Resistance obtaining method and device of lightning protection material with anisotropic conductivity

Abstract

The invention provides a resistance acquisition method and device for a lightning protection material with anisotropic conductivity, and the method comprises the steps: measuring the resistance of a plurality of measurement points in any angle direction of a typical test piece of the lightning protection material on the surface of an aircraft, obtaining the resistivity and initial resistance of the lightning protection material on the surface of the aircraft in each angle direction, carrying out the function fitting through an n-order polynomial, and obtaining the resistance of the lightning protection material on the surface of the aircraft. According to the method, the relational expression of the resistance value of any point in the nonlinear area of the aircraft surface lightning protection material and the reference point is obtained, so that the lightning protection performance of the aircraft surface lightning protection material with anisotropic conductivity can be evaluated more accurately, guidance is provided for the electrical performance design of the aircraft surface, the method is simple to operate, and meanwhile, the method has good application prospects. A resistance calculation result can be used for compiling a model lap joint technical condition, giving a lap joint resistance allowable value of airborne equipment installed on a lightning protection material and a reference point, and guiding aircraft electric lap joint performance index formulation and detection.

Description

Technical Field

[0001] The present application belongs to the field of composite material lightning protection, and in particular, relates to a method and device for obtaining the resistance of a lightning protection material with anisotropic electrical conductivity. Background Art

[0002] With the rapid development of the aerospace field, the era of traditional all-metal structural materials has ended. The aerospace field is using a large number of high-strength, low-quality fiber-reinforced composite materials. However, the conductivity of these materials is much lower than that of aluminum. When struck by lightning, the lightning cannot be quickly conducted away, causing thermal damage to the material. Therefore, lightning protection materials (such as metal mesh, three-in-one lightning protection film, etc.) are needed to provide a conductive path to quickly conduct lightning away to ensure flight safety.

[0003] Once this type of lightning protection material is laid, the resistance value of the airborne equipment installed on the surface of the lightning protection material and the resistance value between structures cannot be accurately calculated using traditional resistance calculation methods because the anisotropic conductivity of the material is not taken into account. Therefore, the inspection indicators of the finished product electrical overlap and the overall structural resistance cannot be clearly defined during the model design stage. Summary of the invention

[0004] The present invention provides a resistance acquisition method and device for a lightning protection material with anisotropic conductivity, which solves the problem that the detection indexes of the finished product electrical overlap and the overall resistance of the structure cannot be clearly defined in the model design stage.

[0005] The first aspect of the present invention provides a method for obtaining the resistance of a lightning protection material having anisotropic conductivity, comprising:

[0006] Determine the coordinates (x, y) of the measuring point on the lightning protection material on the aircraft and the coordinates (X0, Y0) of the reference point;

[0007] According to the coordinates of the measuring point and the reference point, the resistance value between the measuring point and the reference point on the lightning protection material is determined using a preset formula;

[0008] Among them, the reference point and the measurement point are both located in the linear region of the lightning protection material; the resistance and length are linearly related in the linear region; the preset formula is g(α) is the initial resistance of the lightning protection material along the α direction, f(α) is the resistivity per unit length of the lightning protection material along the α direction,

[0009] Optionally, the method further includes:

[0010] Step 1: Take a rectangular test piece, the material and structure of the test piece are the same as the lightning protection material;

[0011] Step 2, measure the curve of the distance and resistance value of the rectangular test piece in the length and width directions;

[0012] Step 3, according to the curve, determine the length L1 of the non-linear resistance change region in the length direction and the length L2 of the non-linear resistance change region in the width direction;

[0013] Step 4, according to L1, determine the distance from the two side edges of the lightning protection material of the on-board linear region in the length direction, and according to L2, determine that the distance from the two side edges of the lightning protection material of the on-board linear region in the width direction is L2.

[0014] Optionally, measuring the curve of the distance and resistance value of the rectangular test piece in the length and width directions includes:

[0015] Fix the position along the width direction, and at intervals of the first preset distance along the length direction, measure the resistance value multiple times, and draw the curve of the distance and resistance value of the rectangular test piece in the length direction

[0016] Fix the position along the length direction, and at intervals of the second preset distance along the width direction, measure the resistance value multiple times, and draw the curve of the distance and resistance value of the rectangular test piece in the width direction.

