CN108645372B - Large-span transmission conductor suspension point dynamic bending strain measurement method - Google Patents

Large-span transmission conductor suspension point dynamic bending strain measurement method Download PDF

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CN108645372B
CN108645372B CN201810567111.9A CN201810567111A CN108645372B CN 108645372 B CN108645372 B CN 108645372B CN 201810567111 A CN201810567111 A CN 201810567111A CN 108645372 B CN108645372 B CN 108645372B
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lead
wind speed
suspension point
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CN108645372A (en
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阳林
冯展浩
郝艳捧
甘久林
李立浧
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South China University of Technology SCUT
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B21/00—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant
    • G01B21/32—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring the deformation in a solid
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
    • G01L1/242—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft

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Abstract

The invention discloses a method for measuring dynamic bending strain of a suspension point of a long-span transmission conductor, which comprises the following steps: s1, monitoring the aeolian vibration state of the lead, and continuously measuring the horizontal tension of the lead by adopting a tension sensor; s2, monitoring the environmental condition of the overhead transmission line, and continuously measuring the wind speed of the conductor in operation by using a wind speed measuring instrument; s3, calculating characteristic parameters of the aeolian vibration of the lead by using an energy balance method according to the measured wind speed; and S4, substituting the amplitude and the frequency of the aeolian vibration of the wire obtained by solving into the inertial force of the known wire vibration to solve and obtain the inertial force F when the wire vibration is stable, and replacing the static fulcrum counter force in the relation of the static bending stress at the suspension point considering the rigidity of the wire by the inertial force F to obtain the dynamic bending stress at the suspension point when the wire vibrates aeolian. According to the method, the suspension point dynamic bending strain is estimated by measuring the horizontal tension and the wind speed of the operation of the conductor, so that the dynamic bending strain value of the large-span power transmission conductor can be more accurately measured, and accidents are avoided.

Description

Large-span transmission conductor suspension point dynamic bending strain measurement method
Technical Field
The invention relates to the technical field of on-line monitoring of breeze vibration of an overhead conductor in the field of electric power, in particular to a method for measuring dynamic bending strain of a suspension point of a long-span transmission conductor.
Background
When stable wind with the wind speed of 0.5-10 m/s blows to the power transmission line, up-and-down alternative karman vortices are generated on the lee side of the lead/ground wire to cause up-and-down alternating force to act on the power transmission line, so that the power transmission line generates up-and-down regular wave-shaped reciprocating motion in a vertical plane. The frequency of the breeze vibration is between 3Hz and 150Hz, the maximum amplitude is generally not more than 1 to 2 times of the diameter of the transmission line, and the duration of the vibration generally reaches hours and sometimes reaches more than days. The strength of the breeze vibration is often evaluated by a cross-sectional strain value generated by bending when the wire vibrates, namely a dynamic bending strain value. The vibration wave forms a wave node at the suspension point, and the node cannot rotate freely under the constraint of the suspension clamp, so that a dynamic bending strain value larger than that in a span is often generated, and the fatigue breakage of the wire is often generated.
Standardization of wire vibration measurement consider measuring the relative displacement A of a wire pair clamp at 89mm from the clamp outlet89The strain is in linear relation with the dynamic bending strain at the suspension point of the wire, and is basically independent of factors such as vibration frequency, wavelength, tension, span, wire clamp and no rotation. Therefore, the cantilever beam type sensor with the good electromechanical coupling characteristic is generally simple in structure and convenient to machine and install at present, and the dynamic bending strain at the suspension point is calculated by measuring the bending amplitude at 89mm of the wire clamp outlet. However, according to the comparison of the measured data, the linear relationship is affected by the vibration frequency, the vibration amplitude, the wire tension and the rigidity, and the like, and may have an error of ± 50%. The influence on each special wire used for the large-span power transmission wire is larger, and particularly when the large-span power transmission wire generates breeze vibration, the horizontal tension of the wire cannot be considered to be kept unchanged, so that the dynamic bending strain at the suspension point of the large-span power transmission wire cannot be accurately estimated.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, and provides a method for measuring the suspension point dynamic bending strain of a large-span power transmission conductor by considering the influence of vibration frequency, wavelength, tension, span and wire rigidity aiming at the breeze vibration of the large-span power transmission conductor.
