron mine; building an underground mining model of the surface iron mine end slope; determining the parameters of the underground mining model of the surface iron mine end slope; numerical simulation of underground mining: utilizing a three-dimensional discrete element method to calculate the numerical simulation of mining of the surface iron mine end slope, so as to obtain a rock layer and ground surface movement rule; predicting the ground surface fissures. The method has the advantages that the problem of predicting of ground surface fissures caused by the end slope mining from the surface iron mine into the underground mine is solved; a three-dimensional geology model of the rock body of the surface iron mine is established by a three-dimensional geology modeling method, and is divided into a discrete block model suitable for the 3DEC calculation; the distribution scope and type of the ground surface fissures in the underground mining process can be predicted, and the support is provided for the safety production of mines.

One embodiment of the invention provides a computer-implemented simulation system for discrete element modeling. The system comprises discrete elements corresponding to objects or particles, where each particle has a predefined set of properties. The system further has an interface for receiving at least one behaviour model for applying to the particles, and supports receipt from the at least one model of one or more custom properties for the particles. The system is responsive to receipt of the one or more custom properties to extend the discrete elements to contain both the predefined set of properties and the one or more custom properties for the particles. The system is operable to perform a simulation using discrete element modeling by applying the at least one behaviour model to the particles and to update accordingly values of the predefined and custom properties. The values of the custom particle properties are stored with the default (built-in) particle property values and can be analysed and visualised in the same way as the default property values.

The invention provides a mineral particle model parameter calibration method based on a discrete element method. The mineral particle model parameter calibration method comprises the steps that a mineral particle model parameter constitutive model based on the discrete element method is built through physical test determination and a preliminary prepared method, and the constitutive model is usedfor being combined with stacking angle determination to carry out a physical and numerical simulation dual-directional test; on the basis of preliminary verification results, mineral particle model parameters are taken as independent variables to carry out an orthogonal numerical test, a stacking angle determination value is taken as an evaluation index to carry out regression analysis, and stacking angle physical test measurement is taken as a target value to build a regression model and determine a mineral particle model parameter optimal combination; and the determined optimal combination is verified through a numerical test again, and the mineral particle model parameters based on the discrete element method are determined finally. The technical scheme solves the problems of high difficulty in obtaining parameters and low measurement accuracy of an existing mineral particle model, and provides effective technical means for determining parameters of mineral particle numerical simulation tests.

The invention discloses a three-dimensional random convex polygon block discrete element method based on a distance potential function. A research object is discretized into a block element system; carrying out contact detection on all block elements according to a nonuniform block discrete element contact detection method provided by the method; defining the distance potential function and carrying out normal contact force calculation on mutually contacting block elements, thereby obtaining normal contact force acting on each target block element and a torque caused by the normal contact force; on the basis of a tangential contact force direction vector calculation method provided by the method, carrying out calculation to obtain tangential contact force of each block element and the torque caused by the tangential contact force according to increment of tangential relative displacement; solving acceleration and angular acceleration of each block element through a rigid motion equation; and calculating velocity and displacement of each block element through a velocity verlet algorithm and describing deformation and motion state of a whole medium according to motion and relative position of each block element.

The invention provides a soil anisotropic mechanical property research idea and method from the microscopic point of view by developing a horizontal loading program and a micro-mechanical parameter monitoring program through a particle discrete element unit method. The method includes the steps of (1) obtaining stress-strain curves and related mechanical parameters of cohesionless soil according to laboratory tests; (2) establishing a plane biaxial specimen to simulate soil original anisotropy according to micromechanics parameters determined in a particle flow biaxial test in step (1); (3) establishing a plane biaxial specimen to simulate soil stress anisotropy according to the micromechanics parameters determined in the particle flow biaxial test in step (1); (4) comparing and analyzing expression rules of soil original anisotropy and the soil stress anisotropy to obtain the difference and relation between the two kinds of anisotropy and finding out microscopic mechanisms of the production of the two kinds of soil anisotropy. The soil anisotropic mechanical property research idea and method provides a new idea for the cohesionless soil anisotropic mechanical property numerical simulation by using the advantages of the particle flow discrete element method in the research of the particulate material microstructure.

The invention relates to a glutinite hydrofracture simulation method based on a discrete element. The method comprises the following steps of: S1, constructing a wall and a well bore, generating particles according to a size grading curve, and performing initial balance calculation, S2, dividing the particles into a matrix and gravel by a cutting method, endowing the matrix and the gravel with different cementing parameters, S3, adding a seepage field and endowing a corresponding flow parameter, S4, applying confining pressure on the external wall based on a servo system, setting a fluid injection speed, S5, monitoring cementing states of the particles in real time, and judging whether micro cracks are generated according to the cementing states, and S6, continuing simulation till penetration of hydraulic cracks occurs. The glutinite hydrofracture simulation method based on the discrete element can characterize crack initiation and expansion mechanisms of the hydraulic cracks preciselyfrom a microscale, and accurately capture a macro distribution morphology of the hydraulic cracks, so that the understanding of a field engineer on an expansion rule of the hydraulic cracks of a glutinite reservoir is enhanced; and a fracture design is improved.

