A method for measuring interface contact performance distribution characteristics

Abstract

The present invention discloses a method for measuring the distribution characteristics of interface contact performance. First, according to the contact interface four-wire method and the high-density electrical method electrode arrangement mode, the relationship between the interface contact resistance and the potential difference under the two electrode arrangements is obtained respectively; then, the relationship between the apparent resistivity and the potential difference in the high-density electrical method is introduced to obtain the relationship between the contact resistance and the apparent resistivity under the two electrode arrangements respectively; then, according to the relationship between the contact resistance and the contact displacement and the relationship between the contact displacement and the contact stress, the relationship between the contact resistance and the contact stress is obtained; finally, the relationship between the contact resistance and the apparent resistivity is introduced into the relationship between the contact resistance and the contact stress, and the interface contact stress-apparent resistivity distribution correlation formula is obtained. By measuring the apparent resistivity, the distribution characteristics of the interface contact stress are obtained, and the interface contact performance distribution characteristics are finally obtained in combination with the interface morphology. The present invention can directly obtain the stress distribution of the contact interface, the method is simple, and the result is accurate.

Description

Technical Field

[0001] The invention belongs to the technical field of interface stress measurement, and in particular relates to a method for measuring distribution characteristics of interface contact performance. Background Art

[0002] The contact interface is the bridge for force transmission, electrical conduction and heat transfer in engineering structures, such as fusion reactor superconducting magnets, aircraft engine bearings, etc. The interface stress level plays a key role in the safety and stability assessment of complex engineering structures, but due to the strong randomness and complexity of the rough interface and the opacity of the contact interface, it is difficult to directly observe and measure the stress distribution at the contact interface.

[0003] Existing contact interface stress distribution measurement methods include direct measurement methods and indirect measurement methods. Direct measurement methods such as X-ray method, Raman spectroscopy, curvature photometry, etc. are difficult to detect rough contact interfaces; while indirect measurement methods break through the limitations of direct measurement methods. In indirect measurement methods, the interface contact stress is obtained indirectly by measuring another physical quantity such as contact resistance. However, existing indirect measurement methods all study the relationship between normal load and contact resistance, rather than the physical relationship between interface contact stress and contact resistance. Therefore, there is a lack of quantitative research methods for interface contact stress, which leads to the inability to directly obtain the stress distribution of the contact interface. Summary of the invention

[0004] In view of the problems existing in the above-mentioned background technology, the purpose of the present invention is to provide a method for measuring the distribution characteristics of interface contact performance.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A method for measuring the distribution characteristics of interface contact performance comprises the following steps:

[0007] S1. According to the contact interface four-wire method electrode arrangement and the high-density electrical method electrode arrangement, the relationship between the interface contact resistance and the potential difference under the two contact interface electrode arrangements is obtained respectively;

[0008] S2, introducing the relationship between apparent resistivity and potential difference in high-density electrical method into the relationship between interface contact resistance and potential difference in step S1, and obtaining the relationship between interface contact resistance and apparent resistivity under two contact interface electrode arrangement modes respectively;

[0009] S3, combining the existing relationship between the contact resistance and the contact displacement at the interface position with the relationship between the contact displacement and the contact stress, to obtain the relationship between the contact resistance and the contact stress at the interface position;

[0010] S4, introducing the relationship between the interface contact resistance and the apparent resistivity obtained in step S2 into the relationship between the contact resistance and the contact stress at the interface position obtained in step S3, and obtaining the interface contact stress-apparent resistivity distribution correlation relationship under the two contact interface electrode arrangement modes; wherein,

[0011] The correlation formula between the interface contact stress and apparent resistivity distribution under the four-wire electrode arrangement is:

[0012] ;

[0013] The correlation formula between the interface contact stress and apparent resistivity distribution under the high-density electrical method electrode arrangement is:

[0014] ;

[0015] In the formula, Interface position The contact stress at is a constant, is the material resistivity of the rough interface, is Young's modulus, Interface position The distance between the highest point of the upper rough interface and the lowest point of the lower rough interface, is the radius of the microconvex body, is the apparent resistivity, is the apparent resistivity of the first layer interface, is the apparent resistivity of the second layer interface, is Poisson's ratio, Calculated by the following formula:

[0016] ,

[0017] in: , is the position coordinate of the measuring point, for The axis corresponds to half the size of the sample to be tested. for The axis corresponds to half the size of the sample to be tested;

[0018] S5. By measuring the apparent resistivity of the contact interface and substituting it into the interface contact stress-apparent resistivity distribution correlation formula, the interface contact stress can be obtained. According to the distribution characteristics of the contact stress and the interface morphology, the distribution characteristics of the interface contact performance are finally obtained.