The purpose of the invention can be realized by the following technical scheme:
a method for measuring the hanging point dynamic bending strain of a large-span transmission conductor, comprising the following steps:
s1, monitoring the breeze vibration state of the lead, continuously measuring the horizontal tension of the lead by adopting a tension sensor, and recording the change of the horizontal tension of the lead;
s2, monitoring the environmental condition of the overhead transmission line, and continuously measuring the wind speed of the conductor in operation by using a wind speed measuring instrument;
s3, according to the wind speed measured in the step S2, calculating characteristic parameters of the aeolian vibration of the lead by using an energy balance method, namely when the aeolian vibration is stable, the power of the wind input lead is equal to the self-damping power of the lead, and obtaining the characteristic parameters of the aeolian vibration of the lead by using a relational expression of the wind speed, the amplitude and the frequency of the aeolian vibration of the lead;
s4, estimating the dynamic bending strain at the suspension point of the wire according to the step S1 and the step S3, namely, solving the amplitude A of the aeolian vibration of the wire0And substituting the frequency F into the known inertial force of the vibration of the wire to solve to obtain the inertial force F when the vibration of the wire is stable, and substituting the inertial force F for the static fulcrum counterforce in the relation expression of the static bending stress at the suspension point considering the rigidity of the wire to obtain the dynamic bending stress at the suspension point when the wire vibrates in breeze.
Further, in step S1, particularly by arranging a tension sensor at the outlet of the wire clamp, the horizontal tension variation of the wire is continuously measured by the tension sensor.
Furthermore, the tension sensor adopts a fiber grating strain sensor.
Further, in step S2, specifically, the anemometer is installed at the wire clamp of the suspension wire, and the anemometer continuously measures the wind speed of the environment where the wire is located.
Further, the specific process of step S3 is:
first, the power P of the wind input conductor is calculatedWThe formula is as follows:
Figure BDA0001684815660000021
in the formula (I), the compound is shown in the specification,
Figure BDA0001684815660000022
representing a dynamic lift coefficient, related to wind speed; ρ represents the air density in kg/m3(ii) a V represents wind speed in m/s; d represents the outer diameter of the wire and has the unit of m;f represents the frequency of the aeolian vibration of the lead in Hz; a. the0The amplitude of the aeolian vibration of the wire is represented and has the unit of m; coefficient of dynamic lift therein
Figure BDA0001684815660000023
The solving formula of (2) is as follows:
Figure BDA0001684815660000024
wherein s represents a Seawa Roha number, which is related to the Reynolds number of the cylinder, and is 0.185 to 0.2 in a practical range, and 0.2 is used herein;
then, the self-damping power P of the wire is calculatedcThe self-damping of the wire is the self-consumption or energy absorption capacity when the wire is vibrated, and is the power consumed by the wire in unit length, and the formula is as follows:
Figure BDA0001684815660000031
in the formula, y0The maximum double amplitude of the wire is shown, and the three coefficients K, β and α are different according to the specification of the wire and can be obtained by a wire self-damping test, such as AACSR-400 type steel core aluminum alloy stranded wire, wherein K is 5.428 multiplied by 10-5、α＝2.967-4.174f×10-3、β＝5.0。
Finally, the amplitude A of the aeolian vibration of the wire is calculated0: when other parameters are known, the frequency f of the aeolian vibration of the wire is taken as a parametric coordinate, and the maximum double amplitude y of the wire is taken0As independent variable, drawing the power P of the air outlet and input wireWSelf-damping power P with wirecA graph of the relationship of (1), P of the same frequencyWAnd PcAmplitude y at curve intersection0I.e. the steady amplitude of the power balance point, i.e. the amplitude a of the aeolian vibration of the wire0(ii) a When the conductor is in breeze vibration stability, the vibration frequency f can be expressed as a single function of the wind speed V:
Figure BDA0001684815660000032
wherein s represents a Seawa-Roha number, and is 0.185 to 0.2 in a practical range, where 0.2 is used, depending on the Reynolds number of the cylinder.
