Method for constructing finite element model of torsional vibration of reciprocating compressor shafting

Abstract

The present invention discloses a method for finite element modeling of torsional vibration of a reciprocating compressor shafting. By using the principle of energy equivalence, the mass of structural components with relative motion to the crankshaft in the reciprocating compressor shafting is converted to the crankpin to simplify the analysis and calculation of shafting torsional vibration (otherwise, the calculation of shafting multibody dynamics must be carried out), and a correction coefficient is applied for the adjustment of the inertia mass of the flywheel and the motor rotor, facilitating the optimization of shafting dynamic parameters. The finite element modeling is constructed by using the APDL language of the ANSYS finite element calculation software. This method not only makes the constructed finite element model of shafting torsional vibration highly consistent, facilitating the upgrade and improvement of this technology during use, but also greatly improves the work efficiency of constructing the finite element model of the reciprocating compressor shafting.

Description

Technical Field

[0001] The present invention belongs to the technical field of ANSYS modeling, and particularly relates to a method for constructing a finite element model of torsional vibration of a reciprocating compressor shafting. Background Technique

[0002] The torsional vibration calculation of the reciprocating compressor shafting is a crucial key technology in the development and research process of crank - connecting rod mechanism products, and has always been the focus of research at home and abroad. The torsional vibration of the reciprocating compressor shafting is actually a dynamic analysis of the shafting. At present, there are mainly two methods for shafting dynamic analysis using finite element analysis software. One is the structural dynamics analysis method, and the other is the multibody dynamics analysis method. Limited by various technologies, the multibody dynamics analysis method is not currently suitable for calculating the torsional vibration of the reciprocating compressor shafting. The method for constructing a finite element model of torsional vibration of the shafting proposed by the present invention is mainly applied to the calculation of shafting torsional vibration using the "structural dynamics analysis method"; when constructing the existing finite element model of torsional vibration of the reciprocating compressor shafting, there is currently no design model or design scheme for the material parameters in the reciprocating compressor shafting, resulting in the inability of technicians in this field to perform effective analysis and design in subsequent dynamic analysis. The modeling method proposed by the present invention not only clarifies the material properties of each combined unit body, but also solves problems such as "excessive calculation amount caused by calculating material property parameters one by one and low model construction efficiency". Summary of the Invention

[0003] The purpose of the embodiment of the present invention is to provide a method for constructing a finite element model of torsional vibration of a reciprocating compressor shafting, which mainly solves the problem that there is currently no design model or design scheme for the material parameters in the reciprocating compressor shafting, resulting in the inability of technicians in this field to perform effective analysis and design in subsequent dynamic analysis.

[0004] To solve the above - mentioned technical problems, the embodiment of the present invention provides the following technical solutions:

[0005] A method for constructing a finite element model of torsional vibration of a reciprocating compressor shafting provided by the first aspect of the present invention includes the following steps:

[0006] S10. According to the characteristics of the materials of each part of the reciprocating compressor shafting, divide the combined unit bodies into unit types such as crank pins, flywheels, motor rotors, and other combined body units according to the geometric model of the shafting, and obtain the parameters of the combined unit bodies of the unit types according to the characteristics of each material of the shafting; wherein, the parameters include elastic modulus E, Poisson's ratio v, and material density;

[0007] Other combined units refer to all combined unit bodies in the reciprocating compressor shafting except for each row of crank pins, flywheels, and motor rotors;

[0008] S20. Control the size of the mesh division of the combined unit according to factors such as the size of the shafting calculation model and the computer configuration, perform finite element mesh division on the shafting geometric model, and complete the construction of the finite element model.

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

[0010] Further, in step S10, the density ρ of the crankpin i has the following expression:

[0011]

[0012] where: ρ is the density of the steel material, with the unit of kg / m 3 ;

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

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

[0015] D3 is the diameter of the crankpin, with the unit of mm;

[0016] AR1 is the transition fillet radius of the crankpin, with the unit of mm;

[0017] i is the number of columns of the crankshaft, with the unit of i = 1 - 6;

[0018] ρ i is the density of the material, with the unit of T / mm 3 .

