WO2015027937A1

WO2015027937A1 - Force transducer, and large-load measuring method capable of multi-angle calibration for airplane

Info

Publication number: WO2015027937A1
Application number: PCT/CN2014/085394
Authority: WO
Inventors: 周良道; 李凯; 李强; 章仕彪; 张鹏飞; 徐春雨; 冒颖; 李卫平
Original assignee: 中国商用飞机有限责任公司; 中国商用飞机有限责任公司上海飞机设计研究院
Priority date: 2013-08-28
Filing date: 2014-08-28
Publication date: 2015-03-05
Also published as: CN103454025A

Abstract

A force transducer (100) and large-load measuring method capable of multi-angle calibration for an airplane; the force transducer (100) is adapted to be installed on a connector of an airplane structure, and comprises: a cylindrical pin (1) having an axial straight groove (11) and an annular groove (13) perpendicular to the straight groove on the wall of the pin; a pin base (2) provided with a lead hole (21) communicating with the straight groove (11); a first strain meter (3) located at the intersection of the straight groove (11) and the annular groove (13); a second strain meter (4) located in the annular groove (13) and forming a central angle of 90° with the first strain meter (3); and a first strain meter connecting line (31) and a second strain meter connecting line (41) electrically connected to an external sensing signal acquisition instrument; and the length directions of the first strain meter (3) and the second strain meter (4) are consistent with the axial direction of the pin (1). Data sensed by the force transducer (100) can be used to determine the magnitude and direction of a load borne by an airplane structure, and can be used to sense a large load.

Description

Load cell and aircraft with large load can be calibrated multi-angle force measurement method

The invention relates to the field of load cells, and more particularly to a large-load calibratable multi-angle load cell for aircraft and a multi-angle force measurement method for large loads of aircraft. Background technique

Mechanical joints are the most critical part of the structure, mainly used for structural connections and load transfer between structures. Therefore, it is possible to accurately measure the magnitude and direction of the load transmitted by the joint, which plays an important role in correctly analyzing the structural stress. At present, joint load cells are available in a wide variety of types, but generally only for one or several specific angle loads. However, in engineering practice, the magnitude and direction of the load to which the joint is subjected is often uncertain, especially when the structure is ultra-static, the magnitude and direction of the force applied to the joint varies with the stiffness distribution of the structure. Therefore, existing joint force sensors are difficult to meet engineering practice requirements.

Summary of the invention

The present invention provides a novel load cell for the above-mentioned deficiencies of the prior art, by which the data sensed by the load cell can determine the magnitude and direction of the load on the aircraft structure, and can be used to sense large loads.

To this end, according to one aspect of the present invention, a load cell is provided, wherein the load cell is adapted to be mounted as a connecting pin on a connection joint of an aircraft structure, and the load cell sensor comprises:

a cylindrical pin body having a first groove extending in the axial direction and a second groove extending in the circumferential direction;

a pin holder, which is located at one end of the pin body, the pin holder is provided with a lead hole, and the lead hole is in communication with the first groove;

a first strain gauge attached to the intersection of the first groove and the second groove; A second strain gauge is attached to the second recess and is formed 90 with the first strain gauge. Center angle

a first strain gauge connection line disposed in the first THJ slot, one end connected to the first strain gauge (3) and the other end electrically connected to the external sensing signal collector through the lead hole;

a second strain gauge connection line disposed in the second recess, one end electrically connected to the second strain gauge and the other end electrically connected to the sensing signal collector through the first recess and the lead hole;

Wherein, the longitudinal direction of the first strain gauge and the second strain gauge coincide with the axial direction of the pin body. Preferably, the second recess is located on the largest bearing surface of the pin body to reduce measurement errors.

Preferably, the depths of the first groove and the second groove are respectively larger than the diameters of the first gauge connection line and the second gauge connection line, thereby preventing the connection line from being damaged by friction.

Preferably, both sides of the first groove and the second groove are chamfered to reduce the influence of the local stress concentration corresponding to the variable gauge and reduce the amount of deformation caused by the structural compression.