Further, the step S4 specifically includes the following steps:
s4.1, calculating the inertia force F when the vibration of the half-wavelength inner conductor is stable according to the following formula:
Figure BDA0001684815660000033
theoretically, when the breeze vibration is stable, F in the formula is the natural frequency considering the rigidity of the electric wire, but the transmission conductor is considered to be a small-rigidity beam which is tensioned, the actual span can reach hundreds of meters, and the error of the inertia force F for the vibration of the conductor is generally not more than 5% by neglecting the bending rigidity of the transmission conductor, so the calculation of the inertia force is more safe;
where m represents the mass per unit length of the wire, λ represents the wavelength of vibration of the wire in the rail, and the unit is m, and when the vibration is stable, it is represented by the following equation:
Figure BDA0001684815660000034
in the formula, T0Indicating the horizontal tension of the wire;
s4.2, calculating the static bending stress sigma at the suspension point considering the rigidity of the wire according to the following equation:
Figure BDA0001684815660000035
where E represents the modulus of elasticity of the wire, and the reference wire parameter, e.g., LGJ-800/100, is 67000N/mm2(ii) a J represents the moment of inertia of the section of the wire, and is equal to pi d for a single-strand wire with the diameter d4A/64; c represents the distance between the maximum bending stress point and the bending neutral layer on the section of the wire, namely the radius r of the strand wire and the reference wire parameter; p is a radical of0Represents the concentrated load applied at the center of the test gear and has the unit ofN; l represents the span, h represents the height difference of the suspension point,
Figure BDA0001684815660000041
is static fulcrum counter force;
s4.3, replacing the static fulcrum counter force in the relation of static bending stress at the suspension point considering the rigidity of the electric wire with the inertia force F of the vibration of the lead to obtain the dynamic bending stress sigma at the suspension point when the lead vibrates in breezec：
Figure BDA0001684815660000042
Dynamic bending stress sigma at suspension point during aeolian vibration of leadcHas a unit of N/mm2According to the relation between the dynamic bending stress and the dynamic bending strain, the dynamic bending strain epsilon of the wire clamp at the aeolian vibration of the wire is obtainedc：
Figure BDA0001684815660000043
Dynamic bending strain epsilon at wire clamp during aeolian vibration of leadcHas the unit of muε。
Compared with the prior art, the invention has the following advantages and beneficial effects:
according to the method for measuring the suspension point dynamic bending strain of the large-span power transmission conductor, the suspension point dynamic bending strain is estimated by measuring the horizontal tension and the wind speed of the conductor in operation, so that the problems of the vibration frequency, the wavelength and the wire rigidity of the power transmission conductor are considered on one hand, and on the other hand, the horizontal tension of the large-span conductor is considered to be changed at any time under the condition of breeze vibration, the dynamic bending strain value of the large-span power transmission conductor can be measured more accurately, the operation condition of the power transmission conductor can be evaluated more accurately, and accidents are avoided.
Drawings
Fig. 1 is a flowchart of a method for measuring bending strain at a suspension point of a large-span power transmission conductor according to an embodiment of the present invention.
Fig. 2 is a schematic installation diagram of a related measuring device in the method for measuring the hanging point bending strain of the large-span power transmission conductor in the embodiment of the invention.
The system comprises a tower cross arm 1, a suspension insulator string 2, a fiber bragg grating tension sensor 3, a wind speed measuring instrument 4 and an overhead transmission line lead 5.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited thereto.
Example (b):
an installation schematic diagram of a related measuring device in the method for measuring the hanging point bending strain of the large-span transmission line is shown in fig. 2, and the method comprises a pole tower cross arm (1), a suspension insulator string (2), a fiber bragg grating tension sensor (3), a wind speed measuring instrument (4) and an overhead transmission line lead (5), wherein a flow chart of the method is shown in fig. 1, and the method comprises the following steps:
s1, monitoring the breeze vibration state of the lead, continuously measuring the horizontal tension of the lead by adopting a tension sensor, and recording the change of the horizontal tension of the lead; the method is realized by arranging the fiber bragg grating tension sensor (3) at the outlet of the wire clamp and continuously measuring the horizontal tension change condition of the wire through the fiber bragg grating tension sensor (3).
