Shaft system torsional vibration finite element model construction method of reciprocating compressor

Abstract

The invention discloses a finite element modeling method for torsional vibration of a reciprocating compressor shafting, which comprises the following steps of: converting the mass of a structural part which has relative motion relative to a crankshaft in the reciprocating compressor shafting to a crank pin by utilizing an energy equivalence principle so as to simplify the analytical calculation of the torsional vibration of the shafting (otherwise, the calculation of shafting multi-body dynamics must be carried out); and a correction coefficient is provided and applied to the adjustment of the inertia mass of the flywheel and the motor rotor, so that the dynamic parameters of the shafting are convenient to optimize. According to the method, finite element modeling is achieved through ANSYS finite element calculation software APDL, the built shaft system torsional vibration finite element model has high consistency, upgrading and improvement of the technology in the using process are facilitated, and the working efficiency of reciprocating compressor shaft system finite element model building is greatly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of ANSYS modeling, and in particular relates to a method for constructing a finite element model of torsional vibration of a reciprocating compressor shaft system. Background Art

[0002] Calculating the torsional vibration of a reciprocating compressor shaft is a crucial technology in the development and manufacturing of crank-connecting rod mechanism products and has been a focus of research both domestically and internationally. Reciprocating compressor shaft torsional vibration is essentially a dynamic analysis of the shaft. Currently, there are two main methods for shaft dynamic analysis using finite element analysis software: structural dynamics analysis and multi-body dynamics analysis. Due to various technical limitations, multi-body dynamics analysis is not currently suitable for calculating torsional vibration of reciprocating compressor shafts. The proposed method for constructing a finite element model of shaft torsional vibration is primarily applicable to shaft torsional vibration calculations using structural dynamics analysis. However, existing finite element models for torsional vibration of reciprocating compressor shafts lack design models or solutions for the material parameters of the reciprocating compressor shaft, hindering effective analysis and design in subsequent dynamic analysis. The proposed modeling method not only clarifies the material properties of each component but also addresses the issues of excessive computational effort and inefficient model construction resulting from the individual calculation of material property parameters. Summary of the Invention

[0003] The purpose of the embodiment of the present invention is to provide a method for constructing a torsional vibration finite element model of a reciprocating compressor shaft system, which mainly solves the problem that there is currently no design model or design scheme for the material parameters in the reciprocating compressor shaft system, which makes it impossible for technical personnel in this field to conduct effective analysis and design in subsequent dynamic analysis.

[0004] To solve the above technical problems, the embodiments of the present invention provide the following technical solutions:

[0005] A first aspect of the present invention provides a method for constructing a finite element model of a reciprocating compressor shaft torsional vibration, the method comprising the following steps:

[0006] S10. Based on the material properties of each component of the reciprocating compressor shaft system and the shaft system geometric model, the combined unit body is divided into unit types such as crankpin, flywheel, motor rotor, and other combined unit units. Parameters of the combined unit body of each unit type are obtained based on the characteristics of each shaft system material; the parameters include elastic modulus E, Poisson's ratio v, and material density.

[0007] Other combined units refer to all combined units in the reciprocating compressor shaft system except for the crank pins, flywheels and motor rotors;

[0008] S20. Control the size of the combined unit mesh based on factors such as the size of the shaft system calculation model and computer configuration, perform finite element meshing on the shaft system geometric model, and complete the construction of the finite element model.

[0009] Furthermore, in step S10, the elastic modulus E is 210000 MPa; and the Poisson's ratio v is 0.3.

[0010] Furthermore, in step S10, the density of the crank pin ρ i The expression is as follows:

[0011]

[0012] Where: ρ is the density of the steel material, in kg / m 3 ;

[0013] CM i is the reciprocating inertia mass of the i-th column of the compressor, in kg;

[0014] CRRM i is the rotational inertia mass of the i-th connecting rod of the compressor, in kg;

[0015] D3 is the diameter of the crank pin, in mm;

[0016] AR1 is the transition fillet radius of the crank pin, in mm;

[0017] i is the number of crankshaft rows, with the unit being i=1 to 6;

[0018] ρ i Density of the material, in T / mm 3 .

[0019] Furthermore, in step S10, the expression of the flywheel density is as follows:

[0020] ρ7=K fl ρ×10 -12 ;

[0021] Where: ρ is the density of the steel material, in kg / m 3 ;

[0022] K fl The unit is the moment of inertia adjustment coefficient;

[0023] ρ7 unit is the density of the material, T / mm 3 .

[0024] Furthermore, in step S10, the density ρ8 of the motor rotor is expressed as:

[0025]

[0026] Among them: GD 2 GD of the motor rotor 2 , unit is kg.m 2 , moment of inertia

[0027] K rot is the moment of inertia adjustment coefficient;

[0028] D and L are geometric dimensions in mm;

[0029] ρ8 is the density of the motor rotor material, in T / mm 3 .

[0030] Furthermore, in step S10, the density ρ9 of the units of other assemblies is expressed as:

[0031] ρ9=ρ×10 -12 ;

[0032] Where: ρ is the density of steel material, kg / m 3 ;

[0033] ρ9——Density of the material, T / mm 3 .

[0034] Furthermore, in step S20, grid size parameters are obtained according to the material properties of each combined unit body, wherein the parameters include the grid size parameter ESIZE_MainShift of each column of main bearings, the grid size parameter ESIZE_CrankPIN of each column of crank pins, the grid size parameter ESIZE_ConnectShift of the connecting shafts between columns, the grid size parameter ESIZE_MotorShift of the motor shaft, the grid size parameter ESIZE_Rotor of the flywheel and the motor rotor, and the grid size parameter ESIZE_Crank of the remaining parts; and the combined unit body is meshed according to the grid size parameters.

