CN105066871B - Can measure the axial deflection of the surface strain axial deflection full bridge full interdigital metal strain gauge - Google Patents

Abstract

A full-bridge full interdigital metal strain gauge capable of measuring the axial deflection of surface strain axial deflection, including a base and four sensitive grids, each of which is connected to a lead wire at both ends, and each sensitive grid includes Sensitive section and transition section, the axes of all sensitive sections are straight lines, arranged in parallel and in the same plane; the direction along the axis of the sensitive section is the axial direction, and the direction perpendicular to the axial direction is transverse; the four sensitive grid resistances are consistent, Under the same strain, the resistance changes are the same. The centers of the four sensitive grids are located on a straight line, which is parallel to the axis of any sensitive section of the four sensitive grids. The four sensitive grids are called from left to right along this straight line. The left sensitive grid, the middle left sensitive grid, the middle right sensitive grid and the right sensitive grid; the centers of the four sensitive grids have deviations in the axial direction, but there is no deviation in the lateral direction; any two sensitive grids are interdigitated. The invention can not only measure the strain but also effectively detect the axial first-order and second-order partial derivatives of the surface strain.

Description

It can measure the axial deflection of the axial deflection of the surface strain, the full bridge and the interdigitated metal strain Variation

technical field

The invention relates to the field of sensors, in particular to a metal strain gauge.

Background technique

The working principle of the metal resistance strain gauge is the resistance strain effect, that is, when the metal wire is subjected to strain, its resistance changes correspondingly with the magnitude of the mechanical deformation (stretch or compression). The theoretical formula for the resistance strain effect is as follows:

Where R is its resistance value, ρ is the resistivity of the metal material, L is the length of the metal material, and S is the cross-sectional area of the metal material. During the process of mechanical deformation of the metal wire under strain, ρ, L, and S will all change, which will inevitably cause changes in the resistance value of the metal material. When the metal material is stretched, the length increases, the cross-sectional area decreases, and the resistance value increases; when it is compressed, the length decreases, the cross-sectional area increases, and the resistance value decreases. Therefore, as long as the change of the resistance value can be measured, the strain of the metal wire can be known. The formula for the resistance change rate of metal materials can be derived from formula (1) and related knowledge of material mechanics

Among them, ΔR is the change in resistance, ΔL is the change in the length of the metal material in the direction of tension or pressure, ε is the strain in the same direction, often called axial strain, and K is the strain sensitivity coefficient of the metal material.

In practical applications, the metal resistance strain gauge is pasted on the surface of the elastic element of the sensor or the mechanical part to be tested. When the elastic element in the sensor or the mechanical part under test is subjected to force to generate strain, the strain gauge pasted on it will also undergo the same mechanical deformation, causing a corresponding change in the resistance of the strain gauge. At this time, the resistance strain gauge converts the mechanical quantity into the output of the change of resistance.

But sometimes we also need to know the partial derivative of the workpiece strain. For example, there are three occasions below, but not limited to these three. The partial derivative of the workpiece surface strain is needed:

First, due to the strain concentration near the sudden change in the shape of the workpiece, it is often the first place where the workpiece is damaged. Monitoring the partial strain derivative near the sudden change in shape can intuitively obtain the degree of strain concentration there.

Second, there are a large number of bending parts in buildings, bridges, and mechanical equipment. The knowledge of material mechanics tells us that the axial strain on the surface of a curved beam is proportional to the section bending moment, and the axial partial derivative of the section bending moment and the section shear strain become Proportional, that is, the cross-sectional shear strain can be obtained through the axial partial derivative of the surface axial strain, and the shear strain cannot be directly measured on the workpiece surface with a strain gauge;

Third, when using elastic mechanics to study workpiece strain, the internal strain is determined by partial differential equations, and the solution of the equation requires boundary conditions, and the partial derivative of workpiece surface strain is one of the boundary conditions, which cannot be provided by general strain gauges.