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

[0020] ρ7 = K fl ρ × 10 -12 ;

[0021] where: ρ is the density of the steel material, with the unit of kg / m 3 ;

[0022] K fl is the rotational inertia adjustment coefficient;

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

[0024] Further, in step S10, the expression of the density ρ8 of the motor rotor is:

[0025]

[0026] Wherein: GD 2 is the GD of the motor rotor 2 , with the unit of kg·m 2 , moment of inertia

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

[0028] D and L are geometric dimensions, with the unit of mm;

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

[0030] Furthermore, in step S10, the expression of the density ρ9 of the units of other combined bodies is:

[0031] ρ9 = ρ × 10 -12 ;

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

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

[0034] Furthermore, in step S20, according to the material properties of each combined unit body, obtain the mesh size parameter variables, wherein the parameter variables include the mesh size parameter variables ESIZE_MainShift of each column of main bearings, the mesh size parameter variables ESIZE_CrankPIN of each column of crank pins, the mesh size parameter variables ESIZE_ConnectShift of the inter-column connecting shafts, the mesh size parameter variables ESIZE_MotorShift of the motor shafts, the mesh size parameter variables ESIZE_Rotor of the flywheels and motor rotors, and the mesh size parameter variables ESIZE_Crank of the remaining parts; and perform mesh division on the combined unit bodies according to the mesh size parameter variables.

[0035] Furthermore, according to the material properties of each combined unit body, obtain the moment of inertia adjustment coefficient parameter variables, including the moment of inertia adjustment coefficient parameter variable KFL of the flywheel and the moment of inertia adjustment coefficient parameter variable KROT of the motor rotor.

[0036] Furthermore, based on the obtained unit type, material density, and mesh size parameter variables of the combined unit bodies as the basic parameter values, add them to the command stream of the computer program to establish a finite element model of the shafting.

[0037] Compared with the existing method of separately modeling each component and then assembling them, when establishing the geometric model of the reciprocating compressor shafting system in the present invention, the parameters of the crankpin, flywheel, motor rotor, and combined unit are defined respectively; and based on these, a geometric model is established. Among them, the defined parameters include the elastic modulus E, Poisson's ratio v, and material density. The combined unit refers to all the combined units in the reciprocating compressor shafting system except for each row of crankpins, flywheels, and motor rotors. In the subsequent modeling of the shafting geometric model, even if the structures are different, as long as the corresponding definition instructions are followed, the density setting of the structure can be achieved, greatly improving the working efficiency of the parametric geometric modeling of the reciprocating compressor shafting system. Moreover, in the finite element model construction method of the present invention, flexible bodies such as pistons, crossheads, and connecting rods that affect the dynamic characteristics of the shafting system are, in the form of equivalent mass, transformed from a multi-body dynamics analysis model of the shafting system to a structural dynamics analysis model of the shafting system by defining the densities of different crankpins, thereby realizing the calculation of the torsional vibration of the shafting system using the structural dynamics method and greatly shortening the solution time of the numerical simulation of the torsional vibration of the compressor shafting system using the multi-body dynamics method. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0039] Figure 1 FIG. is a schematic structural diagram of a crankshaft system in a method for constructing a torsional vibration finite element model of a reciprocating compressor shafting system provided in Embodiment 1 of the present invention;

[0040] Figure 2 FIG. is a schematic diagram of each combined unit body of the shafting geometric model in a method for constructing a torsional vibration finite element model of a reciprocating compressor shafting system provided in Embodiment 1 of the present invention;

[0041] Figure 3 FIG. is a schematic diagram for defining the elastic modulus E and Poisson's ratio v of the material in a method for constructing a torsional vibration finite element model of a reciprocating compressor shafting system provided in Embodiment 1 of the present invention;

[0042] Figure 4 FIG. is a schematic diagram for defining the material density ρ in a method for constructing a torsional vibration finite element model of a reciprocating compressor shafting system provided in Embodiment 1 of the present invention;

[0043] Figure 5 FIG. is a schematic diagram for creating multiple material properties (taking the second one as an example) in a method for constructing a torsional vibration finite element model of a reciprocating compressor shafting system provided in Embodiment 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0045] To make the above objects, features, and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0046] Embodiment 1

[0047] This embodiment provides a method for constructing a finite element model of torsional vibration of a reciprocating compressor shafting according to the first aspect of the present invention. The method includes the following steps:

[0048] S10. Obtain the number of unit bodies according to the crankshaft shafting and refine them into combined unit bodies through addition operations;

