CN100483426C - Method of border modeling with CAD model based discrete element method - Google Patents
Method of border modeling with CAD model based discrete element method Download PDFInfo
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Abstract
本发明涉及一种基于CAD模型的离散元法边界建模方法，包括以下步骤：a)读取和识别以机械部件为边界的CAD模型中所包含的基本图形元素及其拓扑结构和特征参数；b)去除读取和识别基本图形元素中冗余图形；c)设置基本图形元素的运动属性参数和材料特性参数；d)基本图形元素的类型、特征参数、运动属性参数和材料特性参数保存到数据库中；e)由离散元法软件读取存储在数据库中的边界基本图形元素信息，并按离散元法对边界的要求建立每个基本图形元素的离散元法计算实例，再将这些实例存储，以供离散元法计算时使用。解决了现有离散元法不能满足复杂结构和运动方式机械部件的设计、离散元法性能分析、设计修改和再分析的要求等问题。
The present invention relates to a discrete element method boundary modeling method based on a CAD model, comprising the following steps: a) reading and identifying basic graphic elements and their topological structures and characteristic parameters contained in a CAD model with mechanical parts as the boundary; b) remove redundant graphics in reading and identifying basic graphic elements; c) set motion attribute parameters and material property parameters of basic graphic elements; d) save the type, characteristic parameters, motion attribute parameters and material property parameters of basic graphic elements to In the database; e) read the basic graphic element information of the boundary stored in the database by the discrete element method software, and establish the discrete element method calculation instance of each basic graphic element according to the requirements of the discrete element method for the boundary, and then store these instances , for use in discrete element method calculations. It solves the problem that the existing discrete element method cannot meet the requirements of the design of complex structures and moving mechanical parts, the performance analysis of the discrete element method, design modification and reanalysis.
Description
Technical field
When the present invention relates to adopt distinct element method to analyze bulk granular material and mechanical part (claiming the border again) contact action, a kind of method of setting up mechanical part distinct element method analytical model, when being particularly suitable for adopting CAD software design mechanical part, cad model (CAD design drawing) by mechanical part is directly set up its distinct element method analytical model, the situation when adopting the distinct element method software analysis to estimate the mechanical part serviceability then.
Background technology
In industrial and agricultural production, exist the flow process of bulk granular material (as rock, coal, soil, silt, agricultural product and granulated fertilizer etc.) in a large number.During as planting with sowing machine, exist flowing of seed, fertilizer and soil all the time; When ploughing the farmland, exist flowing of soil all the time; Agricultural product results, conveying, classification, processing and packing etc. also exist flowing of relevant bulk granular material all the time.
Flowing of bulk granular material except that outside the Pass having with mechanical property own, also relevant with version, dimensional parameters and the kinematic parameter etc. of associated mechanical components.A good mechanical part design, bulk granular material is flowed according to the formula of anticipation, as seed flows when sowing, reduce unnecessary damage in the flow process, as seed damage when sowing, the saving machine power consumes, and as trench digging with traction power consumption when ploughing soil, must consider the contact action and the dynamics problem thereof of mechanical part and bulk granular material this moment.
The character of bulk granular material is between solid and fluid, though grain pattern is simple, complicated mechanical characteristic is arranged.Adopt the contact action of continuum mechanics method research bulk granular material and mechanical part, can only do shot colony as a wholely to consider, can't analyze the motion process and the intergranular contact action of each particle in the shot colony, thereby can not address this problem well.When carrying out the design of relevant mechanical part at present, mostly rely on experience or test method, both wasted time and energy again less than the ideal designs effect, and only carried the relevant device utilization loss that is caused just to reach 40%, the requirement that end far away reaches optimal design and saves the energy according to estimates by bulk granular material.
