CN116227373A - A DEM-CFD-based simulation optimization method and system for concrete manipulator operation - Google Patents

Abstract

The present invention provides a DEM-CFD-based concrete manipulator operation simulation optimization method and system, adopting discrete element (DEM) and computational fluid dynamics (CFD) coupling calculation method to simulate the wet spraying manipulator operation process, by changing the fluid model The initial conditions make the particle rebound rate the smallest in the calculation, that is, the concrete rebound rate under different wet spraying manipulator working parameters is the smallest. Guided by the wet spraying manipulator working parameters when the concrete rebound rate is the smallest, wet spraying can be realized. Optimal control of concrete manipulator operations.

Description

A DEM-CFD-based simulation optimization method and system for concrete manipulator operation

technical field

The invention belongs to the related technical field of concrete manipulator operation, and in particular relates to a DEM-CFD-based concrete manipulator operation simulation optimization method and system.

Background technique

The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

After entering the 21st century, my country's tunnel engineering has ushered in a new stage of development and construction. Statistics in recent years show that the number and length of tunnels in my country have become the first in the world's tunnel construction. As the construction of high-speed railways between cities advances to areas with complex and changeable topography, the tunnel engineering construction in my country gradually presents the characteristics of high standards, large length, large cross-section, large buried depth, and complex geology. Manual construction is limited by environmental conditions. There are many problems, which no longer meet the current tunnel construction standards. It is imperative to promote the development of tunnel construction equipment in the direction of mechanization, digitization, and intelligence.

With the application of wet spraying trolley in tunnel engineering more and more widely, its construction quality and efficiency are required to be continuously improved to meet the requirements of today's tunnel construction, and the wet spraying concrete mechanical arm is the core component of the wet spraying trolley, controlling Working quality and efficiency of wet spray trolley. The wet shotcrete robotic arm generally has the following eight degrees of freedom: big arm pitch, big arm telescopic, small arm pitch, waist rotation, horizontal arm swing, horizontal arm telescopic, gun post attitude adjustment, and wrist rotation. Through the above eight degrees of freedom, the mechanical arm coordinates the determination of the spray position, spray angle, and spray path, and achieves the "best process principle" according to different construction conditions and situations: one is to ensure that the nozzle is perpendicular to the working surface; the other is that the nozzle and the work surface Keep the distance between the surfaces at about 1 meter.

Compared with manual sprayed concrete construction, the mechanical arm can operate freely in all directions, and can maintain the best spraying angle and spraying distance for a long time. During construction, the working time is greatly shortened, the working efficiency is improved, and the concrete rebound is effectively reduced. The efficiency improves the on-site operation effect. At the same time, the reduction of the rebound rate of concrete reduces the generation of dust on the construction site, effectively improves the construction environment, and reduces the damage to workers' health.

However, the relevant research on the wet spraying concrete manipulator in my country started relatively late, and there is a lack of in-depth mechanism research on the concrete spraying flow field, incident angle, working wind pressure, spraying distance and the trajectory of the manipulator in the wet spraying manipulator. It is impossible to accurately describe the influence of the above factors on the rebound rate of concrete, resulting in poor injection quality, high rebound rate, waste of materials, etc., and even when the working wind pressure is high, weak rocks often fall off after impacting the working face. falling, concrete spalling, etc.

Contents of the invention

In order to overcome the above-mentioned deficiencies in the prior art, the present invention provides a DEM-CFD-based concrete manipulator operation simulation optimization method, using discrete element (DEM) and computational fluid dynamics (CFD) coupling calculation method to simulate wet spraying manipulator operation In the process, by changing the initial conditions of the fluid model, the particle rebound rate in the calculation is minimized, that is, the concrete rebound rate is the smallest under different wet spraying manipulator working parameters, and the wet spraying manipulator works when the concrete rebound rate is the minimum The parameters are used as a guide to realize the optimal control of the operation of the wet shotcrete manipulator.