According to another aspect of the present invention, a large load calibratable multi-angle force measuring method for an aircraft is provided, which uses the above-described load cell, wherein the method comprises the following steps:

1) Mounting the load cell on the connection joint of the aircraft structure;

2) Collecting strain values from the first strain gauge and the second strain gauge by the sensor signal acquisition device

3) Calculate the magnitude of the load F received by the load cell using Equation 1 below: nER where R is the gauge cross-section radius; E is the sensor elastic modulus; L is between the strain gauge sticking section and the load acting section the distance.

Preferably, the method further comprises the step of determining the direction of the load, the step comprising: a) determining the quadrant to which the load F acts based on the magnitude of the strain values ^£ ', ^£ 2;

b) Determine the direction of the load F based on the relationship between the strain value and the absolute value of ^. Preferably, step b) determines the direction of the load F using Equation 2 below:

Θ - arctan- where Θ is the load F and the position of the second strain gauge 4 and the strain gauge The angle between the lines BO of the center O of the face C.

The load cell provided by the invention is arranged with two strain gauges with a central angle of 90°, so it is not limited by the matching relationship between the hole and the pin, that is, the load of the joint can be measured regardless of the clearance fit or the interference fit. Direction; and the load cell does not need to consider the installation angle of the sensor when it is installed; in addition, since the strain gauge of the present invention is located in the groove on the body wall of the sensor, instead of arranging the strain gauge inside the sensor like an existing sensor, The sensor pin body is obviously reduced in material for accommodating the strain gauge, and the sensor placed inside the pin body is obviously enhanced in structural strength and the bearing capacity is also greatly improved, so the present invention is suitable for large loads or not. Determine the joint load measurement for the load size.

These and other aspects of the invention will be apparent from the description of the embodiments described herein. DRAWINGS

The structure and operation of the present invention, as well as further objects and advantages will be better understood from the following description in conjunction with the accompanying drawings in which

1 is a schematic structural view of a load cell according to a preferred embodiment of the present invention; FIG. 2 is a view schematically showing a load applied by the load cell of FIG. 1, a strain gauge attachment cross section, and a load acting cross section and related dimensions;

Fig. 3 is a view schematically showing the load distribution on the sticking section of the strain gauge of Fig. 2.

Description of the reference numerals

100 load cell 1 pin body

2 pin holder 3 first strain gauge

4 second strain gauge 10 body wall

1 1 first groove 13 second groove

21 lead hole 31 first strain gauge cable

41 second strain gauge connection line implementation Specific embodiments of the invention are disclosed herein as required. However, it should be understood that the embodiments disclosed herein are merely exemplary of the invention and may be embodied in various forms. Therefore, the specific details disclosed herein are not considered to be limiting.

The various features disclosed herein are employed in conjunction with features that may not be explicitly disclosed herein.

A load cell of a preferred embodiment of the present invention will now be described with reference to FIGS. 1 through 3.

100.

As shown in Fig. 1, a load cell 100 in accordance with a preferred embodiment of the present invention is adapted to be mounted as a connecting pin to a joint of an aircraft structure. The load cell 100 includes a cylindrical pin body 1, a pin holder 2, a first strain gauge 3, a second strain gauge 4, a first strain gauge connection line 31, and a second strain gauge connection line 41. Wherein, the body wall 10 of the pin body 1 is provided with a first groove 1 1 (ie, a straight groove) extending in the axial direction, that is, a longitudinal direction of the pin body, and a second groove 13 extending in the circumferential direction (ie, the annular groove) It can be seen that the first groove 11 is arranged perpendicular to the second groove 13 on the body wall of the pin body 4. The pin holder 2 is located at one end of the pin body 1. The first strain gauge 3 is attached, for example, by adhesion to the intersection of the first groove 11 and the annular second groove 13. The second strain gauge 4 is adhered to the second groove 13 by, for example, a bonding and forms a central angle of 90 with the first strain gauge 3. That is, the line A of the first strain gauge 3 on the strain gauge pasting section C and the line AO of the center 0 and the position B of the second strain gauge 4 on the strain gauge pasting section C and the line BO of the center 0 The angle ZAOB is 90°, as shown in Figures 2 and 3.

