Resistance-type flexible film strain test and calibration method for special-shaped structure

Abstract

The invention provides a resistance-type flexible film strain test and calibration method for a special-shaped structure. The method comprises the following steps: integrating a resistance-type flexible film strain test unit along the curved surface of a calibration piece of the special-shaped structure; applying an internal pressure load to the special-shaped structure calibration piece to obtain a resistance variable quantity and an annular strain; the internal pressure load is changed, the corresponding resistance variation is measured, the corresponding circumferential strain is calculated, and the corresponding relation between the internal pressure load and the corresponding resistance variation is established; calculating the sensitivity coefficient of the resistive flexible film strain test unit on the special-shaped structure calibration piece; integrating a resistance-type flexible film strain test unit on the annular curved surface of the special-shaped structure test piece, applying an internal load, and measuring the resistance variation; and selecting a corresponding sensitivity coefficient according to the curvature radius and the internal load, and calculating the actual strain. According to the resistance-type flexible film strain test and calibration method provided by the invention, the problem of insufficient acquisition of special-shaped structure strength test strain data caused by difficulty in arranging a conventional resistance strain sensor on a small-curvature radius special-shaped structure is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of industrial equipment strength test, in particular to a method for testing and calibrating the resistance flexible film strain of special-shaped structure. BACKGROUND

[0002] With the increasing requirement of light weight of industrial equipment products, in order to cope with different use scenarios, more and more key bearing parts of equipment structure adopt special-shaped structure design.

[0003] New complex configuration verification and optimization also put forward many new requirements for test technology. In order to meet the coverage and accuracy requirements of high spatial resolution strain monitoring of complex special-shaped structure of equipment, it is urgent to develop flexible strain testing method conforming to the surface of special-shaped structure with small curvature radius. SUMMARY

[0004] To solve the above problems, the present application provides a method for testing and calibrating the resistance flexible film strain of special-shaped structure, which first uses silver paste ink as conductive raw material, adopts screen printing process to print patterned sensing layer on the surface of special-shaped structure of equipment; then adopts magnetron sputtering process to deposit selected metal material as electrode, and performs packaging to obtain resistance flexible film strain testing unit integrated in special-shaped structure; finally, the resistance flexible film strain testing unit is calibrated and tested through internal pressure loading test of different curvature radius special-shaped structure calibration piece, and the specific scheme is as follows:

[0005] A method for testing and calibrating the resistance flexible film strain of special-shaped structure, the method comprising the following steps:

[0006] S1, integrating resistance flexible film strain testing unit on the surface of special-shaped structure calibration piece along the curved surface;

[0007] S2, applying internal pressure load to different curvature radius special-shaped structure calibration piece, and obtaining resistance change amount and hoop strain value corresponding to internal pressure load pressure value;

[0008] S3, changing the internal pressure load pressure value in step S2, and measuring the resistance change amount ΔR γ , calculating the hoop strain value ε γ of the special-shaped structure test piece corresponding to the internal pressure load pressure value by using finite element model to apply the same internal pressure load pressure value, thereby establishing the corresponding relationship between the hoop strain value ε γ and the resistance value change amount ΔR γ of the special-shaped structure with curvature radius γ;

[0009] S4, calculating the sensitivity coefficient K of the resistive flexible film strain test unit in step S1 when the radius of curvature of the special-shaped structure is γ γ ;

[0010] S5, integrating the resistive flexible film strain test unit on the ring surface of the special-shaped structure test piece, applying an internal load to the special-shaped structure test piece, and measuring the resistance change ΔR;

[0011] S6, selecting the sensitivity coefficient K corresponding to the radius of curvature calculated in step S4 according to the radius of curvature γ of the special-shaped structure test piece and the internal load pressure value, and calculating the actual strain ε of the special-shaped structure test piece in response. γ

[0012] Further, the integration method of the resistive flexible film strain test unit in step S1 specifically includes the following steps:

[0013] A1, coating an insulating base layer on the surface of the special-shaped structure;

[0014] A2, after the insulating base layer obtained in step A1 is cured, a flexible printing screen with a strain test unit pattern is attached to the surface of the insulating base, and silver paste ink is coated on the flexible printing screen;

[0015] A3, extruding the silver paste ink, which can pass through the pattern area on the flexible printing screen under the action of extrusion force, to form a patterned sensing layer on the surface of the special-shaped structure;

[0016] A4, removing the flexible printing screen, and then depositing the selected metal material into electrodes by using a magnetron sputtering process;

[0017] A5, packaging a protective layer, and finally forming a special-shaped structure resistive flexible film strain test unit.

