A method and device for accelerated detection of service life of a polymer diaphragm valve core

Abstract

The application discloses a kind of polymer diaphragm valve core's service life accelerated detection method and device;The device includes test module, stress detection module and fluid circulation module.The test module includes test specimen clamping vibration module.Test specimen clamping vibration module includes acoustic wave generating assembly and pressure vessel.Pressure vessel is used to clamp the diaphragm valve core to be measured;Acoustic wave generating assembly is aligned with the position of pressure vessel on which the diaphragm valve core to be measured is installed.In the state that the diaphragm valve core to be measured is loaded into pressure vessel, liquid-filled cavity for simulating the working environment of diaphragm valve core is formed in pressure vessel, and acoustic wave generating assembly is aligned with the diaphragm valve core to be measured, so that acoustic wave generating assembly can drive the diaphragm valve core to be measured to reciprocate.The application uses non-contact non-destructive acoustic wave vibration measurement method to test the service life of diaphragm valve core, can truly simulate the working environment and movement process of diaphragm valve core, and realizes the high acceleration life test of diaphragm.

Description

Technical Field

[0001] This invention belongs to the field of performance testing of ultra-clean flow control components made of polymer materials, and specifically relates to a method and device for accelerating the service life testing of polymer diaphragm valve cores. Background Technology

[0002] PTFE, with its excellent chemical stability and good pressure resistance, has become an ideal sealing material and has been widely used in sealing applications in recent years. In the field of ultra-clean manufacturing, the industry generally uses flexible elements made of ultra-pure perfluoropolymer (PTFE) as the diaphragm valve core. When diaphragm valves are used in ultra-clean manufacturing to control the flow of cleaning fluid, they need to be frequently switched on and off, which poses a challenge to the service life of the diaphragm valve core.

[0003] Because PTFE is a high-molecular polymer, it is not prone to exhibiting phenomena such as metal fatigue fracture damage during fatigue life testing, making it difficult to quickly and effectively determine its service life. Damage to the diaphragm valve core during operation will cause media contamination in the ultra-clean system and a significant reduction in the service life of the workpiece. Therefore, focusing on accelerated detection methods for PTFE diaphragm life is of great significance for high-performance manufacturing in ultra-clean production.

[0004] Currently, common life testing methods for thin-walled components include fatigue life models, progressive damage models, and phenomenological models of residual stiffness and strength. Chinese Patent Publication No. CN111006954A discloses a diaphragm life testing method, including building a life testing platform and diaphragm pressure resistance testing. A high-pressure air source input mechanism and a pressure application mechanism simulate the working state of the diaphragm. This method can repeatedly perform pressure resistance and deformation tests on metal diaphragms. However, if the test object is a polymer material diaphragm, due to its low defect rate, it is difficult to obtain test results showing specimen breakage, resulting in low testing efficiency and discrepancies with actual operating conditions. Currently, there are no methods or devices for accelerated service life testing of polymer material diaphragm valve cores in liquid environments. Summary of the Invention

[0005] The purpose of this invention is to address the problems of unpredictable service life and susceptibility to defects in existing polymer diaphragm valve cores during service, and to provide a method and device for accelerating diaphragm valve core life testing based on service conditions. This invention is a non-contact detection method that rapidly induces defects in the diaphragm valve core by gradually applying step stress under constant or variable temperature conditions; a testing method that simulates the properties and states of liquid media (gradual or accelerated changes in density, pressure, and motion patterns, etc.) under different working media to detect the life of the diaphragm valve core; a method that uses acoustic waves to excite the diaphragm valve core to generate vibration, and performs life testing on the diaphragm valve core under different modes by changing the vibration magnitude, step size, and state dwell time of the acoustic waves; a testing method that uses the clarity of infrared transmission imaging to monitor the internal and surface damage state and extent of the diaphragm valve core in real time; and a life testing device that integrates step stress control, acoustic vibration, and strain monitoring.

[0006] In a first aspect, the present invention provides a method for accelerating the service life testing of a polymer diaphragm valve core, comprising the following steps:

[0007] Step 1: Install the diaphragm valve core to be tested into a pressure vessel; one side of the diaphragm valve core and the inner wall of the pressure vessel together form a filling chamber with an inlet and an outlet. An ultrasonic generator is installed at intervals on the other side of the diaphragm valve core.

[0008] Step 2: Temperature step test.

[0009] Step 2-1. Set the starting temperature value, basic acceleration, temperature test duration, temperature step size, and temperature dwell time.

