CN115310223A - Simulation and mechanical state characterization method for engine rotor bolt set - Google Patents
Simulation and mechanical state characterization method for engine rotor bolt set Download PDFInfo
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- CN115310223A CN115310223A CN202210862248.3A CN202210862248A CN115310223A CN 115310223 A CN115310223 A CN 115310223A CN 202210862248 A CN202210862248 A CN 202210862248A CN 115310223 A CN115310223 A CN 115310223A
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- G06F30/00—Computer-aided design [CAD]
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- G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces
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Abstract
The invention discloses a simulation and mechanical state characterization method for an engine rotor bolt set, which comprises the following steps: s1, establishing an engine rotor model, wherein the model comprises a thin layer unit surface, and extracting an information input file of a structure finite element model; s2, extracting an information input file, and numbering bolt holes by using a method of reading image information by Python; s3, calling the Abaqus load and the function of the analysis step module by using Python, applying pretightening force to the bolt according to the bolt number and the bolt number according to the bolt hole number in the S1, and introducing the Python file into the Abaqus for analysis; and S4, outputting stress change values and connection rigidity change values of all units of cylinders and round tables around the screw rod with the bolt as the axis, which are obtained by Abaqus mechanical analysis in the S3. The invention improves the simulation precision while improving the efficiency of analyzing the bolt connection structure.
Description
Technical Field
The invention relates to the technical field of computer technology and finite element simulation, in particular to a bolt group simulation and mechanical state characterization method.
Background
Bolt sets are widely used in engines. Due to elastic interaction, the final pretightening force and the connection rigidity of the bolt group are greatly influenced by the tightening sequence of the bolt group. Therefore, in order to determine the optimal bolt tightening process, finite element simulation software is used for carrying out simulation analysis on the pretightening force of the bolt group connection.
With the development of computer technology, the method has wide application in processing and analyzing data by using Python, and the modeling and analyzing steps can be greatly simplified by using the Python to perform Abaqus secondary development.
The traditional method needs a great deal of time for the arrangement of the steps of engine rotor bolt modeling and simulation before processing and subsequent analysis. In the traditional method, when the influence of the tightening sequence on the pretightening force and the connection rigidity is analyzed, the data of the whole rotor is mostly processed, and the bolts only play a great role in partial areas of the connection parts. In addition, the influence of the pretightening force of the bolt on the contact rigidity of the joint surface is not considered in the calculation of the traditional method, so that a result obtained by simulation has certain difference from the actual condition. Therefore, when the traditional method is adopted for modeling and simulation, the problems of low efficiency, long time consumption and the like exist, and the effect is not satisfactory.
Disclosure of Invention
The invention aims to solve the defects of the prior art and provides a simulation and mechanical state characterization method of an engine rotor by combining Python. The method can be used for carrying out batch modeling and simulation analysis on part of the structure of the engine rotor model to obtain the stress change value and the connection rigidity change value of the cylinder and the cone around the screw rod with the bolt as the axis.
In order to solve the technical problems, the invention adopts the following technical scheme: a simulation and mechanical state characterization method for an engine rotor bolt set is characterized by comprising the following steps:
step S1: establishing a finite element model of the engine rotor, wherein the finite element model comprises thin-layer unit surfaces which are respectively arranged between a flange plate and a rotor contact surface, and the periphery of a screw rod taking a bolt as an axis is divided into a cone unit at the upper side and a cone unit at the lower side and a cylinder unit in the middle; extracting an information input file of the structure finite element model;
step S2: reading an information input file, and numbering bolt holes by using a method of reading image information by Python;
and step S3: calling the functions of the Abaqus load and the analysis step module by using Python, sequentially applying pretightening force to the bolts according to the bolt hole numbers obtained in the S1 and the bolt numbers, and introducing the Python file into the Abaqus for batch analysis;
and step S4: and outputting stress change values and connection rigidity change values of all units around the screw rod with the bolt as the axis, which are obtained by the Abaqus mechanical analysis in the S3.
Further, in the step S1: the engine rotor model comprises a flange, a rotor and a bolt and a nut, wherein the bolt and the nut are the bolt and the nut after simplifying threads.
Further, the upper surface of the circular truncated cone unit is a contact surface between the head of the bolt and the flange, and the included angle theta between the side edge of the circular truncated cone and the screw is calculated according to the formula:
k is the thickness ratio K of the two rotors is less than or equal to 1; c is the difference between the nominal diameter of the bolt hole and the nominal diameter of the bolt; h is the total thickness of the bolt connecting piece; d, the diameter of the nut supporting surface; the height of the cylinder unit is the distance between the lower surfaces of the two cone units.
