Device and method for measuring true contact area of ​​joint surface under vibration environment

Abstract

The present invention discloses a device and method for measuring the true contact area of ​​a bonding surface under a vibration environment. The device includes: a DC power supply, an ammeter, a voltmeter, a pressure sensor, a pressure loading device, an upper test piece, a lower test piece, a base, a vibration table, and a data processing device. The vibration table applies a vibration load to the contact pair of materials to be tested. The ammeter and voltmeter measure the current and voltage of the contact pair of materials to be tested. The data processing device obtains the fluctuation value of the contact resistance of the bonding surface under the vibration environment. The relationship between the contact resistance of the bonding surface and the true contact area is used to obtain the true contact area of ​​the bonding surface under the vibration environment. The present invention has the advantages of simple structure, easy assembly and disassembly, and real-time monitoring.

Description

Technical Field

[0001] The present invention relates to the field of true contact area measurement technology in the field of joint surface contact theory research, and in particular to a device and method for measuring the true contact area of ​​a joint surface under a vibration environment. Background Art

[0002] There are a large number of mechanical joints in actual engineering applications. Due to the existence of surface roughness, the two contacting surfaces are not in perfect contact, which will reduce the energy transfer performance at the joint surface (contact damping, contact resistance and contact thermal resistance). Existing studies have shown that these contact resistances are related to factors such as load, material properties, and surface morphology. Predicting them is a multidisciplinary cross-disciplinary problem involving materials, mechanics, and geometry, and is relatively complex. The above factors affect the energy transfer performance of the joint surface by affecting the actual contact area of ​​the joint surface. Therefore, obtaining the actual contact area of ​​the mechanical joint surface has extremely important theoretical and practical application value for studying the energy transfer characteristics at the joint surface.

[0003] At present, the research on the true contact area of ​​the bonding surface is based on theoretical and numerical models to predict the contact conditions of the bonding surface under steady-state conditions. Under vibration environment, the research on the contact conditions of the bonding surface is limited, and the contact state of the bonding surface cannot remain stable. Considering the interaction between rough surfaces, vibration will cause fatigue and wear on the contact surface. The true contact area predicted by the existing theoretical and numerical models can only be used as a relevant reference and cannot reflect the changes in the true contact area of ​​the bonding surface under vibration environment. Summary of the Invention

[0004] The purpose of the present invention is to provide a device and method for measuring the true contact area of ​​a bonding surface under a vibration environment. By utilizing the relationship between the contact resistance of the bonding surface and the true contact area, the fluctuation value of the contact resistance at the bonding surface under a vibration environment is tested to obtain the change of the true contact area of ​​the bonding surface under a vibration environment.

[0005] The technical solutions for achieving the purpose of the present invention are:

[0006] A device for measuring the true contact area of ​​a joint surface under a vibration environment, comprising:

[0007] Power supply module, used to provide voltage and current for the test circuit;

[0008] Ammeter, used to test the current in the circuit;

[0009] Voltmeter, used to test the voltage between the upper and lower test pieces;

[0010] Vibration table, used to provide a vibrating contact environment for the upper and lower test pieces;

[0011] A pressure loading device is used to provide initial pressure for the contact between the upper and lower specimens;

[0012] Pressure sensor, used to measure the contact pressure between the upper and lower test pieces;

[0013] The data processing device is connected to the ammeter, voltmeter and pressure sensor and is used to collect and process data and calculate the change of the real contact area of ​​the bonding surface over time.

[0014] A method for measuring the true contact area of ​​a bonding surface under a vibration environment comprises the following steps:

[0015] Step 1: Place the contact pair of the material to be tested vertically on the base, connect the test circuit and turn on the pressure loading device to apply initial contact pressure;

[0016] Step 2: Turn on the DC power supply and calculate the contact resistance of the contact pair of the test materials under the initial pressure based on the values ​​of the voltmeter and ammeter;

[0017] Step 3: Start the vibration table to perform a vibration test, use a data processing device to record relevant data, and calculate the contact resistance fluctuation value at the joint surface.

[0018] Compared with the prior art, the present invention has the following significant advantages:

[0019] The present invention proposes a device and method for measuring the true contact area of ​​a bonding surface under a vibration environment. Using this device and method, technicians can measure the changes in the contact resistance and true contact area of ​​different material contact pairs under a vibration environment. At the same time, by adjusting the vibration table and the pressure loading device, technicians can study the influence of factors such as initial pressure and vibration mode on the contact resistance and true contact area of ​​the material contact pair. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a diagram of the device for measuring the actual contact area of ​​the joint surface under a vibration environment.

[0021] Figure 2 It is a flow chart of the method for measuring the actual contact area of ​​the bonding surface in the embodiment of the present application. DETAILED DESCRIPTION

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0023] like Figure 1As shown, a device for measuring the real contact area of ​​a bonding surface under a vibration environment of the present invention includes: a DC power supply 1, an ammeter 2, a voltmeter 3, a pressure sensor 4, a pressure loading device 5, an upper test piece 6, a lower test piece 7, a base 8, a vibration table 9, and a data processing device 10; the positive pole of the DC power supply 1 is connected to the ammeter 2, and the negative pole is connected to the lower test piece 7 to provide voltage and current for the test circuit; the other end of the ammeter 2 is connected to the upper test piece 6 for testing the current in the circuit; the two ends of the voltmeter 3 are respectively connected to the upper and lower test pieces for testing the voltage of the upper and lower test pieces; the lower test piece 7 is placed on the base 8, and the base is fixed on the vibration table 9; the upper and lower test pieces are placed in contact, and the pressure sensor 4 is placed on the top of the upper test piece 6 for measuring the contact pressure of the upper and lower test pieces; the pressure loading device 5 is installed on the top of the pressure sensor 4 for providing initial pressure; the data processing device 10 is connected to the ammeter 2, the voltmeter 3 and the pressure sensor 4 for collecting and processing data.