[0010] Step 2-2. Introduce a liquid medium into the filling chamber; the ultrasonic generator releases ultrasonic waves, which non-contactly drive the tested diaphragm valve core to vibrate; the acceleration of the ultrasonic generator is the base acceleration set in Step 2-1. The temperature of the liquid medium introduced into the filling chamber is the initial temperature value, and is gradually increased according to the temperature step and temperature residence time.

[0011] Step 2-3. After the preset temperature test duration, observe whether the diaphragm valve core is damaged. If it is damaged, use the current temperature step as the critical temperature step. If the diaphragm valve core is not damaged, increase the temperature step, replace the diaphragm valve core, and repeat step 2-2 until the diaphragm valve core is damaged.

[0012] Steps 2-4. Calculate the accelerating temperature stress v T =T s / S0; where S0 is the diaphragm cross-sectional area of ​​the diaphragm valve core.

[0013] Steps 2-5. Calculate the temperature-dependent fatigue factor K. T =AvT c Where A and c are preset coefficients.

[0014] Step 3: Acoustic vibration step test.

[0015] Step 3-1. Set the base temperature value, initial acceleration, acceleration step size, and acceleration dwell time.

[0016] Step 3-2. Introduce a liquid medium into the filling chamber; the ultrasonic generator releases ultrasonic waves to non-contactly drive the tested diaphragm valve core to vibrate; the temperature of the liquid medium introduced into the filling chamber is the base temperature value; the acceleration of the ultrasonic generator is the initial acceleration set in step 2-1, and is gradually increased according to the acceleration step size and acceleration dwell time. Infrared images of the diaphragm valve core are continuously acquired by an infrared detector to obtain the crease length 'a' on the diaphragm at different stress cycle numbers N; simultaneously, the diaphragm stress and strain of the tested diaphragm valve core are acquired by a strain gauge.

[0017] Step 4: Predict the service life of the polymer diaphragm valve core. s as follows:

[0018]

[0019] Where C, n, p, and q are all fitted parameters; f is the fatigue damage estimate; R is the stress ratio; ΔK is the stress intensity factor amplitude; ΔK th It is the critical stress when the diaphragm begins to show creases in step three; a1 is the crease length when the tested diaphragm valve core breaks.

[0020] Preferably, the expression for the fatigue damage estimate f is:

[0021]

[0022] Among them, S r Represents the stress range; P(·) is the stress range probability density function; F p The expected number of stress peak occurrences per unit time; t is time; N f The stress range S r The number of cycles in which the structure fails.

[0023] The expression for the stress intensity factor amplitude ΔK is:

[0024]

[0025] Where Δσ is the stress amplitude at the crease.

[0026] Preferably, the temperature dwell time is 10 min to 15 min; the temperature step size is 10 °C; and the base acceleration is 5 GRMS. The acceleration step size is 5 GRMS to 15 GRMS.

[0027] Preferably, in step two, the accelerating temperature stress v is calculated. T The critical temperature step T used at that time s The average value of the critical temperature step obtained from multiple experiments is taken.

[0028] Preferably, in step two, the final temperature-dependent fatigue factor K T The final temperature-dependent fatigue factor K is obtained by assigning values ​​to the calculated values ​​of the temperature-dependent fatigue factor. T Take the value that is closest to the temperature fatigue factor among 50%, 63.2%, and 10%.

[0029] Secondly, this invention provides an accelerated service life testing device for polymer diaphragm valve cores, used to perform the aforementioned testing method; it includes a testing module, a stress detection module, and a fluid circulation module. The testing module includes a specimen clamping vibration module. The specimen clamping vibration module includes an acoustic wave generating component and a pressure vessel. The pressure vessel is used to clamp the diaphragm valve core under test; the acoustic wave generating component is aligned with the position of the diaphragm valve core under test on the pressure vessel. With the diaphragm valve core under test installed in the pressure vessel, a liquid-filled chamber is formed inside the pressure vessel to simulate the working environment of the diaphragm valve core, and the acoustic wave generating component is aligned with the diaphragm valve core under test, enabling the acoustic wave generating component to drive the diaphragm valve core under test to reciprocate. An infrared detector is installed inside the pressure vessel; the infrared detector is used to detect the temperature distribution on the diaphragm valve core. The fluid circulation module is used to drive a liquid medium through the liquid-filled chamber in the pressure vessel during the testing process, simulating the working environment of the diaphragm valve core.