The first strain gauge connection line 31 is disposed in the first recess 1 1 , and one end is electrically connected to the first strain gauge 3 and the other end is electrically connected to the external sensing signal collector (not shown) through the pin holder 2 . The second strain gauge connecting wire 41 is disposed in the second groove 13, and one end is electrically connected to the second strain gauge 4 and the other end is electrically connected to the sensing signal collector through the first groove 11 and the pin holder 2. The first strain gauge 3 and the second strain gauge 4 are affixed in the respective grooves, that is, their respective longitudinal directions are preferably coincident with the main bearing direction of the pin body 1, that is, the axial direction of the pin body. Preferably, a lead hole 21 is provided on the pin holder 2, and the first groove 1 1 The first strain gauge connection line 31 and the second strain gauge connection line 41 are connected from the lead hole 21 along the first groove 11.

Preferably, the second groove 13 is disposed on the largest bearing surface of the pin body 1, thereby reducing measurement errors. The so-called maximum bearing surface, for example, may be the abutting surface of the two plates at the engine-wing connection.

Preferably, the depths of the first groove 1 1 and the second groove 13 are respectively larger than the diameters of the first gauge link 31 and the second gauge connection 41. It should be understood that these grooves do not have to be set too deep, preferably slightly larger than the diameter of the connecting wires arranged, so as to accommodate two strain gauges and their connecting lines, so that two strain gauges can be made When the connecting wires are placed in the grooves, they do not protrude beyond the body wall 10 of the pin body 1, thereby preventing damage due to friction, and the pin body 1 does not have to remove too much material, ensuring the entire body. The structural strength and load carrying capacity of the load cell 100. At the same time, the width of the second groove 13 is preferably to facilitate the sticking of the strain gauge. For example, the width of the base of the strain gauge can be 1.5 times; the width of the first groove 11 is preferably arranged to facilitate the arrangement of the first strain gauge wire 31.

Preferably, both sides of the first groove 1 1 and the second groove 13 have chamfers to reduce the influence of local stress concentration on the variable and reduce the amount of deformation caused by the structure being pressed.

As shown in FIG. 2, the second groove 13 to which the second strain gauge 4 is attached has a diameter of 2R, where R is the radius of the strain gauge pasting section C, and L is between the strain gauge pasting section C and the load acting section D. distance. When a load F acts on the pin body 1 on the load acting section D as shown in Fig. 2, the load distribution on the strain gauge pasting section C is as shown in Fig. 3, where F1 is the first component of the load F. That is, the force received by the first strain gauge 3; F2 is the second component of the load F, that is, the force received by the second strain gauge 4. As shown in Fig. 3, Θ is the angle between the load F and the position B of the second strain gauge 4 and the line BO of the center 0 of the strain gauge sticking section C.

Although only two strain gauges are provided in the present embodiment, it should be understood that another annular groove extending along the circumferential direction of the body wall 10, that is, the third groove may be formed in the pin body 1. In this way, a third strain gauge, a fourth strain gauge, a third strain gauge connection line, and a fourth strain gauge connection line can be provided on the load cell 100. Wherein, the third strain gauge For example, by sticking to the intersection of the first groove 11 and the third groove; the fourth strain gauge is attached to the third groove by, for example, pasting and is formed 90 with the third strain gauge. a central strain gauge; the third strain gauge connection line is disposed in the first recess U, and one end is electrically connected to the third strain gauge and the other end is electrically connected to the external sensing signal collector through the pin holder 2; The connecting line is disposed in the third groove, and one end is electrically connected to the fourth strain gauge and the other end is electrically connected to the sensing signal collector through the first groove 11 and the pin holder 2; wherein the third strain gauge The longitudinal direction of the fourth strain gauge coincides with the main bearing direction of the pin body 1, that is, the axial direction. These two strain gauges can be used as a backup for the first and second strain gauges, or as a temperature compensation sheet.

According to another aspect of the present invention, a large load calibratable multi-angle force measuring method for an aircraft is provided, which uses the above-described load cell 100, wherein the method comprises the following steps:

1) Mounting the load cell on the connection joint of the aircraft structure;

2) collecting the strain values A from the first strain gauge 3 and the second strain gauge 4 by the sensor signal collector,

3) Calculate the magnitude of the load F received by the load cell using Equation 1 below:

4^ ' (Formula 1) where R is the strain gauge C section radius; E is the sensor elastic modulus; L is the distance between the strain gauge stick section C and the load acting section D.

