CN112699580A - Calculation method and system for steel pipe rod piece eddy vibration force - Google Patents
Calculation method and system for steel pipe rod piece eddy vibration force Download PDFInfo
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Abstract
本发明公开了一种钢管杆件涡振力的计算方法及系统，包括：基于为被测钢管杆件构建的空间有限元分析模型进行模态分析确定所述被测钢管杆件的自振频率和振型函数；基于所述被测钢管杆件的自振频率和所述被测钢管杆件的外径确定所述被测钢管杆件的升力系数；根据所述被测钢管杆件的振型函数和所述升力系数按照随机振动理论得到所述被测钢管杆件的涡振力。本发明与传统的钢管杆件涡振力计算方法相比，有效解决了未考虑钢管杆件实际端部约束、雷诺数对钢管升力系数影响的问题，提高了涡振力计算的精度，适用范围更广。
The invention discloses a method and system for calculating the vortex vibration force of a steel pipe member, comprising: performing modal analysis based on a spatial finite element analysis model constructed for the steel pipe member to be tested to determine the natural vibration frequency of the steel pipe member to be tested and mode shape function; determine the lift coefficient of the tested steel pipe member based on the natural vibration frequency of the tested steel pipe member and the outer diameter of the tested steel pipe member; according to the vibration of the tested steel pipe member The shape function and the lift coefficient are used to obtain the vortex vibration force of the tested steel pipe member according to the random vibration theory. Compared with the traditional method for calculating the vortex vibration force of a steel pipe member, the invention effectively solves the problem that the actual end constraint of the steel pipe member and the influence of the Reynolds number on the lift coefficient of the steel pipe are not considered, and the accuracy of the calculation of the vortex vibration force is improved. wider.
Description
Technical Field
The invention relates to the field of steel pipes in power transmission and transformation engineering, in particular to a method and a system for calculating a steel pipe rod member vortex vibration force.
Background
The steel pipe structures such as the steel pipe tower of the power transmission line and the lightning rod of the steel pipe of the transformer substation are widely applied to power transmission and transformation projects, the steel pipe structures are designed and checked mainly based on a downwind equivalent static wind load theory, the consideration of transverse wind vortex vibration is lacked in the existing design specification, the wind resistance of the steel pipe structures of the power transmission and transformation projects is insufficient, and the fatigue fracture damage of the connection parts of steel pipe rod pieces can be caused by long-time and large-amplitude vortex vibration. The method for calculating the transverse vortex vibration force of the steel pipe rod piece is a key for accurately calculating the transverse wind load of the steel pipe structure of the power transmission and transformation project and evaluating and designing the fatigue life of the structure, and has important significance for guaranteeing the safe operation of a power grid in a continuously stable wind area.
The vortex-induced wind vibration of the steel tube tower or the steel tube lightning rod is transverse vibration caused by a karman vortex street when part of round section rod pieces of the steel tube tower or the steel tube lightning rod are at a lower wind speed. The falling wind force generated by vortex falling can make the column body generate transverse vibration. Vortex-induced resonance occurs when the dominant frequency of vortex shedding is relatively close to a certain order of frequency of the column. Vortex-induced vibration has the characteristic of frequency locking, and the probability of resonance occurrence is increased. The length-fineness ratio of the steel pipe rod piece which is easy to generate vortex-induced wind vibration is large, and the steel pipe rod piece can be generally regarded as a flexible simply-supported beam or a cantilever beam to study the breeze resonance of the steel pipe rod piece. The steel pipe rod piece oscillation starting critical wind speed, the lift coefficient and the oscillation type function are three key parameters for calculating the vortex oscillation force of the steel pipe rod piece, and the values or regulations of the three parameters in the conventional steel pipe rod piece vortex oscillation force calculation method are insufficient or improve the space.
(1) The steel pipe rod member vortex vibration critical oscillation starting wind speed is evaluated by adopting a semi-theoretical and semi-empirical method according to a simplified model, and the occurrence of vortex-induced vibration disasters cannot be completely controlled in continuous stable wind areas such as northwest and the like. In order to avoid or weaken vortex-induced vibration, DL/T5154-crCurve (first vibration mode), first-order critical oscillation wind speed V of control rod piececrNot less than 15 m/s; by integrating the safety and the economy of engineering, DL/T5254-2010 design technical specification of the steel pipe tower of the overhead transmission line reduces the oscillation starting critical wind speed from 15m/s to 8m/s, so that the method is favorable for saving resources, reducing the weight of the tower and protecting the environment, but increases the resonance probability of certain rod pieces and can directly cause the damage of the rod pieces or connecting nodes.
(2) Steel pipe rod lifting systemNumber CLAnd Reynolds number ReIn relation to the above, the lift coefficient in the subcritical region shows a nonlinear decreasing trend along with the increase of Reynolds number, the value range is approximately 0.2-0.6, and the lift coefficient C in the existing vortex vibration force calculation methodLThe fixed value is 0.25, the rod member vortex vibration force is in direct proportion to the lift coefficient, and the vortex vibration force of the steel pipe rod member in the subcritical region is probably underestimated, so that the probability of vortex-induced fatigue failure of the steel pipe rod member is increased.