[0030] Preferably, the test module further includes a variable temperature chamber. The specimen clamping vibration module is installed inside the variable temperature chamber;

[0031] Preferably, the pressure vessel includes a cylindrical body, a fixed sleeve, a lower sealing ring, and an upper sealing ring. The cylindrical body is fixed inside the temperature-controlled chamber; the inner circumferential surface of the fixed sleeve is threadedly connected to the outer circumferential surface of the cylindrical body. A clamping flange is provided at the end of the inner circumferential surface of the fixed sleeve. The clamping flange of the fixed sleeve is aligned with the end of the cylindrical body. The upper and lower sealing rings are provided between the clamping flange of the fixed sleeve and the end of the cylindrical body. During testing, the edge of the diaphragm valve core is clamped between the upper and lower sealing rings; an inlet and an outlet are provided on the side wall of the cylindrical body.

[0032] Preferably, the specimen clamping vibration module further includes a vibration guiding assembly. The vibration guiding assembly includes a support base, a guide cylinder, and a constant-pressure spring. The support base is fixed inside the cylinder. The guide cylinder is sleeved on the support base, forming a sliding pair; the constant-pressure spring is disposed inside the guide cylinder, with its two ends abutting against the support base and the guide cylinder, respectively. The top center of the guide cylinder has an internal thread structure that matches the external thread on the diaphragm valve core.

[0033] Preferably, the accelerated service life testing device for the polymer diaphragm valve core further includes a force measuring module; the force measuring module includes a force measuring element mounted on the top of the support base. The force measuring element is used to detect the compressive force exerted by the diaphragm valve core on the guide cylinder during vibration.

[0034] Preferably, the acoustic wave generating assembly includes an acoustic wave generator and an acoustic wave probe. The acoustic wave probe is mounted at the bottom of the acoustic wave generator. During detection, the acoustic wave probe is aligned with the diaphragm valve core under test and spaced apart. An infrared detector is ring-shaped and surrounds the acoustic wave probe.

[0035] Preferably, during the testing process, strain gauges are attached to the diaphragm of the diaphragm valve core being tested. These strain gauges are connected to a host computer via a signal amplification receiver.

[0036] Preferably, the fluid circulation module includes a valve body assembly, a fluid storage tank, and a fluid delivery device. The fluid storage tank is mounted on the upper side of the fluid delivery device; the fluid delivery device is mounted on a work cabinet. The valve body assembly includes a third check valve, a first differential pressure reducing valve, a second differential pressure reducing valve, a first check valve, and a second check valve. The output port of the fluid storage tank is connected to the input port of the fluid delivery device; the output port of the fluid delivery device is connected to the input ports of the first and second differential pressure reducing valves; the output port of the first differential pressure reducing valve is connected to the input port of the first check valve; the output port of the second differential pressure reducing valve is connected to the input port of the second check valve. The output ports of both the first and second check valves are connected to the liquid inlet of the inner cylinder of the pressure vessel. The liquid outlet of the inner cylinder of the pressure vessel is connected to the input port of the third differential pressure reducing valve; the output port of the third differential pressure reducing valve is connected to the input port of the third check valve; the output port of the third check valve is connected to the input port of the fluid storage tank.

[0037] The beneficial effects of this invention are as follows:

[0038] 1. This invention uses a non-contact, non-destructive acoustic vibration measurement method to test the life of a diaphragm valve core, which can realistically simulate the working environment and movement process of the diaphragm valve core and achieve high-acceleration life testing of the diaphragm.

[0039] 2. This invention predicts the service life of polymer diaphragm valve cores based on the crease propagation rate caused by fatigue damage, and obtains the temperature-dependent fatigue factor through temperature step test. The temperature-dependent fatigue factor is then incorporated into the service life constructed based on vibration test, thereby improving the accuracy of diaphragm valve core service life prediction. Attached Figure Description

[0040] Figure 1 This is a three-dimensional view of the overall structure of the detection device provided by the present invention.

[0041] Figure 2 This is a three-dimensional view of the structure of the specimen clamping vibration module in the device used in this invention.

[0042] Figure 3 The flowchart is for the detection method provided by the present invention.

[0043] In the diagram: 1. Valve body assembly, 2. Fluid storage tank, 3. Fluid delivery device, 4. Specimen holding module, 5. Host computer, 6. Temperature chamber, 7. Signal amplifier and receiver, 101. Third check valve, 102. First differential pressure reducing valve, 103. Third differential pressure reducing valve, 104. Second differential pressure reducing valve, 105. First check valve, 106. Second check valve, 201. Input conduit, 202. Output conduit, 401. Cylinder, 402. Fixing sleeve, 403. Support base, 404. Guide cylinder, 405. Constant pressure spring, 406. Acoustic wave generator, 407. Acoustic wave probe, 408. Infrared detector, 409. Strain gauge, 410. Fixing sleeve, 411. Lower sealing ring, 412. Upper sealing ring. Detailed Implementation

[0044] The present invention will now be further described with reference to the accompanying drawings.