In order to achieve the above object, one or more embodiments of the present invention provide the following technical solutions: a DEM-CFD-based concrete manipulator operation simulation optimization method, including:

Obtain the material characteristic parameters of wet sprayed concrete, and establish a concrete particle model based on discrete elements;

Obtain the concrete jet flow field under the operation of the wet shotcrete robot arm, and establish a high-pressure air computational fluid model based on computational fluid dynamics;

Coupling the concrete particle model with the high-pressure air calculation fluid model;

The initial conditions of the high-pressure air calculation fluid model were changed to simulate the operation process of the wet shotcrete manipulator under different working parameters.

A second aspect of the present invention provides a DEM-CFD-based wet shotcrete manipulator operation control system, including:

Concrete particle model building module: obtain the material characteristic parameters of wet sprayed concrete, and build a concrete particle model based on discrete elements;

High-pressure air computational fluid model establishment module: obtain the concrete jet flow field under the operation of the wet shotcrete mechanical arm, and establish a high-pressure air computational fluid model based on computational fluid dynamics;

Model coupling module: Coupling the concrete particle model with the high-pressure air calculation fluid model;

Manipulator operation simulation module: change the initial conditions of the high-pressure air calculation fluid model, and simulate the operation process of the wet shotcrete manipulator under different working parameters.

A third aspect of the present invention provides a computer-readable storage medium for storing computer instructions, and when the computer instructions are executed by a processor, the steps described in the above method are completed.

A fourth aspect of the present invention provides an electronic device, including a memory, a processor, and computer instructions stored in the memory and run on the processor. When the computer instructions are executed by the processor, the steps described in the above method are completed. .

The above one or more technical solutions have the following beneficial effects:

(1) Aiming at the actual jet flow field of wet shotcrete, a high-precision simulation model of large-scale particle-fluid system is established, which provides a numerical theoretical model basis for studying the operation of wet shotcrete manipulators.

(2) By changing the initial conditions of the fluid calculation model to simulate the operation process of the wet shotcrete manipulator under different working parameters, it provides a way of thinking for the numerical simulation research method of the wet shotcrete manipulator.

(3) Different working parameters can be set synchronously when the wet shotcrete robotic arm is working, and the comprehensive influence of various working parameters on the concrete rebound rate can be considered at the same time, so as to overcome the disadvantage of only considering a single working parameter in the traditional test and reduce the cost of trial and error , improve the efficiency of theoretical research and equipment research and development.

Advantages of additional aspects of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Description of drawings

The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention, and the schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations to the present invention.

Fig. 1 is the calculation flow chart of simulating the operation process of the wet shotcrete mechanical arm in the first embodiment of the present invention;

Fig. 2 is a schematic diagram of a wet shotcrete mechanical arm in Embodiment 1 of the present invention;

Fig. 3 is a schematic diagram of the construction movement track of the wet spraying robot arm in Embodiment 1 of the present invention;

Fig. 4 is the calculation model schematic diagram of spray gun construction in the embodiment of the present invention;

Fig. 5 is a fitting curve of concrete quality changing with time in Example 1 of the present invention.

Description of drawings, 1. Boom, 2. Forearm, 3. Nozzle, 4. Base, 5. Connecting rod, 6. Rotary motor, 7. Spray gun movement track, 8. Nozzle movement track, 9. Working surface, 10 , spray gun, 11, concrete bundle

Detailed ways

It should be noted that the following detailed description is exemplary and intended to provide further explanation of the present invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It should be noted that the terminology used here is only for describing specific embodiments, and is not intended to limit exemplary embodiments according to the present invention.

In the case of no conflict, the embodiments and the features in the embodiments of the present invention can be combined with each other.

Embodiment one

As shown in Figures 1-4, this embodiment discloses a DEM-CFD-based concrete manipulator operation simulation optimization method, including:

Step 1: Obtain the material characteristic parameters of wet sprayed concrete, and establish a concrete particle model based on discrete elements;

Step 2: Obtain the concrete jet flow field under the operation of the wet shotcrete robotic arm, and establish a high-pressure air computational fluid model based on computational fluid dynamics;

Step 3: Coupling the concrete particle model with the high-pressure air calculation fluid model;

Step 4: Change the initial conditions of the high-pressure air calculation fluid model to simulate the operation process of the wet shotcrete manipulator under different working parameters.