(3) The inclined material or the auxiliary material steel pipe rod piece with larger slenderness ratio in the steel pipe power transmission tower is generally connected with the main material in an inserting mode, the connection mode is semi-rigid connection, the existing vortex vibration force calculation method is simplified into the mode that two ends are hinged to calculate the natural vibration frequency and the vibration mode function, a certain difference exists between the calculated value of the vortex vibration force and the actual situation, and the difference is not considered in the past design practice. The non-independent steel tube lightning rod is erected on the herringbone truss, the end connection of the non-independent steel tube lightning rod is between rigid connection and hinge connection, and the actual situation cannot be accurately reflected by calculating the natural vibration frequency and the vibration mode according to the cantilever beam with the rigid connection at the end.
In conclusion, the critical wind speed, lift coefficient and vibration mode function of the steel pipe rod piece for starting vibration are three key parameters for calculating the vortex vibration force, and the values or regulations of the three parameters in the conventional steel pipe rod piece vortex vibration force calculation method are insufficient or have a space for improving the vortex vibration force. Therefore, the inventor provides a method and a system for calculating the steel pipe rod eddy-vibration force, which effectively consider the influence of the three factors, and provide reference and basis for more accurately calculating the steel pipe rod eddy-vibration force.
Disclosure of Invention
The invention provides a method for calculating the eddy vibration force of a steel pipe rod piece, aiming at three problems in the conventional method for calculating the eddy vibration force of the steel pipe rod piece of a power transmission tower and a lightning rod, which comprises the following steps:
performing modal analysis based on a spatial finite element analysis model constructed for the steel pipe rod to be tested to determine the natural vibration frequency and the vibration mode function of the steel pipe rod to be tested;
determining the lift coefficient of the steel pipe rod piece to be tested based on the natural vibration frequency of the steel pipe rod piece to be tested and the outer diameter of the steel pipe rod piece to be tested;
and obtaining the eddy vibration force of the steel pipe rod piece to be detected according to the vibration mode function and the lift coefficient of the steel pipe rod piece to be detected and a random vibration theory.
Preferably, the determining the natural frequency and the mode shape function of the steel pipe rod to be tested based on modal analysis performed on the spatial finite element analysis model constructed for the steel pipe rod to be tested includes:
a spatial finite element analysis model is constructed for a steel pipe rod to be tested by adopting a spatial linear finite strain beam unit, the end part of the steel pipe tower inserted steel pipe rod is modeled according to the actual size of an inserting plate in the construction process, a steel pipe lightning rod establishes a herringbone space truss model connected with the steel pipe lightning rod, and the end part of the inserting plate and a bottom node of the herringbone truss are fixedly connected and restrained;
and carrying out modal analysis on the steel pipe rod to be tested in the space finite element analysis model by adopting a Lanuss method to obtain the natural vibration frequency and the vibration mode function of the steel pipe rod to be tested.
Preferably, the determining the lift coefficient of the steel pipe rod piece to be tested based on the natural frequency of vibration of the steel pipe rod piece to be tested and the outer diameter of the steel pipe rod piece to be tested includes:
calculating the critical oscillation starting wind speed of the steel pipe rod piece to be detected based on the natural oscillation frequency of the steel pipe rod piece to be detected and the outer diameter of the steel pipe rod piece to be detected;
determining a Reynolds number corresponding to the critical oscillation-starting wind speed based on the critical oscillation-starting wind speed of the steel pipe rod piece to be detected;
and determining a lift coefficient corresponding to the Reynolds number according to a Reynolds number-lift coefficient curve.
Further, the critical oscillation wind speed is calculated according to the following formula:
Vcr＝f1D/St
in the formula: vcrThe critical oscillation starting wind speed of the steel pipe rod piece; f. of1The first-order natural vibration frequency of the steel pipe rod piece is set; d is the outer diameter of the steel pipe rod piece; stIs the strorehal number.
Further, the reynolds number is calculated as follows:
Re＝VcrD/ν
in the formula: reThe Reynolds number corresponding to the critical oscillation starting wind speed; vcrThe critical oscillation starting wind speed of the steel pipe rod piece; ν is air viscosity; d is the outer diameter of the steel pipe rod piece.
Preferably, the obtaining of the eddy vibration force of the steel pipe rod according to the random vibration theory based on the vibration mode function and the lift coefficient of the steel pipe rod includes:
carrying out normalization processing on the vibration mode function of the steel pipe rod piece to be tested;
obtaining a first-order eddy vibration force distribution function of the steel pipe rod piece to be tested according to a random vibration theory based on the vibration mode function and the lift coefficient after normalization processing;
and deriving the first-order eddy vibration force distribution function based on the axial length of the steel pipe rod piece to be measured to obtain a first-order eddy vibration force resultant force.