[0017] Optionally, the method further includes:

[0018] Step 3.1, in the range from 0° to 180°, determine n angles α according to a fixed step size, and the value of n is a positive integer;

[0019] Step 3.2, select at least 5 measurement points in the direction of each angle α of the lightning protection material, and detect the resistance value from each measurement point to the reference point;

[0020] Step 3.3, using the resistance values measured in Step 3.2, for each angle α, adopt a linear function to fit the relationship between the resistance value R of the 5 measurement points and the distance ρ from the measurement point to the reference point, and obtain n linear functions R = b + k·ρ; where,

[0021] Step 3.4, according to the n linear functions, take their slopes k1, k2....kn and intercepts b1, b2....bn as the resistivity and initial resistance of the lightning protection material;

[0022] Step 3.5, use an M-order polynomial to fit the function of the resistivity of the lightning protection material changing with the angle, and obtain the resistivity f(α) per unit length of the lightning protection material along the α direction.

[0023] Optionally, the method further includes:

[0024] Step 3.6, use an L-degree polynomial to perform a function fit on the variation of the initial resistance of the lightning protection material with the angle, and obtain the initial resistance g(α) of the lightning protection material along the α direction.

[0025] Optionally, M is the polynomial order with the smallest fitting error;

[0026]

[0027] In the formula, d m is the coefficient of the m-th order polynomial of the resistivity, and the value of m is a positive integer from 0 to M.

[0028] Optionally, L is the polynomial order with the smallest fitting error;

[0029]

[0030] In the formula, e l is the coefficient of the l-th order polynomial of the initial resistance, and the value of l is a positive integer from 0 to L.

[0031] The second aspect of the present invention provides a resistance acquisition device for a lightning protection material with anisotropic conductivity, which is used to execute the method according to any one of the first aspect.

[0032] Advantageous technical effects of the present application:

[0033] The present invention provides a method and device for obtaining the resistance of a lightning protection material with anisotropic conductivity. By measuring the resistance of multiple measurement points in any angular direction of a typical test piece of the lightning protection material on the surface of an aircraft, the resistivity and initial resistance of the lightning protection material on the surface of the aircraft in each angular direction are obtained, and an n-degree polynomial is used for function fitting to obtain the relationship between the resistance value of any point in the non-linear region of the lightning protection material on the surface of the aircraft and the reference reference point, so as to more accurately evaluate the lightning protection performance of the lightning protection material with anisotropic conductivity on the surface of the aircraft, provide guidance for the electrical performance design of the surface of the aircraft. The method of the present invention is simple to operate. At the same time, the resistance calculation result can be used to compile the technical conditions for model lap joints, give the allowable lap resistance value between the airborne equipment installed on the lightning protection material and the reference point, and guide the formulation and detection of the electrical lap performance index of the aircraft. Description of the Drawings

[0034] Figure 1 is the fitting function curve graph of the measured resistance and the distance from the measurement point to the reference point in the α = 0 rad direction of the lightning protection copper mesh on the surface of the aircraft in the embodiment of the present invention;

[0035] Figure 2 is the fitting function curve graph of the measured resistance and the distance from the measurement point to the reference point in the α = 0.01 rad direction of the lightning protection copper mesh on the surface of the aircraft in the embodiment of the present invention;

[0036] Figure 3 It is a fitting function curve graph of the measured resistance and the distance from the measurement point to the reference point in the direction of α = 0.2 rad of the lightning protection copper mesh on the surface of the aircraft in the embodiment of the present invention;

[0037] Figure 4 It is a fitting function curve graph of the measured resistance and the distance from the measurement point to the reference point in the direction of α = 0.3 rad of the lightning protection copper mesh on the surface of the aircraft in the embodiment of the present invention;

[0038] Figure 5 It is a fitting function curve graph of the measured resistance and the distance from the measurement point to the reference point in the direction of α = 0.45 rad of the lightning protection copper mesh on the surface of the aircraft in the embodiment of the present invention;

[0039] Figure 6 It is a fitting function curve graph of the measured resistance and the distance from the measurement point to the reference point in the direction of α = 0.6 rad of the lightning protection copper mesh on the surface of the aircraft in the embodiment of the present invention;

[0040] Figure 7 It is a fitting function curve graph of the measured resistance and the distance from the measurement point to the reference point in the direction of α = 0.8 rad of the lightning protection copper mesh on the surface of the aircraft in the embodiment of the present invention;

[0041] Figure 8 It is a fitting function curve graph of the measured resistance and the distance from the measurement point to the reference point in the direction of α = 1.1 rad of the lightning protection copper mesh on the surface of the aircraft in the embodiment of the present invention;