In step 1 of this embodiment, the indoor concrete characteristic test is carried out to obtain the characteristic parameters of the wet shotcrete material required in the field operation, wherein the characteristic parameters include: fluidity, water retention, cohesion, density ρ, strength, etc., and Record the particle size distribution of the concrete. According to the obtained concrete characteristic parameters, the concrete particle model is generated in the DEM module, and the corresponding particle contact model and microscopic parameters under the macroscopic material characteristics are calibrated.

Based on the material characteristic parameters of wet shotcrete obtained above, determine the particle radius r and particle number N in the concrete calculation model, and calibrate the mesoscopic parameters of the concrete particle model, including: particle contact model, friction coefficient μ between particles, elasticity Modulus E, stiffness k, bond strength σ and other parameters.

The calibration process of the mesoscopic parameters of the concrete particle model: carry out the numerical simulation of the indoor concrete characteristic test through DEM, first select the appropriate contact model of concrete particles, change the mesoscopic parameters in the contact model, so that the simulated concrete particles show the flow Properties such as property, cohesion, etc. are consistent with those obtained from the actual indoor concrete characteristic test. At this time, the mesoscopic parameters in the contact model are the mesoscopic parameters of the calibrated concrete particle model.

In this embodiment, it also includes: establishing the working surface in the DEM module, and calibrating the microscopic parameters of the particles and the working surface, wherein the parameters include: the contact model between the particles and the working surface, the friction coefficient μ _ball-facet , and the modulus of elasticity E _ball-facet , stiffness k _ball-facet , bond strength σ _ball-facet , etc. enable the particle model to produce bonding and rebound effects, and the spatial distribution of mass on the working surface conforms to reality.

The calibration process of the microscopic parameters of the particles and the working surface: the numerical simulation of the rebound of the concrete particles against the wall is carried out through DEM. Bonding and rebound effects are produced, and the rebound rate is controlled within 20%, and the mass space distribution on the working surface is in line with reality. At this time, the mesoscopic parameters in the contact model are the fineness of the calibrated concrete particles and the working surface. view parameters.

In step 2 of this embodiment, the operating parameters of the wet spraying trolley and the wet spraying concrete mechanical arm are obtained, and the characteristics of the jet flow field during the wet spraying operation are recorded.

Carry out on-site research and record the working parameters of the wet spraying trolley and the wet spraying concrete mechanical arm, including the working wind pressure P, the spraying distance L from the nozzle to the working surface, the spraying path, etc.; record the jet flow field during the wet spraying operation through high-speed camera equipment, Analyze and obtain the initial velocity v0 of concrete particles, the shape of the jet flow field, etc.

According to the actual concrete jet flow field, the high-pressure air calculation fluid model is generated in the CFD module. In order to ensure that the concrete particles are sprayed by the fluid during the whole process, the length of the fluid model should include the length of the nozzle and the distance from the nozzle to the working surface. At the same time, to ensure that the nozzle If there is enough range of motion, the width and height of the fluid model should be slightly larger than the width and height of the established working surface, so as to determine the calculation range of the fluid model. Considering the calculation accuracy, calculation time, modeling workload and other factors, the fluid model in the nozzle Tetrahedral grids of different sizes are used for the jet flow field model from the nozzle to the working surface area, and the flow field inside the nozzle is more complicated, so a smaller-sized tetrahedral grid can be used to refine the grid and improve the calculation accuracy .

In this embodiment, based on the recorded operating parameters of the wet spraying trolley and the wet spraying concrete manipulator, the boundary conditions for the calculation of the fluid model are set, that is, the inlet wind pressure of the high-pressure air flow field is set as the working wind pressure, and the The outlet pressure of the flow field is 100kPa (1 standard atmospheric pressure).

