CN111380476B - Beam type structure deformation measuring method and device based on strain measurement data - Google Patents

Abstract

The invention relates to a beam type structure deformation measuring method based on strain measurement data, which is characterized by being applicable to an indirect measuring method for beam type structure deformation monitoring, wherein the strain data are acquired by adopting a fiber grating sensor. The measurement method provided by the invention can be used for measuring the large deformation of the beam structure, wherein the large deformation is defined to be more than 15% of the length of the beam structure. The method can be widely applied to the fields of real-time deformation measurement, structural health monitoring and the like of beam type structures such as high-aspect-ratio flexible wings, large bridge structures, large buildings and the like.

Description

Beam type structure deformation measuring method and device based on strain measurement data

Technical Field

The invention relates to a method and a device for measuring beam structure deformation based on strain measurement data.

Background

Aircraft structures require extensive testing during the design process, including ground and flight testing in terms of structural function, structural strength, load testing, and the like. In these tests, the amount of deformation of the wing structure is one of the important test data. The method is used for accurately and efficiently measuring the structural deformation, and is very important for analyzing the performance and the state of the structure and providing correct basis for designers.

In addition, composite materials have found widespread use in aerospace structures in recent years, and wing structures are generally of low mass. Meanwhile, for high-altitude long-endurance unmanned aerial vehicles, large civil aircraft, large transport aircraft and other aircrafts, the wing aspect ratio is large, and the flexibility is large. The aircraft can generate large deformation when being subjected to air action during flight. Therefore, the structural deformation measurement method needs to take into account the effect of large deformation of the structure.

The existing structural deformation measuring means commonly comprise displacement meter measurement, optical measurement and infrared instrument measurement. The displacement meter is used for measuring, the cost is low, the operation is simple, and the measuring process is visual. However, when a displacement meter is used for measurement, if the structural deformation is large (for example, the deformation of the flexible wing can reach more than 15% of half-span length), especially the direction change caused by large deformation can cause inaccurate measurement results; in addition, the displacement gauge measurement is hardly suitable for real-time measurement of structural deformation in an airborne test. The optical measurement system is a method developed in recent years for capturing the three-dimensional position of the structure space by a plurality of cameras and then calculating the deformation of the structure, and the method also has the problem of imaging distortion, and the measurement result can be inaccurate if the deformation of the structure is large. The infrared instrument can measure three-dimensional deformation, but the cost is higher, and the operation is complicated, and the measurement process is not directly perceived, can't in time discover when having the problem, does not utilize real-time deformation measurement of structure when airborne is tested.

Therefore, a three-dimensional configuration measuring method applicable to large structural deformation is needed when an aviation structural test is carried out.

Disclosure of Invention

According to an aspect of the present invention, there is provided a beam structure deformation measurement apparatus based on strain measurement data, characterized by comprising:

first to fourth optical fibers S1, S2, S3, S4, each fiber being connected in series with N fiber grating sensors for strain measurement, wherein the X-axis coordinates of the set point of the ith fiber grating sensor among the N fiber grating sensors on the first to fourth optical fibers are the same,

the first optical fiber S1 and the second optical fiber S2 are respectively disposed on the upper surface of the beam structure,

the third optical fiber S3 is disposed on the upper surface of the beam structure,

the fourth optical fiber S4 is disposed on the lower surface of the beam structure,

the X axis points to the length direction of the beam structure, the Y axis points to the normal direction of the upper surface of the beam structure, the Z axis is defined by the right-hand rule,

fiber bragg grating sensor⁽¹⁾ε₁，⁽¹⁾ε₂，⁽¹⁾ε₃，⁽¹⁾ε₄，⁽¹⁾ε₅Connect in series on the first fiber S1, the fiber grating sensor⁽²⁾ε₁，⁽²⁾ε₂，⁽²⁾ε₃，⁽²⁾ε₄，⁽²⁾ε₅The fiber bragg grating sensors are connected in series on a second optical fiber S2, the arrangement directions of the fiber bragg grating sensors are all directions parallel to the X axis,