The seventies in 20th century, Cundall proposes distinct element method, its basic thought is that shot colony is simplified to the set with definite shape and quality particle, give between the contact particle and certain contact mechanics model and Model parameter between particle and Contact Boundary (mechanical part), to consider to reach between the shot the contact action between shot and border and the different physical-mechanical propertiess on bulk solid and border.Distinct element method adopt dynamic relaxation method, Newton second law and the time step each particle of iterative movement velocity and displacement, thereby be particularly suitable for finding the solution nonlinear problem.Because it is discrete, when analyzing the high complexity system, no matter be that big simplification all need not done in bulk solid or border.When adopting cohesive strength or linking mechanical model, can also analyze the destructive process (as pulverizing and cut-out etc.) of shot caking or integral material.Just because of plurality of advantages, make distinct element method become a kind of universal method of research shot group dynamics problem, and it is mobile in Geotechnical Engineering and dust storm, the conveying of bulk granular material, mixing, classification, the caking of particle and collision, soil and mechanical interaction, research fields such as Chemical Processing Equipment and mine equipment are used widely.
When adopting distinct element method to analyze the contact action of bulk granular material and mechanical part, need set up the distinct element method analytical model of mechanical part.But it is up to the present,, also less for the discussion of boundary modeling about the research of distinct element method mostly concentrates on aspects such as the geometric model of prose style free from parallelism particle and contact mechanics model.The distinct element method analysis software of report, though all have the boundary modeling module, but adopt the method for specific function and command stream mostly, also the border design is not combined with its distinct element method performance evaluation, thereby can not satisfy design, distinct element method performance evaluation, the Change In Design of labyrinth and mode of motion mechanical part and the requirement of analyzing again.And the method for directly setting up its distinct element method analytical model by the cad model on border is not appeared in the newspapers as yet.
Summary of the invention
The objective of the invention is the border design not to be combined with its distinct element method performance evaluation in order to solve above-mentioned existing distinct element method, and can not satisfy design, distinct element method performance evaluation, the Change In Design of labyrinth and mode of motion mechanical part and the problems of analyzing again such as requirement, a kind of distinct element method boundary modeling method based on cad model is provided.
Above-mentioned purpose of the present invention is achieved in that accompanying drawings is as follows.
A kind ofly set up the method for its distinct element method analytical model by the cad model that with the mechanical part is the border, this method comprises following 5 steps:
A) reading and discern with the mechanical part is primary graphic element and topological structure and the characteristic parameter that is comprised in the cad model on border;
B) redundant pattern in the primary graphic element is read and discerns in removal;
C) the movement properties parameter and the material characteristic parameter of primary graphic element are set;
D) type of primary graphic element, characteristic parameter, movement properties parameter and material characteristic parameter are saved in the database;
E) read the border primary graphic element information that is stored in the database by distinct element method software, the type and characteristic parameter, primary graphic element movement properties parameter and the primary graphic element material properties parameter that comprise primary graphic element, and the requirement on border is set up the distinct element method calculated examples of each primary graphic element by distinct element method, with these example storages, use when calculating again for distinct element method.
The primary graphic element that reads is straight section, circle and arc section, ellipse and oval segmental arc or plane, sphere, ellipsoid, cylinder and the conical surface etc.;
Primary graphic element with same movement rule, kinematic parameter and material behavior is provided with identical movement properties and material characteristic parameter value;
The movable information of the geological information of primary graphic element type and characteristic parameter, primary graphic element movement properties parameter and the material information of primary graphic element material characteristic parameter store in the database;
Described distinct element method boundary modeling method based on cad model comprises causing that computing machine carries out the computer-readable medium of the instruction of following method, and this method comprises:
A) read and discern primary graphic element and topological structure and the characteristic parameter that is comprised in the cad model of border;
B) redundant pattern in the primary graphic element is read and discerns in removal;
C) the movement properties parameter and the material characteristic parameter of primary graphic element are set;
D) type of primary graphic element, characteristic parameter, movement properties parameter and material characteristic parameter are saved in the database;
E) read the border primary graphic element information that is stored in the database by distinct element method software, the geological information (primary graphic element type and characteristic parameter), movable information (primary graphic element movement properties parameter) and the material information (primary graphic element material properties parameter) that comprise primary graphic element, and the requirement on border is set up the distinct element method calculated examples of each primary graphic element by distinct element method, with these example storages, use when calculating again for distinct element method.