[0019] Furthermore, in step S2, the relationship between the interface contact resistance and the apparent resistivity is as follows:

[0020] (1) Four-wire electrode arrangement:

[0021] ,

[0022] (2) High-density electrochemical electrode arrangement:

[0023] ,

[0024] In the formula, is the contact resistance.

[0025] Furthermore, in step S3, the relationship between the contact resistance and the contact displacement at the interface position is:

[0026] ,

[0027] In the formula, Interface position The contact resistance at Interface position The contact displacement at

[0028] The contact displacement and contact stress have the following relationship:

[0029] ;

[0030] The relationship between the contact resistance and the contact stress at the obtained interface position is:

[0031] .

[0032] Compared with the shortcomings and deficiencies of the prior art, the present invention has the following beneficial effects:

[0033] The present invention establishes an interface contact stress-apparent resistivity distribution correlation formula. According to the formula, the interface contact stress distribution is obtained by measuring the contact interface apparent resistivity distribution, and then the distribution characteristics of the interface contact stress are combined with the interface morphology to obtain the interface contact performance distribution characteristics. The present invention can directly obtain the stress distribution of the contact interface, the method is simple, and the result is accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic diagram of a structure in which a current line is contracted at a contact interface provided by an embodiment of the present invention;

[0035] Figure 2 is a schematic diagram of measuring apparent resistivity using a high-density electrical method provided by an embodiment of the present invention;

[0036] Figure 3 Schematic diagram of the electrode arrangement of the four-wire method provided by an embodiment of the present invention, in which (a) is a schematic diagram of the three-dimensional arrangement, and (b) is a schematic diagram of the planar arrangement;

[0037] Figure 4 Schematic diagram of the arrangement of high-density electrochemical electrodes provided by an embodiment of the present invention, in which (a) is a schematic diagram of a three-dimensional arrangement, and (b) is a schematic diagram of a planar arrangement;

[0038] Figure 5 This is a distribution comparison diagram of the interface contact resistance and the interface contact stress of the stainless steel material provided in an embodiment of the present invention. In the figure, (a) is the measurement result of the interface contact resistance distribution, and (b) is the inversion result of the interface contact stress distribution. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0040] 1. Calculation of apparent resistivity

[0041] Rough interface under normal load F N Under the action, a current of magnitude I is passed. When the current passes through the actual contact surface, the contact resistance is generated, causing the current line to shrink (such as Figure 1 As shown), a voltage drop is generated. The high-density electrical method can measure the apparent resistivity at different depths by changing the electrode spacing. A and B are power supply electrodes, and a current of magnitude I is injected between A and B. M and N are measuring electrodes, and the number of layers in the measuring depth direction is n, as shown in Figure 2 As shown, the calculation formula for apparent resistivity is:

[0042] (1)

[0043] In the formula, is the apparent resistivity, is the potential difference between M and N, , , , They are the distances between A and M, between B and M, between A and N, and between B and N. is a constant.

[0044] 2. Measurement of interface contact resistance

[0045] (1) Four-wire electrode arrangement

[0046] The four-wire electrode arrangement is as follows Figure 3 As shown, according to the four-wire measurement principle, the interface contact resistance of the four-wire electrode arrangement can be obtained as follows: for:

[0047] (2)

[0048] Substituting equation (1) into equation (2), we can obtain the relationship between the interface contact resistance and apparent resistivity of the four-wire electrode arrangement:

[0049] (3).

[0050] (2) High-density electrochemical electrode arrangement

[0051] The arrangement of high-density electrochemical electrodes is as follows: Figure 4 As shown in the figure, 1 at the contact interface represents the first layer interface, and 2 represents the second layer interface. Combined with formula (1), the potential difference between the measuring electrodes M and N is When , we can get:

[0052] The apparent resistivity of the first layer interface is:

[0053] (4)

[0054] After changing the distance between the measuring electrodes, the potential difference between the measuring electrodes M and N is When , the apparent resistivity of the second layer interface is:

[0055] (5)

[0056] According to the measurement principle of high-density electrical method, the interface contact resistance of the high-density electrical method electrode arrangement is obtained as follows: for:

[0057] (6)

[0058] In the formula, is the potential difference between the first layer interface and the second layer interface.

[0059] 3. Correlation between interface contact stress and contact resistance distribution

[0060] Interface location Contact resistance Contact displacement The following relationship exists:

[0061] (7)

[0062] In the formula, Interface position The distance between the highest point of the upper rough interface and the lowest point of the lower rough interface, is the material resistivity of the rough interface, is the radius of the microconvex body.

[0063] According to existing research, the relationship between interface contact displacement and contact stress is:

[0064] (8)

[0065] in, is Young's modulus, is Poisson's ratio, Interface position The contact stress at Calculated by the following formula:

[0066]

[0067] Where: , is the position coordinate of the measuring point, for The axis corresponds to half the size of the sample to be tested. for The axis corresponds to half the size of the test specimen.