S2, monitoring the environmental condition of the overhead transmission line, and continuously measuring the wind speed of the conductor in operation by using a wind speed measuring instrument; specifically, the wind speed measuring instrument (4) is arranged at a wire clamp of a suspension wire, and the wind speed of the environment where the wire is located is continuously measured through the wind speed measuring instrument (4).
S3, according to the wind speed measured in the step S2, calculating characteristic parameters of the aeolian vibration of the lead by using an energy balance method, namely when the aeolian vibration is stable, the power of the wind input lead is equal to the self-damping power of the lead, and obtaining the characteristic parameters of the aeolian vibration of the lead by using a relational expression of the wind speed, the amplitude and the frequency of the aeolian vibration of the lead; the specific process is as follows: first, the power P of the wind input conductor is calculatedWThe formula is as follows:
Figure BDA0001684815660000051
in the formula (I), the compound is shown in the specification,
Figure BDA0001684815660000052
representing a dynamic lift coefficient, related to wind speed; ρ represents the air density in kg/m3(ii) a V represents wind speed in m/s; d represents the outer diameter of the wire and has the unit of m; f represents the frequency of the aeolian vibration of the lead in Hz; a. the0The amplitude of the aeolian vibration of the wire is represented and has the unit of m; coefficient of dynamic lift therein
Figure BDA0001684815660000053
The solving formula of (2) is as follows:
Figure BDA0001684815660000054
wherein s represents a Seawa Roha number, which is related to the Reynolds number of the cylinder, and is 0.185 to 0.2 in a practical range, and 0.2 is used herein;
then, the self-damping power P of the wire is calculatedcThe self-damping of the wire is the self-consumption or energy absorption capacity when the wire is vibrated, and is the power consumed by the wire in unit length, and the formula is as follows:
Figure BDA0001684815660000055
in the formula, y0The maximum double amplitude of the wire is shown, and the three coefficients K, β and α are different according to the specification of the wire and can be obtained by a wire self-damping test, such as AACSR-400 type steel core aluminum alloy stranded wire, wherein K is 5.428 multiplied by 10-5、α＝2.967-4.174f×10-3、β＝5.0。
Finally, the amplitude A of the aeolian vibration of the wire is calculated0: when other parameters are known, the frequency f of the aeolian vibration of the wire is taken as a parametric coordinate, and the maximum double amplitude y of the wire is taken0As independent variable, drawing the power P of the air outlet and input wireWSelf-damping power P with wirecA graph of the relationship of (1), P of the same frequencyWAnd PcAmplitude y at curve intersection0I.e. the steady amplitude of the power balance point, i.e. the amplitude a of the aeolian vibration of the wire0(ii) a When the conductor is in breeze vibration stability, the vibration frequency f can be expressed as a single function of the wind speed V:
Figure BDA0001684815660000061
wherein s represents a Seawa-Roha number, and is 0.185 to 0.2 in a practical range, where 0.2 is used, depending on the Reynolds number of the cylinder.
