CN110516365A - A method of test bolt joint stiffness - Google Patents
A method of test bolt joint stiffness Download PDFInfo
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- CN110516365A CN110516365A CN201910804044.2A CN201910804044A CN110516365A CN 110516365 A CN110516365 A CN 110516365A CN 201910804044 A CN201910804044 A CN 201910804044A CN 110516365 A CN110516365 A CN 110516365A
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- 238000012360 testing method Methods 0.000 title claims abstract description 37
- 238000000034 method Methods 0.000 title claims abstract description 22
- 206010023230 Joint stiffness Diseases 0.000 title claims abstract description 15
- 238000004088 simulation Methods 0.000 claims abstract description 31
- 238000005457 optimization Methods 0.000 claims abstract description 24
- 238000013461 design Methods 0.000 claims abstract description 19
- 230000003068 static effect Effects 0.000 claims abstract description 12
- 238000006073 displacement reaction Methods 0.000 claims abstract description 9
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- 238000004364 calculation method Methods 0.000 claims description 3
- 238000005259 measurement Methods 0.000 claims description 2
- 230000008878 coupling Effects 0.000 abstract description 3
- 238000010168 coupling process Methods 0.000 abstract description 3
- 238000005859 coupling reaction Methods 0.000 abstract description 3
- 238000012937 correction Methods 0.000 description 3
- 239000011159 matrix material Substances 0.000 description 3
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Abstract
The invention discloses a kind of methods for testing bolt joint stiffness, for bolt joint stiffness problem, modal test is carried out to bolt fastening structure, obtain structural natural frequencies and its corresponding vibration shape, the numerical simulation model that bolt fastening structure is established using finite element software is bolted by spring simulation.Using the coupling stiffness of spring as design variable, Optimized model is established by target or constraint of the residual error between Numerical Simulation Results and corresponding test result.The spring rate that eigenfrequncies and vibration models meet required precision is obtained by solving optimization model, numerical simulation model is corrected using spring rate, structural stress and displacement is calculated, is compared with Static Test Results, analyzes the error of bolt fastening structure rigidity.Influence of the bolt joint stiffness to structural mechanical property is analyzed by the numerical example, search model amendment improves the validity and the scope of application of numerical simulation model precision, provides theoretical foundation and engineering experience for bolt fastening structure modeling.
Description
Technical field
The invention belongs to Structural Design technical fields, more particularly to measure bolt by Finite Element Model Updating
The method of connection structure rigidity.
Background technique
Finite element correction technique seeks to the advantages of using both physical prototyping test and finite element simulation, with a small amount of sample
Machine is tested data obtained and is modified to finite element model, and more accurately finite element model is obtained, so as to substitute
The manufacture of those complicated, costly physical prototypings, saves money and shortens the lead time.Finite Element Model Updating oneself
Through developing decades, modification method is extremely abundant, each method is all absorbed in certain a part of correction model: as matrix type is repaired
Correction method is mainly the stiffness matrix and mass matrix for correcting finite element model；Parametric type method mainly corrects finite element model
Physical parameter, material property etc..Modified target is all to allow the calculated result and physical prototyping test result of finite element model
It is consistent.
In actual engineering structure, being bolted simple with it, reliable and the advantages that being convenient to mount and dismount is widely used.Such as
What carries out Dynamic Modeling and model validation to bolt fastening structure, with the dynamic characteristics and response of model prediction structure, really
The dynamic behavior for reflecting practical structures is the major issue for influencing Important Project equipment numerical simulation confidence level.For example, navigating
In the complete machine Dynamic Modeling of empty engine, the finite element model of refinement is established for single casing, FEM modal analysis and modal is general
It coincide preferably with test result, but for the casing after connection, it is then larger to calculate error.It is between aero-engine casing to adopt more
A large amount of bolted in the presence of the difficulty for increasing modeling with the bolt connection of whole circle, this is to cause complete machine kinetic model not
Enough accurate one of reasons, have seriously affected the precision of complete machine Analysis of Dynamic Characteristics and response prediction.
The method of the Modifying model of Structural Dynamics is varied at present, most of to need test parallel with numerical simulation；
Using experiment value Optimized model, to obtain more accurate simulation value.A large amount of scholars have done a large amount of fundamental test researchs, mention
A variety of new methods, new technology, new equipment, achievement are significant out.Bolt fastening structure kinetic model is relatively fewer；It is overall to consider spiral shell
It tethers and connects the problems such as middle presence rubs, contacts, tightening, a large amount of personnel have carried out different connection structures different types of
Modeling.But every kind of model is only applicable to specific type of attachment, increases the work of bolt fastening structure Modifying model in this way
Amount.Therefore, the present invention, which is used, carries out Modifying model to bolt fastening structure for the method for connection unit stiffness optimization, considers knot
The vibration shape and frequency of structure to obtain more accurate bolt fastening structure kinetic model, and increase its application scenarios.
