Sludge bin design and optimization method based on finite element analysis

Abstract

The invention discloses a sludge bin design and optimization method based on finite element analysis. The method comprises the steps that 1, a three-dimensional model of a sludge bin is established; 2, material characteristic values are added into the three-dimensional model of the sludge stock bin, and grid division is carried out; 3, after boundary strip constraint conditions and loads are added into the three-dimensional model of the sludge bin, finite element analysis software is operated, and a strength analysis result is obtained; 4, judging whether the strength analysis result meets the strength design requirement or not; if the strength analysis result does not meet the strength design requirement, returning to the step 1; if the strength analysis result meets the strength design requirement, entering the step 5; 5, carrying out optimization design to obtain an optimization design result; and 6, judging whether the optimization design result is optimal and meets the strength design requirement or not, if so, outputting the optimal three-dimensional model of the sludge bin, and if not, repeating the steps 1-5. According to the invention, the stress condition of the discharge bin under the target load can be accurately simulated, and the structure is optimized.

Description

Technical Field

[0001] The present invention belongs to the technical field of sludge silo structure design, and particularly relates to a design and optimization method of a sludge silo based on finite element analysis. Background Technique

[0002] Sludge is the product after sewage treatment, and it is an extremely complex heterogeneous body composed of organic fragments, bacterial cells, inorganic particles, colloids, etc. The main characteristics of sludge are high moisture content, high organic matter content, easy to rot and stink, and the particles are fine, with a small specific gravity, showing a colloidal liquid state, which is a thick substance between liquid and solid. A sludge silo is a device used to store sludge. After the sludge is dewatered, it is transported to the sludge silo for temporary storage by a conveying device. After the sludge reaches a certain amount, it is unloaded into a transport vehicle and transported to a designated place.

[0003] The sludge silo mainly consists of a support frame, a silo body, a sliding frame, a discharge screw, etc. Among them, the support frame and the silo body are the key stress-bearing components of the sludge silo, and the maximum stress, strength, and deflection are all important indicators for design. Since the manufacturing cost of the sludge silo is high and the cycle is long, it is difficult to conduct physical scheme verification in the initial stage of design. The traditional design method of the sludge silo is empirical design, that is, first, a technical person designs a scheme, and then manually checks the structure of the silo. If the requirements of strength, deflection, etc. are not met, it is returned for modification and checking until a scheme that meets the requirements is obtained. This design method has low efficiency, long time consumption, and depends on the experience level of technical personnel. At the same time, there are problems such as overly conservative design resulting in poor economic benefits.

[0004] With the development of modern computational mechanics, finite element simulation analysis has greatly improved the efficiency and accuracy of analysis. However, many technical personnel spend a lot of time on mesh generation due to lack of finite element simulation experience, and the unreasonable mesh generation leads to a decrease in analysis accuracy. Therefore, in order to ensure the safety and stability of the sludge silo during storage, ensure the rationality and reliability of the stress-bearing parts, ensure the economic rationality of the silo size, and ensure the reasonable mesh generation of the finite element model, it is necessary to carry out research on the design and optimization of the sludge silo based on finite element simulation. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art, provide a design and optimization method of a sludge silo based on finite element analysis, solve the problems existing in the traditional design method, improve the efficiency of structural design and the rationality of finite element model mesh generation, ensure the stability of the sludge silo during storage and transportation, and save material and processing costs.

[0006] To achieve the above purpose, the technical solution of the present invention is:

[0007] A design and optimization method of a sludge silo based on finite element analysis, including:

[0008] Step 1: Establish a 3D model of the sludge bunker;

[0009] Step 2: Add material property values to the 3D model of the sludge bunker and perform mesh division;

[0010] Step 3: Add boundary bar constraint conditions and loads to the 3D model of the sludge bunker, and then run finite element analysis software to obtain the strength analysis result;

[0011] Step 4: Determine whether the strength analysis result meets the strength design requirements; if the strength analysis result does not meet the strength design requirements, return to Step 1; if the strength analysis result meets the strength design requirements, proceed to Step 5;

[0012] Step 5: Conduct an optimization design to obtain the optimization design result;

[0013] Step 6: Determine whether the optimization design result is optimal and meets the strength design requirements. If so, output the optimal 3D model of the sludge bunker; if not, repeat Steps 1 - 5.