S4, estimating the dynamic bending strain at the suspension point of the wire according to the step S1 and the step S3, namely, solving the amplitude A of the aeolian vibration of the wire0And substituting the frequency F into the known inertial force of the vibration of the wire to solve to obtain the inertial force F when the vibration of the wire is stable, and substituting the inertial force F for the static fulcrum counterforce in the relation expression of the static bending stress at the suspension point considering the rigidity of the wire to obtain the dynamic bending stress at the suspension point when the wire vibrates in breeze. The method specifically comprises the following steps:
s4.1, calculating the inertia force F when the vibration of the half-wavelength inner conductor is stable according to the following formula:
Figure BDA0001684815660000062
theoretically, when the breeze vibration is stable, F in the formula is the natural frequency considering the rigidity of the electric wire, but the transmission conductor is considered to be a small-rigidity beam which is tensioned, the actual span can reach hundreds of meters, and the error of the inertia force F for the vibration of the conductor is generally not more than 5% by neglecting the bending rigidity of the transmission conductor, so the calculation of the inertia force is more safe;
where m represents the mass per unit length of the wire, λ represents the wavelength of vibration of the wire in the rail, and the unit is m, and when the vibration is stable, it is represented by the following equation:
Figure BDA0001684815660000063
in the formula, T0Indicating the horizontal tension of the wire;
s4.2, calculating the static bending stress sigma at the suspension point considering the rigidity of the wire according to the following equation:
Figure BDA0001684815660000064
where E represents the modulus of elasticity of the wire, and the reference wire parameter, e.g., LGJ-800/100, is 67000N/mm2(ii) a J represents the moment of inertia of the section of the wire, and is equal to pi d for a single-strand wire with the diameter d4A/64; c represents the distance between the maximum bending stress point and the bending neutral layer on the section of the wire, namely the radius r of the strand wire and the reference wire parameter; p is a radical of0The unit of the concentrated load applied to the center of the test gear is N; l represents the span, h represents the height difference of the suspension point,
Figure BDA0001684815660000071
is static fulcrum counter force;
s4.3, replacing the static fulcrum counter force in the relation of static bending stress at the suspension point considering the rigidity of the electric wire with the inertia force F of the vibration of the lead to obtain the dynamic bending stress sigma at the suspension point when the lead vibrates in breezec：
Figure BDA0001684815660000072
Dynamic bending stress sigma at suspension point during aeolian vibration of leadcHas a unit of N/mm2According to the relation between the dynamic bending stress and the dynamic bending strain, the dynamic bending strain epsilon of the wire clamp at the aeolian vibration of the wire is obtainedc：
Figure BDA0001684815660000073
Dynamic bending strain epsilon at wire clamp during aeolian vibration of leadcHas the unit of muε。
The above description is only for the preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art can substitute or change the technical solution of the present invention and the inventive concept within the scope of the present invention, which is disclosed by the present invention, and the equivalent or change thereof belongs to the protection scope of the present invention.

Claims (4)

1. A method for measuring the suspension point dynamic bending strain of a large-span transmission conductor is characterized by comprising the following steps:
s1, monitoring the breeze vibration state of the wire, continuously measuring the horizontal tension of the wire by using a tension sensor, and recording the change of the horizontal tension of the wire, wherein the tension sensor is arranged at the outlet of the wire clamp, and the change of the horizontal tension of the wire is continuously measured by the tension sensor;
s2, monitoring the environmental condition of the overhead transmission line, and continuously measuring the wind speed of the conductor in operation by using a wind speed measuring instrument; specifically, the wind speed measuring instrument is arranged at a wire clamp for hanging the wire, and the wind speed measuring instrument continuously measures the wind speed of the environment where the wire is located;
s3, according to the wind speed measured in the step S2, calculating characteristic parameters of the aeolian vibration of the lead by using an energy balance method, namely when the aeolian vibration is stable, the power of the wind input lead is equal to the self-damping power of the lead, and obtaining the characteristic parameters of the aeolian vibration of the lead by using a relational expression of the wind speed, the amplitude and the frequency of the aeolian vibration of the lead;
s4, estimating the dynamic bending strain at the suspension point of the wire according to the step S1 and the step S3, namely, solving the amplitude A of the aeolian vibration of the wire0And substituting the frequency F into the known inertial force of the vibration of the wire to solve to obtain the inertial force F when the vibration of the wire is stable, and substituting the inertial force F for the static fulcrum counterforce in the relation expression of the static bending stress at the suspension point considering the rigidity of the wire to obtain the dynamic bending stress at the suspension point when the wire vibrates in breeze.
2. The method for measuring the hanging point dynamic bending strain of the large-span power transmission conductor according to claim 1, characterized by comprising the following steps: the tension sensor adopts a fiber bragg grating strain sensor.