A kind of computer-readable medium, the primary graphic element that reads are straight section, circle and arc section, ellipse and oval segmental arc or plane, sphere, ellipsoid, cylinder and the conical surface etc.;
A kind of computer-readable medium, the primary graphic element with same movement rule, kinematic parameter and material behavior is provided with identical movement properties and material characteristic parameter value;
A kind of computer-readable medium, the geological information of primary graphic element (primary graphic element type and characteristic parameter), movable information (primary graphic element movement properties parameter) and material information (primary graphic element material characteristic parameter) store in the database;
A kind of computer-readable medium reads and discerns primary graphic element, removes redundant pattern in the primary graphic element and the movement properties parameter and the material characteristic parameter of primary graphic element are set, and realizes by man-machine interaction mode.
The characteristics of this method are: 1. can directly be generated its distinct element method analytical model by the cad model of mechanical part, and also can realize the integrated of CAD software and distinct element method performance evaluation software on this basis, thereby organically combine with its distinct element method performance evaluation with the mechanical part CAD design of bulk granular material contact action; 2. can pass through to revise the cad model of mechanical part in the design phase, mechanical part to different structure and size carries out performance evaluation and evaluation, working resistance, wear condition assay as plough, the degree of depth, width and the soil mobility status assay of plough trench digging, simple grain rate during sowing, hole rate and seed broken rate assay etc. directly produce design decision with the optimization of realization mechanical part organization plan and dimensional parameters or according to designing requirement; 3. can carry out the dynamic simulation of the mechanical part course of work by the cad model of mechanical part, analyze the mechanical part of its working mechanism and invention new principle thus, this existing method for designing and designing technique can't realize.
Description of drawings
Fig. 1 makes up the cad model (front view) of inner hole precision metering device;
Fig. 2 makes up the distinct element method analytical model of inner hole precision seeder;
The Process Simulation of (when diameter is 158mm) combination inner hole precision seeder when Fig. 3 (a) changes seed wheel diameter in the cad model;
The Process Simulation of (when diameter is 218mm) combination inner hole precision seeder when Fig. 3 (b) changes seed wheel diameter in the cad model;
The Process Simulation of combination inner hole precision seeder when Fig. 4 (a) changes pack hole diameter (diameter is 14mm) in the cad model;
Pack hole diameter (diameter is 24mm) makes up the Process Simulation of inner hole precision seeder constantly in Fig. 4 (b) change cad model;
The Process Simulation of combination inner hole precision seeder when Fig. 5 (a) changes bulk granular material (ellipse grains seed) geometric model;
The Process Simulation of combination inner hole precision seeder when Fig. 5 (b) changes bulk granular material (rounded grain seed) geometric model;
The Process Simulation of combination inner hole precision seeder when Fig. 6 (a) changes distinct element method calculating parameter (when seed wheel angular velocity omega, ω=π rad/s);
The Process Simulation of combination inner hole precision seeder when Fig. 6 (b) changes distinct element method calculating parameter (seed wheel angular velocity omega, ω=2 π rad/s);
The Process Simulation of another kind of hole roller formula feed mechanism for seed when Fig. 7 (a) changes cad model;
The Process Simulation of second kind of hole roller formula feed mechanism for seed when Fig. 7 (b) changes cad model;
The Process Simulation of a kind of ejector dozer of Fig. 8;
The Process Simulation of a kind of dozer of Fig. 9;
Figure 10 makes up the experiment of the inner hole precision seeder course of work;
Figure 11 makes up inner hole precision seeder Process Simulation;
The distinct element method boundary modeling method of Figure 12 cad model and the computation process block diagram of distinct element method;
The integrated analysis design software structure and the process flow diagram of a kind of mechanical part with the bulk granular material contact action of Figure 13.