The invention relates to a discrete element combined particle and a discrete element stacking test simulation method thereof. The discrete element combined particle comprises Clump particles at various degrees of sphericity; each Clump particle is composed of a unit ball A, a unit ball B, a unit ball C and a unit ball D; the unit ball A, the unit ball B and the unit ball C are in equal radius; the unit ball A, the unit ball B and the unit ball C are arrayed on the periphery of the unit ball D in a circumferential distribution form; the unit ball A, the unit ball B and the unit ball C are all tangent or intersected with the unit ball D; and the value n of the degree of sphericity of the Clump particles is more than or equal to 0.33 but less than or equal to 1. According to the invention, a discrete element method is adopted for developing the Clump particles and performing the stacking test simulation; a friction coefficient of the practical particle is directly utilized to simulate the mechanical characteristics of the sand particles according to the statistical result of the degree of sphericity of the particles; the defect of the traditional ball particle adopting a bigger friction coefficient is avoided; and the mechanical property is more approximate to the mechanical property of the practical sand soil.

The invention provides a calculation method and system for a rockfill concrete rockfill pile-up process. The method includes: establishing a three-dimensional model of an initial state of a rockfill block, wherein the rockfill block comprises a certain number of block rockfill bodies; analyzing the accumulation process and the final accumulation form of the three-dimensional model according to thefinite element/discrete element coupling analysis method. The finite element/discrete element coupled analysis method, which combines the finite element method to simulate structural stress and deformation with the discrete element method to track block motion, is called finite element/discrete element coupled analysis method. The method retains the advantages of finite element method and discrete element method, which can solve the kinematics and failure mechanics problems of multi-body. In the process of calculating the final accumulation form of the rockfill concrete rockfill block, thereare the characteristics of a large number of block rockfill bodies, complex stress and deformation of the rockfill body with the change of the stress. The mechanical analysis of the invention can completely depict the progressive accumulation process of the rockfill block under the action of the stress, and the calculation result is more accurate.

The invention discloses a method for simulating a discrete element muck pile form. The method comprises the steps of step 1, respectively giving a bulk modulus and a shear modulus of an integrated rock mass to normal lumpiness and shear lumpiness of an artificial joint; step 2, forecasting forecasted blasting lumpiness of all points in positions which are away from the center of a blast hole in different distances by adopting a Harries blasting model aiming at an integrated rock mass model; step 3, zoning the integrated rock mass model, and taking an average value of the forecasted blasting lumpiness of all points in all zones as preset lumpiness of discrete blocks in the all zones; step 4, setting the artificial joint according to the preset lumpiness of the discrete blocks in the all zones, setting the artificial joint in an oblique and orthogonal way, and dispersing the integrated rock mass model by adopting a discrete element method; step 5, carrying out muck pile form simulation on the dispersed integrated rock mass model by adopting the discrete element method. The method disclosed by the invention has the advantages that the operation is simple, the efficiency and the accuracy of muck pile form simulation can be obviously increased, the discrete element muck pile form is more accordant with engineering practice, and the application prospect is wide.

The invention discloses a smashed-state coarse aggregate discrete element method. The smashed-state coarse aggregate discrete element method comprises the following steps: (1) performing initial screening of coarse aggregate particles; (2) performing CT scanning; (3) performing PFC2D modeling of discrete element software; (4) calibrating parameters of a single-particle-size coarse aggregate particle contact rigidity model; (5) performing statistics to obtain the smashing amount of single-particle-size coarse aggregate particle under penetration resistance; (6) performing statistics to obtain the smashing amount of different grades of coarse aggregate particles under penetration resistance; and (7) correcting parallel connection model parameters based on the coarse aggregate particle smashing amount. Through adoption of the smashed-state coarse aggregate discrete element method, the problem that virtual coarse aggregate particles cannot be smashed in a road engineering discrete elementsimulation process is solved. Micro model parameters of particles of different particle sizes are determined by a Cluster model in discrete element software in conjunction with statistics of the smashing amount in an indoor penetration resistance test in order to simulate a smashing process of a particle material under the action of external resistance, and the virtual coarse aggregate particle shape rebuilding accuracy is ensured by image scanning.

The invention discloses a high-temperature performance virtual track test method for an asphalt mixture. The method comprises the following steps: inputting material mix proportion parameters; reconstructing a virtual track test piece; inputting parameters of a material micromodel; setting a virtual test loading environment; setting a virtual test monitoring system; operating a virtual test; and post-processing virtual test data. A discrete element method adopted by the high-temperature performance virtual track test method for the asphalt mixture is suitable for analyzing large deformation ofa discontinuous medium material and a particle material, in particular analyzing and evaluating high-temperature performance of the asphalt mixture. The test result is reliable, the test period can be shortened greatly, the test cost is lowered, and the problem that the test is limited by site and time is solved. Meanwhile, the test process can be replayed, repeated and reproduced, so that the scientific research and teaching efficiency is improved greatly.