Summary of the invention
The present invention is directed to bolt joint stiffness problem, carries out modal test to bolt fastening structure, obtains the intrinsic frequency of structure
Rate and its corresponding vibration shape, the numerical simulation model of bolt fastening structure is established using finite element software, simulates bolt by spring
Connection.Using the coupling stiffness of spring as design variable, using the residual error between Numerical Simulation Results and corresponding test result as target
Or Optimized model is established in constraint.The spring rate that eigenfrequncies and vibration models meet required precision is obtained by solving optimization model,
Numerical simulation model is corrected using spring rate, structural stress and displacement is calculated, is compared with Static Test Results, analyzes spiral shell
The error of bolt connecting structure rigidity.Influence of the bolt joint stiffness to structural mechanical property is analyzed by the numerical example, explores mould
Type amendment improve numerical simulation model precision validity and the scope of application, for bolt fastening structure modeling provide theoretical foundation with
Engineering experience.To achieve the goals above, the present invention to achieve the goals above, the present invention adopts the following technical scheme:
A method of test bolt joint stiffness, this method comprises the following steps:
Step 1: establishing single span frame structure is bolted finite element model (here using the bush in MSC.Nastran
Unit simulation is bolted), model is fixed in x-y plane.Stroke for carrying out the definition of material, determining constraint and grid
Point.Establish finite element model.
Step 2: carrying out model analysis to finite element model, and matched with the vibration shape of realistic model, chooses the first rank or the
Second-order modal.
Step 3: establish mathematic optimal model, write MSC.Nastran optimization card, setting optimized initial value, step-length and
Its convergence precision and alternative manner.
Step 4: submit the optimization card write to be iterated calculating to MSC.Nastran, frequency after extraction iteration
Bush element stiffness after value, the vibration shape and iteration.
Step 5: the rigidity of the bush unit after iteration is re-entered model, statics verifying is carried out, one is given and appoints
The power in meaning direction compares master mould with the deformation quantity of the model after optimization.
Step 6: the rigidity of the bush unit after iteration is re-entered model, dynamics verifying is carried out, mould is re-started
State analysis compares master mould with the variation of the vibration shape and frequency before and after the model after optimization.
The present invention compared with prior art the advantages of be:
Based on integrally-built mechanics property analysis, it is bolted with bush unit simulation, calls directly MSC.Nastran
The direct operation of card, without to program carry out secondary development, calculation amount can be reduced, and reduce calculate the time, finally obtain
With practical more similar bolt joint stiffness, the method for the finite element model of more accurate beam is provided for engineer.
Detailed description of the invention
Fig. 1 is single span frame models.
Fig. 2 is single span frame structure experiment second-order modal bending vibation mode picture.
Fig. 3 is the target of single span frame structure optimization and design variable iterativecurve (a) is (design of bush unit K6 rigidity
Variable) iteration history is (b) objective function iteration history.
Fig. 4 is the flow chart to the method for measuring bolt fastening structure rigidity by Finite Element Model Updating.
Specific embodiment
As shown in Figure 1, providing a kind of method for measuring bolt joint stiffness by Model Updating Technique in the present invention, specifically
Solution is as follows:
The first step, establishes finite element model, and connecting portion is bolted using the bush unit simulation of MSC.Nastran.
Here selecting the bush unit main cause in MSC.Nastran is that bush unit is a six degree of freedom spring
Unit can be simulated preferably in conjunction with practical experience and is bolted.It can more preferable simulation be hinged or rigid connection.
Second step is to carry out model analysis to finite element model with MSC.Nastran to obtain the vibration shape and inherently frequency of mode
Rate.
Third step establishes mathematic optimal model, write MSC.Nastran optimization card, setting optimized initial value, step-length and
Its convergence precision and alternative manner.
Intensity, the frequency of structure and the structural eigenvector for considering bolt fastening structure, optimize.With numerical simulation knot
Residual error between fruit and corresponding test result is target or Optimized model is established in constraint, and spring rate is that design variable establishes optimization
Model.
Objective function --- the residual error between vibration shape value emulation knot number fruit and corresponding test result
Constraint condition --- the residual error between frequency values simulation result and corresponding test result is less than or equal to ε
Design variable --- the rigidity of bush unit
Wherein:
K --- bush element stiffness is design variable；
N --- design variable number；
Eu(k) --- the residual error between vibration shape value emulation knot number fruit and corresponding test result；
The number of the testing site of m --- selection；
uj(k) --- the finite element model calculated value of j-th of modal displacement；
ut j--- the realistic model test measurements of j-th of modal displacement；
Ef(k) --- the residual error between frequency values simulation result and corresponding test result；
F (k) --- frequency simulation calculation value；
ft--- the test value of frequency；
ε --- residual error (depending on engineering practice)；
Iteration step length is the variable of design variable and the ratio (real number greater than 0) of initial value；
4th step submits the optimization card write to be iterated calculating, frequency after extraction iteration to MSC.Nastran
Bush element stiffness after value, the vibration shape and iteration.