[0049] S20. According to the characteristics of the materials of each part of the reciprocating compressor shafting, divide the combined unit bodies into unit types such as crank pins, flywheels, motor rotors, and other combined body units according to the geometric model of the shafting, and obtain the parameters of the combined unit bodies of the unit types according to the characteristics of the materials of the shafting; among them, the parameters include elastic modulus E, Poisson's ratio v, and material density;

[0050] The other combined unit bodies refer to all the combined unit bodies in the reciprocating compressor shafting except for each row of 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 method for obtaining the material density of each combined unit body is as follows:

[0053] The density ρ i of the crank pin has the following expression:

[0054]

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

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

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

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

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

[0060] i is the number of columns of the crankshaft, where i = 1 - 6;

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

[0062] The expression for the density of the flywheel 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 is the moment of inertia adjustment coefficient;

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

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

[0068]

[0069] where: GD 2 is the GD of the motor rotor 2 , in 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 for the density ρ9 of the unit of other assemblies is:

[0074] ρ9 = ρ × 10 -12 ;

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

[0076] ρ9 —— is the density of the material, in T / mm 3 .

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

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

[0079] In this embodiment, in step S20, according to the material properties of each combined unit body, obtain the mesh size parameters. Among them, the parameters include the mesh size parameter ESIZE_MainShift of each column of main bearings, the mesh size parameter ESIZE_CrankPIN of each column of crank pins, the mesh size parameter ESIZE_ConnectShift of the inter-column connecting shaft, the mesh size parameter ESIZE_MotorShift of the motor shaft, the mesh size parameter ESIZE_Rotor of the flywheel and the motor rotor, and the mesh size parameter ESIZE_Crank of the remaining part; and perform mesh division of the combined unit body according to the mesh size parameters.

[0080] Then, taking the obtained element type, material density, and mesh size parameters of the combined unit body as the basic parameter values, add them to the command stream of the computer program, establish the finite element model of the shafting, and finally form a finite element model as Figure 1 shown.

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

[0082] Regarding step S10, the ANSYS software provides users with nearly 300 different element types. With the development of technology, some element types have been replaced by new element types, making the application range of element types wider and the calculation results more in line with objective reality. Whether it is element strain, element stress, element stiffness, equivalent load vector, element mass matrix, or element damping matrix, they are all related to the shape function N of the element. Different element types have their corresponding shape functions. Therefore, choosing the appropriate element type has a decisive impact on the torsional vibration analysis of the reciprocating compressor shafting. The torsional vibration calculation of the reciprocating compressor shafting belongs to a type of structural analysis. Considering that the finite element analysis of the shafting uses a solid geometric model and the mesh division uses the basic type of free division, the shafting element type is selected as the tetrahedron 10-node solid187 element with very wide practicability, as Figure 2 shown in.

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

[0084] 1. Definition of the material properties of the shafting

[0085] In the torsional vibration calculation model of the shafting, the stress σ of the element is related to the elastic matrix D of the element, the strain matrix B of the element, and the displacement vector {δ e} of the element, etc. Among them, the strain matrix B of the element and the displacement vector {δ e} are related not only to the geometric model but also to the element shape function N. The geometric model of the shafting and the shape function of the element are completed through the construction of the geometric model of the shafting and the selection of the element type. The elastic matrix D is a function of the elastic modulus E and Poisson's ratio v of the material. Therefore, it is essential to define the elastic modulus E and Poisson's ratio v of the material. According to the characteristics of the materials that make up the reciprocating compressor shafting, the elastic modulus E of the material is defined as 210000 MPa, and Poisson's ratio v is defined as 0.3. At the same time, the inertial mass of the shafting is an important load in the calculation of the dynamic characteristics of the shafting. Therefore, defining the material density is also an important content. Since the finite element model of the shafting needs to consider the influence of the inertial masses of the connecting rods, crossheads, pistons, etc. in each column on the dynamic characteristics of the shafting, and also needs to be able to adjust its moment of inertia without modifying the geometric dimensions of the flywheel and motor rotor, it is necessary to define 9 different material densities ρ for the solid187 element type, including 6 material densities of the crank pins (applying the inertial masses of the connecting rods, crossheads, pistons, etc.), 2 material densities of the flywheel and motor rotor (adjusting their respective moments of inertia), and 1 material density of the remaining structures (all combined unit bodies except the crank pins, flywheel, and motor rotor in each column). In summary, the finite element analysis model of the shafting torsional vibration needs to define the properties of 3 materials, namely the elastic modulus E, Poisson's ratio v, and material density.