Contents of the invention

In order to overcome the deficiency that the existing metal strain gauges cannot detect the strain deflection, the present invention provides a shaft that can measure the axial deflection of the surface strain and can effectively detect the axial first-order and second-order deflection of the surface strain. Towards deviation full bridge full interdigitated metal strain gauges.

The technical solution adopted by the present invention to solve its technical problems is:

A full-bridge full-interdigital metal strain gauge capable of measuring the axial deflection of surface strain axial deflection, including a base, and the metal strain gauge also includes four sensitive grids, each of which is connected to a lead wire at both ends. Outlet, the four sensitive grids are fixed on the base;

Each sensitive grid includes a sensitive section and a transition section, the two ends of the sensitive section are transition sections, the sensitive section is in the shape of a long and thin strip, the transition section is in a thick and short shape, and the resistance of the sensitive section is much greater than the The resistance of the transition section, the resistance change value of the sensitive section under the same strain state is much greater than the resistance change value of the transition section, and the resistance change value of the transition section is close to 0;

All the centroids of the cross-sections of each sensitive section constitute the axis of the sensitive section. The axis of the sensitive section is a straight line segment. The axes of the sensitive sections are parallel and located in the same plane. In the plane defined by the axes of the sensitive section, The direction is the axial direction, and the direction perpendicular to the axial direction is the transverse direction; the shape and size of all cross-sections of each sensitive section are consistent; take the midpoint position of the axis of each sensitive section and use the resistance value of the sensitive section to form the nominal mass of the sensitive section The nominal mass point of each sensitive section, the centroid position formed by the nominal mass points of each sensitive section is the center of the sensitive grid;

The total resistance of the sensitive sections of the four sensitive grids is the same, and the total resistance change values of the sensitive sections of the four sensitive grids are consistent under the same strain, and the centers of the four sensitive grids are located on a straight line, which is parallel to the four sensitive grids. For any axis of the sensitive section of the grid, the four sensitive grids are called the left sensitive grid, the middle left sensitive grid, the middle right sensitive grid and the right sensitive grid from left to right along this straight line direction; on the plane determined by the axes of each sensitive section, any The two sensitive grids are interdigitated;

The centers of the four sensitive grids have deviations in the axial direction and no deviations in the lateral direction. The distance between the center of the left sensitive grid and the center of the middle left sensitive grid is Δx ₁ ; the distance between the center of the middle left sensitive grid and the center of the middle right sensitive grid is Δx ₂ , the distance between the middle right sensitive grid center and the right sensitive grid center is Δx ₃ , the distance between the left sensitive grid center and the middle right sensitive grid center is Δx ₄ =Δx ₁ +Δx ₂ , the distance between the middle left sensitive grid center and the right sensitive grid center is Δx ₅ =Δx ₂ +Δx ₃ , the distance between the center of the left sensitive grid and the center of the right sensitive grid is Δx ₆ =Δx ₁ +Δx ₂ +Δx ₃ .

In the present invention, the total resistances of the sensitive sections of the four sensitive grids should be consistent, and the changes in the total resistance of the sensitive sections of the four sensitive grids should be consistent under the same strain. Since the measurement bridge has four bridge arms, the four sensitive gates can be arranged in the four bridges in a certain order, so this strain gauge is called a full bridge. For example, the cross-sections of the sensitive sections of the four sensitive grids are all the same, the materials are consistent, and the sum of the lengths of the sensitive sections of the four sensitive grids is equal.

The axial distance between any two sensitive grids in the four sensitive grids is one of Δxi ( _i =1,2,...,6), and _Δxi is generally smaller than or even much smaller than the length of each sensitive section. Arrangement refers to: on the plane where the axes of the sensitive sections of the two sensitive grids are located, the sensitive sections of the two sensitive grids are randomly distributed in the direction perpendicular to the axis of the sensitive sections, and the order and times of the sensitive sections of the two sensitive grids appearing in this direction No restrictions. Thus, the four sensitive gates form a full interdigital arrangement. Since the relative positions of the left sensitive grid, the middle left sensitive grid, the middle right sensitive grid and the right sensitive grid are ensured to be quite accurately fixed by the strain gauge production process, this is also one of the keys for the invention to detect the axial partial derivative of the workpiece strain .