fiber bragg grating sensor⁽³⁾ε₁，⁽³⁾ε₂，⁽³⁾ε₃，⁽³⁾ε₄，⁽³⁾ε₅The third optical fiber S3 is connected in series, the arrangement direction of the sensors alternately forms an angle of +45 degrees with the X axis,

fiber bragg grating sensor⁽⁴⁾ε₁，⁽⁴⁾ε₂，⁽⁴⁾ε₃，⁽⁴⁾ε₄，⁽⁴⁾ε₅The fourth optical fiber S4 are connected in series, the arrangement directions of the sensors are all parallel to the Z axis,

wherein the content of the first and second substances,

with E₁，E₂，E₃Three basis vectors, E, respectively, representing a coordinate system₁Along the length direction of the beam;

in g₁(s)，g₂(s)，g₃(s) three basis vectors representing the local coordinate system at length s before beam deformation, respectively;

with G₁(s)，G₂(s)，G₃(s) represent three basis vectors of the local coordinate system at length s after the beam is deformed, and have:

G₁(s)＝[G₁₁(s) G₁₂(s) G₁₃(s)]^T，

G₂(s)＝[G₂₁(s) G₂₂(s) G₂₃(s)]^T，

G₃(s)＝[G₃₁(s) G₃₂(s) G₃₃(s)]^T；

representing a space position vector of the central reference axis s in the reference coordinate system before the beam is deformed by r(s);

and R(s) represents the space position vector of the center reference axis s in the reference coordinate system after the beam is deformed, and the space position vector comprises:

R(s_i)＝[R_i1 R_i2 R_i3]^T. Column vector in inventive content step five

Can be defined according to the position vector and the base vector of the coordinate system:

，

the beam structure deformation measuring device is adapted to perform the following operations:

A) the arrangement position of the fiber grating sensor on each optical fiber is sequentially represented as:

wherein the content of the first and second substances,

the distance between the first optical fiber S3 and the fourth optical fiber S4 and the center line of the beam type structure at the ith measuring point is shown, wherein the ith measuring point is the position of the ith fiber grating sensor on each optical fiber;

a coordinate component in the Y direction relative to the structural beam structure centerline at the ith measurement point of the first optical fiber S1;

represents the coordinate component of the first optical fiber S1 in the Z direction relative to the structural beam structure centerline at the ith test point;

represents the coordinate component of the second optical fiber S2 in the Y direction relative to the structural beam structure centerline at the ith measuring point;

represents the Z-direction coordinate component of the second optical fiber S2 relative to the structural beam structure centerline at the ith test point,

B) adopting optical fiber measurement technology to measure structural strain at the position of each group of 4 sensors with the same X coordinate⁽¹⁾ε_i}_i＝1,2,…N,{⁽²⁾ε_i}_i＝1,2,…N,{⁽³⁾ε_i}_i＝1,2,…N,{⁽⁴⁾ε_i}_i＝1,2,…NWherein: {⁽¹⁾ε_i}_i＝1,2,…NThe structural strain measured at the ith test point on the first optical fiber S1; {⁽²⁾ε_i}_i＝1,2,…NThe structural strain measured at the ith test point on the second optical fiber S2; {⁽³⁾ε_i}_i＝1,2,…NThe structural strain measured at the ith test point on the third optical fiber S3; {⁽⁴⁾ε_i}_i＝1,2,…NThe structural strain measured at the ith test point on the fourth fiber S4,

C) calculating the three-dimensional curvature of the beam structure center line at each ith measurement point according to the measured structural strain and the following relation

D) The structural deformation-curvature relationship is calculated according to the following system of equations:

wherein

E) Calculating the structural deformation at the measuring point according to the relation in the step (C) and the step (D):

is a column vector of 12X1, the 1 st, 5 th and 9 th elements of which respectively correspond to the three-dimensional positions of the structure at the measuring point i in the space,

representing the position vector of the structure at the end point position, thereby representing the three-dimensional position of the ith measuring point after the beam structure is deformed as