[0086] The density definitions of the materials of each combined unit are as follows:

[0087] (1) The density of the crank pins in each column

[0088] Since the reciprocating inertial mass and the rotational inertial mass of the connecting rod need to be applied at the crank pins in each column, the density ρ of the crank pins in each column can be calculated according to Equation (3-5) i

[0089]

[0090] In the formula, ρ —— is the density of the steel material, kg / m 3

[0091] CM i —— the reciprocating inertia mass of the i-th column of the compressor, kg

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

[0093] D3—— the diameter of the crankpin, mm

[0094] AR1—— the transition fillet radius of the crankpin, mm

[0095] i—— the number of columns of the crankshaft, i = 1 to 6

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

[0097] (2) The density ρ7 of the flywheel

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

[0099] ρ7 = K fl ρ × 10 -12 (3-6)

[0100] In the formula, ρ—— is the density of the steel material, kg / m 3

[0101] K fl —— the moment of inertia adjustment coefficient

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

[0103] (3) The density ρ8 of the motor rotor

[0104] Since the equivalence of the motor rotor is calculated according to the geometric dimensions of the given cylinder model and the rotor moment of inertia, where the geometric dimensions of the model are as shown in Figure 2 (d) the structural schematic diagram of the motor shaft, then the density ρ8 of the motor rotor can be calculated by Equation (3-7),

[0105]

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

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

[0108] D, L—— Geometric dimensions, mm

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

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

[0111] For other structures of the shafting except for the above-mentioned crank pins, flywheels, and motor rotors in each column, structural steel materials are used. Therefore, the density of this part of the assembly material is the density of steel, as shown in Equation (3-8).

[0112] ρ9 = ρ × 10 -12 (3-8)

[0113] In the formula, ρ—— Density of steel material, kg / m 3

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

[0115] For the setting of parameters such as the elastic modulus E, Poisson's ratio v, and material density ρ of each assembly material, considering that the material properties of each part of the crankshaft shafting remain unchanged under working conditions, the various parameters are defined as constants, such as the command flows (M3-78) to (M3-80). Taking the first material as an example, the GUI operations for defining the elastic modulus E and Poisson's ratio v of the material are as Figure 3 shown; the GUI operation for defining the material density ρ is as Figure 4 described; for the operation of creating multiple material properties, taking the creation of the second material property as an example, as Figure 5 shown. First, create the second material, and then create their respective material properties according to the method of creating the first material property. The general command flow for creating the i-th material property for the first element type is as shown in (M3-81) to (M3-85). According to the calculation method of the 9 material densities above, calculate rou_i in the command flow (M3-85) respectively, that is, rou_i = ρ i . Define the material properties of the 9 materials (i = 1 to 9) used for the finite element mesh division of the shafting according to the general command flows (M3-81) to (M3-85).

[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 to the elastic modulus parameter P_ex (M3-80)

[0119] The command stream for defining the material property of the i-th material is

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

[0121] MPTEMP,1,0! Define the material property of the i-th type for the first type of element (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. Finite element mesh generation of the shafting

[0126] The geometric model of the shafting drawn using ANSYS software consists of four different elements: key points, lines, surfaces, and volumes. However, in the process of finite element analysis of the shafting, the required elements can only be elements and nodes with specific properties. In addition, whether in terms of structural deformation, displacement, or stress, etc., they are also defined for each element and node. Therefore, before performing finite element analysis of the shafting, it is necessary to perform finite element mesh generation on the geometric model.

[0127] 2.1 Control of combined body mesh generation

[0128] The finite element mesh generation of the shafting is performed on Figure 2 the 45 unit bodies with different shapes and sizes shown. According to the volume of each unit body and the stress distribution of the shafting in engineering practice, in order to save computer resources and try to meet the calculation accuracy of the finite element analysis of the shafting, the meshes in the key analysis parts are usually refined when selecting the mesh size, while the meshes in the parts with relatively small stress values and less important structures can be coarsened appropriately. Therefore, the size of the combined body mesh generation should be controlled according to factors such as the size of the shafting calculation model and the computer configuration. This article will Figure 2The mesh sizes of 45 assemblies are divided into 6 types. The mesh sizes of the main bearings in each column are defined as the parameter ESIZE_MainShift, such as (a), (m), (o), (aa), (ac), (ao), etc.; the mesh sizes of the crank pins in each column are defined as the parameter ESIZE_CrankPIN, such as (e), (i), (s), (w), (ag), (ak), etc.; the mesh sizes of the connecting shafts between columns are 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 sizes of the flywheel (aq) and the motor rotor (as) are defined as the parameter ESIZE_Rotor; the mesh sizes of the remaining parts are defined as the parameter ESIZE_