Using the linear relationship between the resistance change value and strain of metal materials, first, it can be used to measure strain like ordinary strain gauges; second, the resistance difference between any two of the four sensitive grids and the center of the two sensitive grids The distance ratio reflects the axial deflection of the strain; third, the difference between the sum of the resistances of the right sensitive grid and the left sensitive grid minus the sum of the resistances of the middle left sensitive grid and the middle right sensitive grid and the axial second order deflection of the strain Proportional.

In the process, care should be taken to keep the total resistance of the transition section of each sensitive gate and the change of the transition section resistance under external strain consistent to increase the measurement accuracy. If the resistance of the transition section and the change of resistance under strain cannot be ignored, it can also be used as a system error. Eliminated during detection.

Further, the metal strain gauge also includes a cover sheet, and the cover sheet covers the sensitive grid and the base.

Still further, the sensitive grid is a wire-type, foil-type, film-type or thick-film-type sensitive grid.

Furthermore, the base is an adhesive film base, a glass fiber base, an asbestos base, a metal base or a temporary base.

The four sensitive gates are arranged on the substrate from left to right. Of course, other arrangements are also possible.

The beneficial effects of the invention are mainly manifested in that not only the surface strain of the workpiece can be measured, but also the axial first-order and second-order partial derivatives of the surface strain can be effectively detected.

Description of drawings

Fig. 1 is a schematic diagram of an axial deviation full bridge full interdigital metal strain gauge capable of measuring the axial deflection of surface strain.

Fig. 2 is a top view of the axial deviation full bridge full interdigital metal strain gauge capable of measuring the axial deflection of the surface strain.

Figure 3 is a schematic diagram of the measuring bridge.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings.

Referring to Figures 1 to 3, an axial deviation full bridge full interdigital metal strain gauge capable of measuring the axial deflection of surface strain includes a base, and the metal strain gauge also includes four sensitive grids, each sensitive grid Two ends of each are respectively connected to a lead wire, and the four sensitive grids are fixed on the substrate;

Each sensitive grid includes a sensitive section and a transition section, the two ends of the sensitive section are transition sections, the sensitive section is in the shape of a long and thin strip, the transition section is in a thick and short shape, and the resistance of the sensitive section is much greater than the The resistance of the transition section, the resistance change value of the sensitive section under the same strain state is much greater than the resistance change value of the transition section, and the resistance change value of the transition section is close to 0;

All the centroids of the cross-sections of each sensitive section constitute the axis of the sensitive section. The axis of the sensitive section is a straight line segment. The axes of the sensitive sections are parallel and located in the same plane. In the plane defined by the axes of the sensitive section, The direction is the axial direction, and the direction perpendicular to the axial direction is the transverse direction; the shape and size of all cross-sections of each sensitive section are consistent; take the midpoint position of the axis of each sensitive section and use the resistance value of the sensitive section to form the nominal mass of the sensitive section The nominal mass point of each sensitive section, the centroid position formed by the nominal mass points of each sensitive section is the center of the sensitive grid;

The total resistance of the sensitive sections of the four sensitive grids is the same, and the total resistance change values of the sensitive sections of the four sensitive grids are consistent under the same strain, and the centers of the four sensitive grids are located on a straight line, which is parallel to the four sensitive grids. For any axis of the sensitive section of the grid, the four sensitive grids are called the left sensitive grid, the middle left sensitive grid, the middle right sensitive grid and the right sensitive grid from left to right along this straight line direction; on the plane determined by the axes of each sensitive section, any The two sensitive grids are interdigitated;

The centers of the four sensitive grids have deviations in the axial direction and no deviations in the lateral direction. The distance between the center of the left sensitive grid and the center of the middle left sensitive grid is Δx ₁ ; the distance between the center of the middle left sensitive grid and the center of the middle right sensitive grid is Δx ₂ , the distance between the middle right sensitive grid center and the right sensitive grid center is Δx ₃ , the distance between the left sensitive grid center and the middle right sensitive grid center is Δx ₄ =Δx ₁ +Δx ₂ , the distance between the middle left sensitive grid center and the right sensitive grid center is Δx ₅ =Δx ₂ +Δx ₃ , the distance between the center of the left sensitive grid and the center of the right sensitive grid is Δx ₆ =Δx ₁ +Δx ₂ +Δx ₃ .