[0042] Figure 9 It is a fitting function curve graph of the measured resistance and the distance from the measurement point to the reference point in the direction of α = 1.25 rad of the lightning protection copper mesh on the surface of the aircraft in the embodiment of the present invention;

[0043] Figure 10 It is a fitting function curve graph of the measured resistance and the distance from the measurement point to the reference point in the direction of α = 1.57 rad of the lightning protection copper mesh on the surface of the aircraft in the embodiment of the present invention;

[0044] Figure 11 It is a fitting function curve graph of the resistivity of the lightning protection copper mesh on the surface of the aircraft varying with α in the embodiment of the present invention;

[0045] Figure 12 It is a fitting function curve graph of the initial resistance of the lightning protection copper mesh on the surface of the aircraft varying with α in the embodiment of the present invention;

[0046] Figure 13 It is a schematic flow chart of the method for obtaining the resistance of the lightning protection material with anisotropic conductivity in the embodiment of the present invention. Detailed implementation manners

[0047] The following introduces the specific content of the technical solution provided by the present invention in conjunction with the accompanying drawings.

[0048] Please refer to Figures 1-13 , the present invention provides a method and device for obtaining the resistance of a lightning protection material with anisotropic conductivity, which solves the problem of detecting the allowable resistance values of the finished product electrical lap joint and the overall structure during the model design stage. These allowable resistance values can guide the process and carry out the inspection of the electrical lap joint resistance and the overall machine resistance value of the equipment installed outside the fuselage.

[0049] The method for obtaining the resistance of the lightning protection material with anisotropic conductivity proposed by the present invention includes:

[0050] Determine the coordinates (x, y) of the measurement points on the lightning protection material on the aircraft and the coordinates (X0, Y0) of the reference points;

[0051] According to the coordinates of the measurement points and the reference points, use a preset formula to determine the resistance value between the measurement points and the reference points on the lightning protection material;

[0052] Among them, considering that the edge effect of laying the copper mesh structure will cause the formula to fail to achieve the fitting effect, both the reference point and the measurement point should be selected within the linear region of the lightning protection material; within the linear region, for a fixed α angle direction, the resistance from the measurement point to the reference point and the length are linearly related; the preset formula is Among them, g(α) is the starting resistance of the lightning protection material along the α direction, and f(α) is the resistivity per unit length of the lightning protection material along the α direction.

[0053] The determination methods of g(α) and f(α) are as follows: Step 1 Determine the linear region

[0054] Step 1.1, take a rectangular test piece, the material and structure of the test piece are the same as those of the lightning protection material, such as making a lightning protection conductive adhesive film test piece of 4000mm×940mm with a weight of 73g / m 2 ;

[0055] Step 1.2, measure the curves of the distance and resistance value of the rectangular test piece in the length and width directions. For example, taking a point on the edge as the reference, select 1 point every 100mm from the length and width for testing, and draw the curve of the resistance value changing with the distance;

[0056] Step 1.3, according to the curve, determine the length L1 of the non-linear change region of the resistance in the length direction and the length L2 of the non-linear change region of the resistance in the width direction;

[0057] Step 1.4, according to L1, determine the distance from the two edges of the lightning protection material in the length direction of the on-aircraft linear region, and according to L2, determine the distance from the two edges of the lightning protection material in the width direction of the on-aircraft linear region as L2.

[0058] Step 2 Determine the expression of f(α)

[0059] Step 2.1, determine n angles α in the range from 0° to 180° at a fixed step size, where n is a positive integer.

[0060] Step 2.2, select at least 5 measurement points in each direction of angle α of the lightning protection material, and detect the resistance value from each measurement point to the reference point.

[0061] Step 2.3, using the resistance values measured in Step 2.2, for each angle α, fit the relationship between the resistance value R of the 5 measurement points and the distance ρ from the measurement point to the reference point with a linear function, and obtain n linear functions R = b + k·ρ; where,

[0062] Step 2.4, according to the n linear functions, take their slopes k1, k2....kn and intercepts b1, b2....bn as the resistivity and initial resistance of the lightning protection material.

[0063] Step 2.5, use an M-order polynomial to fit the function of the resistivity of the lightning protection material changing with the angle, and obtain the resistivity f(α) per unit length of the lightning protection material along the α direction.

[0064] M is the order of the polynomial with the smallest fitting error.