[0014] Optionally, the establishment of the 3D model of the sludge bunker includes:

[0015] First, establish a support frame model for the lower part of the structure in 3D software, and determine the coordinates of the top nodes of the columns in the support frame; then establish a silo body model for the upper part of the structure, and determine the coordinates of the bottom nodes of the square silo body; merge the support frame model file for the lower part of the structure and the silo body model file for the upper part of the structure according to the node coordinates to complete the assembly of the 3D model of the sludge bunker;

[0016] The support frame model is modeled using beam elements and truss elements; the silo body model is modeled using plate elements.

[0017] Optionally, the material property values include material data, cross-section, and plate thickness, and mesh division is performed; the structural material is Q235 or Q345, and the structural material parameters include: elastic modulus 2.06×108 KN / m 2 , Poisson's ratio 0.3, unit weight 76.98 KN / m 3 ;

[0018] Optionally, the mesh division includes:

[0019] The 3D model of the support frame does not need to be meshed;

[0020] The silo body model is meshed in the following way:

[0021] The plate element adopts a mapping grid 4-node area division method or an automatic mesh generation method. The plate element includes a silo bottom plate element and a silo wall plate element. The silo bottom plate element is regularly divided according to the position of the beam element in the support frame that contacts the silo bottom. The silo wall plate element is regularly divided according to the modeling position of the stiffeners around the silo wall. The quadrilateral mesh type is selected, and the dividing boundary line element is selected. The stress concentration area of the quadrilateral mesh type is refined by 2-5 mm.

[0022] Optionally, the boundary bar constraint condition is the fixed constraint at the bottom of the column of the support frame. The boundary condition is selected as a general support, and the support condition type selects the six degrees of freedom of the six-direction constraint nodes of Dx, Dy, Dz, Rx, Ry, and Rz.

[0023] Optionally, the loads include the self-weight of the structure, the vertical pressure load of the sludge acting on the silo bottom, the fluid pressure load of the sludge acting on the silo wall, the wind load, and the seismic action.

[0024] Optionally, the calculation method of the vertical pressure load of the sludge acting on the silo bottom is as follows:

[0025]

[0026] In the formula: γ—the gravity density of the stored material; ρ—the hydraulic radius of the net cross-section of the silo body; k—the lateral pressure coefficient of the stored material; μ—the friction coefficient; s is the depth of the sludge.

[0027] Optionally, the calculation method of the horizontal pressure value per unit area of the sludge acting on the silo wall is as follows:

[0028]

[0029] In the formula: γ—the gravity density of the stored material; ρ—the hydraulic radius of the net cross-section of the silo body; k—the lateral pressure coefficient of the stored material; μ—the friction coefficient; s is the depth of the sludge.

[0030] Optionally, the water content of the sludge is 70%, the density is 1300 kg / m 3 , the internal friction angle is 30°, and the sludge storage load calculation coefficient ξ is 0.333.

[0031] Optionally, the 3D software is Midas Gen software.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] The present invention provides a method for designing and optimizing a sludge silo based on finite element analysis. By establishing a three-dimensional model and performing finite element analysis, the stress condition of the silo under the target load can be accurately simulated. Using simulation analysis instead of actual processing tests improves the design accuracy, effectively reduces risks and costs; through the iterative process of simulation, the optimization process of the sludge silo is better understood, avoiding repeated waste caused by empirical design; by inputting the actual parameters of the sludge and performing mesh division according to the positions of the components of the model, the accuracy of finite element analysis is improved, ensuring the stability of the sludge silo during storage and transportation. Description of the Drawings

[0034] Figure 1 is the flow chart of the steps of the method for designing and optimizing a sludge silo based on finite element analysis provided by an embodiment of the present invention;

[0035] Figure 2 is the three-dimensional solid model of the sludge silo provided by an embodiment of the present invention;

[0036] Figure 3 is the stress result of the plate element of the sludge silo provided by an embodiment of the present invention;

[0037] Figure 4 is the stress result of the beam element of the sludge silo provided by an embodiment of the present invention;

[0038] Figure 5 is the stress result of the optimized plate element of the sludge silo provided by an embodiment of the present invention;

[0039] Figure 6 is the stress result of the optimized beam element of the sludge silo provided by an embodiment of the present invention. Detailed Embodiments

[0040] Embodiment:

[0041] The technical solutions of the present invention will be further described below with reference to the drawings and embodiments.