In this embodiment, an example of a full-bridge full-interdigital metal strain gauge that can measure the axial deviation of the axial deflection of the surface strain includes a base 1, a left sensitive grid 2 in the order of left and right in Figure 2, and a middle left sensitive grid. Grid 3, middle right sensitive grid 4, right sensitive grid 5, eight lead-out lines 6, can also have cover sheet (not shown in each accompanying drawing).

The left sensitive grid 2, the middle left sensitive grid 3, the middle right sensitive grid 4 and the right sensitive grid 5 can be fixed on the base 1, which are used to keep the fixed shape, position and size of each sensitive grid; the base 1 is very thin, so that the test The strain on the surface of the component is accurately transmitted to the left sensitive grid 2, the middle left sensitive grid 3, the middle right sensitive grid 4 and the right sensitive grid 5. The substrate 1 can be an adhesive film substrate, a fiberglass substrate, an asbestos substrate, a metal substrate, and a temporary substrate. The substrate is usually fixed on the tested part of the test piece by means of bonding, welding, ceramic spraying and the like. Some lines for positioning the strain gauges can also be printed on the substrate 1 .

The cover sheet is made of materials such as paper or glue, covering the left sensitive grid 2, the middle left sensitive grid 3, the middle right sensitive grid 4, the right sensitive grid 5 and the base 1, and plays the role of moisture-proof, corrosion-proof, damage-proof, etc. The protective layer.

The lead wire 6 is used to connect the sensitive grid and the measuring circuit. The left sensitive grid 2, the middle left sensitive grid 3, the middle right sensitive grid 4 and the right sensitive grid 5 each have two lead wires 6, which are paired with foil and membrane strain gauges. 6 is connected with the left sensitive grid 2, the middle left sensitive grid 3, the middle right sensitive grid 4 or the right sensitive grid 5 are integrated. The pins of the left sensitive grid 2 are 6-1 and 6-2, the pins of the middle left sensitive grid 3 are 6-3 and 6-4, the pins of the middle right sensitive grid 4 are 6-5 and 6-6, The pins of the right sensitive gate 5 are 6-7 and 6-8.

The left sensitive grid 2, the middle left sensitive grid 3, the middle right sensitive grid 4 and the right sensitive grid 5 can be wire type, foil type, thin film type, thick film type according to their metal sensitive materials and processing technology. No matter what kind of left sensitive grid 2, the middle left sensitive grid 3, the thickness of the middle right sensitive grid 4 and the right sensitive grid 5 are all very small, so that the left sensitive grid 2, the middle left sensitive grid 3, the middle right sensitive grid 4 and the right sensitive grid The axial length of the grid 5 varies with the deformation of the workpiece to which it is attached. The basic innovation of the present invention lies in the cooperation between the left sensitive grid 2, the middle left sensitive grid 3, the middle right sensitive grid 4 and the right sensitive grid 5, which has the following main points:

First, four sensitive gates are arranged on the substrate, which are called left sensitive gate 2 , middle left sensitive gate 3 , middle right sensitive gate 4 and right sensitive gate 5 .

Second, the left sensitive grid 2, the middle left sensitive grid 3, the middle right sensitive grid 4 and the right sensitive grid 5 can be divided into a plurality of transition sections 7 and a plurality of sensitive sections 8, and each transition section 7 connects each sensitive section 8 form a sensitive gate. In comparison, the sensitive section 8 is elongated, has a large resistance and its resistance is more sensitive to strain; the transition section 7 is basically thick and short, so that the resistance of the transition section is small and insensitive to strain, In the working state, the resistance change is close to 0, so the sum of the resistance of the sensitive section is basically the total resistance of a single sensitive gate. Figure 2 marks the sensitive section 8 and the transition section 7 in more detail for a clearer perspective.