[0065]

[0066] In the formula, d m is the coefficient of the m-th order polynomial of the resistivity, and m takes positive integers from 0 to M.

[0067] Step 3 Determine the expression of g(α)

[0068] Step 3.6, use an L-order polynomial to fit the function of the initial resistance of the lightning protection material changing with the angle, and obtain the initial resistance g(α) of the lightning protection material along the α direction.

[0069] L is the order of the polynomial with the smallest fitting error.

[0070]

[0071] In the formula, e l is the coefficient of the l-th order polynomial of the initial resistance, and l takes positive integers from 0 to L.

Claims

1. A method for obtaining the resistance of a lightning protection material with anisotropic conductivity, characterized in that, Including: Determine the coordinates (x, y) of the measurement points on the lightning protection material on the aircraft and the coordinates (X0, Y0) of the reference point; According to the coordinates of the measurement point and the reference point, use a preset formula to determine the resistance value between the measurement point and the reference point on the lightning protection material; Among them, the reference point and the measurement point are both located in the linear region of the lightning protection material; The resistance and length are linearly related in the linear region; the preset formula is g(α) is the initial resistance of the lightning protection material along the α direction, and f(α) is the resistivity per unit length of the lightning protection material along the α direction 2. The method for obtaining the resistance of the lightning protection material with anisotropic conductivity according to claim 1, characterized in that, The method further includes: Step 1, take a rectangular test piece, the material and structure of the test piece are the same as those of the lightning protection material; Step 2, measure the curve of the distance and resistance value of the rectangular test piece in the length and width directions; Step 3, according to the curve, determine the length L1 of the non-linear resistance change region in the length direction and the length L2 of the non-linear resistance change region in the width direction; Step 4, according to L1, determine the distance from the two side edges of the lightning protection material in the length direction of the on-board linear region, and according to L2, determine the distance from the two side edges of the lightning protection material in the width direction of the on-board linear region as L2.

3. The method for obtaining the resistance of the lightning protection material with anisotropic conductivity according to claim 1, characterized in that, Measuring the curve of the distance and resistance value of the rectangular test piece in the length and width directions includes: Fix the position in the width direction, and at intervals of a first preset distance in the length direction, measure the resistance value multiple times, and draw the curve of the distance and resistance value of the rectangular test piece in the length direction Fix the position in the length direction, and at intervals of a second preset distance in the width direction, measure the resistance value multiple times, and draw the curve of the distance and resistance value of the rectangular test piece in the width direction.

4. The method for obtaining the resistance of the lightning protection material with anisotropic conductivity according to claim 1, characterized in that The method further includes: Step 3.1, in the range from 0° to 180°, determine n angles α according to a fixed step size, and the value of n is a positive integer; Step 3.2, select at least 5 measurement points in each angle α direction of the lightning protection material, and detect the resistance value from each measurement point to the reference point; Step 3.3, using the resistance values measured in Step 3.2, for each angle α, a linear function is used to fit the relationship between the resistance value R of the 5 measurement points and the distance ρ of the measurement point from the reference point, obtaining n linear functions R = b + k·ρ; where, Step 3.4, according to n linear functions, take their slopes k1, k2....kn and intercepts b1, b2....bn as the resistivity and initial resistance of the lightning protection material; Step 3.5, use an M-order polynomial to fit the function of the resistivity of the lightning protection material changing with the angle, and obtain the resistivity per unit length f(α) of the lightning protection material along the α direction.

5. The method for obtaining the resistance of the lightning protection material with anisotropic conductivity according to claim 4, characterized in that, The method further includes: Step 3.6, use an L-order polynomial to fit the function of the initial resistance of the lightning protection material changing with the angle, and obtain the initial resistance g(α) of the lightning protection material along the α direction.

6. The method for obtaining the resistance of the lightning protection material with anisotropic conductivity according to claim 4, wherein M is the order of the polynomial with the smallest fitting error; where d m is the coefficient of the m-th order polynomial of the resistivity, and m takes positive integers from 0 to M.

7. The method for obtaining the resistance of the lightning protection material with anisotropic conductivity according to claim 5, characterized in that, L is the order of the polynomial with the smallest fitting error; where e l is the coefficient of the l-th order polynomial of the starting resistance, and l takes positive integers from 0 to L.

8. A device for obtaining the resistance of a lightning protection material with anisotropic conductivity, characterized in that, For performing the method according to any one of claims 1-7.

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