Further, the first-order eddy vibration force distribution function of the measured steel pipe rod is shown as the following formula:
in the formula: n isd1Is a first-order vortex vibration force distribution function of the steel pipe rod piece;
normalizing the mode shape function to obtain the mode shape function; rhoaIs the air density; vcrThe critical oscillation starting wind speed of the steel pipe rod piece is obtained; d is the outer diameter of the steel pipe rod piece; cLIs the coefficient of lift; xi1Is the damping ratio; and x is the coordinate along the axial direction of the steel pipe rod piece.
Further, the resultant force of the first-order vortex vibration force is as follows:
in the formula: n is a radical ofd1The resultant force of the first-order vortex vibration force is obtained; n isd1Is a first-order vortex vibration force distribution function of the steel pipe rod piece; l is the calculated length of the steel pipe rod piece; and x is the coordinate along the axial direction of the steel pipe rod piece.
Based on the same inventive concept, the invention also provides a computing system of the steel pipe rod piece eddy vibration force, which comprises:
the finite element analysis module is used for carrying out modal analysis on the basis of a spatial finite element analysis model constructed for the steel pipe rod piece to be tested to determine the natural vibration frequency and the vibration mode function of the steel pipe rod piece to be tested;
the lift coefficient determining module is used for determining the lift coefficient of the steel pipe rod piece to be tested on the basis of the natural vibration frequency of the steel pipe rod piece to be tested and the outer diameter of the steel pipe rod piece to be tested;
and the vortex vibration force calculation module is used for obtaining the vortex vibration force of the steel pipe rod piece to be detected according to the vibration mode function of the steel pipe rod piece to be detected and the lift coefficient according to a random vibration theory.
Preferably, the finite element analysis module is specifically configured to:
a spatial finite element analysis model is constructed for a steel pipe rod to be tested by adopting a spatial linear finite strain beam unit, the end part of the steel pipe tower inserted steel pipe rod is modeled according to the actual size of an inserting plate in the construction process, a steel pipe lightning rod establishes a herringbone space truss model connected with the steel pipe lightning rod, and the end part of the inserting plate and a bottom node of the herringbone truss are fixedly connected and restrained;
and carrying out modal analysis on the steel pipe rod to be tested in the space finite element analysis model by adopting a Lanuss method to obtain the natural vibration frequency and the vibration mode function of the steel pipe rod to be tested.
Compared with the prior art, the invention has the beneficial effects that:
according to the technical scheme provided by the invention, modal analysis is carried out on the basis of a spatial finite element analysis model constructed for the steel pipe rod piece to be tested to determine the natural vibration frequency and the vibration mode function of the steel pipe rod piece to be tested; determining the lift coefficient of the steel pipe rod piece to be tested based on the natural vibration frequency of the steel pipe rod piece to be tested and the outer diameter of the steel pipe rod piece to be tested; and obtaining the eddy vibration force of the steel pipe rod piece to be detected according to the vibration mode function and the lift coefficient of the steel pipe rod piece to be detected and a random vibration theory. Compared with the traditional steel pipe rod piece eddy vibration force calculation method, the method effectively solves the problem that the actual end part constraint of the steel pipe rod piece and the influence of Reynolds number on the lift coefficient of the steel pipe are not considered, improves the accuracy of eddy vibration force calculation, and has wider application range.
Drawings
FIG. 1 is a flow chart of a method for calculating the eddy vibration force of a steel pipe rod according to the present invention;
FIG. 2 is a geometric dimension diagram of a typical steel pipe rod piece and a connecting node of the steel pipe tower;
FIG. 3 is a cross sectional view of a finite element model end of a steel pipe rod according to an embodiment of the present invention;
FIG. 4 shows the Reynolds number R of the steel pipe in the example of the inventioneCoefficient of lift CLA graph is shown schematically;
FIG. 5 is a schematic diagram illustrating a comparison of normalized mode shapes of steel tube bars according to an embodiment of the present invention;
FIG. 6 is a frame diagram of a computing system for the eddy force of a steel pipe rod according to the present invention;
wherein, 1 is the steel pipe member to be tested, 2 is the picture peg, 3 is the connecting steel pipe, 4 is the connecting bolt, and 5 is the welding seam.
Detailed Description
For a better understanding of the present invention, reference is made to the following description taken in conjunction with the accompanying drawings and examples.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In this embodiment, the critical wind speed, lift coefficient and vibration mode function of the steel pipe rod oscillation starting are three key parameters for calculating the eddy vibration force of the steel pipe rod, and values or regulations of the three parameters in the conventional steel pipe rod eddy vibration force calculation method are storedIn the shortage or improvement space. Firstly, the steel pipe rod member vortex vibration critical oscillation starting wind speed is valued by adopting a semi-theoretical and semi-empirical method according to a simplified theoretical model, and the occurrence of vortex vibration disasters cannot be completely controlled in a continuous stable wind area; secondly, the lift coefficient C in the existing vortex vibration force calculation methodLTaking a fixed value of 0.25, the eddy vibration force of the steel pipe rod in the subcritical region is probably underestimated; thirdly, the existing vortex vibration force calculation method calculates the natural vibration frequency and the vibration mode function according to an ideal simple supported beam or a cantilever beam, and the actual situation of a steel pipe tower rod or a steel pipe lightning rod cannot be accurately reflected. The three defects result in that the accuracy of the vortex vibration force of the steel tube tower or the lightning rod steel tube rod calculated according to the traditional method needs to be improved. Therefore, a steel pipe rod member eddy vibration force calculation method which effectively considers the influence of the three factors needs to be provided, and reference and basis are provided for more accurately calculating the steel pipe rod member eddy vibration force.