[0024] The method for measuring the true contact area of ​​a bonding surface under a vibration environment is based on a bonding surface contact resistance measuring device under a vibration environment. After applying initial pressure, turning on a DC power supply, and starting a vibration table, the bonding surface contact resistance fluctuation value is obtained according to data measured by a voltmeter and an ammeter. The relationship between the bonding surface contact resistance and the true contact area is used to calculate the change of the true contact area of ​​the bonding surface over time through a formula operation. The method specifically includes the following steps:

[0025] (a) Measure the voltage U(t) and current I(t) of the upper and lower specimens using a voltmeter and ammeter, collect the relevant data using a data processing device, and calculate the contact resistance fluctuation value at the bonding surface according to Equation 1;

[0026]

[0027] Where R1 is the resistance of the upper specimen, and R2 is the resistance of the lower specimen;

[0028] (b) According to the Holm electrical contact model, the equivalent contact radius of the bonding surface is calculated by Equation 2;

[0029]

[0030] Where ρ1 is the resistivity of the upper specimen material, and ρ2 is the resistivity of the lower specimen material;

[0031] (c) According to Equation 3, the change of the actual contact area of ​​the bonding surface under vibration conditions is obtained;

[0032] S(t)=πa 2 (3)

[0033] Combine Figure 2 The present invention provides a method for measuring the true contact area of ​​a bonding surface under a vibration environment, comprising the following steps:

[0034] Step 1: Place the contact pair of the material to be tested vertically on the base, connect the test circuit and turn on the pressure loading device to apply initial contact pressure;

[0035] The specific value of the initial pressure can be determined by the tester according to the test requirements;

[0036] Step 2: Turn on the DC power supply and calculate the contact resistance of the contact pair of the test materials under the initial pressure based on the values ​​of the voltmeter and ammeter;

[0037] Step 3: Start the vibration table to perform a vibration test, use a data processing device to record relevant data, and calculate the contact resistance fluctuation value at the bonding surface according to Formula 1;

[0038] Among them, the vibration amplitude, frequency and vibration mode can be set by the tester according to the test requirements;

[0039]

[0040] Where R1 is the resistance of the upper specimen, and R2 is the resistance of the lower specimen;

[0041] Step 4: According to the Holm electrical contact model, the equivalent contact radius of the bonding surface is calculated by equation 2;

[0042]

[0043] Step 5: According to formula 3, the actual contact area change of the joint surface under vibration environment is obtained;

[0044] S(t)=πa 2 (3)

[0045] Where S(t) is the actual contact area of ​​the bonding surface.

[0046] The upper test piece 6 and the lower test piece 7 are made of the same or different conductive materials, and the upper and lower contact surfaces are processed in the same or different ways. When the vibration table is not used, the contact resistance of the bonding surface of different pressures and different materials can be measured.

Claims

1. A device for measuring the true contact area of ​​a joint surface under a vibration environment, characterized in that: include: Power supply module, used to provide voltage and current for the test circuit; Ammeter, used to test the current in the circuit; Voltmeter, used to test the voltage between the upper and lower test pieces; Vibration table, used to provide a vibrating contact environment for the upper and lower test pieces; A pressure loading device is used to provide initial pressure for the contact between the upper and lower specimens; Pressure sensor, used to measure the contact pressure between the upper and lower test pieces; A data processing device, connected to the ammeter, voltmeter and pressure sensor, is used to collect and process data and calculate the change of the actual contact area of ​​the bonding surface over time; The process of the data processing device calculating the change of the real contact area of ​​the bonding surface over time is as follows: According to formula (1), the contact resistance fluctuation value at the bonding surface is calculated as follows: Where R1 is the resistance of the upper specimen, R2 is the resistance of the lower specimen, U(t) and I(t) are the voltage and current measured by the voltmeter and ammeter respectively; Calculate the equivalent contact radius of the bonding surface: Where ρ1 is the resistivity of the upper specimen material, and ρ2 is the resistivity of the lower specimen material; Obtain the actual contact area change of the bonding surface under vibration environment: S(t)=πa 2 (3)。 2. The device for measuring the true contact area of ​​a joint surface under a vibration environment according to claim 1, characterized in that: The relationship between the contact resistance of the junction surface and the actual contact area is calculated using the Holm electrical contact model.

3. A method for measuring the true contact area of ​​a bonding surface under a vibration environment, characterized in that: The following steps are involved: Step 1: Place the contact pair of the material to be tested vertically on the base, connect the test circuit and turn on the pressure loading device to apply initial contact pressure; Step 2: Turn on the DC power supply and calculate the contact resistance of the contact pair of the test materials under the initial pressure based on the values ​​of the voltmeter and ammeter; Step 3: Start the vibration table to perform a vibration test, use a data processing device to record relevant data, and calculate the contact resistance fluctuation value at the joint surface; The process of calculating the contact resistance fluctuation value at the joint surface is: According to formula (1), the contact resistance fluctuation value at the bonding surface is calculated as follows: Where R1 is the resistance of the upper specimen, R2 is the resistance of the lower specimen, U(t) and I(t) are the voltage and current measured by the voltmeter and ammeter respectively; Calculate the equivalent contact radius of the bonding surface: Where ρ1 is the resistivity of the upper specimen material, and ρ2 is the resistivity of the lower specimen material; Obtain the actual contact area change of the bonding surface under vibration environment: S(t)=πa 2 (3)。 4. The method for measuring the true contact area of ​​a bonding surface under a vibration environment according to claim 3, characterized in that: When the vibration table is not used, it is used to measure the contact resistance of the bonding surfaces of different pressures and different materials.

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