[0035] Furthermore, according to the material properties of each combined unit body, the rotational inertia adjustment coefficient parameter is obtained, including the rotational inertia adjustment coefficient parameter KFL of the flywheel and the rotational inertia adjustment coefficient parameter KROT of the motor rotor.

[0036] Furthermore, the obtained unit type, material density, and mesh size parameters of the combined unit body are used as basic parameter values ​​and added into the command stream of the computer program to establish a finite element model of the shaft system.

[0037] Compared with the prior art method of modeling each component separately and then assembling them, the present invention defines the parameters of the crankpin, flywheel, motor rotor and assembly unit separately when building the geometric model of the reciprocating compressor shaft system; and uses this to establish a geometric model; wherein the defined parameters include elastic modulus E, Poisson's ratio v, and material density; the assembly unit is all assembly units in the reciprocating compressor shaft system except for the crankpins, flywheels and motor rotors in each row; in the subsequent shaft system geometric modeling, even if the structure is different, the density setting of the structure can be achieved by simply following the corresponding definition instructions, greatly improving the work efficiency of the parametric geometric modeling of the reciprocating compressor shaft system. In addition, the finite element model construction method of the present invention converts the flexible bodies such as pistons, crossheads, and connecting rods that affect the dynamic characteristics of the shaft system into equivalent masses by defining the densities of different crankpins to achieve the transformation of the shaft system from a multi-body dynamics analysis model to a shaft system structural dynamics analysis model, thereby realizing the calculation of the shaft system torsional vibration using the structural dynamics method, and greatly shortening the solution time of the numerical simulation of the compressor shaft system torsional vibration using the multi-body dynamics method. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below.

[0039] Figure 1 A schematic structural diagram of a crankshaft system in a method for constructing a torsional vibration finite element model of a reciprocating compressor shaft system provided in the first embodiment of the present invention;

[0040] Figure 2 A schematic diagram of each combined unit body of the shaft system geometric model in a method for constructing a finite element model of torsional vibration of a reciprocating compressor shaft system provided in the first embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of defining the material elastic modulus E and Poisson's ratio v in a method for constructing a finite element model of torsional vibration of a reciprocating compressor shaft system provided in the first embodiment of the present invention;

[0042] Figure 4 A schematic diagram of defining material density ρ in a method for constructing a finite element model of torsional vibration of a reciprocating compressor shaft system provided in the first embodiment of the present invention;

[0043] Figure 5 This is a schematic diagram of creating multiple material properties (taking the second type as an example) in a method for constructing a finite element model of torsional vibration of a reciprocating compressor shaft system provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0044] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0045] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0046] Example 1

[0047] This embodiment provides a method for constructing a finite element model of a reciprocating compressor shaft system torsional vibration according to the first aspect of the present invention, the method comprising the following steps:

[0048] S10. Obtain the number of units according to the crankshaft axis system and refine them into combined units through addition operations;

[0049] S20. Based on the material properties of each component of the reciprocating compressor shaft system and the shaft system geometric model, the assembled unit body is divided into unit types such as crankpin, flywheel, motor rotor, and other assembled unit bodies. Parameters of the assembled unit body of each unit type are obtained based on the characteristics of each shaft system material; the parameters include elastic modulus E, Poisson's ratio v, and material density.

[0050] Other combined units refer to all combined units in the reciprocating compressor shaft system except for the crank pins, flywheels and motor rotors;

[0051] Among them, the elastic modulus E is a fixed value of 210000 MPa; the Poisson's ratio v is a fixed value of 0.3.

[0052] The material density of each combined unit is obtained as follows:

[0053] Density ρ of the crank pin i The expression is as follows:

[0054]

[0055] Where: ρ is the density of the steel material, in kg / m 3 ;

[0056] CM i is the reciprocating inertia mass of the i-th column of the compressor, in kg;

[0057] CRRM i is the rotational inertia mass of the i-th connecting rod of the compressor, in kg;

[0058] D3 is the diameter of the crank pin, in mm;

[0059] AR1 is the transition fillet radius of the crank pin, in mm;

[0060] i is the number of crankshaft rows, with the unit being i=1 to 6;

[0061] ρ i Density of the material, in T / mm 3 .

[0062] The expression for the flywheel density is as follows:

[0063] ρ7=K fl ρ×10 -12 ;

[0064] Where: ρ is the density of the steel material, in kg / m 3 ;

[0065] K fl The unit is the moment of inertia adjustment coefficient;

[0066] ρ7 unit is the density of the material, T / mm 3 .

[0067] The expression of the motor rotor density ρ8 is:

[0068]

[0069] Among them: GD 2 GD of the motor rotor 2 , unit is kg.m 2 , moment of inertia

[0070] K rot is the moment of inertia adjustment coefficient;

[0071] D and L are geometric dimensions in mm;

[0072] ρ8 is the density of the motor rotor material, in T / mm 3 .

[0073] The expression of the density ρ9 of the unit of other assemblies is:

[0074] ρ9=ρ×10 -12 ;

[0075] Where: ρ is the density of steel material, kg / m 3 ;

[0076] ρ9——Density of the material, T / mm 3 .