[0018] Preferably, the insulating base layer in step A1 is a polyimide insulating film.

[0019] Preferably, the extruded silver paste ink in step A3 is extruded by a profiled scraper, and the profiled scraper is driven by a five-axis mechanical arm to move at a constant speed. The outer contour of the profiled scraper is formed by a curved surface which is the same as the shape of the outer surface of the special-shaped structure.

[0020] Preferably, the packaging protective layer in step A5 is a dimethylsiloxane flexible polymer material.

[0021] Preferably, the ring strain value ε γ in step S2 is calculated under the same internal pressure load pressure value by using a finite element model. ​

[0022] Preferably, the sensitivity coefficient K γ The calculation formula is as follows:

[0023]

[0024] Wherein, γ is the curvature radius of the special-shaped structure, △R γ is the resistance change of the resistance flexible film strain testing unit, R is the initial resistance value of the resistance flexible film strain testing unit without deformation, △R γ / R represents the resistance value change rate of the patterned sensing layer, ε γ is the circumferential strain of the special-shaped mechanism calibration piece with a radius of γ under the action of internal pressure load measured by the calibration test.

[0025] Preferably, the actual strain ε of the special-shaped structure test piece in the step S6 is calculated according to the following formula:

[0026]

[0027] Further, the patterned sensing layer has directionality and conductivity, and the direction of the strain to be obtained should be consistent with the test direction of the patterned sensing layer.

[0028] When the special-shaped structure is deformed in response to internal load, the patterned sensing layer will deform with the structure, and the resistance value will change accordingly, and then the special-shaped structure strain response parameters can be calculated.

[0029] The test accuracy of the resistance flexible film strain testing unit integrated on the surface of the special-shaped structure with different curvatures is affected by the structure curvature of the test direction of the patterned sensing layer, and the influence of the structure curvature of the direction perpendicular to the test direction of the patterned sensing layer can be ignored.

[0030] Compared with the prior art, the beneficial effects obtained by the present application are as follows:

[0031] The special-shaped structure resistance flexible film strain testing and calibration method provided by the present application adopts internal pressure test of special-shaped structure calibration pieces with different curvatures to calibrate the resistance flexible film strain testing unit and obtain correction data; the process is simple, the calibration and test process is easy to operate, and the problem of insufficient special-shaped structure strength test strain data caused by the difficulty of laying conventional strain sensors on the surface of equipment special-shaped structure with small curvature radius is solved. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0033] Figure 1 The present application provides a printing process schematic diagram of the special-shaped structure surface resistance type flexible film strain test unit.

[0034] Figure 2 The present application provides a special-shaped structure resistance type flexible film strain test layout schematic diagram.

[0035] Figure 3 The present application provides a resistance type flexible film strain test calibration method schematic diagram.

[0036] Markings in the drawings:

[0037] 1, special-shaped structure of typical equipment; 2, small curvature radius equipment structure; 3, resistance type flexible film strain test unit; 4, insulating base layer; 5, patterned sensing layer; 6, profiling scraper; 7, flexible printing screen; 8, silver paste ink; 9, flexible printing screen pattern area; 10, electrode; 11, protective layer; 12, cylindrical structure; 13, top cover; 14, bottom plate; 15, sealing ring; 16, filling and pressurizing port; 17, pressure relief and liquid discharge port; 18, fastening bolt.

[0038] Specific implementation

[0039] The present application provides a special-shaped structure resistance type flexible film strain test and calibration method, which will be further described in detail in combination with the accompanying drawings and specific embodiments. The advantages and features of the present application will be more apparent according to the following description and claims. It should be noted that the accompanying drawings are very simplified and non-precise ratios are used, which are only used to facilitate and clarify the purpose of assisting the description of the embodiments of the present application.