5th step carries out statics verifying, and whether the rigidity after verifying iteration meets statics standard.
Step 6: carrying out dynamics verifying, check whether to meet dynamic criteria.Rigidity after obtaining iteration, brings original into
Model measures the error of the vibration shape and frequency.
The present invention disclose it is a kind of by Modifying model measure bolt joint stiffness method the following steps are included: (1) establish
Model is fixed in x-y plane by finite element model.It carries out the definition of material, determine constraint and the division of grid.Foundation has
Limit meta-model.(2) model analysis is carried out to finite element model, and is matched with the vibration shape of realistic model, choose the first rank or second
Rank mode.(3) mathematic optimal model is established, MSC.Nastran optimization card, setting optimized initial value, step-length and its receipts are write
Hold back precision and alternative manner.(4) it submits the optimization card write to be iterated calculating to MSC.Nastran, extracts frequency after iteration
Bush element stiffness after the value of rate, the vibration shape and iteration.(5) statics verifying is carried out, whether the rigidity after verifying iteration meets
Statics standard.(6) dynamics verifying is carried out, checks whether to meet dynamic criteria.
The present invention is directed to bolt joint stiffness problem, carries out modal test to bolt fastening structure, obtains the intrinsic frequency of structure
Rate and its corresponding vibration shape, the numerical simulation model of bolt fastening structure is established using finite element software, simulates bolt by spring
Connection.Using the coupling stiffness of spring as design variable, using the residual error between Numerical Simulation Results and corresponding test result as target
Or Optimized model is established in constraint.The spring rate that eigenfrequncies and vibration models meet required precision is obtained by solving optimization model,
Numerical simulation model is corrected using spring rate, structural stress and displacement is calculated, is compared with Static Test Results, analyzes spiral shell
The error of bolt connecting structure rigidity.Influence of the bolt joint stiffness to structural mechanical property is analyzed by the numerical example, explores mould
Type amendment improve numerical simulation model precision validity and the scope of application, for bolt fastening structure modeling provide theoretical foundation with
Engineering experience.
Implement example
The single span frame structure example connected below with reference to one using bush unit is to specific implementation step of the invention
It is described in detail.
The first step establishes finite element model, as shown in Figure 1, connecting portion uses the bush unit simulation of MSC.Nastran
It is bolted, rod piece is defined using beam unit, material is using Q235, elasticity modulus 210GPa, Poisson's ratio 0.3, density
7850kg/m3.Wherein bottom end is two fixing end constraints, and total is constrained in x-y plane.
Second step is to carry out model analysis to finite element model with MSC.Nastran to obtain the vibration shape of second-order modal and solid
There is frequency.The vibration shape is as shown in Fig. 2, frequency is 10.11073Hz
Step 3: establish mathematic optimal model, write MSC.Nastran optimization card, setting optimized initial value, step-length and
Its convergence precision and alternative manner.
Given two design variable initial values are 1000N/m, iteration step length 0.4.
Step 4: submit the optimization card write to be iterated calculating to MSC.Nastran, frequency after extraction iteration
Bush element stiffness after value, the vibration shape and iteration.
F06 file is obtained after submitting analysis, includes our the shown, objective functions of required design variable table 1 in file
Shown in table 2, shown in constraint condition table 3.
Step 5: carrying out statics verifying, whether the rigidity after verifying iteration meets statics standard.
Here the power test optimization front and back strain error that No. 12 finite elements points are applied with a 10000N, passes through section here
Point displacement embodies, and 8-18 node (modal displacement is obvious) is chosen here, as a result shown in table 4
Step 6: carrying out dynamics verifying, check whether to meet dynamic criteria.
After obtaining rigidity, the rigidity after optimizing is re-entered, the error of the vibration shape and frequency is calculated, as a result shown in table 5.