Third, the cross-sectional shape of the sensitive section 8 of the left sensitive grid 2, the middle left sensitive grid 3, the middle right sensitive grid 4 and the right sensitive grid 5 is all the same, and the left sensitive grid 2, the middle left sensitive grid 3, and the middle right sensitive grid 4 and the sum of the respective sensitive section 8 lengths of the right sensitive grid 5 are the same. Neglecting the resistance of the transition section 7, the total resistances of the left sensitive grid 2, the middle left sensitive grid 3, the middle right sensitive grid 4 and the right sensitive grid 5 are all equal, and the total resistance changes of the four sensitive grids under the same strain should be consistent.

Fourth, the sensitive section 8 of each sensitive grid is in the shape of a long and thin strip, and the centroids of all the cross-sections of each sensitive section 8 form the axis of the sensitive section. The axis of the sensitive section 8 is a straight line segment, and the axes of each sensitive section 8 are parallel. and lie in the same plane. The projection shapes of all cross sections of each sensitive section 8 along the axis direction of the sensitive section are consistent. Take the midpoint position of the axis of each sensitive section and use the resistance value of the sensitive section to form the nominal mass of the sensitive section, and the centroid position formed by the nominal mass points of each sensitive section is the center of the sensitive grid;

Fifth, looking down at the left sensitive grid 2, the middle left sensitive grid 3, the middle right sensitive grid 4 and the right sensitive grid 5, they all have symmetry axes and the symmetry axes coincide (x-axis in Fig. 2), the left sensitive grid 2, the middle The sensitive segments 8 of the left sensitive grid 3 , the middle right sensitive grid 4 and the right sensitive grid 5 are all parallel to the axis of symmetry, and the sensitive segments 8 of each sensitive grid are distributed symmetrically about this axis. Therefore, it can be said that the left sensitive grid 2, the middle left sensitive grid 3, the middle right sensitive grid 4 and the right sensitive grid 5 are coaxial, that is, their central positions have axial deviation without lateral deviation, and the left sensitive grid 2, the middle left sensitive grid The center positions of the grid 3, the middle right sensitive grid 4 and the right sensitive grid 5 are all on the x-axis. According to the top view of the strain gauge in Figure 2, the center of the left sensitive grid 2 is at the intersection of the x axis and the y _L axis, the center of the left sensitive grid 3 is at the intersection of the x axis and the y _ML axis, and the center of the right sensitive grid 4 is at the intersection of the x axis and the y ML axis. The intersection of the x axis and the y _MR axis, the center of the right sensitive grid 5 is at the intersection of the x axis and the y _R axis.

Sixth, the left sensitive grid 2, the middle left sensitive grid 3, the middle right sensitive grid 4 and the right sensitive grid 5 are interdigitated, and the centers of these sensitive grids are all on the same symmetry axis x-axis. It can be noticed that the distance between the center of the left sensitive grid 2 and the center of the middle left sensitive grid 3 is Δx ₁ ; the distance between the center of the middle left sensitive grid 3 and the center of the middle right sensitive grid 4 is Δx ₂ The distance between the center of the grid 5 is Δx ₃ , the distance between the center of the left sensitive grid 2 and the center of the middle right sensitive grid 4 is Δx ₄ =Δx ₁ +Δx ₂ , the distance between the center of the middle left sensitive grid 3 and the center of the right sensitive grid 5 is Δx ₅ =Δx ₂ +Δx ₃ , the distance between the center of the left sensitive grid 2 and the center of the right sensitive grid 5 is Δx ₆ =Δx ₁ +Δx ₂ +Δx ₃ , these distances are all smaller than the length of the sensitive section 8, as shown in Figure 2 . Since the relative positions of the left sensitive grid 2, the middle left sensitive grid 3, the middle right sensitive grid 4 and the right sensitive grid 5 are ensured to be quite accurately fixed by the strain gauge production process, this is why the present invention can detect the workpiece strain axial partial derivative one of the keys.