[0068] The expression of contact displacement can be obtained by transforming formula (8):

[0069] (9)

[0070] Substituting equation (9) into equation (7), we can get the interface position The expression of contact resistance at is:

[0071] (10)

[0072] Combining equation (3) with equation (10), the correlation formula between interface contact stress and apparent resistivity distribution under the four-wire electrode arrangement is obtained:

[0073] (11);

[0074] Combining equation (6) with equation (10), the correlation formula between interface contact stress and apparent resistivity distribution under high-density electrical method electrode arrangement is obtained:

[0075] (12).

[0076] 4. By measuring the apparent resistivity of the contact interface and substituting it into the interface contact stress-apparent resistivity distribution correlation formula, the interface contact stress can be obtained. According to the distribution characteristics of the contact stress and the interface morphology, the interface contact performance distribution characteristics can be finally obtained. In addition, by measuring the apparent resistivity of the contact interface, the contact resistance can be calculated according to the relationship between the contact resistance and the apparent resistivity. Combined with the interface contact stress calculated by the interface contact stress-apparent resistivity distribution correlation formula, the relationship between the interface contact stress and the contact resistance can be obtained.

[0077] 5. Measure the distribution of contact resistance at the contact interface of stainless steel material. The measurement results are as follows: Figure 5 (a) is shown. The interface contact stress distribution is inverted using the interface contact stress-apparent resistivity distribution correlation formula of formula (11), where: =2, =7.2×10 -7 Ω·m, =200GPa, =5×10 -5 m, =0.326, the result is Figure 5 (b) Comparison Figure 5 (a) and (b) show that the interface contact stress is low where the contact resistance is high, which is consistent with the law of macroscopic resistance change, indicating the correctness of the interface contact stress distribution obtained by the interface contact stress-apparent resistivity distribution correlation formula established according to the present invention.

[0078] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for measuring the distribution characteristics of interface contact performance, characterized in that: The steps include: S1. According to the contact interface four-wire method electrode arrangement and the high-density electrical method electrode arrangement, the relationship between the interface contact resistance and the potential difference under the two contact interface electrode arrangements is obtained respectively; S2, introducing the relationship between apparent resistivity and potential difference in high-density electrical method into the relationship between interface contact resistance and potential difference in step S1, and obtaining the relationship between interface contact resistance and apparent resistivity under two contact interface electrode arrangement modes respectively; S3, combining the existing relationship between the contact resistance and the contact displacement at the interface position with the relationship between the contact displacement and the contact stress, to obtain the relationship between the contact resistance and the contact stress at the interface position; S4, introducing the relationship between the interface contact resistance and the apparent resistivity obtained in step S2 into the relationship between the contact resistance and the contact stress at the interface position obtained in step S3, and obtaining the interface contact stress-apparent resistivity distribution correlation relationship under the two contact interface electrode arrangement modes; wherein, The correlation formula between the interface contact stress and apparent resistivity distribution under the four-wire electrode arrangement is: ； The correlation formula between the interface contact stress and apparent resistivity distribution under the high-density electrical method electrode arrangement is: ； In the formula, Interface position The contact stress at is a constant, is the material resistivity of the rough interface, is Young's modulus, Interface position The distance between the highest point of the upper rough interface and the lowest point of the lower rough interface, is the radius of the microconvex body, is the apparent resistivity, is the apparent resistivity of the first layer interface, is the apparent resistivity of the second layer interface, is Poisson's ratio, Calculated by the following formula: ， in: , is the position coordinate of the measuring point, for The axis corresponds to half the size of the sample to be tested. for The axis corresponds to half the size of the sample to be tested; S5. By measuring the apparent resistivity of the contact interface and substituting it into the interface contact stress-apparent resistivity distribution correlation formula, the interface contact stress can be obtained. According to the distribution characteristics of the contact stress and the interface morphology, the distribution characteristics of the interface contact performance are finally obtained.

2. The method for measuring the distribution characteristics of interface contact performance according to claim 1, characterized in that: In step S2, the relationship between the interface contact resistance and the apparent resistivity is as follows: (1) Four-wire electrode arrangement: ， (2) High-density electrochemical electrode arrangement: ， In the formula, is the contact resistance.

3. The method for measuring the distribution characteristics of interface contact performance according to claim 2, characterized in that: In step S3, the relationship between the contact resistance and the contact displacement at the interface position is: ， In the formula, Interface position The contact resistance at Interface position The contact displacement at The contact displacement and contact stress have the following relationship: ； The relationship between the contact resistance and the contact stress at the obtained interface position is: 。

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