1 design variable iterative data of table
2 objective function iterative data of table
3 frequency of table changes table
The verifying of 4 statics of table
The verifying of 5 dynamics of table
Claims (2)
1. a kind of method for testing bolt joint stiffness, it is characterised in that: this method comprises the following steps,
Step 1: establishing single span frame structure is bolted finite element model, here using the bush unit in MSC.Nastran
Simulation is bolted, and model is fixed in x-y plane；It carries out the definition of material, determine constraint and the division of grid；It establishes
Finite element model；
Step 2: carrying out model analysis to finite element model, and matched with the vibration shape of realistic model, chooses the first rank or second-order
Mode；
Step 3: establishing mathematic optimal model, MSC.Nastran optimization card, setting optimized initial value, step-length and its receipts are write
Hold back precision and alternative manner；
Step 4: submit the optimization card write to be iterated calculating to MSC.Nastran, the value of frequency, vibration after extraction iteration
Bush element stiffness after type and iteration；
Step 5: the rigidity of the bush unit after iteration is re-entered model, statics verifying is carried out, gives any side
To power, compare master mould with optimization after model deformation quantity；
Step 6: the rigidity of the bush unit after iteration is re-entered model, dynamics verifying is carried out, re-starts mode point
Analysis compares master mould with the variation of the vibration shape and frequency before and after the model after optimization.
2. a kind of method for testing bolt joint stiffness according to claim 1, it is characterised in that: establish mathematical optimization mould
Type writes MSC.Nastran optimization card, setting optimized initial value, step-length and its convergence precision and alternative manner；
Intensity, the frequency of structure and the structural eigenvector for considering bolt fastening structure, optimize；With Numerical Simulation Results with
Residual error between corresponding test result is target or Optimized model is established in constraint, and spring rate is that design variable establishes optimization mould
Type；
Objective function --- the residual error between vibration shape value emulation knot number fruit and corresponding test result
Constraint condition --- the residual error between frequency values simulation result and corresponding test result is less than or equal to ε
Design variable --- the rigidity of bush unit
Wherein:
K --- bush element stiffness is design variable；
N --- design variable number；
Eu(k) --- the residual error between vibration shape value emulation knot number fruit and corresponding test result；
The number of the testing site of m --- selection；
uj(k) --- the finite element model calculated value of j-th of modal displacement；
ut j--- the realistic model test measurements of j-th of modal displacement；
Ef(k) --- the residual error between frequency values simulation result and corresponding test result；
F (k) --- frequency simulation calculation value；
ft--- the test value of frequency；
ε --- residual error；
Iteration step length is the variable of design variable and the ratio of initial value, the real number greater than 0.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112685841A (en) * | 2021-01-28 | 2021-04-20 | 西安交通大学 | Finite element modeling and correcting method and system for structure with connection relation |
| CN112765738A (en) * | 2020-12-31 | 2021-05-07 | 浙江理工大学 | Method for designing annular sealing structure of multistage centrifugal pump based on modal analysis |
| CN113033040A (en) * | 2021-03-05 | 2021-06-25 | 一汽奔腾轿车有限公司 | Accurate modeling method for vehicle flexible connection |
| CN113806990A (en) * | 2021-10-21 | 2021-12-17 | 珠海格力智能装备有限公司 | Nitrogen spring simulation analysis method and system |
| CN114330041A (en) * | 2021-11-04 | 2022-04-12 | 中国农业大学 | Method for analyzing inherent characteristics of bolt connection structure |
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Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112765738A (en) * | 2020-12-31 | 2021-05-07 | 浙江理工大学 | Method for designing annular sealing structure of multistage centrifugal pump based on modal analysis |
| CN112765738B (en) * | 2020-12-31 | 2022-05-27 | 浙江理工大学 | Method for designing annular sealing structure of multistage centrifugal pump based on modal analysis |
| CN112685841A (en) * | 2021-01-28 | 2021-04-20 | 西安交通大学 | Finite element modeling and correcting method and system for structure with connection relation |
| CN112685841B (en) * | 2021-01-28 | 2022-12-09 | 西安交通大学 | Finite element modeling and correcting method and system for structure with connection relation |
| CN113033040A (en) * | 2021-03-05 | 2021-06-25 | 一汽奔腾轿车有限公司 | Accurate modeling method for vehicle flexible connection |
| CN113033040B (en) * | 2021-03-05 | 2023-02-21 | 一汽奔腾轿车有限公司 | Accurate modeling method for vehicle flexible connection |
| CN113806990A (en) * | 2021-10-21 | 2021-12-17 | 珠海格力智能装备有限公司 | Nitrogen spring simulation analysis method and system |
| CN113806990B (en) * | 2021-10-21 | 2024-02-20 | 珠海格力智能装备有限公司 | Nitrogen spring simulation analysis method and system |
| CN114330041A (en) * | 2021-11-04 | 2022-04-12 | 中国农业大学 | Method for analyzing inherent characteristics of bolt connection structure |
| CN114330041B (en) * | 2021-11-04 | 2024-05-28 | 中国农业大学 | Inherent characteristic analysis method for bolt connection structure |
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Application publication date: 20191129 |