In this example, the coarse-grained method is used to modify the established sprayed concrete particle-fluid system, further enlarge the particle size of the model, reduce the calculation model scale, shorten the calculation time, and ensure that the calculation effect of the coarse-grained model is consistent with the original model. The model calculations have the same effect. The coarse-grained method is derived based on the energy conservation of the impulse theorem, and the interparticle force of the modified fluid-solid coupling model is:

为粗粒化后空气与颗粒间的相互作用力，/>

为原系统(粗粒化之前的耦合模型)空气与颗粒间的相互作用力，α为粗粒化颗粒与原颗粒的粒径比。in,

is the interaction force between air and particles after coarse-graining, />

is the interaction force between air and particles in the original system (coupling model before coarse-graining), and α is the particle size ratio of coarse-grained particles and original particles.

The magnitude of the force between particles and fluid:

为粗粒化后颗粒间的相互作用力，/>

为原系统颗粒间的相互作用力。in,

is the interaction force between particles after coarse-graining, />

is the interaction force between particles in the original system.

In step 3 of this embodiment, the high-pressure air calculation fluid model in the CFD module and the concrete particle model generated in the DEM module are used for coupling calculation and simulation, and the calculation is stopped when the set iteration steps are reached, and a simulation of the operation process of the wet shotcrete manipulator is completed. , to realize the high-precision simulation of the operation of the wet shotcrete manipulator.

Specifically, DEM simulation calculations can provide information such as particle position, velocity, angular velocity, and volume for CFD calculations, while CFD can provide information such as force and torque for discrete element calculations.

CFD first calculates the flow field of one time step, and then DEM starts the iterative calculation of the current time step. In this time step, DEM obtains the CFD flow field information, including the drag force and other interphase forces, and introduces the interphase forces into the particle motion calculation. In , after the DEM completes one step of calculation, the particle information and interphase force are transmitted back to the CFD module, and CFD performs the flow field calculation of the next time step.

In this embodiment, by changing the initial parameters of the fluid calculation model, wherein the initial parameters include: the speed of motion of the nozzle, the path of motion, the distance between the nozzle and the working surface, and the size of the included angle, and repeat step 3 to obtain the different initial conditions. The rebound rate of concrete, and draw a change curve, which can reflect the operating effect of the wet shotcrete manipulator under different working parameters; according to the drawn concrete rebound rate change curve, combined with digital intelligent methods, optimize the wet shotcrete The control system of the mechanical arm can control and adjust the operation of the wet shotcrete mechanical arm according to the complex tunnel construction site conditions in a timely manner, and reduce the concrete rebound rate during construction.

Figure 5 shows the fitting curve of concrete quality with time. Among them, are respectively the fitting curve of the concrete mass sprayed by the spray gun and the time-varying fitting curve of the bonded concrete mass on the working face.

Embodiment two

The purpose of this embodiment is to provide a DEM-CFD-based wet shotcrete manipulator operation control system, including:

Concrete particle model building module: obtain the material characteristic parameters of wet sprayed concrete, and build a concrete particle model based on discrete elements;

High-pressure air computational fluid model establishment module: obtain the concrete jet flow field under the operation of the wet shotcrete mechanical arm, and establish a high-pressure air computational fluid model based on computational fluid dynamics;

Model coupling module: Coupling the concrete particle model with the high-pressure air calculation fluid model;

Manipulator operation simulation module: change the initial conditions of the high-pressure air calculation fluid model, and simulate the operation process of the wet shotcrete manipulator under different working parameters.

Embodiment Three

The purpose of this embodiment is to provide a computer device, including a memory, a processor, and a computer program stored in the memory and operable on the processor, and the processor implements the steps of the above method when executing the program.

Embodiment Four

The purpose of this embodiment is to provide a computer-readable storage medium.

A computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the steps of the above-mentioned method are executed.

The steps involved in the devices of the above embodiments 2, 3 and 4 correspond to the method embodiment 1, and for specific implementation, please refer to the relevant description of the embodiment 1. The term "computer-readable storage medium" shall be construed to include a single medium or multiple media including one or more sets of instructions; and shall also be construed to include any medium capable of storing, encoding, or carrying A set of instructions to execute and cause the processor to execute any method in the present invention.

Those skilled in the art should understand that each module or each step of the present invention described above can be realized by a general-purpose computer device, optionally, they can be realized by a program code executable by the computing device, thereby, they can be stored in a memory The device is executed by a computing device, or they are made into individual integrated circuit modules, or multiple modules or steps among them are made into a single integrated circuit module for realization. The invention is not limited to any specific combination of hardware and software.