According to another aspect of the present invention, there is provided a beam structure deformation measurement method based on strain measurement data, comprising:

the first optical fiber S1 and the second optical fiber S2 are respectively disposed on the upper surface of the beam structure,

the third optical fiber S3 is disposed on the upper surface of the beam structure,

the fourth optical fiber S4 is disposed on the lower surface of the beam structure,

each optical fiber is connected with N fiber grating sensors in series for strain measurement, wherein the X-axis coordinates of the set points of the ith fiber grating sensor in the N fiber grating sensors on the first to fourth optical fibers are the same, the X-axis points to the length direction of the beam structure, the Y-axis points to the normal direction of the upper surface of the beam structure, and the Z-axis is defined by the right-hand rule, which specifically includes:

opening and closing optical fiber grating sensor⁽¹⁾ε₁，⁽¹⁾ε₂，⁽¹⁾ε₃，⁽¹⁾ε₄，⁽¹⁾ε₅Connect in series with the first fiber S1 to make the fiber grating sensor⁽²⁾ε₁，⁽²⁾ε₂，⁽²⁾ε₃，⁽²⁾ε₄，⁽²⁾ε₅The fiber bragg grating sensors are connected in series on a second optical fiber S2, wherein the arrangement directions of the fiber bragg grating sensors are all directions parallel to the X axis,

opening and closing optical fiber grating sensor⁽³⁾ε₁，⁽³⁾ε₂，⁽³⁾ε₃，⁽³⁾ε₄，⁽³⁾ε₅Are connected in series to a third optical fibre S3, wherein the sensors are arranged alternately at +45 deg. to the X axis,

opening and closing optical fiber grating sensor⁽⁴⁾ε₁，⁽⁴⁾ε₂，⁽⁴⁾ε₃，⁽⁴⁾ε₄，⁽⁴⁾ε₅Are connected in series to a fourth optical fibre S4, wherein the sensors are all arranged in a direction parallel to the Z axis,

with E₁，E₂，E₃Three basis vectors, E, respectively, representing a coordinate system₁Along the length direction of the beam;

in g₁(s)，g₂(s)，g₃(s) three basis vectors representing the local coordinate system at length s before beam deformation, respectively;

with G₁(s)，G₂(s)，G₃(s) represent three basis vectors of the local coordinate system at length s after the beam is deformed, and have:

G₁(s)＝[G₁₁(s) G₁₂(s) G₁₃(s)]^T，

G₂(s)＝[G₂₁(s) G₂₂(s) G₂₃(s)]^T，

G₃(s)＝[G₃₁(s) G₃₂(s) G₃₃(s)]^T；

representing a space position vector of the central reference axis s in the reference coordinate system before the beam is deformed by r(s);

and R(s) represents the space position vector of the center reference axis s in the reference coordinate system after the beam is deformed, and the space position vector comprises:

R(s_i)＝[R_i1 R_i2 R_i3]^T，

the beam structure deformation measurement method further includes:

A) the arrangement position of the fiber grating sensor on each optical fiber is sequentially represented as:

wherein the content of the first and second substances,

the distance between the first optical fiber S3 and the fourth optical fiber S4 and the center line of the beam type structure at the ith measuring point is shown, wherein the ith measuring point is the position of the ith fiber grating sensor on each optical fiber;

a coordinate component in the Y direction relative to the structural beam structure centerline at the ith measurement point of the first optical fiber S1;

represents the coordinate component of the first optical fiber S1 in the Z direction relative to the structural beam structure centerline at the ith test point;

represents the coordinate component of the second optical fiber S2 in the Y direction relative to the structural beam structure centerline at the ith measuring point;

represents the Z-direction coordinate component of the second optical fiber S2 relative to the structural beam structure centerline at the ith test point,

B) adopting optical fiber measurement technology to measure X-rayStructural strain retaining tone at the same position of each group of 4 sensors⁽¹⁾ε_i}_i＝1,2,…N,{⁽²⁾ε_i}_i＝1,2,…N,{⁽³⁾ε_i}_i＝1,2,…N,{⁽⁴⁾ε_i}_i＝1,2,…NWherein: {⁽¹⁾ε_i}_i＝1,2,…NThe structural strain measured at the ith test point on the first optical fiber S1; {⁽²⁾ε_i}_i＝1,2,…NThe structural strain measured at the ith test point on the second optical fiber S2; {⁽³⁾ε_i}_i＝1,2,…NThe structural strain measured at the ith test point on the third optical fiber S3; {⁽⁴⁾ε_i}_i＝1,2,…NThe structural strain measured at the ith test point on the fourth fiber S4,