[0077] In this embodiment, it is also necessary to obtain the rotational inertia adjustment coefficient parameters according to the material properties of each combined unit, including the rotational inertia adjustment coefficient parameter KFL of the flywheel and the rotational inertia adjustment coefficient parameter KROT of the motor rotor.

[0078] S30. Control the size of the combined unit body mesh division based on factors such as the size of the shaft system calculation model and computer configuration, perform finite element mesh division on the shaft system geometric model, and complete the construction of the finite element model.

[0079] In this embodiment, in step S20, grid size parameters are obtained according to the material properties of each combined unit body, wherein the parameters include the grid size parameter ESIZE_MainShift of each row of main bearings, the grid size parameter ESIZE_CrankPIN of each row of crank pins, the grid size parameter ESIZE_ConnectShift of the connecting shafts between rows, the grid size parameter ESIZE_MotorShift of the motor shaft, the grid size parameter ESIZE_Rotor of the flywheel and the motor rotor, and the grid size parameter ESIZE_Crank of the remaining parts; and the combined unit body is meshed according to the grid size parameters.

[0080] Then, the obtained unit type, material density, and grid size parameters of the combined unit body are added to the command stream of the computer program to establish the finite element model of the shaft system, and finally the following is formed: Figure 1 The finite element model is shown.

[0081] The following will describe the specific modeling process of each step:

[0082] For step S10, ANSYS software provides users with nearly 300 different unit types. With the development of technology, some unit types are replaced by new unit types, making the application range of unit types wider and the calculation results more in line with objective reality. Whether it is unit strain, unit stress, unit stiffness, equivalent load vector, unit mass matrix, or unit damping matrix, they are all related to the unit shape function N. Different unit types have their corresponding shape functions. Therefore, the selection of appropriate unit types has a decisive influence on the torsional vibration analysis of the reciprocating compressor shaft system. The torsional vibration calculation of the reciprocating compressor shaft system belongs to a type of structural analysis (Structural). Taking into account that the finite element analysis of the shaft system adopts a solid (solid) geometric model and the mesh division adopts the basic type of free division (Free), therefore, the shaft system unit type selects the tetrahedron 10-node solid187 unit with very wide practicality, such as Figure 2 As shown in .

[0083] ANSYS software provides filters for selecting element types and other analysis options. The system defaults to Structural. When Structural is checked, the various operations in the Main Menu will only display options related to structural analysis.

[0084] 1. Definition of shafting material properties

[0085] In the calculation model of shaft torsional vibration, the stress σ of the unit is related to the elastic matrix D of the unit, the strain matrix B of the unit, and the displacement vector {δ e}, etc., where the unit strain matrix B, the unit displacement vector {δ e}In addition to being related to the geometric model, it is also related to the unit shape function N. The geometric model of the axis system and the shape function of the unit are completed through the construction of the axis system geometric model and the selection of the unit type. The elastic matrix D is a function of the material's elastic modulus E and Poisson's ratio v. Therefore, defining these two parameters is essential. Based on the characteristics of the materials that make up the reciprocating compressor shaft system, the material elastic modulus E is defined as 210,000 MPa, and the Poisson's ratio v is defined as 0.3. Furthermore, the inertial mass of the shaft system is an important load in the calculation of the shaft system's dynamic characteristics. Therefore, defining the material density is also crucial. The shaft system finite element model must consider the effects of the inertial masses of each connecting rod, crosshead, and piston on the shaft system's dynamic characteristics, while also adjusting the moment of inertia of the flywheel and motor rotor without modifying their geometric dimensions. Therefore, nine different material densities ρ are defined for the solid187 element type. These include six crankpin material densities (for applying the inertial masses of the connecting rod, crosshead, and piston), two flywheel and motor rotor material densities (for adjusting their respective moments of inertia), and one material density for the remaining structure (for all assembled elements excluding the crankpins, flywheel, and motor rotor). In summary, the finite element analysis model of shafting torsional vibration needs to define three material properties: elastic modulus E, Poisson's ratio v, and material density.

[0086] The density of each composite material is defined as follows:

[0087] (1) Density of crank pins in each row

[0088] Since reciprocating inertia mass and connecting rod rotation inertia mass need to be applied to each row of crank pins, the density ρ of each row of crank pins can be calculated according to formula (3-5): i

[0089]

[0090] Where, ρ is the density of steel material, kg / m 3

[0091] CM i ——Reciprocating inertia mass of the i-th row of compressor, kg

[0092] CRRM i ——The rotational inertia mass of the i-th connecting rod of the compressor, kg

[0093] D3——crank pin diameter, mm

[0094] AR1——Transition fillet radius of crank pin, mm

[0095] i——the number of crankshaft rows, i=1~6

[0096] ρ i ——Density of the material, T / mm 3

[0097] (2) Flywheel density ρ7

[0098] Since the flywheel is equivalent to the steel density and its own moment of inertia, the flywheel density ρ7 can be obtained according to formula (3-6), where K fl It is an adjustment coefficient that is added to adjust the moment of inertia without changing the geometric dimensions.