[0129] Crank. The command flow for controlling the initial value assignment of the assembly mesh parameters is shown in (M3-86) to (M3-91), and the command flow for controlling the assignment of the moment of inertia coefficients of the flywheel and the 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 combined body mesh

[0146] When reconstructing other geometric models using the APDL parametric language in ANSYS software, due to changes in the structural dimensions of some crankshafts, the body numbers of the same structure may change. To make the parametric mesh generation program universal, it is necessary to redefine each body number in the par6Mv.MAC file before mesh generation (see Appendix 2 for the definition of each body number parameter variable) to adapt to the correct call of parameters by the mesh generation program. The command flow for the mesh generation of any combined body can be designed according to the following structure:

[0147] (1) Mesh generation of the combined body (j, i, ESIZE_NAME, m, n, VV1,..., VVn)

[0148] TYPE,j !*j represents the jth element type

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

[0150] REAL,

[0151] ESYS,0

[0152] SECNUM,

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

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

[0155] !*m is the total number of cell bodies to be meshed, and n is the total number of lines 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] Taking the meshing of a single entity and multiple entities as examples respectively, the basic method of the combined entity meshing is introduced. Regarding the meshing of a single entity, this article takes Figure 2 (a) The meshing of the element body is introduced: As can be seen from the content described earlier in this chapter, its element type is 1, density is ρ9, the mesh size parameter is ESIZE_Mainshift, m = 1, n = 1, and the parameter of the entity number to be meshed is v1. Therefore, the expression for the meshing of the element body is the meshing of the combined entity (1, 9, ESIZE_Mainshift, 1, 1, v1); Regarding the meshing of multiple entities, this article takes Figure 2 (b) - (d) The meshing of three element bodies is introduced: Similarly, from the content described earlier in this chapter, the expressions for the meshing of these three element bodies are the meshing of the combined entity (1, 9, ESIZE_Crank, 3, 3, v2, v3, v4).

[0168] The command stream for the meshing of the combined entity (1, 9, ESIZE_Mainshift, 1, 1, v1) is shown in M3 - 94 to M3 - 110. The difference between the meshing of the combined entity (1, 9, ESIZE_Crank, 3, 3, v2, v3, v4) and the meshing of the combined entity (1, 9, ESIZE_Mainshift, 1, 1, v1) is that the command stream M3 - 100 to M3 - 101 is replaced with the command stream M3 - 111 to M3 - 114, and v1 is replaced with v2, v3, v4.

[0169] ① The meshing of the combined entity (1, 9, ESIZE_Mainshift, 1, 1, v1)

[0170] TYPE,1! *j represents the jth element type (M3 - 94)

[0171] MAT,9! *i represents the ith material property (M3 - 95)

[0172] REAL, (M3 - 96)

[0173] ESYS,0 (M3 - 97)

[0174] SECNUM, (M3 - 98)

[0175] ESIZE,ESIZE_Mainshift,0,! *ESIZE_NAME represents the mesh size parameter (M3 - 99)

[0176] FLST,5,1,6,ORDE,1! *m = 1, n = 1 (M3 - 100)

[0177] FITEM,5,v1! *VV1 is the body number parameter variable of the meshed body element (M3 - 101)

[0178] CM,_Y,VOLU (M3 - 102)

[0179] VSEL,,,,P51X (M3 - 103)

[0180] CM,_Y1,VOLU (M3 - 104)

[0181] CHKMSH,'VOLU' (M3 - 105)

[0182] CMSEL,S,_Y (M3 - 106)

[0183] VMESH,_Y1 (M3 - 107)

[0184] CMDELE,_Y (M3 - 108)

[0185] CMDELE,_Y1 (M3 - 109)

[0186] CMDELE,_Y2 (M3 - 110)

[0187] The process of meshing the combined body (1, 9, ESIZE_Mainshift, 1, 1, v1)

[0188] ② The meshing of the combined body (1, 9, ESIZE_Crank, 3, 3, v2, v3, v4)