Preferably, the method further comprises the step of determining the direction of the load, the step of determining the load comprising: a) determining the quadrant of the load F by determining the magnitude of the root strain value, ^ε , -;

b) Determine the direction of the load F based on the strain value and the absolute value ratio relationship of ^ε - . Wherein the quadrant of the load F in step a) can be determined as follows: when > 0 and ε ₂ > 0

The load acts within the first quadrant; _{£| < 0} , ε ₂ > 0 , and the load acts in the second quadrant. Similarly, the third quadrant and the fourth quadrant can be determined.

Preferably, step b) determines the direction of the load F using Equation 2 below:

Θ = arctan (formula 2) In the formula, Θ is the angle between the load F and the line B where the second strain gauge 4 is located and the line BO of the strain gauge pasting section C.

The technical contents and technical features of the present invention have been disclosed as above, but it will be understood that those skilled in the art can make various changes and modifications to the above-described structures and shapes, including separately disclosed or claimed herein. Combinations of technical features, obviously including other combinations of these features. These variations and/or combinations are all within the technical scope of the present invention and fall within the scope of the claims of the present invention. It is to be noted that the use of a single element in the claims is intended to include one or more of such elements. In addition, any reference signs in the claims should not be construed as limiting the scope of the invention.

Claims

claims

1. A load measuring sensor (100), characterized in that the load measuring sensor is suitable as a connecting pin to be installed on a connecting joint of an aircraft structure, the load measuring sensor includes: a cylindrical pin body (1), which The body wall has a first groove (11) extending along the axial direction and a second groove (13) extending along the circumferential direction;

The pin seat (2) is located at one end of the pin body (1). The pin seat (2) is provided with a lead hole (21), and the lead hole (21) is connected to the first groove (11). Pass; the first strain gauge (3), which is attached to the intersection of the first groove (11) and the second groove (13);

The second strain gauge (4) is attached to the second groove (13) and is in contact with the first strain gauge.

(3) Constitute a central angle of 90°;

The first strain gauge connecting wire (31) is arranged in the first groove (11), one end is electrically connected to the first strain gauge (3), and the other end passes through the lead hole (21) and is electrically connected to the external sensing signal. collector;

The second strain gauge connecting wire (41) is arranged in the second groove (13), with one end electrically connected to the second strain gauge (4) and the other end passing through the first groove (11) and the lead hole (21) Electrically connected to the sensing signal collector;

Wherein, the length direction of the first strain gauge (3) and the second strain gauge (4) is consistent with the axial direction of the pin body (1).

2. The load cell (100) according to claim 1, characterized in that the second groove (13) is located on the maximum bending surface of the pin body (1).

3. The load cell (100) according to claim 1, characterized in that the depths of the first groove (11) and the second groove (13) are respectively greater than the first strain gauge connection line ( 31) and the diameter of the second strain gauge connection line (41).

4. The load cell (100) according to claim 1, characterized in that both sides of the first groove (11) and the second groove (13) have chamfers.

5. A calibrated multi-angle force measurement method for aircraft with large loads, which uses the load cell (100) according to any one of claims 1 to 4, characterized in that the method includes the following steps: 1) Install the load cell on the connecting joint of the aircraft structure;

2) Collect the strain values from the first strain gauge (3) and the second strain gauge (4) respectively through the sensing signal collector.

3) Use the following formula 1 to calculate the load F on the load cell:

1 ₂ , 2

F = -^-^ ^{+ £} 2

In the formula, R is the radius of the strain gauge pasting section; E is the elastic modulus of the sensor; L is the distance between the strain gauge pasting section and the load application section.

6. The calibrated multi-angle force measurement method for aircraft with large loads according to claim 5, characterized in that the method further includes the step of determining the load direction, which step includes: a) according to the strain value, ^ determine the quadrant on which the load F acts; b) determine the direction of the load F according to the absolute value ratio of the strain value and ^.

7. The large-load calibrated multi-angle force measurement method for aircraft according to claim 6, characterized in that step b) uses the following formula 2 to determine the direction of the load F:

Θ = arctan—I

In the formula, Θ is the angle between the load F and the line BO connecting the position B of the second strain gauge (4) and the center 0 of the section where the strain gauge is pasted.