In summary, in the present invention, the left sensitive grid 2, the middle left sensitive grid 3, the middle right sensitive grid 4 and the right sensitive grid 5 are equal in size, the directions are coaxial without lateral deviation, and the centers of each sensitive grid form six different axial distances , intersecting each other.

The resistance of the left sensitive grid is marked as RL, the resistance of the middle left sensitive grid is marked as R _ML , the resistance of the middle right sensitive grid is marked as _{R MR} , and the resistance of the right sensitive grid is marked as _RR . In the free state, the resistances of the four sensitive gates are equal to R ₀ . When the strain gauge of the present invention is placed on a certain strained surface, two sensitive grids are taken, one of which must be left and the other must be right. The resistance of the sensitive grid on the left is recorded as R ₀ +ΔR _l , the resistance of the sensitive grid on the right is recorded as R ₀ +ΔR _r , the distance between the two sensitive grids is Δxi, and _i is one of 1 to 6. The difference in the strain at the center of the two sensitive grids causes the difference in the resistance variation between the two. The relationship between the sensitive grid resistance and the surface strain is:

Where i=1,2,...,6, ε _l is the strain at the center of the left sensitive grid, ε _r is the strain at the right sensitive grid, and x is the midpoint of the line connecting the centers of the two sensitive grids. This is the principle of the present invention to measure the axial deflection of surface strain. The above formula is actually a numerical calculation of the partial derivative. According to the theory of numerical differentiation, this is to calculate the differential with Δx _i /2 as the step size. The error of the partial derivative calculation is not more than level, which is The high-order infinitesimal quantity has relatively high precision. Using the four strain gauges of the strain gauge of the present invention, the Δx ₁ = Δx ₃ of the strain gauge is limited, and the numerical calculation method using the relationship between the sensitive grid resistance and the surface strain and the second-order partial derivative is as follows:

Where x ₀ is the midpoint of the center of the four sensitive grids of the strain gauge, that is, the intersection of the x-axis and the y-axis in Figure 2, ε _L is the strain at the center of the left sensitive grid, and ε _ML is the strain at the center of the middle left sensitive grid, ε _MR is the strain at the center of the left sensitive grid, and ε _R is the strain at the center of the right sensitive grid.

This embodiment can be used to measure strain and strain axial deflection by using the bridge. Assuming that the bridge input voltage is u _i and the output voltage is u _o , the schematic diagram of the measuring bridge is shown in FIG. 3 . When there is no workpiece strain, the resistances of the bridge arms of the bridge are respectively marked as R ₁ , R ₂ , R ₃ , and R ₄ in the clockwise direction, and these symbols are also used to mark the bridge where the resistance is located if there is no confusion. Sensitive gates or resistors of strain gauges can be placed on each bridge. Same as the general arrangement of strain gauges, if sensitive grids are installed on multiple bridge arms, there are qualitative requirements for the order and strain of each installation position. When there is no workpiece strain, the output voltage formula of the bridge is

At this time, it is required that the bridge balance is u _o = 0, so the so-called bridge balance condition R ₁ R ₃ -R ₂ R ₄ = 0 must be satisfied, and the bridge used further satisfies

R ₁ ＝R ₂ ＝R ₃ ＝R ₄ , (6) because, first, when the condition (6) is met, the sensitivity of the strain gauge is the highest according to the relevant theory; second, the method of measuring strain or strain axial deflection requires Condition (6) holds. When the strain gage also strains with the external strain, the above bridge equilibrium condition is generally no longer valid, at this time

Since ΔR _i << R _i (i=1,2,3,4) the first ≈, the second ≈negligible part ΔR ₁ ΔR ₃ -ΔR ₂ ΔR ₄ is also very small, and can be used in engineering It is much smaller than the more reserved part. Generally, the voltage obtained by formula (7) can be used to measure the strain; the axial deflection of the strain can be combined with formula (3), formula (4) and formula (7), and the sensitive grid and resistance of each bridge arm can be reasonably designed and arranged to obtain and strain The voltage value u _o with which the axial first-order partial conduction or second-order partial conductance has a linear relationship, and this voltage is a weak signal that needs to be amplified.