Embodiment
Further specify particular content of the present invention below in conjunction with the accompanying drawing illustrated embodiment.
In general, the cad model of mechanical part (CAD design drawing) is a more complicated, but they all are made up of some primary graphic elements (hereinafter to be referred as primary graphic element), as straight-line segment, circular arc, elliptic arc etc. (two-dimensional CAD model) or (three-dimensional CAD models) such as plane, sphere, ellipsoid, cylinder and the conical surfaces, as a kind of general modeling method, be that to set up model be feasible method on the basis with the primary graphic element.The method concrete steps of setting up border distinct element method analytical model by cad model that the present invention proposes are: 1. read and discern the primary graphic element and topological structure and the characteristic parameter that are comprised in the cad model of border (mechanical part); 2. remove redundant pattern element in the primary graphic element; 3. the movement properties parameter and the material characteristic parameter of primary graphic element are set; 4. the type of primary graphic element, characteristic parameter, movement properties parameter and material characteristic parameter store in the database; 5. read the primary graphic element information that is stored in the database by distinct element method software, comprise geological information (primary graphic element type and characteristic parameter), movable information (primary graphic element movement properties parameter) and material information (primary graphic element material characteristic parameter), and set up the distinct element method calculated examples of each primary graphic element, again with each calculated examples storage, use when calculating, promptly set up the border distinct element method analytical model that comprises border (mechanical part) geometric model, kinematics model and material behavior thus for distinct element method.
It is to comprise which primary graphic element and type in the cad model of identification border that primary graphic element reads, and extracts characteristic parameter, as the starting point and the terminating point of straight-line segment; The center of circular arc, radius, start-stop angle; The center of sphere, radius, start-stop position etc.
The redundant pattern of removing in the primary graphic element is to remove the disappearance part of some primary graphic element, as the rectangular window on the circular hole on the plane, sphere or the conical surface etc.
Movement properties is set is distinguished border (parts) the given different motion characteristic value of primary graphic element of Different Exercise Mode, when distinct element method calculating reappears with result of calculation emulation, to adopt different processing modes, as translation and rotation, to-and-fro movement and periodicity variable motion etc.In order when distinct element method calculates, to consider the different physical-mechanical propertiess on different materials border, adopted the method for adding material characteristic parameter, have different material characteristic parameters as rigidity with soft border, the rough and smooth border etc.These 2 functions are undertaken by man-machine interaction mode, the user selects one or more primary graphic elements in cad model, by adding the parameter of expression Different Exercise Mode and dissimilar material properties, realize the binding of geological information, movable information and the material information of primary graphic element with this.
The user also needs primary graphic element type, characteristic parameter, movement properties parameter and material characteristic parameter after handling are saved in the database, so that read this data when the distinct element method analytical calculation after the CAD design drawing is carried out above-mentioned processing.
During the distinct element method analytical calculation, read the border primary graphic element information that is stored in the database by distinct element method software, the geological information (primary graphic element type and characteristic parameter), movable information (primary graphic element movement properties parameter) and the material information (primary graphic element material characteristic parameter) that comprise primary graphic element, and the requirement on border is set up the distinct element method calculated examples of each primary graphic element by distinct element method, with these example storages, use when calculating again for distinct element method.After the user designs or has chosen a cad model and the above-mentioned processing of process, distinct element method software can take out corresponding primary graphic element and parameter automatically in database, primary graphic element of every taking-up is just created a distinct element method calculated examples according to its type and parameter, and then with this example storage, use when calculating, so promptly set up the border distinct element method analytical model that comprises boundary geometrical model, kinematics model and material behavior for distinct element method.