C) calculating the three-dimensional curvature of the beam structure center line at each ith measurement point according to the measured structural strain and the following relation

D) The structural deformation-curvature relationship is calculated according to the following system of equations:

wherein

E) Calculating the structural deformation at the measuring point according to the relation in the step (C) and the step (D):

is a column vector of 12X1, the 1 st, 5 th and 9 th elements of which respectively correspond to the three-dimensional positions of the structure at the measuring point i in the space,

wherein the column vector

Is determined as:

representing the position vector of the structure at the end point position, thereby representing the three-dimensional position of the ith measuring point after the beam structure is deformed as

Drawings

Fig. 1 is a schematic diagram of a strain sensor arrangement of a beam structure deformation measurement device based on strain measurement data according to one embodiment of the present invention.

Fig. 2 is a schematic view of a deformation configuration of a beam structure suitable for applying the beam structure deformation measurement apparatus based on strain measurement data according to the present invention.

Detailed Description

In order to overcome the defects of the prior art and achieve the aim, the invention provides a structural deformation measuring method based on strain measurement data, which is suitable for a beam type structure such as a wing, a tail wing and the like. In the method, strain measurement data is acquired by a fiber grating sensor. The invention comprises the following steps:

step one, selecting N measuring points on a test piece along the length direction of a beam, respectively pasting 1 fiber grating sensor on each optical fiber at each measuring point, and determining the pasting position of the fiber grating sensors:

wherein the content of the first and second substances,

represents the distance from the beam structure centerline at the ith test point for fiber number S3 and fiber number S4;

a coordinate component in the Y direction of the optical fiber denoted by the number S1 with respect to the center line of the structural beam structure at the i-th measurement point;

a coordinate component in the Z direction from the center line of the structural beam structure at the i-th measuring point of the optical fiber with the number S1;

a coordinate component in the Y direction of the optical fiber denoted by the number S2 with respect to the center line of the structural beam structure at the i-th measurement point;

the optical fiber denoted by the number S2 is in the opposite structural beam structure at the ith test pointThe coordinate component of the center line in the Z direction.

Step two, adopting an optical fiber measurement technology to measure the structural strain of the positions of the 4 sensors at each measuring point: {⁽¹⁾ε_i}_i＝1,2,…N,{⁽²⁾ε_i}_i＝1,2,…N,{⁽³⁾ε_i}_i＝1,2,…N,{⁽⁴⁾ε_i}_i＝1,2,…N{⁽¹⁾ε_i}_i＝1,2,…NRepresents the structural strain measured at the ith test point in the optical fiber numbered S1; {⁽²⁾ε_i}_i＝1,2,…NRepresents the structural strain measured at the ith test point in the optical fiber numbered S2; {⁽³⁾ε_i}_i＝1,2,…NRepresents the structural strain measured at the ith test point in the optical fiber numbered S3; {⁽⁴⁾ε_i}_i＝1,2,…NThe structural strain measured at the ith station in the fiber numbered S4 is shown.

Step three, calculating the three-dimensional curvature of the central line of the beam structure at each measuring point i according to the measured strain and the following relational expression

Step four, calculating a structural deformation-curvature relation according to the following equation:

wherein

Step five, calculating the structural deformation at the measuring point according to the relational expression in the step three and the step four:

among them, in the above-mentioned case,

is a 12X1 column vector defined as follows:

its 1 st, 5 th and 9 th elements respectively correspond to the three-dimensional deformation of the structure at the measuring point i in the space. Wherein the definition of each element is shown in figure 2.

Shown is the position vector of the structure at the end position (the left-most root shown in fig. 1).

The method is not only suitable for the condition of beam root solid support, but also can directly measure the beam structure deformation under different constraint conditions only by determining boundary conditions.

The invention is further described below with reference to the accompanying drawings.