Claims (5)

1. a kind of full interdigitated metal foil gauge of axial deviation full-bridge of the axial local derviation of measurable surface strain, including substrate, its It is characterised by：The metal strain plate also includes four sensitive grids, and the two ends of each sensitive grid connect a lead-out wire, institute respectively State and four sensitive grids are fixed in substrate；

Each sensitive grid includes sensitive segment and changeover portion, and the two ends of the sensitive segment are changeover portion, and the sensitive segment is in elongate strip Shape, the changeover portion is in tubbiness shape, and the resistance of the sensitive segment is much larger than institute under the resistance of the changeover portion, same strain state The increased resistance value for stating sensitive segment is much larger than the increased resistance value of the changeover portion, the increased resistance value of the changeover portion close to 0；

All cross section centres of form of each sensitive segment constitute sensitive segment axis, and the sensitive segment axis is straight line section, each sensitivity The diameter parallel of section and it is generally aligned in the same plane, sensitive segment axis is determined in plane, be along the sensitive segment axis direction Axially, with axially vertical direction for laterally；All shape of cross section sizes of each sensitive segment are consistent；Take each sensitive segment Axis point midway and the nominal particle that place sensitive segment is constituted by nominal mass of the sensitive segment resistance value, each sensitive segment The centroid position that nominal particle is collectively forming is the center of sensitive grid；

The sensitive segment all-in resistance of four sensitive grids is consistent, and four sensitive grids all-in resistance of sensitive segment under identical strain becomes Change value is consistent, and four sensitive grids are centrally located on straight line, and the straight line is quick parallel to any one of four sensitive grids Feel section axis, four sensitive grids are referred to as left sensitive grid, middle left sensitive grid, middle right sensitive grid from left to right along this rectilinear direction With right sensitive grid；Each sensitive segment axis is determined in plane, is in interdigital arrangement between any two sensitive grid；

There is deviation at four sensitive grid centers in the axial direction, in the horizontal zero deflection, left sensitive grid center and middle left sensitive grid center Distance be Δ x₁；The distance at middle left sensitive grid center and middle right sensitive grid center is Δ x₂, middle right sensitive grid center and right sensitivity Grid centre distance is Δ x₃, the distance at left sensitive grid center and middle right sensitive grid center is Δ x₄=Δ x₁+Δx₂, middle left sensitivity Grid center is Δ x with right sensitive grid centre distance₅=Δ x₂+Δx₃, left sensitive grid center is Δ x with right sensitive grid centre distance₆ =Δ x₁+Δx₂+Δx₃。

2. the full interdigitated metal strain of axial deviation full-bridge of the axial local derviation of measurable surface strain as claimed in claim 1 Piece, it is characterised in that：The metal strain plate also includes cover plate, and the cover plate is covered in the sensitive grid and substrate.

3. the full interdigitated metal of axial deviation full-bridge of the axial local derviation of measurable surface strain as claimed in claim 1 or 2 should Become piece, it is characterised in that：The sensitive grid is wire form, foil, diaphragm type or thick-film type sensitive grid.

4. the full interdigitated metal of axial deviation full-bridge of the axial local derviation of measurable surface strain as claimed in claim 1 or 2 should Become piece, it is characterised in that：The substrate is glued membrane substrate, glass fabric substrates, asbestos base bottom, metallic substrates or temporary substrate.

5. the full interdigitated metal of axial deviation full-bridge of the axial local derviation of measurable surface strain as claimed in claim 1 or 2 should Become piece, it is characterised in that：Four sensitive grids are arranged in substrate from left to right.