The computation process of distinct element method is: determine the position of primary graphic element in coordinate system, a certain instantaneous border according to the border primary graphic element geological information, movable information and the material information that read, the contact condition of definite again primary graphic element at this moment and prose style free from parallelism particle is also found the solution contact point and is calculated contact force, obtain the movement velocity and the displacement of this instantaneous each prose style free from parallelism particle again by Newton second law and numerical integration method, also need the distortion of computation bound for soft border.Instantaneous at next, primary graphic element moves to a reposition according to the given characteristics of motion, redefine the position of primary graphic element in coordinate system again, and then the contact condition of definite primary graphic element and this instantaneous prose style free from parallelism particle and find the solution contact point and the calculating contact force, again obtain the movement velocity and the displacement of this instantaneous each prose style free from parallelism particle again by Newton second law and numerical integration method, so repeat promptly to have finished the distinct element method analytical calculation of bulk granular material and mechanical part contact action.
By as can be seen above-mentioned, the distinct element method analytical model of mechanical part is set up in employing based on cad model, when distinct element method calculates, the mechanical part primary graphic element is the same with prose style free from parallelism particle to be handled, difference only is: the mechanical part primary graphic element is different with prose style free from parallelism coating of particles, and primary graphic element is by given characteristics of motion motion.
In an embodiment of the present invention, constituted a kind of software application to realize said method, this software application package is drawn together being used for of being constituted and is caused that computing machine refers to the instruction of the described method of row, these instructions can be stored on the computer-readable medium of any kind, and these media can unconfinedly comprise CD-ROM, floppy disk, tape and solid-state memory etc.
AutoCAD2000 software is being carried out on the basis of secondary development, utilize Object ARX2000 to read for the primary graphic element that AutoCAD adds, remove redundant pattern in the primary graphic element, the genus characterisitic parameter is set, storage waits the executable order of computing machine, thereby realized reading and discerning of primary graphic element and topological structure, remove redundant pattern in the primary graphic element, primary graphic element is set belongs to characterisitic parameter etc., wherein removing redundant pattern in the primary graphic element is to adopt the method for asking the primary graphic element intersection point, primary graphic element after the processing utilizes ADO, the ODBC technology stores in the Access database one by one, read the primary graphic element data in the database when distinct element method calculates and create the distinct element method calculated examples of each primary graphic element, and then these example pointers are deposited in the array, use when calculating for distinct element method, promptly realized thus setting up its distinct element method analytical model by the cad model of mechanical part, and also realized distinct element method performance evaluation software integrated of AutoCAD software and independent development on this basis, thereby develop a kind of integrated analysis design software of mechanical part of and bulk granular material contact action.
Fig. 1 is a kind of internal filling type precision seeder---the cad model of combination inner hole precision seeder, Fig. 2 this feed mechanism for seed distinct element method analytical model for using this integrated analysis design software to set up by cad model, Fig. 3, Fig. 4, Fig. 5 and Fig. 6 are respectively and use this software by revising parameter, bulk granular material (seed) geometric model and distinct element method calculating parameter in the cad model, the distinct element method performance evaluation and the Process Simulation of this feed mechanism for seed that obtains, the circular or oval seed grain of representing among the figure.Fig. 7 is for using distinct element method performance evaluation and the Process Simulation of this software by other two kinds of hole roller formula feed mechanism for seeds of revising cad model and obtaining, Fig. 8 and Fig. 9 are for a change behind cad model and the contact mechanics model, the distinct element method performance evaluation and the Process Simulation of a kind of ejector dozer and a kind of dozer, the circular soil particle of representing among the figure.Figure 10 is under the identical condition of work with Figure 11 of being taken by KodakPS-220 high-speed video camera system, the practical working situation of combination inner hole precision seeder, relatively Figure 10 and Figure 11 are as can be known, the mass motion trend comparison of seed is similar in the combination inner hole precision seeder, has proved the feasibility and the advantage of this method and software thus.