[0189] TYPE,1! *j represents the jth element type MAT,9! *i represents the ith material property REAL,

[0190] ESYS,0

[0191] SECNUM,

[0192] ESIZE,ESIZE_Crank,0,! *ESIZE_NAME represents the mesh size parameter variable FLST,5,3,6,ORDE,3! *m = 3, n = 3

[0193] (M3 - 111)

[0194] FITEM,5,v2! *VV1 = v2, VV1 is the body number parameter variable of the meshed body element (M3 - 112)

[0195] FITEM,5,v3! *VV1 = v3, VV1 is the volume number parameter variable of the meshed body element (M3 - 113)

[0196] FITEM,5,v4! *VV1 = v4, VV1 is the volume number parameter variable of the meshed body element (M3 - 114)

[0197] CM,_Y,VOLU

[0198] VSEL,,,,P51X

[0199] CM,_Y1,VOLU

[0200] CHKMSH,'VOLU'

[0201] CMSEL,S,_Y

[0202] VMESH,_Y1

[0203] CMDELE,_Y

[0204] CMDELE,_Y1

[0205] CMDELE,_Y2

[0206] Construction of the shafting finite element model

[0207] Now, the method and basic process of constructing the shafting finite element model will be introduced in the form of command stream. The construction of the reciprocating compressor shafting finite element model mainly includes the selection of element types, the definition of material properties, mesh generation, etc. The content of this command stream is as follows,

[0208] / PREP7! *Start executing the Preprocessor commands

[0209] par6Mv! *Read all parameters defined in the par6Mv.MAC file

[0210] *SET,pi,3.1415926! *Define the value of π

[0211] *SET,P_DENS,7850! *Define the parameter value of density

[0212] *SET,P_PRXY,0.3! *Define the parameter value of Poisson's ratio

[0213] *SET,P_ex,2.1E+005! *Define the parameter value of elastic modulus

[0214] ET,1,SOLID187 !*Define the first element type as SOLID187

[0215] !*Define the properties of the first material (the first column crankpin)

[0216] MPTEMP,,,,,,,,

[0217] MPTEMP,1,0

[0218] MPDATA,EX,1,,P_ex

[0219] MPDATA,PRXY,1,,P_prxy

[0220] MPTEMP,,,,,,,,

[0221] MPTEMP,1,0

[0222] 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))

[0223] !*Define the properties of the second material (the second column crankpin)

[0224] MPTEMP,,,,,,,,

[0225] MPTEMP,1,0

[0226] MPDATA,EX,2,,P_ex

[0227] MPDATA,PRXY,2,,P_prxy

[0228] MPTEMP,,,,,,,,

[0229] MPTEMP,1,0

[0230] 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))

[0231] !*Define the properties of the third material (the third column crankpin)

[0232] MPTEMP,,,,,,,,

[0233] MPTEMP,1,0

[0234] MPDATA,EX,3,,P_ex

[0235] MPDATA,PRXY,3,,P_prxy

[0236] MPTEMP,,,,,,,,

[0237] MPTEMP,1,0

[0238] 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))

[0239] ! * Define the properties of the 4th material (the 4th column crankpin)

[0240] MPTEMP,,,,,,,,

[0241] MPTEMP,1,0

[0242] MPDATA,EX,4,,P_ex

[0243] MPDATA,PRXY,4,,P_prxy

[0244] MPTEMP,,,,,,,,

[0245] MPTEMP,1,0

[0246] 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))

[0247] ! * Define the properties of the 5th material (the 5th column crankpin)

[0248] MPTEMP,,,,,,,,

[0249] MPTEMP,1,0

[0250] MPDATA,EX,5,,P_ex

[0251] MPDATA,PRXY,5,,P_prxy

[0252] MPTEMP,,,,,,,,

[0253] MPTEMP,1,0

[0254] 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))

[0255] ! * Define the properties of the 6th material (the 6th column crank pin)

[0256] MPTEMP,,,,,,,,

[0257] MPTEMP,1,0

[0258] MPDATA,EX,6,,P_ex

[0259] MPDATA,PRXY,6,,P_prxy

[0260] MPTEMP,,,,,,,,

[0261] MPTEMP,1,0

[0262] 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))

[0263] ! * Define the properties of the 7th material (7 is the density of the flywheel, and the moment of inertia of the flywheel is considered adjustable)