The invention relates to a discrete-element-method-based corn threshing process analysis method. The method is used for researching the corn threshing process. The method comprises the following steps of: establishing a global coordinate system x-y-z and a first local coordinate system X-Y-Z; establishing a discrete element method analysis model of corn ears and corncobs by a spherical particle polymerization method, wherein a connection line of the spherical center of a certain sphere i which is used for forming a corn grain or a corncob and the spherical center of another composed sphere j which is contacted with the corn grain or the corncob is taken as an X' axis, and a Y' axis and a Z' axis meet a right-hand screw rule; transforming contact action repulsion of all composed spheres of each grain which is calculated in the previous step to a third local coordinate system X''-Y''-Z'', and solving resultant force; and when the corn grain is not separated from the corncob if the connection force is less than the connection force determined by the test, evaluating the new position of the remained grain relative to the corncob and updating the position of the corn grain in the third local coordinate system X''-Y''-Z''.

A method of manufacturing a glove that includes discrete elements and component systems, such as, but not limited to, lights, electrical cautery, suction, and irrigation, attached to the surgical glove. The gloves produced by this method can be used as surgical gloves or for other industrial applications. In a particular application, the method includes providing a former comprising a hand-shaped portion and a first surgical system comprising a first surgical instrument, and a first switch for controlling the first surgical system. The former includes a first depression for receiving the first surgical system. The first depression is adapted to produce an interference fit with at least a portion of the first surgical system. The first surgical system can be loaded into the first depression and a polymer coating can be applied over the loaded former to form a surgical glove.

The invention provides a numerical simulation method for predicting a selective laser melting single-melt-channel forming defect. The method comprises the steps that S1, establishing a powder bed particle model through EDEM software; s2, selecting a powder bed particle material, and gridding the powder bed particle model; s3, establishing a multi-physical-field model for simulating required heat transfer and molten pool driving force; and S4, selecting laser power and scanning speed as objects to respectively simulate multiple groups of different process parameters. The invention provides a numerical simulation method for predicting the selective laser melting single-melt-channel forming defect, the powder bed model is established through a discrete element method, a heat transfer and molten pool driving force multi-physical-field model is constructed, and numerical simulation is carried out on single-melt-channel forming to obtain a final morphology result; and the formed single meltchannel is evaluated, the defect phenomenon is analyzed, and reference is provided for optimization of technological parameters.

The invention discloses a rapid search method for a discrete element pore system based on GPU matrix calculation. The method comprises the following steps of: establishing a grid number matrix; a preliminary adjacent particle array is established, each particle being centered relative to its adjacent particle; first, a neighbor matrix N is obtained in discrete element calculation; and sorting theN matrixes in the row direction according to the connection angles, and converting the N matrixes into a connection matrix C; and using a connection matrix control search algorithm to find out a reverse connection index matrix CI of the connection matrix C and a next connection index matrix CN; and then, starting from the initial connection, a next connected index matrix CN is used for searching nodes forwards until the nodes return to the original point, and all pores of the accumulation body are obtained through the method. According to the method, the speed of a discrete element numerical method is remarkably increased, a rapid and simple method is provided for finding all holes in the fluid-solid coupling process, and dynamic simulation of a large-scale fluid-solid coupling system canbe achieved.

The invention discloses a modeling method of a discrete element fluid-solid coupling grid model based on ABAQUS-PFC3D. The method comprises the following steps: building a pretreatment grid-junction model with ABAQUS, rewriting information of the model so as to determine unit and junction information and geometric characteristics imported into a PFC flow domain grid model, importing a fluid grid into a PFC3D simulation platform, and endowing the fluid grid with hydrodynamic parameters; building sphere and wall elements, endowing with micro-parameters and initial conditions, and performing iterative operation of fluid-solid coupling analysis till balance.

The invention discloses a cross-domain simulation method and a cross-domain simulation device for large-scale pedestrian motion in a hub. A cross-domain granular discrete element method is introduced into pedestrian simulation, so that the input magnitude and the calculation efficiency are improved on the basis of keeping the simulation precision, and simulation of the large-scale pedestrian motion in the traffic hub is realized. The method comprises the following steps: S1, acquiring physical property data of pedestrians to be simulated, and constructing a pedestrian model of the pedestrians to be simulated based on the granular discrete element method; S2, acquiring geometric property data of a channel to be simulated, and constructing a channel model of the channel to be simulated; S3, constructing a stress model of pedestrian granules based on a social force model and a contact model of the granular discrete element method; and S4, putting the pedestrian model into the channel model, updating motion states of the pedestrian granules of the pedestrian model in real time by adopting the stress model, and performing pedestrian simulation on the pedestrians to be simulated.