Referring to fig. 1, the method for calculating the steel pipe rod eddy-vibration force provided by the present embodiment includes:
s1, performing modal analysis based on a spatial finite element analysis model constructed for the steel pipe rod piece to be tested to determine the natural vibration frequency and the vibration mode function of the steel pipe rod piece to be tested;
s2, determining the lift coefficient of the steel pipe rod piece to be tested based on the natural frequency of the steel pipe rod piece to be tested and the outer diameter of the steel pipe rod piece to be tested;
and S3 obtaining the eddy vibration force of the steel pipe rod piece to be tested according to the vibration mode function and the lift coefficient of the steel pipe rod piece to be tested and a random vibration theory.
The problem that the actual end part constraint of the steel pipe rod piece and the influence of the Reynolds number on the lift coefficient of the steel pipe are not considered in the existing method can be effectively solved through the embodiment, the calculation precision of the vortex vibration force is improved, and the application range is wider.
The vortex vibration force calculated in the embodiment is the key for accurately calculating the transverse wind load of the steel pipe structure of the power transmission and transformation project and carrying out structural fatigue life assessment and design, and the vortex vibration force is generated because the vortex-induced wind vibration of the steel pipe tower or the steel pipe lightning rod is transverse vibration caused by the karman vortex street when part of the rod pieces with the circular cross sections are at lower wind speed.
The karman vortex street phenomenon is that when a steady incoming flow under certain conditions bypasses some objects, two sides of the objects periodically drop out double-row line vortices which have opposite rotation directions and are arranged regularly. Initially, the two lines of line vortices keep moving forward, and then they interfere with each other and attract each other, and the interference is increased to form a non-linear so-called vortex street. Karman vortex street is a phenomenon studied by viscous incompressible fluid dynamics. The fluid can generate a Karman vortex street when flowing around a high chimney, a high-rise building, an electric wire, an oil pipeline and a tube bundle of a heat exchanger, and the Karman vortex street under different Reynolds numbers. The karman vortex street acts on the steel pipe lightning rod, when a certain wind speed acts, vortex-induced resonance of the lightning rod is caused, at the moment, the lightning rod oscillates most severely, the amplitude is maximum, the resonance causes the cross section of the fixing bolt of the lightning rod to be partially cut off, the mechanical strength is reduced, and the lightning rod is finally broken. Therefore, in order to ensure that the mechanical strength of the lightning rod meets the design requirements under various weather conditions, especially in windy weather, it is necessary to study the karman vortex street phenomenon acting on the lightning rod to determine the conditions for vortex-induced resonance, and consider the conditions in the design to avoid the occurrence of faults.
Meanwhile, the influence of the karman vortex street on the mechanical strength of the steel pipe lightning rod is mainly reflected in vortex-induced resonance, and the steel pipe lightning rod at the most upstream of the windward side of a wind field can generate the vortex-induced resonance in a flow field with lower turbulence intensity and under the condition of proper wind speed; and under the continuous effect of vortex-induced resonance reciprocating load, the flange plate connecting bolt at the bottom of the steel tube lightning rod is easy to generate fatigue cracking, so that the effective working area of the bolt is continuously reduced, and the damaged working bolt is thoroughly broken until a certain windy weather process occurs, and finally the whole steel tube lightning rod is toppled. Therefore, to minimize the impact of karman vortex street on the lightning rod, it is necessary to avoid the occurrence of vortex-induced resonance, and the existing improvement measures are to avoid the occurrence of vortex-induced resonance by improving the pneumatic control measures of the lightning rod.
In this embodiment, the step S1 may be implemented by:
according to the actual conditions of steel pipe members of power transmission towers or lightning rodsEstablishing a space finite element analysis model in a beam form, and determining the natural vibration frequency f of the steel pipe rod piece through modal analysis1Sum mode function
The S1 specifically includes: a steel pipe rod and a rod end constraint model are established by adopting a space linear finite strain beam unit, wherein the end part of the steel pipe tower inserted steel pipe rod is modeled according to the actual size of an inserting plate, a herringbone space truss model connected with the steel pipe lightning rod is established by the steel pipe lightning rod, and the end part of the inserting plate and a bottom node of the herringbone truss are fixedly connected and constrained. Performing modal analysis on the steel pipe rod piece by adopting a Lanuss method to obtain the first-order natural vibration frequency f of the steel pipe rod piece1And first order mode
In the present embodiment, the S2 may be implemented by the following steps;
calculating the critical oscillation starting wind speed of the steel pipe rod piece to be detected based on the natural oscillation frequency of the steel pipe rod piece to be detected and the outer diameter of the steel pipe rod piece to be detected;
determining a Reynolds number corresponding to the critical oscillation-starting wind speed based on the critical oscillation-starting wind speed of the steel pipe rod piece to be detected;
and determining a lift coefficient corresponding to the Reynolds number according to a Reynolds number-lift coefficient curve.