[0099] ρ7=K fl ρ×10 -12 (3-6)

[0100] Where, ρ is the density of steel material, kg / m 3

[0101] K fl ——Moment of inertia adjustment coefficient

[0102] ρ7——Density of the material, T / mm 3

[0103] (3) Density of the motor rotor ρ8

[0104] Since the equivalent of the motor rotor is calculated based on the given cylindrical model geometry and rotor moment of inertia, the model geometry is as follows: Figure 2 (d) As shown in the schematic diagram of the motor shaft structure, the density ρ8 of the motor rotor can be calculated by formula (3-7),

[0105]

[0106] Where GD 2 ——GD of the motor rotor 2 , kg.m 2 , moment of inertia

[0107] K rot ——Moment of inertia adjustment coefficient

[0108] D, L——geometric dimensions, mm

[0109] ρ8——density of motor rotor material, T / mm 3

[0110] (4) Density of the remaining assemblies ρ9

[0111] Except for the crank pins, flywheels, and motor rotors mentioned above, the rest of the shaft structure is made of structural steel. Therefore, the density of this part of the assembly material is the density of steel, as shown in formula (3-8):

[0112] ρ9=ρ×10 -12 (3-8)

[0113] Where, ρ is the density of steel material, kg / m 3

[0114] ρ9——Density of the material, T / mm 3

[0115] The parameters of the elastic modulus E, Poisson's ratio v, and material density ρ of each assembly material are set. Considering that the material properties of the crankshaft shaft system remain unchanged under working conditions, each parameter is defined as a constant, such as the command flow (M3-78) to (M3-80). Taking the first material as an example, the GUI operations for defining the material elastic modulus E and Poisson's ratio v are as follows: Figure 3 As shown; the GUI operation to define the material density ρ is as follows Figure 4 As described above; for the operation of creating multiple material properties, take the creation of the second material property as an example, Figure 5 First, create the second material, and then create the respective material properties according to the method of creating the first material properties. The general command flow for creating the i-th material property for the first element type is shown in (M3-81) to (M3-85). According to the calculation method of the above 9 material densities, calculate rou_i in the command flow (M3-85), that is, rou_i = ρ i . According to the general command flow (M3-81) ~ (M3-85), the material properties of the nine materials (i = 1 ~ 9) used for the finite element mesh division of the shaft system are defined respectively.

[0116] *SET,P_DENS,7850! *Assign a value to the density parameter P_DENS (M3-78)

[0117] *SET,P_PRXY,0.3! *Assign a value to the Poisson's ratio parameter P_PRXY (M3-79)

[0118] *SET,P_ex,2.1E+005! *Assign the value of the elastic modulus parameter P_ex (M3-80)

[0119] The command flow to define the properties of the i-th material is,

[0120] MPTEMP,,,,,,,, (M3-81)

[0121] MPTEMP,1,0 ! *Defines the i-th material property for the first element type (M3-82)

[0122] MPDATA,EX,i,,P_ex! *Define the elastic modulus of the i-th material as P_ex(M3-83)

[0123] MPDATA,PRXY,i,,P_PRXY! *Define the Poisson's ratio of the i-th material as P_PRXY(M3-84)

[0124] MPDATA,DENS,i,,rou_i! *Define the density of the i-th material as rou_i (M3-85)

[0125] 2. Shaft system finite element mesh division

[0126] The shaft system geometric model drawn using ANSYS software is composed of four different elements: key points, lines, surfaces, and bodies. However, in the finite element analysis of the shaft system, the required elements can only be units and nodes with specific properties. In addition, whether in terms of structural deformation, displacement or stress, they are also defined for each unit and node. Therefore, before performing the finite element analysis of the shaft system, the geometric model must be divided into finite element meshes.

[0127] 2.1 Control of assembly mesh division

[0128] The finite element meshing of the shaft system is Figure 2 The 45 units of different shapes and sizes are operated according to the volume of each unit and the stress distribution of the shaft system in engineering practice. In order to save computer resources and meet the calculation accuracy of the shaft system finite element analysis as much as possible, the mesh size should usually be refined in the key analysis parts, while the mesh of those parts with relatively small stress values ​​and less important structures can be appropriately coarsened. Therefore, the size of the combined mesh division should be controlled according to factors such as the size of the shaft system calculation model and the computer configuration. Figure 2The mesh sizes of the 45 assemblies are divided into 6 types. The mesh size of each column of main bearings is defined as the parameter ESIZE_MainShift, such as (a), (m), (o), (aa), (ac), (ao), etc.; the mesh size of each column of crankpins is defined as the parameter ESIZE_CrankPIN, such as (e), (i), (s), (w), (ag), (ak), etc.; the mesh size of the connecting shaft between columns is defined as the parameter ESIZE_ConnectShift, such as (n), (ab), (ap), etc.; the mesh size of the motor shaft (ar) is defined as the parameter ESIZE_MotorShift; the mesh size of the flywheel (aq) and the motor rotor (as) is defined as the parameter ESIZE_Rotor; the mesh size of the remaining parts is defined as the parameter ESIZE_

[0129] Crank. The command flow for assigning the initial values ​​of the grid parameters of the control assembly is shown in (M3-86) to (M3-91), and the command flow for assigning the moment of inertia coefficients of the flywheel and motor rotor is shown in (M3-92) to (M3-93).