Fig. 1 is a schematic diagram of a strain sensor arrangement. The strain sensor is a fiber grating sensor, and N strain sensors (N is 5 in figure 1)) The fiber grating sensor is connected in series in an optical fiber, and specifically, the sensor⁽¹⁾ε₁，⁽¹⁾ε₂，⁽¹⁾ε₃，⁽¹⁾ε₄，⁽¹⁾ε₅Connected in series in the optical fiber S1; transducer opening⁽²⁾ε₁，⁽²⁾ε₂，⁽²⁾ε₃，⁽²⁾ε₄，⁽²⁾ε₅Connected in series in the optical fiber S2; transducer opening⁽³⁾ε₁，⁽³⁾ε₂，⁽³⁾ε₃，⁽³⁾ε₄，⁽³⁾ε₅Connected in series in the optical fiber S3; transducer opening⁽⁴⁾ε₁，⁽⁴⁾ε₂，⁽⁴⁾ε₃，⁽⁴⁾ε₄，⁽⁴⁾ε₅Is connected in series in the optical fiber S3. The sensor has the advantages of light weight, electromagnetic interference resistance and the like, and is convenient for airborne arrangement. The coordinate system shown in fig. 1 is defined as follows: the origin is located at the center of the cross section of the root of the beam, the X axis points to the length direction of the beam, the Y axis points to the out-of-plane bending direction, and the Z axis is defined by the right-hand rule. And the coordinate positions of the sensors at the ith measuring point in the four optical fibers in the X-axis direction are the same. The optical fibers S1, S2 are arranged on the upper surface of the beam, respectively, in a direction parallel to the X axis. The optical fibers S3 are arranged on the upper surface of the beam, and the directions of the sensors at all measuring points on the S3 and the X axis are alternately arranged at an angle of +/-45 degrees; the optical fiber S4 is disposed on the lower surface of the beam with the sensor direction parallel to the Z-axis.

FIG. 2 is a schematic view of a beam structure deformation configuration, wherein E₁，E₂，E₃Three base vectors of a reference coordinate system can be selected at will, and the origin of the coordinate system is the center of the cross section of the root part of the beam, E₁Along the length direction of the beam; g₁(s)，g₂(s)，g₃(s) three basis vectors of a local coordinate system at the length s before the beam is deformed respectively; g₁(s)，G₂(s)，G₃(s) three basis vectors of the local coordinate system at the length s after the beam is deformed, and having G₁(s)＝[G₁₁(s) G₁₂(s) G₁₃(s)]^T，G₂(s)＝[G₂₁(s) G₂₂(s) G₂₃(s)]^T，G₃(s)＝[G₃₁(s) G₃₂(s) G₃₃(s)]^T(ii) a r(s) is a spatial position vector of the central reference axis s in the reference coordinate system before the beam is deformed; r(s) is a space position vector of the center reference axis s in the reference coordinate system after the beam is deformed, and R(s)_i)＝[R_i1 R_i2 R_i3]^T. Column vector in inventive content step five

Can be defined according to the position vector and the base vector of the coordinate system:

。

shown is the position vector of the structure at the end position (the left-most root shown in fig. 1).

Step one, selecting N measuring points on a test piece along the length direction of a beam, respectively pasting 1 fiber grating sensor on each optical fiber at each measuring point, and determining the pasting position of the fiber grating sensors:

wherein the content of the first and second substances,

represents the distance from the beam structure centerline at the ith test point for fiber number S3 and fiber number S4;

a coordinate component in the Y direction of the optical fiber denoted by the number S1 with respect to the center line of the structural beam structure at the i-th measurement point;

a coordinate component in the Z direction from the center line of the structural beam structure at the i-th measuring point of the optical fiber with the number S1;

a coordinate component in the Y direction of the optical fiber denoted by the number S2 with respect to the center line of the structural beam structure at the i-th measurement point;

the coordinate component in the Z direction of the optical fiber denoted by number S2 with respect to the center line of the structural beam structure at the i-th measurement point.