[0042] In the present application, the water content of the sludge stored in the sludge silo is 70%, the density is 1300 kg / m 3 , the internal friction angle is 30°, and according to the internal friction angle, the sludge storage load calculation coefficient ξ is 0.333; the structural geometric model of the sludge silo includes a silo body located at the upper part of the structure, and the silo body is connected to a support frame located at the lower part of the structure by welding; the silo body is composed of a silo bottom, a silo wall and a silo body; the support frame is composed of columns, frame beams, cross beams and diagonal braces, etc.

[0043] Refer to Figure 1 As shown, the method for designing and optimizing a sludge silo based on finite element analysis provided by this embodiment mainly includes the following steps:

[0044] Step 1: Establish a 3D model of the sludge silo;

[0045] Step 2: Add material property values to the 3D model of the sludge silo and perform mesh division;

[0046] Step 3: Add boundary bar constraint conditions and loads to the 3D model of the sludge silo and then run finite element analysis software to obtain the strength analysis result;

[0047] Step 4: Determine whether the strength analysis result meets the strength design requirements; if the strength analysis result does not meet the strength design requirements, return to Step 1; if the strength analysis result meets the strength design requirements, proceed to Step 5;

[0048] Step 5: Conduct optimization design to obtain the optimization design result;

[0049] Step 6: Determine whether the optimization design result is optimal and meets the strength design requirements. If so, output the optimal 3D model of the sludge silo; if not, repeat Steps 1 - 5.

[0050] It can be seen that through establishing a 3D model and performing finite element analysis, this method can accurately simulate the stress condition of the silo under the target load. Using simulation analysis instead of actual processing tests improves the design accuracy, effectively reduces risks and costs; through the iterative process of simulation, the optimization process of the sludge silo is better understood, avoiding repeated waste caused by empirical design; by inputting actual sludge parameters and performing fine mesh division according to the positions of each component of the model, the accuracy of finite element analysis is improved, ensuring the stability of the sludge silo during storage and transportation.

[0051] In a specific embodiment, the above Step 1 includes:

[0052] Establish a 3D model of the support frame at the lower part of the structure in Midas Gen software, determine the coordinates of the top nodes of the columns in the support frame. The support frame includes column frame beams, cross beams, etc. The 3D model of the support frame is completed by first establishing nodes and then establishing elements; then, in a new file, determine the coordinates of the bottom nodes of the square silo body in the same way and establish the silo body model at the upper part of the structure. The square silo body includes silo walls, silo bottoms, silo tops, etc. Finally, according to the node coordinates, assemble the two models into a 3D model of the sludge silo through the function of merging data files in Midas Gen. By operating in this way, the assembly of the 3D model of the sludge silo can be efficiently completed.

[0053] In a specific embodiment, the material characteristic values in step 2 include material data, cross-section and plate thickness, which are added in the material characteristic values in the Midas Gen software characteristic column. The materials mainly include two types of steel, Q235 and Q345. The cross-sections include I-shaped cross-sections, channel steels, circular tubes, box-shaped cross-sections, etc. The I-shaped cross-section dimensions include HW 300×300×10 / 15, HN400×200×8 / 13, HN 200×100×5.5 / 8, etc. The mesh division in step 2 includes: Since the support frame at the lower part of the structure is modeled using beam elements or truss elements, there is no need for mesh division. What needs to be meshed is the silo body modeled using plate elements. The plate elements adopt the mapping mesh 4-node area division method or the automatic mesh division method. The plate elements include the silo bottom plate elements and the silo wall plate elements. Among them, the silo bottom plate elements are regularly divided according to the position of the beam element model in the support frame at the lower part of the structure that contacts the silo bottom, and the silo wall plate elements are regularly divided according to the modeling position of the peripheral stiffeners of the silo wall. Select the quadrilateral mesh type, select the dividing boundary line elements, and refine the quadrilateral mesh type by 2 - 5 mm at the stress concentration points. By meshing in the above way, the mesh division time can be effectively saved, and the mesh division is reasonable, which is beneficial to improving the accuracy of subsequent finite element analysis.