Although the specific implementation of the present invention has been described above in conjunction with the accompanying drawings, it is not a limitation to the protection scope of the present invention. Those skilled in the art should understand that on the basis of the technical solution of the present invention, those skilled in the art do not need to pay creative work Various modifications or variations that can be made are still within the protection scope of the present invention.

Claims (10)

1. A DEM-CFD-based concrete manipulator operation simulation optimization method, is characterized in that, comprising: Obtain the material characteristic parameters of wet sprayed concrete, and establish a concrete particle model based on discrete elements; Obtain the concrete jet flow field under the operation of the wet shotcrete robot arm, and establish a high-pressure air computational fluid model based on computational fluid dynamics; Coupling the concrete particle model with the high-pressure air calculation fluid model; The initial conditions of the high-pressure air calculation fluid model were changed to simulate the operation process of the wet shotcrete manipulator under different working parameters. 2. a kind of DEM-CFD-based concrete manipulator operation simulation optimization method as claimed in claim 1, is characterized in that, also comprises: obtain the concrete rebound rate under the different initial conditions of high-pressure air calculation fluid model, and draw rebound Elasticity change curve, the actual wet shotcrete manipulator is controlled by the working parameters of the wet shotcrete manipulator when the concrete rebound rate is the minimum. 3. A kind of DEM-CFD-based concrete manipulator operation simulation optimization method as claimed in claim 1, is characterized in that, the material characteristic parameter of described wet shotcrete comprises: fluidity, water retention, cohesiveness, density , strength and particle size distribution. 4. A kind of DEM-CFD-based concrete manipulator operation simulation optimization method as claimed in claim 1, it is characterized in that, based on discrete element establishment working surface, based on the concrete particle model calibration concrete particle and the mesoscopic parameter of working surface, The mesoscopic parameters include: the contact model between the particles and the working surface, friction coefficient, elastic modulus t, stiffness, and bond strength. 5. A kind of DEM-CFD-based concrete manipulator operation simulation optimization method as claimed in claim 1, is characterized in that, the working parameter of described manipulator comprises: spraying distance, spray path, nozzle movement from nozzle to working surface speed, movement route. 6. A kind of DEM-CFD-based concrete manipulator operation simulation optimization method as claimed in claim 1, is characterized in that, the setting of the boundary condition of described high-pressure air calculation fluid model is: set high-pressure air flow field inlet The wind pressure is the working wind pressure of the mechanical arm, and the outlet pressure of the high-pressure air flow field is the standard atmospheric pressure. 7. A kind of DEM-CFD-based concrete manipulator operation simulation optimization method as claimed in claim 1, is characterized in that, described high-pressure air calculation fluid model comprises the length of nozzle and the distance from nozzle to working face, and high-pressure air The width and height of the computational fluid model are greater than the width and height of the established working surface. 8. A DEM-CFD-based wet shotcrete manipulator operation control system, characterized in that it comprises: Concrete particle model building module: obtain the material characteristic parameters of wet sprayed concrete, and build a concrete particle model based on discrete elements; High-pressure air computational fluid model establishment module: obtain the concrete jet flow field under the operation of the wet shotcrete mechanical arm, and establish a high-pressure air computational fluid model based on computational fluid dynamics; Model coupling module: Coupling the concrete particle model with the high-pressure air calculation fluid model; Manipulator operation simulation module: change the initial conditions of the high-pressure air calculation fluid model, and simulate the operation process of the wet shotcrete manipulator under different working parameters. 9. A computer-readable storage medium, on which a computer program is stored, it is characterized in that, when the program is executed by a processor, a kind of concrete based on DEM-CFD as described in any one of claims 1-7 is realized Steps in an optimization method for manipulator operation simulation. 10. A processing device, comprising a memory, a processor, and a computer program stored on the memory and operable on the processor, characterized in that, when the processor executes the program, it realizes any of claims 1-7. A step in a DEM-CFD-based concrete manipulator operation simulation optimization method described in one item.

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