[0040] The special-shaped structure calibration member in the embodiment adopts a cylindrical structure as shown in Figure 2 .

[0041] S1, integrate the resistance type flexible film strain test unit on the curved surface of the cylindrical structure, the integration process is as shown in Figure 1 , and the specific method is as follows:

[0042] A1, coat a polyimide insulating film on the surface of the cylindrical structure as an insulating base layer 4;

[0043] A2, after the polyimide insulating film insulating substrate layer 4 obtained in step A1 is cured, the flexible printing screen 7 with strain test unit pattern 9 is attached to the surface of the insulating substrate layer 4, and the silver paste ink 8 is coated on the flexible printing screen 7;

[0044] A3, the silver paste ink 8 is extruded by the silicone rubber material profiling scraper 6, and the profiling scraper is driven by the five-axis mechanical arm to move at a constant speed, and the silver paste ink 8 can pass through the pattern 9 area on the flexible printing screen 7 under the action of the extrusion force, and a patterned sensing layer 5 is formed on the surface of the cylindrical structure;

[0045] A4, the flexible printing screen 7 is removed, and then a selected metal material is deposited as an electrode 10 by a magnetron sputtering process;

[0046] A5, the protective layer 11 made of polydimethylsiloxane flexible polymer material is used for packaging, and finally the cylindrical structure resistance type flexible thin film strain test unit 3 is formed;

[0047] S2, the inner pressure load is applied to the different curvature radius special-shaped structure calibration piece, and the resistance change amount corresponding to the inner pressure load pressure value and the hoop strain value are obtained;

[0048] The inner pressure load is applied to the special-shaped structure calibration piece with a curvature radius of γ, and the specific method is as follows: first, the resistance type flexible thin film strain test unit 3 is integrated on the surface of the cylindrical cylinder structure 12 along the cylindrical hoop; then the inner pressure load is applied to the cylindrical cylinder structure 12 with different curvature radii, and the pre-tightening force is applied to the fastening bolt 18, so that the top cover 13, the bottom plate 14 and the sealing ring 15 are tightly attached to the cylindrical cylinder structure 12, and the inner pressure load is applied by injecting water through the pressure injection port 16 in the cylindrical cylinder structure 12, as shown in Figure 3 ;

[0049] The resistance change amount ΔR γ corresponding to the inner pressure load pressure is measured, and the hoop strain value ε γ of the special-shaped structure calibration piece corresponding to the same inner pressure load pressure value is calculated by using the finite element model under the load condition of the same inner pressure load pressure value;

[0050] S3, the inner pressure load pressure value in step S2 is changed, the resistance change amount ΔR γ corresponding to the inner pressure load pressure is measured, and the hoop strain value ε γ of the cylindrical structure corresponding to the same inner pressure load pressure value is calculated by using the finite element model under the load condition of the same inner pressure load pressure value; γ , thereby establishing the corresponding relationship between the hoop strain value ε γ of the cylindrical structure with a curvature radius of γ and the resistance value change amount ΔR γ ;

[0051] S4, calculating the sensitivity coefficient K of the resistive flexible film strain test unit in step S1 for a cylindrical structure with a curvature radius of γ γ , and the calculation formula is as follows:

[0052]

[0053] wherein γ is the curvature radius of the special-shaped structure, ΔR γ is the resistance change of the resistive flexible film strain test unit, R is the initial resistance value of the resistive flexible film strain test unit without deformation, ΔR γ / R represents the resistance change rate of the patterned sensing layer, ε γ is the hoop strain of the cylindrical structure with a radius of γ under the action of internal pressure load measured by the calibration test;

[0054] S5, integrating the resistive flexible film strain test unit on the hoop surface of the special-shaped structure test piece, applying internal load to the special-shaped structure test piece, and measuring the resistance change ΔR of the patterned sensing layer;

[0055] S6, according to the curvature radius γ and the internal load pressure value of the special-shaped structure test piece, selecting the sensitivity coefficient K corresponding to the curvature radius calculated in step S4 γ , and further calculating the actual strain ε of the special-shaped structure test piece, and the calculation formula is as follows:

[0056]

[0057] wherein ΔR is the resistance change of the resistive flexible film strain test unit in the special-shaped structure test piece.