Step two, adopting an optical fiber measurement technology to measure the structural strain of the positions of the 4 sensors at each measuring point: {⁽¹⁾ε_i}_i＝1,2,…N,{⁽²⁾ε_i}_i＝1,2,…N,{⁽³⁾ε_i}_i＝1,2,…N,{⁽⁴⁾ε_i}_i＝1,2,…N{⁽¹⁾ε_i}_i＝1,2,…NRepresents the structural strain measured at the ith test point in the optical fiber numbered S1; {⁽²⁾ε_i}_i＝1,2,…NRepresents the structural strain measured at the ith test point in the optical fiber numbered S2; {⁽³⁾ε_i}_i＝1,2,…NRepresents the structural strain measured at the ith test point in the optical fiber numbered S3; {⁽⁴⁾ε_i}_i＝1,2,…NThe structural strain measured at the ith station in the fiber numbered S4 is shown.

Step three, calculating the three-dimensional curvature of the central line of the beam structure at each measuring point i according to the measured strain and the following relational expression

Step four, calculating a structural deformation-curvature relation according to the following equation:

wherein

Step five, calculating the structural deformation at the measuring point according to the relational expression in the step three and the step four:

among them, in the above-mentioned case,

is a column vector of 12X1, whose elements 1,5 and 9 correspond to the three-dimensional positions of the structure at the measurement point i in space, respectively.

Shown is the position vector of the structure at the end position (the left-most root shown in fig. 1).

Thus, the three-dimensional position of the beam structure at the measuring point i after deformation is

After the three-dimensional positions of the measuring points are known, a continuous beam structure deformation curve can be obtained through a spline interpolation method.

Claims (4)

1. A beam structure deformation measuring device based on strain measurement data is characterized by comprising:

first to fourth optical fibers S1, S2, S3, S4, each fiber being connected in series with N fiber grating sensors for strain measurement, wherein the X-axis coordinates of the set point of the ith fiber grating sensor among the N fiber grating sensors on the first to fourth optical fibers are the same,

the first optical fiber S1 and the second optical fiber S2 are respectively disposed on the upper surface of the beam structure,

the third optical fiber S3 is disposed on the upper surface of the beam structure,

the fourth optical fiber S4 is disposed on the lower surface of the beam structure,

the X axis points to the length direction of the beam structure, the Y axis points to the normal direction of the upper surface of the beam structure, the Z axis is defined by the right-hand rule,

fiber bragg grating sensor⁽¹⁾ε₁，⁽¹⁾ε₂，⁽¹⁾ε₃，⁽¹⁾ε₄，⁽¹⁾ε₅Connect in series on the first fiber S1, the fiber grating sensor⁽²⁾ε₁，⁽²⁾ε₂，⁽²⁾ε₃，⁽²⁾ε₄，⁽²⁾ε₅The fiber bragg grating sensors are connected in series on a second optical fiber S2, the arrangement directions of the fiber bragg grating sensors are all directions parallel to the X axis,

fiber bragg grating sensor⁽³⁾ε₁，⁽³⁾ε₂，⁽³⁾ε₃，⁽³⁾ε₄，⁽³⁾ε₅The third optical fiber S3 is connected in series, the arrangement direction of the sensors alternately forms an angle of +45 degrees with the X axis,

fiber bragg grating sensor⁽⁴⁾ε₁，⁽⁴⁾ε₂，⁽⁴⁾ε₃，⁽⁴⁾ε₄，⁽⁴⁾ε₅The fourth optical fiber S4 are connected in series, the arrangement directions of the sensors are all parallel to the Z axis,

wherein the content of the first and second substances,

with E₁，E₂，E₃Three basis vectors, E, respectively, representing a coordinate system₁Along the length direction of the beam;

in g₁(s)，g₂(s)，g₃(s) three basis vectors representing the local coordinate system at length s before beam deformation, respectively;

with G₁(s)，G₂(s)，G₃(s) represent three basis vectors of the local coordinate system at length s after the beam is deformed, and have:

G₁(s)＝[G₁₁(s) G₁₂(s) G₁₃(s)]^T，

G₂(s)＝[G₂₁(s) G₂₂(s) G₂₃(s)]^T，

G₃(s)＝[G₃₁(s) G₃₂(s) G₃₃(s)]^T；

representing a space position vector of the central reference axis s in the reference coordinate system before the beam is deformed by r(s);

and R(s) represents the space position vector of the center reference axis s in the reference coordinate system after the beam is deformed, and the space position vector comprises:

R(s_i)＝[R_i1 R_i2 R_i3]^T，

column vector

According to the spatial position vector and the base vector of the coordinate system, defining:

，

the beam structure deformation measuring device is adapted to perform the following operations:

A) the arrangement position of the fiber grating sensor on each optical fiber is sequentially represented as:

wherein the content of the first and second substances,

the distance between the first optical fiber S3 and the fourth optical fiber S4 and the center line of the beam type structure at the ith measuring point is shown, wherein the ith measuring point is the position of the ith fiber grating sensor on each optical fiber;

a coordinate component in the Y direction relative to the structural beam structure centerline at the ith measurement point of the first optical fiber S1;

represents the coordinate component of the first optical fiber S1 in the Z direction relative to the structural beam structure centerline at the ith test point;

represents the coordinate component of the second optical fiber S2 in the Y direction relative to the structural beam structure centerline at the ith measuring point;

represents the Z-direction coordinate component of the second optical fiber S2 relative to the structural beam structure centerline at the ith test point,

B) adopting optical fiber measurement technology to measure structural strain at the position of each group of 4 sensors with the same X coordinate⁽¹⁾ε_i}_i＝1,2,…N,{⁽²⁾ε_i}_i＝1,2,…N,{⁽³⁾ε_i}_i＝1,2,…N,{⁽⁴⁾ε_i}_i＝1,2,…NWherein: {⁽¹⁾ε_i}_i＝1,2,…NThe measured structure at the i-th measuring point on the first optical fiber S1Changing; {⁽²⁾ε_i}_i＝1,2,…NThe structural strain measured at the ith test point on the second optical fiber S2; {⁽³⁾ε_i}_i＝1,2,…NThe structural strain measured at the ith test point on the third optical fiber S3; {⁽⁴⁾ε_i}_i＝1,2,…NThe structural strain measured at the ith test point on the fourth fiber S4,

C) calculating the three-dimensional curvature of the beam structure center line at each ith measurement point according to the measured structural strain and the following relation

D) The structural deformation-curvature relationship is calculated according to the following system of equations:

wherein

E) Calculating the structural deformation at the measuring point according to the relation in the step (C) and the step (D):

is a column vector of 12X1, the 1 st, 5 th and 9 th elements of which respectively correspond to the three-dimensional positions of the structure at the measuring point i in the space,

representing a position vector of the structure at the location of the end point,

thus, the three-dimensional position of the i-th measurement point after deformation of the beam structure is represented as

2. The beam structure deformation measuring device according to claim 1, wherein:

after determining the three-dimensional position of each measuring point

And then, obtaining a continuous beam structure deformation curve by a spline interpolation method.

3. A beam structure deformation measurement method based on strain measurement data is characterized by comprising the following steps:

the first optical fiber S1 and the second optical fiber S2 are respectively disposed on the upper surface of the beam structure,

the third optical fiber S3 is disposed on the upper surface of the beam structure,

the fourth optical fiber S4 is disposed on the lower surface of the beam structure,

each optical fiber is connected with N fiber grating sensors in series for strain measurement, wherein the X-axis coordinates of the set points of the ith fiber grating sensor in the N fiber grating sensors on the first to fourth optical fibers are the same, the X-axis points to the length direction of the beam structure, the Y-axis points to the normal direction of the upper surface of the beam structure, and the Z-axis is defined by the right-hand rule, which specifically includes:

opening and closing optical fiber grating sensor⁽¹⁾ε₁，⁽¹⁾ε₂，⁽¹⁾ε₃，⁽¹⁾ε₄，⁽¹⁾ε₅Connect in series with the first fiber S1 to make the fiber grating sensor⁽²⁾ε₁，⁽²⁾ε₂，⁽²⁾ε₃，⁽²⁾ε₄，⁽²⁾ε₅The fiber bragg grating sensors are connected in series on a second optical fiber S2, wherein the arrangement directions of the fiber bragg grating sensors are all directions parallel to the X axis,