[0130] *SET,ESIZE_CrankPIN,40

[0131] (M3-86)

[0132] *SET,ESIZE_Mainshift,50

[0133] (M3-87)

[0134] *SET,ESIZE_ConnectShift,80

[0135] (M3-88)

[0136] *SET,ESIZE_MotorShift,100

[0137] (M3-89)

[0138] *SET,ESIZE_Rotor,150

[0139] (M3-90)

[0140] *SET,ESIZE_Crank,50

[0141] (M3-91)

[0142] *SET,KFL,1(M3-92)

[0143] *SET,KROT,1

[0144] (M3-93)

[0145] 2.2 Division of the assembly grid

[0146] When using the APDL parametric language in ANSYS software to rebuild other geometric models, the size of some crankshaft structures may change, which may cause the body number of the same structure to change. In order to make the parametric meshing program universal, it is necessary to redefine the body number in the par6Mv.MAC file before meshing (the definition of each body number parameter is shown in Appendix 2) to adapt to the correct call of the parameters by the meshing program. The command flow for meshing any combination of bodies can be designed according to the following structure:

[0147] (1) Meshing of the assembly (j, i, ESIZE_NAME, m, n, VV1, ..., VVn)

[0148] TYPE,j! *j indicates the unit type

[0149] MAT,i! *i represents the i-th material property

[0150] REAL,

[0151] ESYS,0

[0152] SECNUM,

[0153] ESIZE,ESIZE_NAME,0,! *ESIZE_NAME represents the grid size parameter

[0154] FLST,5,m,6,ORDE,n

[0155] ! *m is the total number of cells divided into grids, and n is the total number of rows of "FITEM,5,**" below

[0156]

[0157] CM,_Y,VOLU

[0158] VSEL,,,,P51X

[0159] CM,_Y1,VOLU

[0160] CHKMSH,'VOLU'

[0161] CMSEL,S,_Y

[0162] VMESH,_Y1

[0163] CMDELE,_Y

[0164] CMDELE,_Y1

[0165] CMDELE,_Y2

[0166] (2) Application Examples

[0167] Now we take the meshing of a single body and multiple bodies as examples to introduce the basic methods of meshing of the above-mentioned combination. Figure 2 (a) Introduction to unit body meshing: As mentioned earlier in this chapter, the unit type is 1, the density is ρ9, the grid size parameter is ESIZE_Mainshift, m=1, n=1, and the parameter of the meshed body number is v1. Therefore, the expression for unit body meshing is the meshing of the combined body (1, 9, ESIZE_Mainshift, 1, 1, v1). Regarding meshing of multiple bodies, this paper uses Figure 2 (b) to (d) The mesh division of the three unit bodies is introduced: Similarly, from the content described earlier in this chapter, the expression for the mesh division of these three unit bodies is the mesh division of the combination (1, 9, ESIZE_Crank, 3, 3, v2, v3, v4).

[0168] The command flow for meshing the assembly (1, 9, ESIZE_Mainshift, 1, 1, v1) is shown in M3-94 through M3-110. The difference between meshing the assembly (1, 9, ESIZE_Crank, 3, 3, v2, v3, v4) and meshing the assembly (1, 9, ESIZE_Mainshift, 1, 1, v1) is that command flows M3-100 through M3-101 are replaced with command flows M3-111 through M3-114, and v1 is replaced with v2, v3, and v4.

[0169] ① Meshing of the assembly (1, 9, ESIZE_Mainshift, 1, 1, v1)

[0170] TYPE,1! *j indicates the unit type

[0171] (M3-94)

[0172] MAT,9! *i represents the i-th material property

[0173] (M3-95)

[0174] REAL, (M3-96)

[0175] ESYS, 0 (M3-97)

[0176] SECNUM, (M3-98)

[0177] ESIZE,ESIZE_Mainshift,0,! *ESIZE_NAME represents the grid size parameter (M3-99)

[0179] FLST,5,1,6,ORDE,1! *m=1, n=1

[0180] (M3-100)

[0181] FITEM,5,v1! *VV1 is the volume number parameter of the mesh unit to be divided (M3-101)

[0182] CM,_Y,VOLU

[0183] (M3-102)

[0184] VSEL,,,,P51X (M3-103)

[0185] CM,_Y1,VOLU (M3-104)

[0186] CHKMSH,'VOLU' (M3-105)

[0187] CMSEL,S,_Y

[0188] (M3-106)

[0189] VMESH,_Y1

[0190] (M3-107)

[0191] CMDELE,_Y (M3-108)

[0192] CMDELE,_Y1 (M3-109)

[0193] CMDELE,_Y2 (M3-110)

[0194] The process of meshing the assembly (1, 9, ESIZE_Mainshift, 1, 1, v1)

[0195] ②Meshing of the assembly (1, 9, ESIZE_Crank, 3, 3, v2, v3, v4)

[0196] TYPE,1! *j indicates the unit type MAT,9! *i represents the i-th material property REAL,

[0197] ESYS,0

[0198] SECNUM,

[0199] ESIZE,ESIZE_Crank,0, ! *ESIZE_NAME represents the grid size parameter FLST,5,3,6,ORDE,3! *m=3, n=3

[0200] (M3-111)

[0201] FITEM,5,v2! *VV1=v2, VV1 is the volume number parameter of the mesh unit to be divided (M3-112)

[0202] FITEM,5,v3! *VV1=v3, VV1 is the volume number parameter of the mesh unit to be divided (M3-113)

[0203] FITEM,5,v4! *VV1=v4, VV1 is the volume number parameter of the mesh unit to be divided (M3-114)

[0204] CM,_Y,VOLU

[0205] VSEL,,,,P51X

[0206] CM,_Y1,VOLU

[0207] CHKMSH,'VOLU'

[0208] CMSEL,S,_Y

[0209] VMESH,_Y1

[0210] CMDELE,_Y

[0211] CMDELE,_Y1

[0212] CMDELE,_Y2

[0213] Construction of shaft system finite element model

[0214] Now, we will introduce the method and basic process of constructing the shaft finite element model in the form of command flow. The construction of the reciprocating compressor shaft finite element model mainly includes the selection of unit type, definition of material properties, mesh division, etc. The contents of the command flow are as follows:

[0215] / PREP7 ! *Start executing Preprocessor (pre-processing) command

[0216] par6Mv! *Read all parameters defined in the par6Mv.MAC file

[0217] *SET,pi,3.1415926! *Define the value of π

[0218] *SET,P_DENS,7850! *Define the parameter value of density

[0219] *SET,P_PRXY,0.3! *Define the parameter value of Poisson's ratio

[0220] *SET,P_ex,2.1E+005! *Defines the parameter value of the elastic modulus

[0221] ET,1,SOLID187! *Define the first element type as SOLID187

[0222] !* Define the properties of the first material (column 1 crankpin)

[0223] MPTEMP,,,,,,,,

[0224] MPTEMP,1,0

[0225] MPDATA,EX,1,,P_ex

[0226] MPDATA,PRXY,1,,P_prxy

[0227] MPTEMP,,,,,,,,

[0228] MPTEMP,1,0

[0229] MPDATA,DENS,1,,P_DENS*1E-12*(1+(CM1 / 2+CRRM) / (((PI / 4)*D3*D3*L4+2*PI*AR1*AR1*(AR1*5 / 3+D3-(PI / 4)*(2*AR1+D3)))*P_DENS*1E-9))

[0230] !* Define the properties of the second material (column 2 crankpin)

[0231] MPTEMP,,,,,,,,

[0232] MPTEMP,1,0

[0233] MPDATA,EX,2,,P_ex

[0234] MPDATA,PRXY,2,,P_prxy

[0235] MPTEMP,,,,,,,,

[0236] MPTEMP,1,0

[0237] MPDATA,DENS,2,,P_DENS*1E-12*(1+(CM2 / 2+CRRM) / (((PI / 4)*D3*D3*L4+2*PI*AR1*AR1*(AR1*5 / 3+D3-(PI / 4)*(2*AR1+D3)))*P_DENS*1E-9))

[0238] !* Define the properties of the 3rd material (3rd column crankpin)

[0239] MPTEMP,,,,,,,,

[0240] MPTEMP,1,0

[0241] MPDATA,EX,3,,P_ex

[0242] MPDATA,PRXY,3,,P_prxy

[0243] MPTEMP,,,,,,,,

[0244] MPTEMP,1,0

[0245] MPDATA,DENS,3,,P_DENS*1E-12*(1+(CM3 / 2+CRRM) / (((PI / 4)*D3*D3*L4+2*PI*AR1*AR1*(AR1*5 / 3+D3-(PI / 4)*(2*AR1+D3)))*P_DENS*1E-9))

[0246] !* Define the properties of the 4th material (4th column crankpin)

[0247] MPTEMP,,,,,,,,

[0248] MPTEMP,1,0

[0249] MPDATA,EX,4,,P_ex

[0250] MPDATA,PRXY,4,,P_prxy

[0251] MPTEMP,,,,,,,,

[0252] MPTEMP,1,0

[0253] MPDATA,DENS,4,,P_DENS*1E-12*(1+(CM4 / 2+CRRM) / (((PI / 4)*D3*D3*L4+2*PI*AR1*AR1*(AR1*5 / 3+D3-(PI / 4)*(2*AR1+D3)))*P_DENS*1E-9))

[0254] !* Define the properties of the 5th material (5th column crankpin)

[0255] MPTEMP,,,,,,,,

[0256] MPTEMP,1,0

[0257] MPDATA,EX,5,,P_ex

[0258] MPDATA,PRXY,5,,P_prxy

[0259] MPTEMP,,,,,,,,

[0260] MPTEMP,1,0

[0261] MPDATA,DENS,5,,P_DENS*1E-12*(1+(CM5 / 2+CRRM) / (((PI / 4)*D3*D3*L4+2*PI*AR1*AR1*(AR1*5 / 3+D3-(PI / 4)*(2*AR1+D3)))*P_DENS*1E-9))

[0262] !* Define the properties of the 6th material (6th column crankpin)

[0263] MPTEMP,,,,,,,,

[0264] MPTEMP,1,0

[0265] MPDATA,EX,6,,P_ex

[0266] MPDATA,PRXY,6,,P_prxy

[0267] MPTEMP,,,,,,,,

[0268] MPTEMP,1,0

[0269] MPDATA,DENS,6,,P_DENS*1E-12*(1+(CM6 / 2+CRRM) / (((PI / 4)*D3*D3*L4+2*PI*AR1*AR1*(AR1*5 / 3+D3-(PI / 4)*(2*AR1+D3)))*P_DENS*1E-9))

[0270] ! *Define the properties of the 7th material (7 is the density of the flywheel, and consider that the flywheel moment of inertia is adjustable)

[0271] MPTEMP,,,,,,,,

[0272] MPTEMP,1,0

[0273] MPDATA,EX,7,,P_ex

[0274] MPDATA,PRXY,7,,P_prxy

[0275] MPTEMP,,,,,,,,

[0276] MPTEMP,1,0

[0277] MPDATA,DENS,7,,KFL*P_DENS*1E-12

[0278] ! *Define the properties of the 8th material (8 is the density of the motor rotor, considering the adjustable rotor inertia)