[0058] Although the present application has been disclosed with the above preferred embodiments, it is not intended to limit the present application, and any person skilled in the art can make possible changes and modifications to the technical solutions of the present application by using the disclosed methods and technical contents without departing from the spirit and scope of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, which does not depart from the content of the technical solutions of the present application, belongs to the protection scope of the technical solutions of the present application. The contents not described in detail in the specification of the present application are the known technology of the person skilled in the art.

Claims

1. A method for resistance flexible thin film strain testing and calibration for a profiled structure, characterized in that, The method comprises the following steps: S1, integrating a flexible resistive film strain test unit on the surface of the special-shaped structure calibration member along the curved surface; S2, applying an internal pressure load to the special-shaped structure calibration member with different radii of curvature, and obtaining the resistance change value and the hoop strain value corresponding to the internal pressure load pressure value; S3, changing the internal ballast pressure value in step S2, measuring the resistance change amount AR corresponding to the internal ballast pressure γ , applying the same internal ballast pressure value to the load condition by using the finite element model, calculating the hoop strain value of the anisotropic structure test piece corresponding to the internal ballast pressure value γ , thereby establishing the corresponding relationship between the hoop strain value AR of the anisotropic structure with a curvature radius of γ and the resistance value change amount γ γ ;​ S4, calculate the sensitivity coefficient K of the resistive flexible film strain test unit in the special-shaped structure when the curvature radius is γ γ ; S5, integrating a flexible resistive film strain test unit on the hoop curved surface of the special-shaped structure test piece, and applying an internal load to the special-shaped structure test piece to measure the resistance change value ΔR; S6、According to the curvature radius γ and the internal load pressure value of the special-shaped structure test piece, the sensitivity coefficient K corresponding to the curvature radius calculated in step S4 is selected γ The actual strain ε of the special-shaped structure test piece is calculated.

2. The method of claim 1, wherein the method further comprises: The integration method of the flexible resistive film strain test unit in step S1 comprises the following steps: A1, coating an insulating base layer on the surface of the special-shaped structure; A2, after the insulating base layer obtained in step A1 is cured, a flexible printing screen with a strain test unit pattern is attached to the surface of the insulating base, and silver paste ink is coated on the flexible printing screen; A3, extruding the silver paste ink, which can pass through the pattern area on the flexible printing screen under the action of extrusion force to form a patterned sensing layer on the surface of the special-shaped structure; A4, removing the flexible printing screen, and then depositing the selected metal material into electrodes by using a magnetron sputtering process; A5, packaging a protective layer, and finally forming a special-shaped structure resistive flexible film strain test unit.

3. The method of claim 2, wherein the method further comprises: The insulating base layer in step A1 is a polyimide insulating film.

4. The resistive flexible film strain test and calibration method of claim 2, wherein, In step A3, the silver paste ink is extruded by using a profiled scraper, and the profiled scraper is driven by a five-axis mechanical arm to move at a uniform speed. The curved surface formed by the outer contour of the profiled scraper along the movement trajectory driven by the five-axis mechanical arm is the same as the shape of the outer surface of the special-shaped structure.

5. The resistive flexible film strain testing and calibration method of claim 2, wherein, The packaging protective layer in step A5 is a dimethylsiloxane flexible polymer material.

6. The resistive flexible film strain testing and calibration method of claim 1, wherein, The hoop strain value ε in step S2 γ is calculated under the same load condition in which the same internal pressure load pressure value is applied using a finite element model.

7. The resistive flexible film strain testing and calibration method of claim 1, wherein, The sensitivity coefficient K γ The calculation formula is as follows: wherein γ is the radius of curvature of the heterostructure, and ΔR γ is the resistance change of the flexible resistive film strain testing unit, R is the initial resistance value of the flexible resistive film strain testing unit without deformation, and ΔR γ / R represents the resistance change rate of the patterned sensing layer, and ε γ is the circumferential strain of the heterostructure calibration piece with a radius of γ under the action of internal pressure load measured by the calibration test.

8. The resistive flexible film strain testing and calibration method of claim 1, wherein, The actual strain ε of the special-shaped structure test piece in step S6 is calculated according to the following formula:

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