[0264] MPTEMP,,,,,,,,

[0265] MPTEMP,1,0

[0266] MPDATA,EX,7,,P_ex

[0267] MPDATA,PRXY,7,,P_prxy

[0268] MPTEMP,,,,,,,,

[0269] MPTEMP,1,0

[0270] MPDATA,DENS,7,,KFL*P_DENS*1E-12

[0271] ! * Define the properties of the 8th material (8 is the density of the motor rotor, considering the adjustable rotor inertia situation)

[0272] MPTEMP,,,,,,,,

[0273] MPTEMP,1,0

[0274] MPDATA,EX,8,,P_ex

[0275] MPDATA,PRXY,8,,P_prxy

[0276] MPTEMP,,,,,,,,

[0277] MPTEMP,1,0

[0278] DDDD1 = (D26 * D26 * D26 * D26 - D21 * D21 * D21 * D21) * L45

[0279] DDDD2 = (D15 * D15 * D15 * D15 - D16 * D16 * D16 * D16) * L45

[0280] DDDD3 = (D20 * D20 * D20 * D20 - D15 * D15 * D15 * D15) * L36

[0281] DDDD4 = (D21 * D21 * D21 * D21 - D20 * D20 * D20 * D20) * L42

[0282] DDDD = DDDD1 + DDDD2 + DDDD3 + DDDD4

[0283] MPDATA,DENS,8,,KROT * 8000 * CGDD / (DDDD * PI)

[0284] ! * Define the properties of the 9th material (9 is the density ROU of steel)

[0285] MPTEMP,,,,,,,,

[0286] MPTEMP,1,0

[0287] MPDATA,EX,9,,P_ex

[0288] MPDATA,PRXY,9,,P_prxy

[0289] MPTEMP,,,,,,,,

[0290] MPTEMP,1,0

[0291] MPDATA, DENS, 9, , P_DENS * 1E - 12

[0292] ! * Mesh generation for the main bearing in the first column ( Figure 2 (a))

[0293] Mesh generation for the combined body (1, 9, ESIZE_Mainshift, 1, 1, v1)

[0294] ! * Mesh generation for the left crank throw in the first and second columns (including the L2 boss) ( Figure 2 (b) - (d)) Mesh generation for the combined body (1, 9, ESIZE_Crank, 3, 3, v2, v3, v4)

[0295] ! * Mesh generation for the crank pin in the first column ( Figure 2 (e))

[0296] Mesh generation for the combined body (1, 1, ESIZE_CrankPIN, 1, 1, v5)

[0297] ! * Mesh generation for the middle crank throw of the first and second crankshafts (including the L2 boss) ( Figure 2 (f) - (h)) Mesh generation for the combined body (1, 9, ESIZE_Crank, 3, 3, v6, v7, v8)

[0298] ! * Mesh generation for the crank pin in the second column

[0299] Mesh generation for the combined body (1, 2, ESIZE_CrankPIN, 1, 1, v9)

[0300] ! * Mesh generation for the right crank throw in the first and second columns (including the L2 boss)

[0301] Mesh generation for the combined body (1, 9, ESIZE_Crank, 3, 3, v10, v11, v12)! * Mesh generation for the main bearing in the second column

[0302] Mesh generation for the combined body (1, 9, ESIZE_Mainshift, 1, 1, v13)

[0303] ! * Mesh generation for the intermediate connecting shaft of the main bearings in the second and third columns

[0304] Mesh generation for the combined body (1, 9, ESIZE_ConnectShift, 1, 1, v14)

[0305] ! * Mesh generation for the main bearing in the third column

[0306] Mesh generation for the combined body (1, 9, ESIZE_Mainshift, 1, 1, v15)

[0307] ! * Mesh generation for the left crank throws of the 3rd and 4th columns (including the L2 boss)

[0308] Mesh generation for the combined body (1, 9, ESIZE_Crank, 3, 3, v16, v17, v18)! * Mesh generation for the crankpin of the 3rd column

[0309] Mesh generation for the combined body (1, 3, ESIZE_CrankPIN, 1, 1, v19)

[0310] ! * Mesh generation for the middle crank throws of the 3rd and 4th columns of the crankshaft (including the L2 boss)

[0311] Mesh generation for the combined body (1, 9, ESIZE_Crank, 3, 3, v20, v21, v22)! * Mesh generation for the crankpin of the 4th column