In one embodiment, the S2 specifically includes:
s201 according to the self-vibration frequency f of the steel pipe rod piece1Calculating the critical oscillation starting wind speed V according to the outer diameter D of the steel pipecr；
S202 calculating and critical oscillation starting wind speed VcrReynolds number R of corresponding steel pipe rodeAccording to Reynolds number ReCoefficient of lift CLCurve determination of lift coefficient C of steel pipe rodL。
Further, S201 may be implemented by the following steps:
the first-order natural frequency f of the steel pipe rod obtained according to the step S11And the outer diameter D of the steel pipe rod pieceCalculating the critical oscillation starting wind speed V of the steel pipe rod piece according to the formula (a)cr：
Vcr＝f1D/St(a)
In the formula: stFor the Strorahal number, the circular cross-section may be 0.2 in the subcritical region.
Further, S202 may be implemented by the following steps:
according to the critical oscillation starting wind speed V of the steel pipe rod piece obtained in the step 201crCalculating the critical oscillation wind speed V according to the formula (b)crReynolds number R of corresponding steel pipe rode：
Re＝VcrD/ν(b)
In the formula: vcrThe critical oscillation starting wind speed (m/s) of the steel pipe rod piece is obtained; nu is air viscosity and takes the value of 1.45 multiplied by 10-5m2S; d is the outer diameter (m) of the steel pipe rod piece.
Reynolds number R of the steel pipe rod obtained according to equation (b)eReynolds number R determined by reference to wind tunnel testeCoefficient of lift CLCurve at the Reynolds number ReCoefficient of lift CLDetermining Reynolds number R of steel pipe rod in curveeLift coefficient C of corresponding steel pipe rod pieceL。
In the present embodiment, the S3 may be implemented by the following steps;
carrying out normalization processing on the vibration mode function of the steel pipe rod piece to be tested;
obtaining a first-order eddy vibration force distribution function of the steel pipe rod piece to be tested according to a random vibration theory based on the vibration mode function and the lift coefficient after normalization processing;
and deriving the first-order eddy vibration force distribution function based on the axial length of the steel pipe rod piece to be measured to obtain a first-order eddy vibration force resultant force.
The process of implementing the S3 is equivalent to normalizing the vibration mode function of the semi-rigid constraint steel tube, and providing a steel tube member vortex vibration force calculation method effectively considering the influence of the three parameters according to a steel tube member vortex vibration force calculation formula based on a random vibration theory, and specifically includes:
analyzing the S1 mode to obtain mode shape function
Is subjected to normalization processing to obtain
To facilitate the integration of the vortex vibration force function, a polynomial fitting is adopted to normalize the vibration mode
Lift coefficient C determined from S202LCalculating a first-order eddy-vibration-force distribution function n of the steel pipe bar member according to the formulas (c) and (d)d1(N/m) and the resultant force N of the first-order eddy vibration forced1(N)：
In the formula: rhoaFor the air density, 1.25kg/m is usually taken3；ξ1For the damping ratio, 0.01 is generally adopted for the steel structure; l is the calculated length (m) of the steel pipe rod piece; and x is a coordinate (m) along the axial direction of the steel pipe rod piece.
In one embodiment, when the vortex vibration force of the steel pipe rod is calculated, a space finite element analysis model is firstly established according to the actual constraint mode of the steel pipe rod of the power transmission tower or the lightning rod, and the natural vibration frequency f of the steel pipe rod is determined through modal analysis1Sum mode function
According to the self-vibration frequency f of the steel pipe rod1Calculating the critical oscillation starting wind speed V according to the outer diameter D of the steel pipecr(ii) a Calculating and critical oscillation starting wind speed VcrReynolds number R of corresponding steel pipe rodeAccording to Reynolds number ReCoefficient of lift CLCurve determination of lift coefficient C of steel pipe rodL(ii) a Most preferablyAnd then normalizing the vibration mode function of the semi-rigid constraint steel pipe rod piece, and providing a steel pipe rod piece vortex vibration force calculation method and a steel pipe rod piece vortex vibration force calculation system which effectively consider the influence of the three factors according to a steel pipe rod piece vortex vibration force calculation formula based on a random vibration theory, so as to provide reference and basis for more accurately calculating the steel pipe rod piece vortex vibration force. Compared with the traditional steel pipe rod piece vortex vibration force calculation method, the method provided by the invention effectively solves the problems that the actual end part constraint of the steel pipe rod piece is not considered, and the influence of Reynolds number on the lift coefficient of the steel pipe is not considered, and has better applicability and higher precision.