Further, the normal load of the bolt in the range of the circular truncated cone unit and the cylindrical unit accounts for 98.7% -99.2% of the pretightening force of the bolt.
Further, in the step S1, the diameter of the thin layer unit is the same as the diameter of the divided end surface of the cylinder unit, the diameter of the cylinder is equal to the diameter of the lower bottom surface of the circular truncated cone, the height of the circular truncated cone is 1/2 of the thickness of the rotor, and the thickness of the thin layer unit is 1/30-1/100 of the diameter of the thin layer unit.
Further, contact rigidity and stress variation values are introduced into a prediction function composite, and the influence of the flange rotor contact surface on the tightening sequence is comprehensively analyzed, wherein the formula is as follows:
Compose＝Change j +100(κ upj +κ downj +κ mediumj +κ linkj )，j＝1,2,3...n
wherein, change j Representing the stress variation amount, kappa, of the round platform cylinder unit around the jth bolt after all the bolts are screwed upj Representing the rigidity value of the flange bolt in the range of the jth bolt close to the circular truncated cone of the bolt head after all the bolts are screwed; kappa downj Representing the rigidity value of the flange bolt in the range that the jth bolt is close to the nut circular truncated cone after all the bolts are screwed; k is a radical of formula mediumj Representing the rigidity value of the flange bolt in the jth bolt cylinder range after all the bolts are tightened; k is a radical of linkj Representing the total contact rigidity between the flange and the rotor junction surface or between the rotor and the rotor; all the quantities in the formula are dimensionless quantities.
Further, the air conditioner is provided with a fan,
wherein i represents the serial number of the grids in the range of the bolt cylinder and the cone, j represents the serial number of the bolt tightening sequence, n represents the total number of the bolts needing to be tightened, and sigma represents the total number of the bolts needing to be tightened in Representing the stress value, σ, of the ith grid after the nth bolt has been tightened ij Represents the stress value of the ith grid after the jth bolt is screwed down, m j Representing the total number of grids contained in the jth tightening bolt circular table, cylinder, note: the stress unit in the calculation process of the formula is MPa.
Further, the air conditioner is characterized in that,
k linkj represents the contact rigidity of the Q-th contact surface after the jth bolt is screwed, and Q represents the boltTotal number of contact surfaces between the connectors (not including the bolts).
Further, for any adjacent bolt, the distance between the geometric centers of the two bolts is less than 50cm.
Compared with the prior art, the invention has the beneficial effects that:
(1) according to the method, the secondary development function of python on the Abaqus is utilized, the bolt tightening process is analyzed in batches under the condition of one-time operation, and compared with the traditional successive analysis method, the operation steps are greatly simplified.
(2) The function of calling data in the Abaqus through python is adopted, the stress change value and the connection rigidity change value of the cylinder and the round table body around the screw rod with the bolt as the axis are obtained, and the value range of the included angle between the side edge of the round table body and the axis is given. By narrowing the data processing range, the calculation efficiency is greatly improved.
(3) The contact surface between the flange rotors is changed into the thin-layer unit surface through python, the contact rigidity value between the contact surfaces is creatively introduced into the connection rigidity, and the accuracy of the calculation result is improved, so that the problems of low efficiency, inaccurate calculation result and the like of the traditional method are solved.
(4) The method combines the stress change value and the rigidity change value, and compared with the traditional method only considering stress or rigidity, the method is more comprehensive and the obtained result is more reliable.
Drawings
FIG. 1 is a schematic view of a conventional process
FIG. 2 is a schematic view of the method of the present invention
Fig. 3 shows the division range of the circular truncated cone and the cylinder with the bolt as the axis and the thin layer unit on the contact surface. Wherein (1) represents a cone, (2) represents a thin layer unit, (3) represents a cylinder, (4) represents a rotor, and (5) represents a flange
FIG. 4 is a schematic diagram of steps of importing a python file into abaqus for batch analysis and then processing data by using python.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, those skilled in the art can obtain many other embodiments without creative efforts, and all of them are within the protection scope of the present invention.
The present invention will be further explained with reference to the accompanying drawings and embodiments, for example, fig. 1 is a schematic diagram of the steps of a conventional method, fig. 2 is a schematic diagram of the method of the present invention, and a method for simulating and characterizing the mechanical state of a bolt set of an engine rotor.