Though the present invention can have various changes and modifications, its certain embodiments is to represent by the mode of example in accompanying drawing and the explanation followed.Yet should be appreciated that accompanying drawing and explanation are not to limit the invention to described certain embodiments.The disclosure is to cover distortion, equivalent and the remodeling that all belong to the spirit and scope of the present invention of claims definition.
Though describe the present invention, should be appreciated that embodiment is exemplary, and scope of the present invention is not limited to these embodiment with reference to certain embodiments.Many variations, remodeling, additional and to improve be feasible to described embodiment.Particularly these variations can comprise computing machine or other data processing equipment, comprise computer-readable medium (such as floppy disk, CD-ROM, the DVD-ROM etc.) memory storage of software, firmware or other enforcement said method programming, computer memory etc.These variations, remodeling, additional and improvement are considered to belong in following claim in the described scope of the present invention.
Claims (4)
1, a kind of distinct element method boundary modeling method based on cad model is characterized in that this method comprises following 5 steps:
A) reading and discern with the mechanical part is primary graphic element and topological structure and the characteristic parameter that is comprised in the cad model on border;
B) redundant pattern in the primary graphic element is read and discerns in removal;
C) the movement properties parameter and the material characteristic parameter of primary graphic element are set;
D) type of primary graphic element, characteristic parameter, movement properties parameter and material characteristic parameter are saved in the database;
E) read the border primary graphic element information that is stored in the database by distinct element method software, the type and characteristic parameter, primary graphic element movement properties parameter and the primary graphic element material properties parameter that comprise primary graphic element, and the requirement on border is set up the distinct element method calculated examples of each primary graphic element by distinct element method, with these example storages, use when calculating again for distinct element method.
2, the distinct element method boundary modeling method based on cad model according to claim 1 is characterized in that the primary graphic element that reads is straight section, circle and arc section, ellipse and oval segmental arc or plane, sphere, ellipsoid, cylinder and the conical surface;
3, the distinct element method boundary modeling method based on cad model according to claim 1, the primary graphic element that it is characterized in that having same movement rule, kinematic parameter and material behavior is provided with identical movement properties and material characteristic parameter value.
4, the distinct element method boundary modeling method based on cad model according to claim 1 is characterized in that the geological information of primary graphic element type and characteristic parameter, the movable information of primary graphic element movement properties parameter and the material information of primary graphic element material characteristic parameter store in the database.
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| FR2907938B1 (en) * | 2006-10-27 | 2008-12-19 | Peugeot Citroen Automobiles Sa | METHOD FOR COMPUTER ASSISTED DESIGN OF A MECHANICAL ASSEMBLY |
| US7814443B2 (en) * | 2007-01-16 | 2010-10-12 | International Business Machines Corporation | Graph-based pattern matching in L3GO designs |
| CN102415243B (en) * | 2011-10-04 | 2013-10-30 | 吉林大学 | Discrete-element-method-based corn threshing process analysis method |
| CN102298660B (en) * | 2011-10-10 | 2013-05-15 | 吉林大学 | A General Method of Discrete Element Method Boundary Modeling |
| CN103235854B (en) * | 2013-04-24 | 2016-01-20 | 武汉大学 | Contact determination methods in a kind of discrete element emulation between spheric grain and triangle gridding |
| CN107644120B (en) * | 2017-08-16 | 2020-10-09 | 南京大学 | A Simulation Method of a Universal Numerical Simulation Box for 3D Discrete Element Rapid Modeling of Rock and Soil |
| CN109241607B (en) * | 2017-09-27 | 2023-05-30 | 山东农业大学 | Proportioning variable fertilization discrete element model parameter calibration method based on correlation vector machine |
| CN108520138B (en) * | 2018-04-02 | 2022-03-11 | 重庆大学 | Block discrete element model generation method based on progressive finite element mesh and segmentation method |
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