[0279] MPTEMP,,,,,,,,

[0280] MPTEMP,1,0

[0281] MPDATA,EX,8,,P_ex

[0282] MPDATA,PRXY,8,,P_prxy

[0283] MPTEMP,,,,,,,,

[0284] MPTEMP,1,0

[0285] DDDD1=(D26*D26*D26*D26-D21*D21*D21*D21)*L45

[0286] DDDD2=(D15*D15*D15*D15-D16*D16*D16*D16)*L45

[0287] DDDD3=(D20*D20*D20*D20-D15*D15*D15*D15)*L36

[0288] DDDD4=(D21*D21*D21*D21-D20*D20*D20*D20)*L42

[0289] DDDD=DDDD1+DDDD2+DDDD3+DDDD4

[0290] MPDATA,DENS,8,,KROT*8000*CGDD / (DDDD*PI)

[0291] ! *Define the properties of the 9th material (9 is the density ROU of steel)

[0292] MPTEMP,,,,,,,,

[0293] MPTEMP,1,0

[0294] MPDATA,EX,9,,P_ex

[0295] MPDATA,PRXY,9,,P_prxy

[0296] MPTEMP,,,,,,,,

[0297] MPTEMP,1,0

[0298] MPDATA,DENS,9,,P_DENS*1E-12

[0299] ! * Grid division of the first column main bearing ( Figure 2 (a))

[0300] Meshing of the assembly (1, 9, ESIZE_Mainshift, 1, 1, v1)

[0301] ! * Left-hand bend meshing of the 1st and 2nd columns (including L2 boss) ( Figure 2 (b) to (d)) Meshing of the assembly (1, 9, ESIZE_Crank, 3, 3, v2, v3, v4)

[0302] ! * Column 1 crank pin mesh division ( Figure 2 (e))

[0303] Meshing of the assembly (1, 1, ESIZE_CrankPIN, 1, 1, v5)

[0304] ! *Mesh division of the 1st and 2nd crankshaft turns (including L2 boss) Figure 2 (f) to (h)) Meshing of the assembly (1, 9, ESIZE_Crank, 3, 3, v6, v7, v8)

[0305] ! *Crank pin meshing in column 2

[0306] Meshing of the assembly (1, 2, ESIZE_CrankPIN, 1, 1, v9)

[0307] ! *Right bend meshing of the 1st and 2nd columns (including L2 boss)

[0308] Meshing of the assembly (1, 9, ESIZE_Crank, 3, 3, v10, v11, v12)! * Meshing of the second column main bearing

[0309] Meshing of the assembly (1, 9, ESIZE_Mainshift, 1, 1, v13)

[0310] ! *Grid division of the intermediate connecting shaft of the 2nd and 3rd rows of main bearings

[0311] Meshing of the assembly (1, 9, ESIZE_ConnectShift, 1, 1, v14)

[0312] ! *Meshing of the third row of main bearings

[0313] Meshing of the assembly (1, 9, ESIZE_Mainshift, 1, 1, v15)

[0314] ! *Meshing of the 3rd and 4th columns of left bends (including L2 boss)

[0315] Meshing of the assembly (1, 9, ESIZE_Crank, 3, 3, v16, v17, v18)! *Meshing of the crank pin in the 3rd column

[0316] Meshing of the assembly (1, 3, ESIZE_CrankPIN, 1, 1, v19)

[0317] ! *Meshing of the 3rd and 4th row crankshaft turns (including L2 boss)

[0318] Meshing of the assembly (1, 9, ESIZE_Crank, 3, 3, v20, v21, v22)! * Meshing of the crank pin in the 4th column

[0319] Meshing of the assembly (1, 4, ESIZE_CrankPIN, 1, 1, v23)

[0320] ! *Right bend meshing of the 3rd and 4th columns (including L2 boss)

[0321] Meshing of the assembly (1, 9, ESIZE_Crank, 3, 3, v24, v25, v26)! * Meshing of the 4th column main bearing

[0322] Meshing of the assembly (1, 9, ESIZE_Mainshift, 1, 1, v27)

[0323] ! *Grid division of the intermediate connecting shaft of the 4th and 5th rows of main bearings

[0324] Meshing of the assembly (1, 9, ESIZE_ConnectShift, 1, 1, v28)

[0325] ! *Mesh division of the 5th column main bearing

[0326] Meshing of the assembly (1, 9, ESIZE_Mainshift, 1, 1, v29)

[0327] ! *Meshing of the 5th and 6th columns (including L2 boss)

[0328] Meshing of the assembly (1, 9, ESIZE_Crank, 3, 3, v30, v31, v32)

[0329] ! *5th column crankpin mesh division

[0330] Meshing of the assembly (1, 5, ESIZE_CrankPIN, 1, 1, v33)

[0331] ! *Meshing of the 5th and 6th crankshaft turns (including L2 boss)

[0332] Meshing of the assembly (1, 9, ESIZE_Crank, 3, 3, v34, v35, v36)

[0333] ! *6th column crankpin mesh division

[0334] Meshing of the assembly (1, 6, ESIZE_CrankPIN, 1, 1, v37)

[0335] ! *Right bend meshing of columns 5 and 6 (including L2 boss)

[0336] Meshing of the assembly (1, 9, ESIZE_Crank, 3, 3, v38, v39, v40)

[0337] ! *6th column main bearing mesh division

[0338] Meshing of the assembly (1, 9, ESIZE_Mainshift, 1, 1, v41)

[0339] ! *Meshing of crankshaft drive end

[0340] Meshing of the assembly (1, 9, ESIZE_ConnectShift, 1, 1, v42)

[0341] ! * Flywheel structure mesh division

[0342] Meshing of the assembly (1, 7, ESIZE_Rotor, 1, 1, v43)