opening and closing optical fiber grating sensor⁽³⁾ε₁，⁽³⁾ε₂，⁽³⁾ε₃，⁽³⁾ε₄，⁽³⁾ε₅Are connected in series to a third optical fibre S3, wherein the sensors are arranged alternately at +45 deg. to the X axis,

opening and closing optical fiber grating sensor⁽⁴⁾ε₁，⁽⁴⁾ε₂，⁽⁴⁾ε₃，⁽⁴⁾ε₄，⁽⁴⁾ε₅Are connected in series to a fourth optical fibre S4, wherein the sensors are all arranged in a direction parallel to the Z axis,

with E₁，E₂，E₃Three basis vectors, E, respectively, representing a coordinate system₁Along the length direction of the beam;

in g₁(s)，g₂(s)，g₃(s) three basis vectors representing the local coordinate system at length s before beam deformation, respectively;

with G₁(s)，G₂(s)，G₃(s) represent three basis vectors of the local coordinate system at length s after the beam is deformed, and have:

G₁(s)＝[G₁₁(s) G₁₂(s) G₁₃(s)]^T，

G₂(s)＝[G₂₁(s) G₂₂(s) G₂₃(s)]^T，

G₃(s)＝[G₃₁(s) G₃₂(s) G₃₃(s)]^T；

representing a space position vector of the central reference axis s in the reference coordinate system before the beam is deformed by r(s);

and R(s) represents the space position vector of the center reference axis s in the reference coordinate system after the beam is deformed, and the space position vector comprises:

R(s_i)＝[R_i1 R_i2 R_i3]^T，

the beam structure deformation measurement method further includes:

A) the arrangement position of the fiber grating sensor on each optical fiber is sequentially represented as:

wherein the content of the first and second substances,

the distance between the first optical fiber S3 and the fourth optical fiber S4 and the center line of the beam type structure at the ith measuring point is shown, wherein the ith measuring point is the position of the ith fiber grating sensor on each optical fiber;

a coordinate component in the Y direction relative to the structural beam structure centerline at the ith measurement point of the first optical fiber S1;

represents the coordinate component of the first optical fiber S1 in the Z direction relative to the structural beam structure centerline at the ith test point;

represents the coordinate component of the second optical fiber S2 in the Y direction relative to the structural beam structure centerline at the ith measuring point;

represents the Z-direction coordinate component of the second optical fiber S2 relative to the structural beam structure centerline at the ith test point,

B) adopting optical fiber measurement technology to measure structural strain at the position of each group of 4 sensors with the same X coordinate⁽¹⁾ε_i}_i＝1,2,…N,{⁽²⁾ε_i}_i＝1,2,…N,{⁽³⁾ε_i}_i＝1,2,…N,{⁽⁴⁾ε_i}_i＝1,2,…NWherein: {⁽¹⁾ε_i}_i＝1,2,…NThe structural strain measured at the ith test point on the first optical fiber S1; {⁽²⁾ε_i}_i＝1,2,…NThe structural strain measured at the ith test point on the second optical fiber S2; {⁽³⁾ε_i}_i＝1,2,…NThe structural strain measured at the ith test point on the third optical fiber S3; {⁽⁴⁾ε_i}_i＝1,2,…NThe structural strain measured at the ith test point on the fourth fiber S4,

C) calculating the three-dimensional curvature of the beam structure center line at each ith measurement point according to the measured structural strain and the following relation

D) The structural deformation-curvature relationship is calculated according to the following system of equations:

wherein

E) Calculating the structural deformation at the measuring point according to the relation in the step (C) and the step (D):

is a column vector of 12X1, the 1 st, 5 th and 9 th elements of which respectively correspond to the three-dimensional positions of the structure at the measuring point i in the space,

wherein the column vector

Is determined as:

representing a position vector of the structure at the location of the end point,

thus, the three-dimensional position of the i-th measurement point after deformation of the beam structure is represented as

4. A beam structure deformation measurement method according to claim 3, characterized by further comprising:

after determining the three-dimensional position of each measuring point

And then, obtaining a continuous beam structure deformation curve by a spline interpolation method.

Images