[0054] In a specific embodiment, the boundary condition constraint in step 3 takes the fixed constraint at the bottom of the columns of the support frame at the lower part of the structure. The boundary condition is selected as general support, and the support condition type selects the six degrees of freedom of the six-direction constraint nodes, namely Dx, Dy, Dz, Rx, Ry, and Rz.

[0055] The added loads include the self-weight of the structure, the vertical pressure of the sludge acting on the silo bottom, the horizontal pressure of the sludge acting on the silo wall, wind load, and seismic action. Before adding the loads, it is necessary to add load cases, which are added in the static load case in the load menu bar of the software. Specifically, the self-weight of the structure is added in the self-weight option in the load menu bar of the software; the vertical pressure of the sludge acting on the silo bottom is added in the pressure load option of the software, and the input value P1 is 22.48; the horizontal pressure of the sludge acting on the silo wall is added in the fluid pressure load option of the software, the input reference height is 6.3 m, the input uniform pressure load is 0, and the input fluid specific weight is 4.329; before adding the wind load, it is necessary to add the velocity pressure, and the basic wind pressure is 0.3 KN / m 2 , and then add the wind loads WX and WY through the surface wind pressure selection; before adding the seismic action, it is necessary to input the nodal mass, and the values of mX and mY are both 1.6 KN / g. Add the response spectrum function in the seismic action option, select the seismic fortification intensity as 7 (0.10g), and finally add the seismic actions RX and RY in the response spectrum option.

[0056] Specifically, the vertical pressure load of the sludge acting on the silo bottom is calculated in the following way:

[0057]

[0058] Where: γ is the gravitational density of the stored material; ρ is the hydraulic radius of the net cross-section of the silo body; k is the lateral pressure coefficient of the stored material; μ is the friction coefficient; and S is the sludge depth.

[0059] The horizontal pressure load exerted by the sludge on the silo wall is calculated as follows:

[0060]

[0061] Where: γ is the gravitational density of the stored material; ρ is the hydraulic radius of the net cross-section of the silo body; k is the lateral pressure coefficient of the stored material; μ is the friction coefficient; and S is the sludge depth.

[0062] In this way, through the above calculation method, the vertical pressure load exerted by the sludge on the silo bottom and the horizontal pressure load exerted by the sludge on the silo wall can be accurately calculated.

[0063] Specifically, in step 4, in the load combination option in the software result menu bar, select the automatic generation of load combinations for steel structure design. Enter the plate element stress window option, select the CBS:slCB1 load combination, and select the display types including contour lines and legends. The results are as Figure 3 shown. Enter the beam element stress window option, also select the CBS:slCB1 load combination, and select the display types including contour lines and legends. The results are as Figure 4 shown. Enter the design bar menu, select the steel member design option, select the steel member check, and obtain the check results to determine whether the design requirements are met.

[0064] Specifically, after the operations in steps 1 - 4, the optimization design of the sludge silo in step 5 includes: optimizing the specifications of each component of the sludge silo. First, optimize the square silo body by optimizing the 16-mm-thick steel plate of the silo wall to 12 mm thick, the 12-mm-thick of the silo bottom to 10 mm thick, and the 10-mm-thick steel plate of the silo top to 8 mm thick; then optimize each component of the support frame. Optimize the HW300×300×10 / 15 specification column to 250×250×9 / 14, and optimize the HN400×200×8 / 13 specification frame beam to 350×175×7 / 11. Other components are optimized in the same way.

[0065] After passing the optimized model through step 3, the simulation stress results are as Figure 5 and Figure 6 shown. Check the steel members, and the results show that all members meet the design requirements.

[0066] In summary, the present method can accurately simulate the stress condition of the silo under the target load, optimize the structure, thereby providing a more accurate direction for the optimized design, ultimately ensuring the structural performance while achieving the lightweight of the structure and effectively reducing the cost.

[0067] The above embodiments are only for illustrating the technical concept and characteristics of the present invention, and the purpose is to enable those of ordinary skill in the art to understand the content of the present invention and implement it accordingly, and it is not intended to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the essence of the content of the present invention should be covered within the protection scope of the present invention.