[0343] ! * Motor shaft mesh division

[0344] Meshing of the assembly (1, 9, ESIZE_Motorshift, 1, 1, v44)

[0345] ! *Motor rotor mesh division

[0346] Meshing of the assembly (1, 8, ESIZE_Rotor, 1, 1, v45)

[0347] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for constructing a finite element model of torsional vibration of a reciprocating compressor shaft system, characterized in that: The method comprises the following steps: S10. According to the characteristics of the materials of each part of the shaft system of the reciprocating compressor, the combined unit body is divided into unit types of crank pin, flywheel, motor rotor and other combined unit units by using the shaft system geometric model, and the parameters of the combined unit body of the unit type are obtained according to the characteristics of each material of the shaft system; wherein the parameters include elastic modulus E, Poisson's ratio v, and material density; Other combined units are all combined units in the reciprocating compressor shaft system except for the crank pins, flywheels and motor rotors of each row; S20. According to the size of the shaft system calculation model and the computer configuration, the size of the combined unit body mesh division is controlled, the shaft system geometric model is meshed by finite element, and the unit type and parameters of the combined unit body are integrated to complete the construction of the finite element model.

2. The method for constructing a finite element model of torsional vibration of a reciprocating compressor shaft system according to claim 1, characterized in that: In step S10, the elastic modulus E is 210000 MPa; the Poisson's ratio v is 0.

3.

3. The method for constructing a finite element model of torsional vibration of a reciprocating compressor shaft system according to claim 1, characterized in that: In step S10, the density of the crank pin ρ i The expression is as follows: Where: ρ is the density of the steel material, in kg / m 3 ; CM i is the reciprocating inertia mass of the i-th row of the compressor, in kg; CRRM i is the rotational inertia mass of the i-th connecting rod of the compressor, in kg; D3 is the diameter of the crank pin, in mm; AR1 is the transition fillet radius of the crank pin, in mm; i is the number of crankshaft columns, i=1~6; ρ i Density of the material, in T / mm 3 .

4. The method for constructing a finite element model of torsional vibration of a reciprocating compressor shaft system according to claim 1, characterized in that: In step S10, the expression of the flywheel density is as follows: ρ7=K fl ρ×10 -12 ; Where: ρ is the density of the steel material, in kg / m 3 ; K fl The unit is the moment of inertia adjustment factor; ρ7 unit is the density of the material, T / mm 3 .

5. The method for constructing a finite element model of torsional vibration of a reciprocating compressor shaft system according to claim 1, characterized in that: In step S10, the expression of the density ρ8 of the motor rotor is: Among them: GD 2 GD of the motor rotor 2 , unit is kg.m 2 , moment of inertia K rot is the moment of inertia adjustment coefficient; D and L are geometric dimensions in mm; ρ8 is the density of the motor rotor material, in T / mm 3 .

6. The method for constructing a finite element model of torsional vibration of a reciprocating compressor shaft system according to claim 1, characterized in that: In step S10, the expression of the density ρ9 of the unit of other assemblies is: p9=p×10 -12 ; Where: ρ——density of steel material, kg / m 3 ; ρ9——Density of material, T / mm 3 .

7. The method for constructing a finite element model of torsional vibration of a reciprocating compressor shaft system according to claim 1, characterized in that: In step S20, grid size parameters are obtained according to the material properties of each combined unit body, wherein the parameters include the grid size parameters ESIZE_MainShift of each column of main bearings, the grid size parameters ESIZE_CrankPIN of each column of crank pins, the grid size parameters ESIZE_ConnectShift of the connecting shafts between columns, the grid size parameters ESIZE_MotorShift of the motor shaft, the grid size parameters ESIZE_Rotor of the flywheel and the motor rotor, and the grid size parameters ESIZE_Crank of the remaining parts; and the combined unit body is meshed according to the grid size parameters.

8. The method for constructing a finite element model of a reciprocating compressor shaft system torsional vibration according to any one of claims 4 or 5, characterized in that: According to the material properties of each combined unit body, the rotational inertia adjustment coefficient parameter is obtained, including the rotational inertia adjustment coefficient parameter KFL of the flywheel and the rotational inertia adjustment coefficient parameter KROT of the motor rotor.

9. The method for constructing a finite element model of torsional vibration of a reciprocating compressor shaft system according to claim 1, characterized in that: The basic parameter values ​​of the unit type, material density and mesh size parameters of the combined unit body are added to the command stream of the computer program to establish the finite element model of the shaft system.

10. The method for constructing a finite element model of torsional vibration of a reciprocating compressor shaft system according to claim 7, characterized in that: Combined unit volume meshing includes: When using the APDL parametric language in ANSYS software to rebuild other geometric modeling, it is necessary to redefine each combined unit in the par6Mv.MAC file before meshing to adapt to the correct call of parameters by the meshing program. The command flow for meshing any combination is designed according to the following structure: Meshing of the assembly: j, i, ESIZE_NAME, m, n, VV1, ..., VVn in, TYPE,j! *j indicates the unit type MAT,i! *i represents the i-th material property REAL, ESYS,0 SECNUM, ESIZE,ESIZE_NAME,0,! *ESIZE_NAME represents the grid size parameter FLST,5,m,6,ORDE,n ! *m is the total number of combined units divided into grids, and n is the total number of rows of "FITEM,5,**" below CM,_Y,VOLU VSEL,,,,P51XCM,_Y1,VOLUCHKMSH,'VOLU'CMSEL,S,_YVMESH,_Y1CMDELE,_YCMDELE,_Y1CMDELE,_Y2.

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