In a specific application scenario, the method is adopted to calculate the steel pipe rod member eddy vibration force:
taking a certain 1000kV power transmission line steel pipe power transmission tower as an example, the specification of a steel pipe rod piece generating vortex vibration is phi 168 multiplied by 4, the calculated length L of the steel pipe rod piece is 8.567m, the material of the rod piece is Q345, the geometric dimension diagram of the steel pipe rod piece and a connecting node is shown in an attached figure 2, in the figure 2, a measured steel pipe rod piece 1 is the steel pipe rod piece generating vortex vibration, the measured steel pipe rod piece 1 is connected with a connecting steel pipe 3 through an inserting plate 2 and a connecting bolt 4, wherein one end of the measured steel pipe rod piece 1 is inserted into the inserting plate 2, and a welding line 5 is arranged on the contact surface of one end of the measured steel pipe rod piece 1 and.
Firstly, a steel pipe rod and rod end constraint model is established by adopting a space linear finite strain beam unit according to the method of S1, wherein the end part of the steel pipe tower inserted steel pipe rod is modeled according to the actual size of an inserting plate, and the cross section of the end part of the steel pipe rod finite element model is shown in the attached figure 3. Performing modal analysis on the steel pipe rod piece by adopting a Lanuss method to obtain the first-order natural vibration frequency f of the steel pipe rod piece16.98Hz and first order mode
The expression of (a) is:
according to the method of step S201, the steel pipe pole obtained from step S1First order natural frequency f1The critical oscillation wind speed V of the steel pipe rod piece is calculated according to the formula (a) when the steel pipe outer diameter D is 0.168m and 6.98Hzcr＝f1D/St＝6.98×0.168/0.2＝5.86(m/s)；
Adopting the step S202 method, according to the critical oscillation starting wind speed V of the steel pipe rod piece obtained in the step S201crCalculating the critical oscillation starting wind speed V according to the formula (b) when the speed is 5.86m/scrReynolds number R of corresponding steel pipe rode＝VcrD/ν＝5.86×0.168/1.45×10-5＝6.79×104Reynolds number R determined according to the wind tunnel test shown in FIG. 4eCoefficient of lift CLCurve, determining lift coefficient C of steel pipe rodL＝0.283；
Adopting the method of step S3 to analyze the mode shape function obtained from the mode shape analysis of step S1
Is subjected to normalization processing to obtain
As shown in fig. 5, the normalized mode shape is compared with the approximate theoretical mode shape in the present embodiment, and it can be seen from fig. 5 that the result deviation obtained by the calculation method provided in the present embodiment is smaller and closer to the actual situation. To facilitate the integration of the vortex vibration force function, a polynomial fitting is adopted to normalize the vibration mode
Fitting coefficient p in the formula9＝－58.77，p8＝431.3，p7＝－1167，p6＝1607，p5＝－1257，p4＝580.1，p3＝－159.4，p2＝22.07，p1＝1.781，p0＝－0.006959；
According to coefficient of lift CL0.283, air density ρa＝1.25kg/m3Damping ratio xi1And (3) when the calculated length L of the steel pipe rod is 0.01, 8.567, and calculating the first-order eddy vibration force distribution force of the steel pipe rod by adopting a numerical integration method according to the formula (c):
and (3) calculating the resultant force of the first-order eddy vibration force of the steel pipe rod piece by adopting a numerical integration method according to the formula (d):
the embodiment can show that the calculation method of the steel pipe rod member vortex vibration force provided by the embodiment improves the calculation accuracy of the steel pipe rod member vortex vibration force after considering the influence on the steel pipe rod member oscillation starting critical wind speed, the lift coefficient and the vibration mode function, and is suitable for engineering application.
Based on the same inventive concept, as shown in fig. 6, the present invention further provides a computing system for a steel pipe rod eddy force, comprising:
the finite element analysis module is used for carrying out modal analysis on the basis of a spatial finite element analysis model constructed for the steel pipe rod piece to be tested to determine the natural vibration frequency and the vibration mode function of the steel pipe rod piece to be tested;
the lift coefficient determining module is used for determining the lift coefficient of the steel pipe rod piece to be tested on the basis of the natural vibration frequency of the steel pipe rod piece to be tested and the outer diameter of the steel pipe rod piece to be tested;
and the vortex vibration force calculation module is used for obtaining the vortex vibration force of the steel pipe rod piece to be detected according to the vibration mode function of the steel pipe rod piece to be detected and the lift coefficient according to a random vibration theory.
In an embodiment, the finite element analysis module is specifically configured to:
a spatial finite element analysis model is constructed for a steel pipe rod to be tested by adopting a spatial linear finite strain beam unit, the end part of the steel pipe tower inserted steel pipe rod is modeled according to the actual size of an inserting plate in the construction process, a steel pipe lightning rod establishes a herringbone space truss model connected with the steel pipe lightning rod, and the end part of the inserting plate and a bottom node of the herringbone truss are fixedly connected and restrained;
and carrying out modal analysis on the steel pipe rod to be tested in the space finite element analysis model by adopting a Lanuss method to obtain the natural vibration frequency and the vibration mode function of the steel pipe rod to be tested.