The method comprises the following steps: and (3) modeling the thin layer unit, namely calculating the diameter of the thin layer unit according to the action range of the bolt, wherein the thickness of the thin layer unit is 1/30-1/100 of the diameter of the thin layer unit, taking 1/50 of the diameter, obtaining the elastic modulus and the shear modulus of the thin layer unit through theoretical calculation, and establishing a model of the thin layer unit.
Step two: in Abaqus parts such as rotors, flanges, bolts, etc. are built and assembled together with the lamellar units, which are assembled in a multi-layer structure as shown in fig. 3. And setting material parameters, and carrying out contact setting and meshing. Extracting an information input file, wherein file information comprises: dimension information of the engine rotor model part, material parameters, contact condition, grid information and analysis steps. The file is opened with python.
Step three: according to the calculation formula of the angle theta,
wherein K = h 1 /h 2 ＝25/25＝1≤1；C＝d 2 -d 1 ＝1；H＝h 2 +h 3 +h 4 +2*h 5 ；D＝3.7；
And calculating to determine that the inclination angle of the side edge of the circular truncated cone is 19 degrees, and setting the range of the cylinder and the circular truncated cone body to be divided in the program. The bolts are numbered using python image analysis functionality.
The cylinder and the circular truncated cone are defined areas on the rotor, the circular truncated cone area is a range which is included by rotating 180 degrees around the screw rod by taking the longest part of the bolt head as the upper side, and the cylinder area is a range which is formed by rotating 180 degrees around the screw rod by taking the diameter of the bottom edge of the circular truncated cone.
Step four: as shown in fig. 4, the sequence of bolts to be loaded with pretension, the stress values of the bolts, and the loading surfaces are input in the program. When loading with the python setting, the different tightening sequences are programmed directly. And converting the written python program into an inp file.
Step five: and importing the inp file into Abaqus, performing post-processing analysis on the engine rotor by using the Abaqus, outputting rigidity values and stress values of the bolts of the divided cylinders and truncated cones, and outputting rpy and MTX files. And under different tightening sequences, outputting an rpy file and an MTX file respectively.
And storing the rpy file and the MTX file output in each step, performing a data processing function by using python, and inputting the data into the python for analysis.
Step six: and outputting a calculated value of the prediction function by utilizing python, and obtaining the optimal tightening sequence by comparing the sizes of predicted values under different tightening sequences. The larger the predicted value is, the worse the tightening order is, and the smaller the value is, the smaller the interaction occurring between the bolts after the bolts are tightened is proved, and the better the tightening order is.
Experimental conditions required for the invention: one small server, a python program, abaqus software, a model drawing, a bolt tightening sequence, a bolt stress value and the like.
According to another mode of realisation of the invention, when the spacer is applied between the bolt and the rotor, the spacer and the nut are considered as one and the same part. The area of the upper surface of the circular truncated cone is the area in the diameter area of the gasket.
When the gasket is rectangular, the shortest side of the rectangle is used as the diameter to construct a circular area, the gasket and the nut in the circular area are regarded as a whole, and the area of the upper surface of the circular table is the area in the diameter area of the gasket.
After the gasket is additionally arranged, two end faces of the cylinder are not consistent any more, and the cylinder is changed into a circular truncated cone area.
According to another implementation mode of the invention, when the thickness of the rotor and the flange is thin enough (less than 3 mm), the circular truncated cone part can be converted into the cylindrical part, so that the calculation accuracy is improved.
The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.
The technical means disclosed in the scheme of the invention are not limited to the technical means disclosed in the above embodiments, but also include the technical means formed by any combination of the above technical features. It should be noted that modifications and adaptations can be made by those skilled in the art without departing from the principles of the present invention and are intended to be within the scope of the present invention.
Claims (9)
1. A simulation and mechanical state characterization method for an engine rotor bolt group is characterized by comprising the following steps:
step S1: establishing a finite element model of the engine rotor, wherein the finite element model comprises a thin layer unit surface, the thin layer unit surface is respectively arranged between a flange plate and a rotor contact surface, and the periphery of a screw rod taking a bolt as an axis is divided into a cone unit at the upper side and a cone unit at the lower side and a cylinder unit in the middle; extracting an information input file of the structure finite element model;
step S2: reading an information input file, and numbering bolt holes by using a method of reading image information by Python;
and step S3: calling the functions of the Abaqus load and the analysis step module by using Python, sequentially applying pretightening force to the bolts according to the bolt hole numbers obtained in the S1 and the bolt numbers, and introducing the Python file into the Abaqus for batch analysis;
and step S4: and outputting stress change values and connection rigidity change values of all units around the screw rod with the bolt as the axis, which are obtained by the Abaqus mechanical analysis in the S3.