Claims

1. A sludge silo design and optimization method based on finite element analysis, characterized in that: include: Step 1: Establish a three-dimensional model of the sludge silo; Step 2: Add material property values ​​to the 3D model of the sludge silo and perform meshing; Step 3: After adding boundary constraints and loads to the three-dimensional model of the sludge silo, run finite element analysis software to obtain strength analysis results; Step 4: Determine whether the strength analysis results meet the strength design requirements; If the strength analysis result does not meet the strength design requirements, return to step 1; If the strength analysis results meet the strength design requirements, proceed to step 5; Step 5: Perform optimization design and obtain optimization design results; Step 6: Determine whether the optimization design result is optimal and meets the strength design requirements. If so, output the optimal sludge silo three-dimensional model. If not, repeat steps 1-5.

2. The sludge silo design and optimization method based on finite element analysis according to claim 1, characterized in that: The establishment of the sludge silo three-dimensional model comprises: First, a support frame model of the lower part of the structure is established in the three-dimensional software to determine the node coordinates of the top of the column in the support frame; then, a silo model of the upper part of the structure is established to determine the node coordinates of the bottom of the square silo; according to the node coordinates, the support frame model of the lower part of the structure and the silo model file of the upper part of the structure are merged to complete the assembly of the three-dimensional model of the sludge silo; The support frame model is modeled using beam units and truss units; the warehouse body model is modeled using plate units.

3. The sludge silo design and optimization method based on finite element analysis according to claim 1, characterized in that: The material property values ​​include material data, cross section and plate thickness, and meshing is performed; The structural material is Q235 or Q345, and the structural material parameters include: elastic modulus 2.06×108KN / m 2 , Poisson's ratio 0.3, bulk density 76.98KN / m 3 .

4. The sludge silo design and optimization method based on finite element analysis according to claim 3, characterized in that: The grid division includes: The three-dimensional model of the support frame does not need to be meshed; The warehouse model is meshed in the following way: The plate unit adopts a mapping grid 4-node area division method or an automatic grid division method. The plate unit includes a warehouse bottom plate unit and a warehouse wall plate unit. The warehouse bottom plate unit is divided regularly according to the position of the beam unit in contact with the warehouse bottom in the support frame; the warehouse wall plate unit is divided regularly according to the modeling position of the peripheral reinforcement ribs of the warehouse wall. The quadrilateral grid type is selected, the split boundary line unit is selected, and the stress concentration of the quadrilateral grid type is refined by 2-5mm.

5. The sludge silo design and optimization method based on finite element analysis according to claim 1, characterized in that: The boundary strip constraint condition is a fixed constraint on the bottom of the column of the support frame, the boundary condition selects general support, and the support condition type selects the six degrees of freedom of the six direction constraint nodes of Dx, Dy, Dz, Rx, Ry, and Rz.

6. The sludge silo design and optimization method based on finite element analysis according to claim 1, characterized in that: The loads include the deadweight of the structure, the vertical pressure load of the sludge acting on the bottom of the silo, the fluid pressure load of the sludge acting on the silo wall, the wind load and the earthquake effect.

7. The sludge silo design and optimization method based on finite element analysis according to claim 6, characterized in that: The calculation method of the vertical pressure load of the sludge acting on the bottom of the silo is: In the formula: γ is the gravity density of the storage material; ρ is the hydraulic radius of the net cross-section of the silo; k is the pressure coefficient of the storage material side; μ is the friction coefficient; s is the sludge depth.

8. The sludge silo design and optimization method based on finite element analysis according to claim 6, characterized in that: The calculation method of the horizontal pressure value of the sludge acting on the unit area of ​​the silo wall is: In the formula: γ is the gravity density of the storage material; ρ is the hydraulic radius of the net cross-section of the silo; k is the pressure coefficient of the storage material side; μ is the friction coefficient; s is the sludge depth.

9. The sludge silo design and optimization method based on finite element analysis according to claim 6, characterized in that: The water content of the sludge is 70% and the density is 1300kg / m 3 , the internal friction angle is 30°, and the sludge storage load calculation coefficient ξ is 0.

333.

10. The sludge silo design and optimization method based on finite element analysis according to claim 2, characterized in that: The three-dimensional software is Midas Gen software.

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