In an embodiment, the lift coefficient determination module is specifically configured to:
calculating the critical oscillation starting wind speed of the steel pipe rod piece to be detected based on the natural oscillation frequency of the steel pipe rod piece to be detected and the outer diameter of the steel pipe rod piece to be detected;
determining a Reynolds number corresponding to the critical oscillation-starting wind speed based on the critical oscillation-starting wind speed of the steel pipe rod piece to be detected;
and determining a lift coefficient corresponding to the Reynolds number according to a Reynolds number-lift coefficient curve.
Specifically, the critical oscillation wind speed is calculated according to the following formula:
Vcr＝f1D/St
in the formula: vcrThe critical oscillation starting wind speed of the steel pipe rod piece; f. of1The first-order natural vibration frequency of the steel pipe rod piece is set; d is the outer diameter of the steel pipe rod piece; stIs the strorehal number.
Specifically, the reynolds number is calculated according to the following formula:
Re＝VcrD/ν
in the formula: reThe Reynolds number corresponding to the critical oscillation starting wind speed; vcrThe critical oscillation starting wind speed of the steel pipe rod piece; ν is air viscosity; d is the outer diameter of the steel pipe rod piece.
In an embodiment, the vortex force calculation module is specifically configured to:
carrying out normalization processing on the vibration mode function of the steel pipe rod piece to be tested;
obtaining a first-order eddy vibration force distribution function of the steel pipe rod piece to be tested according to a random vibration theory based on the vibration mode function and the lift coefficient after normalization processing;
and deriving the first-order eddy vibration force distribution function based on the axial length of the steel pipe rod piece to be measured to obtain a first-order eddy vibration force resultant force.
Specifically, the first-order eddy-vibration force distribution function of the measured steel pipe rod is as follows:
in the formula: n isd1Is a first-order vortex vibration force distribution function of the steel pipe rod piece;
normalizing the mode shape function to obtain the mode shape function; rhoaIs the air density; vcrThe critical oscillation starting wind speed of the steel pipe rod piece is obtained; d is the outer diameter of the steel pipe rod piece; cLIs the coefficient of lift; xi1Is the damping ratio; and x is the coordinate along the axial direction of the steel pipe rod piece.
Specifically, the resultant force of the first-order vortex vibration force is as follows:
in the formula: n is a radical ofd1The resultant force of the first-order vortex vibration force is obtained; n isd1Is a first-order vortex vibration force distribution function of the steel pipe rod piece; l is the calculated length of the steel pipe rod piece; and x is the coordinate along the axial direction of the steel pipe rod piece.
It will be understood by those skilled in the art that all or part of the flow of the method according to the above-described embodiment may be implemented by a computer program, which may be stored in a computer-readable storage medium and used to implement the steps of the above-described embodiments of the method when the computer program is executed by a processor. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying said computer program code, media, usb disk, removable hard disk, magnetic diskette, optical disk, computer memory, read-only memory, random access memory, electrical carrier wave signals, telecommunication signals, software distribution media, etc. It should be noted that the computer readable medium may contain content that is subject to appropriate increase or decrease as required by legislation and patent practice in jurisdictions, for example, in some jurisdictions, computer readable media does not include electrical carrier signals and telecommunications signals as is required by legislation and patent practice.
Furthermore, the invention also provides a storage device. In one embodiment of the storage device according to the present invention, the storage device may be configured to store a program for executing the method for calculating the steel pipe rod eddy-current force of the above-described method embodiment, and the program may be loaded and executed by a processor to implement the above-described method for calculating the steel pipe rod eddy-current force. For convenience of explanation, only the parts related to the embodiments of the present invention are shown, and details of the specific techniques are not disclosed. The storage device may be a storage device apparatus formed by including various electronic devices, and optionally, a non-transitory computer-readable storage medium is stored in the embodiment of the present invention.
Furthermore, the invention also provides a control device. In an embodiment of the control device according to the present invention, the control device comprises a processor and a storage device, the storage device may be configured to store a program for executing the method for calculating the steel pipe rod eddy-vibration force of the above-mentioned method embodiment, and the processor may be configured to execute a program in the storage device, the program including but not limited to a program for executing the method for calculating the steel pipe rod eddy-vibration force of the above-mentioned method embodiment. For convenience of explanation, only the parts related to the embodiments of the present invention are shown, and details of the specific techniques are not disclosed. The control device may be a control device apparatus formed including various electronic apparatuses.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.
Claims (10)
1. A method for calculating the eddy vibration force of a steel pipe rod is characterized by comprising the following steps:
performing modal analysis based on a spatial finite element analysis model constructed for the steel pipe rod to be tested to determine the natural vibration frequency and the vibration mode function of the steel pipe rod to be tested;
determining the lift coefficient of the steel pipe rod piece to be tested based on the natural vibration frequency of the steel pipe rod piece to be tested and the outer diameter of the steel pipe rod piece to be tested;
and obtaining the eddy vibration force of the steel pipe rod piece to be detected according to the vibration mode function and the lift coefficient of the steel pipe rod piece to be detected and a random vibration theory.