3. The method for measuring the hanging point dynamic bending strain of the long-span power transmission conductor according to claim 1, wherein the specific process of the step S3 is as follows:
first, the power P of the wind input conductor is calculatedWThe formula is as follows:
Figure FDA0002434908040000011
in the formula (I), the compound is shown in the specification,
Figure FDA0002434908040000012
representing a dynamic lift coefficient, related to wind speed; ρ represents the air density in kg/m3(ii) a V represents wind speed in m/s; d represents the outer diameter of the wire and has the unit of m; f represents the frequency of the aeolian vibration of the lead in Hz; a. the0The amplitude of the aeolian vibration of the wire is represented and has the unit of m; coefficient of dynamic lift therein
Figure FDA0002434908040000013
The solving formula of (2) is as follows:
Figure FDA0002434908040000014
wherein s represents a Seawa Roha number, which is related to the Reynolds number of the cylinder, and is 0.185 to 0.2 in a practical range, and 0.2 is used herein;
then, the self-damping power P of the wire is calculatedcThe formula is as follows:
Figure FDA0002434908040000021
in the formula, y0The maximum double amplitude of the wire is shown, and the three coefficients K, β and α are different according to the specification of the wire and can be obtained through a wire self-damping test;
finally, the amplitude A of the aeolian vibration of the wire is calculated0: when other parameters are known, the frequency of the aeolian vibration of the wire is usedThe ratio f is a parameter coordinate and the maximum double amplitude y of the wire0As independent variable, drawing the power P of the air outlet and input wireWSelf-damping power P with wirecA graph of the relationship of (1), P of the same frequencyWAnd PcAmplitude y at curve intersection0I.e. the steady amplitude of the power balance point, i.e. the amplitude a of the aeolian vibration of the wire0(ii) a When the conductor is in breeze vibration stability, the vibration frequency f can be expressed as a single function of the wind speed V:
Figure FDA0002434908040000022
wherein s represents a Seawa-Roha number, and is 0.185 to 0.2 in a practical range, where 0.2 is used, depending on the Reynolds number of the cylinder.
4. The method for measuring the hanging point dynamic bending strain of the long-span power transmission conductor according to claim 3, wherein the step S4 specifically comprises the following steps:
s4.1, calculating the inertia force F when the vibration of the half-wavelength inner conductor is stable according to the following formula:
Figure FDA0002434908040000023
in the formula, dx is an arbitrary micro-segment wire, x is the length direction of the wire, m represents the mass of the wire per unit length, λ represents the wavelength of the vibration of the wire in the step, and the unit is m, and when the vibration is stable, the vibration is expressed by the following formula:
Figure FDA0002434908040000024
in the formula, T0Indicating the horizontal tension of the wire; s represents the Strouhal number;
s4.2, calculating the static bending stress sigma at the suspension point considering the rigidity of the wire according to the following equation:
Figure FDA0002434908040000025
wherein E represents the elastic coefficient of the wire; j represents the inertia moment of the section of the wire, and is equal to pi D for a single-stranded wire with the outer diameter D4A/64; c represents the distance between the maximum bending stress point on the section of the wire and a bending neutral layer, and the radius r of the strand wire is referred to herein; p is a radical of0The unit of the concentrated load applied to the center of the test gear is N; l represents the span, h represents the height difference of the suspension point,
Figure FDA0002434908040000031
is static fulcrum counter force;
s4.3, replacing the static fulcrum counter force in the relation of static bending stress at the suspension point considering the rigidity of the electric wire with the inertia force F of the vibration of the lead to obtain the dynamic bending stress sigma at the suspension point when the lead vibrates in breezec：
Figure FDA0002434908040000032
Dynamic bending stress sigma at suspension point during aeolian vibration of leadcHas a unit of N/mm2According to the relation between the dynamic bending stress and the dynamic bending strain, the dynamic bending strain epsilon of the wire clamp at the aeolian vibration of the wire is obtainedc：
Figure FDA0002434908040000033
Dynamic bending strain epsilon at wire clamp during aeolian vibration of leadcHas the unit of muε。
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