2. The method for simulating and characterizing the mechanical state of the bolt set of the engine rotor as claimed in claim 1, wherein in the step S1: the engine rotor model comprises a flange, a rotor and a bolt and a nut, wherein the bolt and the nut are the bolt and the nut after simplifying threads.
3. The method for simulating and characterizing the mechanical state of the engine rotor bolt group according to claim 1, wherein in step S1, the upper surface of the cone unit is a contact surface between a bolt head and a flange, and an included angle θ between a side edge and a screw is calculated according to a formula:
k is the thickness ratio K of the two rotors is less than or equal to 1; c is the difference between the nominal diameter of the bolt hole and the nominal diameter of the bolt; h is the total thickness of the bolt connecting piece; d, the diameter of the nut supporting surface; the height of the cylinder unit is the distance between the lower surfaces of the two cone units.
4. The method for simulating and characterizing the mechanical state of the engine rotor bolt group according to claim 3, wherein normal loads of bolts in the range of the circular truncated cone and the cylinder unit account for 98.7% -99.2% of pretightening force of the bolts, and the height of the circular truncated cone is 1/2 of the thickness of the rotor.
5. The modeling and simulation method for the bolt group of the engine rotor as claimed in claim 1, wherein in the step S1, the diameter of the thin layer unit is the same as the diameter of the divided end surface of the cylinder unit, the diameter of the cylinder is equal to the diameter of the lower bottom surface of the truncated cone, the height of the truncated cone is 1/2 of the thickness of the flange, and the thickness of the thin layer unit is 1/30-1/100 of the diameter of the thin layer unit.
6. The method for simulating and characterizing the mechanical state of the bolt group of the engine rotor according to claim 1, wherein the contact rigidity and the stress variation value are introduced into a prediction function Comose, and the influence of the flange rotor contact surface on the tightening sequence is comprehensively analyzed, and the formula is as follows:
Compose＝Change j +100(κ upj +k downj +κ mediumj +κ linkj )，j＝1，2，3…n
wherein, change j Representing the stress variation amount, kappa, of the round platform cylinder unit around the jth bolt after all the bolts are screwed upj Representing the rigidity value of the flange bolt in the range of the jth bolt close to the circular truncated cone of the bolt head after all the bolts are screwed; kappa type downj Representing the rigidity value of the flange bolt in the range that the jth bolt is close to the nut circular truncated cone after all the bolts are screwed; kappa mediumj Representing the rigidity value of the flange bolt in the range of the jth bolt cylinder after all the bolts are screwed; kappa type linkj Representing the total contact rigidity between the flange and the rotor junction surface or between the rotor and the rotor; all the quantities in the formula are dimensionless quantities.
7. The method for simulating and characterizing the mechanical state of the bolt set of the engine rotor according to claim 6,
wherein, i represents the serial number of the grid in the range of the bolt cylinder and the cone, j represents the serial number of the bolt tightening sequence, n represents the total number of the bolts needing to be tightened, and sigma represents the total number of the bolts needing to be tightened in Representing the stress value, σ, of the ith grid after the nth bolt has been tightened ij Represents the stress value of the ith grid after the jth bolt is screwed down, m j Represents the total number of grids contained within the jth tightening bolt round, cylinder, note: the stress unit in the calculation process of the formula is MPa.
8. The method for simulating and characterizing the mechanical state of the bolt set of the engine rotor according to claim 6,
k linkqj represents the contact stiffness of the Q-th contact surface after the jth bolt is tightened, and Q represents the total number of contact surfaces between the bolted connections (excluding the bolts).
9. The method for simulating and characterizing the mechanical state of the bolt set of the engine rotor as claimed in claim 4, wherein the distance between the geometric centers of the bolts is less than 50cm for any adjacent bolt.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117494532A (en) * | 2024-01-02 | 2024-02-02 | 航天精工股份有限公司 | Automatic finite element pretightening force data batch transmission and simulation calculation control method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117494532A (en) * | 2024-01-02 | 2024-02-02 | 航天精工股份有限公司 | Automatic finite element pretightening force data batch transmission and simulation calculation control method |
| CN117494532B (en) * | 2024-01-02 | 2024-04-16 | 航天精工股份有限公司 | Automatic finite element pretightening force data batch transmission and simulation calculation control method |
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