2. The method of claim 1, wherein determining the natural frequency and mode shape function of the steel pipe rod under test based on modal analysis based on a spatial finite element analysis model constructed for the steel pipe rod under test comprises:
a spatial finite element analysis model is constructed for a steel pipe rod to be tested by adopting a spatial linear finite strain beam unit, the end part of the steel pipe tower inserted steel pipe rod is modeled according to the actual size of an inserting plate in the construction process, a steel pipe lightning rod establishes a herringbone space truss model connected with the steel pipe lightning rod, and the end part of the inserting plate and a bottom node of the herringbone truss are fixedly connected and restrained;
and carrying out modal analysis on the steel pipe rod to be tested in the space finite element analysis model by adopting a Lanuss method to obtain the natural vibration frequency and the vibration mode function of the steel pipe rod to be tested.
3. The method of claim 1, wherein determining the lift coefficient of the steel pipe rod under test based on the natural frequency of vibration of the steel pipe rod under test and the outer diameter of the steel pipe rod under test comprises:
calculating the critical oscillation starting wind speed of the steel pipe rod piece to be detected based on the natural oscillation frequency of the steel pipe rod piece to be detected and the outer diameter of the steel pipe rod piece to be detected;
determining a Reynolds number corresponding to the critical oscillation-starting wind speed based on the critical oscillation-starting wind speed of the steel pipe rod piece to be detected;
and determining a lift coefficient corresponding to the Reynolds number according to a Reynolds number-lift coefficient curve.
4. The method of claim 3, wherein the critical start-up wind speed is calculated as:
Vcr＝f1D/St
in the formula: vcrThe critical oscillation starting wind speed of the steel pipe rod piece; f. of1The first-order natural vibration frequency of the steel pipe rod piece is set; d is the outer diameter of the steel pipe rod piece; stIs the strorehal number.
5. The method of claim 3, wherein the Reynolds number is calculated as:
Re＝VcrD/ν
in the formula: reThe Reynolds number corresponding to the critical oscillation starting wind speed; vcrThe critical oscillation starting wind speed of the steel pipe rod piece; ν is air viscosity; d is the outer diameter of the steel pipe rod piece.
6. The method of claim 1, wherein the obtaining the eddy vibration force of the steel pipe rod piece under test according to the random vibration theory according to the mode shape function and the lift coefficient of the steel pipe rod piece under test comprises:
carrying out normalization processing on the vibration mode function of the steel pipe rod piece to be tested;
obtaining a first-order eddy vibration force distribution function of the steel pipe rod piece to be tested according to a random vibration theory based on the vibration mode function and the lift coefficient after normalization processing;
and deriving the first-order eddy vibration force distribution function based on the axial length of the steel pipe rod piece to be measured to obtain a first-order eddy vibration force resultant force.
7. The method of claim 6, wherein the first-order eddy force distribution function of the steel pipe rod under test is as follows:
in the formula: n isd1Is a first-order vortex vibration force distribution function of the steel pipe rod piece;
normalizing the mode shape function to obtain the mode shape function; rhoaIs the air density; vcrThe critical oscillation starting wind speed of the steel pipe rod piece is obtained; d is the outer diameter of the steel pipe rod piece; cLIs the coefficient of lift; xi1Is the damping ratio; and x is the coordinate along the axial direction of the steel pipe rod piece.
8. The method of claim 6, wherein the first order eddy current force resultant is represented by the following equation:
in the formula: n is a radical ofd1The resultant force of the first-order vortex vibration force is obtained; n isd1Is a first-order vortex vibration force distribution function of the steel pipe rod piece; l is the calculated length of the steel pipe rod piece; and x is the coordinate along the axial direction of the steel pipe rod piece.
9. A calculation system of steel pipe member vortex force, comprising:
the finite element analysis module is used for carrying out modal analysis on the basis of a spatial finite element analysis model constructed for the steel pipe rod piece to be tested to determine the natural vibration frequency and the vibration mode function of the steel pipe rod piece to be tested;
the lift coefficient determining module is used for determining the lift coefficient of the steel pipe rod piece to be tested on the basis of the natural vibration frequency of the steel pipe rod piece to be tested and the outer diameter of the steel pipe rod piece to be tested;
and the vortex vibration force calculation module is used for obtaining the vortex vibration force of the steel pipe rod piece to be detected according to the vibration mode function of the steel pipe rod piece to be detected and the lift coefficient according to a random vibration theory.
10. The system of claim 9, wherein the finite element analysis module is specifically configured to:
a spatial finite element analysis model is constructed for a steel pipe rod to be tested by adopting a spatial linear finite strain beam unit, the end part of the steel pipe tower inserted steel pipe rod is modeled according to the actual size of an inserting plate in the construction process, a steel pipe lightning rod establishes a herringbone space truss model connected with the steel pipe lightning rod, and the end part of the inserting plate and a bottom node of the herringbone truss are fixedly connected and restrained;
and carrying out modal analysis on the steel pipe rod to be tested in the space finite element analysis model by adopting a Lanuss method to obtain the natural vibration frequency and the vibration mode function of the steel pipe rod to be tested.
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