[0312] Mesh generation for the combined body (1, 4, ESIZE_CrankPIN, 1, 1, v23)

[0313] ! * Mesh generation for the right crank throws of the 3rd and 4th columns (including the L2 boss)

[0314] Mesh generation for the combined body (1, 9, ESIZE_Crank, 3, 3, v24, v25, v26)! * Mesh generation for the main bearing of the 4th column

[0315] Mesh generation for the combined body (1, 9, ESIZE_Mainshift, 1, 1, v27)

[0316] ! * Mesh generation for the intermediate connecting shaft of the main bearings of the 4th and 5th columns

[0317] Mesh generation for the combined body (1, 9, ESIZE_ConnectShift, 1, 1, v28)

[0318] ! * Mesh generation for the main bearing of the 5th column

[0319] Mesh generation for the combined body (1, 9, ESIZE_Mainshift, 1, 1, v29)

[0320] ! * Mesh generation for the left crank throws of the 5th and 6th columns (including the L2 boss)

[0321] Mesh generation for the combined body (1, 9, ESIZE_Crank, 3, 3, v30, v31, v32)

[0322] ! * Mesh generation for the crankpin of the 5th column

[0323] Mesh generation for the combined body (1, 5, ESIZE_CrankPIN, 1, 1, v33)

[0324] ! * Mesh generation of the middle crankpin of the 5th and 6th column crankshafts (including L2 boss)

[0325] Mesh generation of the combined body (1, 9, ESIZE_Crank, 3, 3, v34, v35, v36)

[0326] ! * Mesh generation of the crankpin of the 6th column

[0327] Mesh generation of the combined body (1, 6, ESIZE_CrankPIN, 1, 1, v37)

[0328] ! * Mesh generation of the right crankthrow of the 5th and 6th columns (including L2 boss)

[0329] Mesh generation of the combined body (1, 9, ESIZE_Crank, 3, 3, v38, v39, v40)

[0330] ! * Mesh generation of the main bearing of the 6th column

[0331] Mesh generation of the combined body (1, 9, ESIZE_Mainshift, 1, 1, v41)

[0332] ! * Mesh generation of the drive end of the crankshaft

[0333] Mesh generation of the combined body (1, 9, ESIZE_ConnectShift, 1, 1, v42)

[0334] ! * Mesh generation of the flywheel structure

[0335] Mesh generation of the combined body (1, 7, ESIZE_Rotor, 1, 1, v43)

[0336] ! * Mesh generation of the motor shaft

[0337] Mesh generation of the combined body (1, 9, ESIZE_Motorshift, 1, 1, v44)

[0338] ! * Mesh generation of the motor rotor

[0339] Mesh generation of the combined body (1, 8, ESIZE_Rotor, 1, 1, v45)

[0340] The above are only the specific implementation manners of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope 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 reciprocating compressor shaft system, the combined unit body is divided into unit types of crank pin, flywheel, motor rotor and other combined unit units based on 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 , 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. Control the size of the combined unit body mesh division according to the size of the shaft system calculation model and the computer configuration, perform finite element mesh division on the shaft system geometric model, and integrate the unit type and parameters of the combined unit body to complete the construction of the finite element model; In step S10, the density of the crank pin The expression is as follows: ； in: is the density of steel material, in kg / m 3 ; is the reciprocating inertia mass of the i-th row of the compressor, in kg; is the rotational inertia mass of the i-th connecting rod of the compressor, in kg; is the diameter of the crank pin, in mm; is the transition fillet radius of the crank pin, in mm; The number of crankshaft columns, in units of i=1~6; Density of the material, in T / mm 3 .

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 210000Mpa; Poisson's ratio 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 expression of the flywheel density is as follows: ； in: is the density of steel material, in kg / m 3 ; The unit is the moment of inertia adjustment factor; The unit is the density of the material, 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 density of the motor rotor The expression is: ； in: GD of the motor rotor 2 , unit is kg.m 2 , moment of inertia ; is the moment of inertia adjustment coefficient; , is the geometric dimension, in mm; The density of the motor rotor material, in 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 density of the units of other assemblies The expression is: ； in: ——density of steel material, kg / m 3 ; ——Density of the material, 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 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.

7. The method for constructing a finite element model of a reciprocating compressor shaft system torsional vibration according to any one of claims 3 or 4, 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.

8. 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.

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