[0045] like Figure 1 and 2 As shown, an accelerated service life testing device for a polymer diaphragm valve core includes a testing module, a stress detection module, an infrared transmission imaging module, a force measurement module, a fluid circulation module, a host computer 5, and a signal amplification and receiver 7. The testing module includes a variable temperature chamber 6 and a specimen clamping vibration module 4. The variable temperature chamber 6 is equipped with a high-power resistance wire, capable of providing the high heating rate required for a rapid temperature change test chamber. The specimen clamping vibration module 4 is installed inside the variable temperature chamber; the specimen clamping vibration module 4 includes an acoustic wave generating component, a vibration guiding component, and a pressure vessel. The pressure vessel is used to mount the diaphragm valve core under test; the acoustic wave generating component is used to apply ultrasonic vibration to the diaphragm valve core under test.

[0046] The pressure vessel includes a cylindrical body 401, a fixed sleeve 402, a lower sealing ring 411, and an upper sealing ring 412. The cylindrical body 401 is fixed inside the temperature-controlled chamber 6; the inner circumferential surface of the fixed sleeve 402 is threadedly connected to the outer circumferential surface of the cylindrical body 401. A clamping flange is provided at the end of the inner circumferential surface of the fixed sleeve 402. The clamping flange of the fixed sleeve 402 is aligned with the end of the cylindrical body 401. The upper sealing ring 412 and the lower sealing ring 411 are provided between the clamping flange of the fixed sleeve 402 and the end of the cylindrical body 401. During the testing process, the edge of the diaphragm valve core is clamped between the upper sealing ring 412 and the lower sealing ring 411; the diaphragm valve core divides the inner cavity of the cylindrical body 401 into an independent filling chamber and a testing chamber. Fluid is introduced into the filling chamber to simulate the working environment of the diaphragm valve core. An inlet and an outlet are provided on the side wall of the cylindrical body 401. The inlet and outlet are connected to the filling chamber.

[0047] The vibration guiding assembly includes a support base 403, a guide cylinder 404, and a constant pressure spring 405. The support base 403 is fixed inside the cylinder 401. The guide cylinder 404 is sleeved on the support base 403 and forms a sliding pair; the constant pressure spring 405 is disposed inside the guide cylinder 404, and its two ends abut against the support base 403 and the guide cylinder 404 respectively.

[0048] The top center of the guide cylinder 404 is provided with an internal thread structure that matches the external thread on the diaphragm valve core; thus, the diaphragm valve core and the guide cylinder 404 can be fixed together by the threaded connection during the test. The bottom of the support base 403 closes the through hole at the bottom end of the cylinder 401. The through hole at the bottom end of the cylinder 401 is used to fix the cylinder 401 to the inner cavity of the temperature chamber 6. During the test, multiple diaphragm valve cores to be tested are clamped one by one inside the device for accelerated destructive testing; in each accelerated destructive test, the diaphragm valve core is replaced after damage occurs on the diaphragm surface, and the next set of tests is performed.

[0049] The acoustic wave generating assembly includes a fixing sleeve 410, an acoustic wave generator 406, and an acoustic wave probe 407. The acoustic wave probe 407 is mounted on the bottom of the acoustic wave generator 406. The fixing sleeve 410 is fixed to the top opening of the temperature chamber 6 and aligned with the diaphragm valve core under test; the outer circumferential surface of the acoustic wave probe 407 is interference-fitted with the central hole of the fixing sleeve 410. During the test, the acoustic wave probe 407 is aligned with the diaphragm valve core, and the diaphragm valve core is driven to reciprocate up and down by ultrasonic waves without contact.

[0050] The force measuring module includes a force measuring element mounted on top of the support 403. The force measuring element is used to detect the compressive force exerted by the diaphragm valve core on the guide cylinder 404 during vibration. The force measuring module can perform real-time control calculations, automatically record and save experimental data and curves, view database records in real time, and automatically calculate elastic modulus and fatigue life at the end of the experiment.

[0051] The infrared transmission imaging module includes an infrared detector 408; the annular infrared detector 408 is mounted on the bottom surface of the fixing sleeve 410 and surrounds the bottom of the acoustic probe 407. The infrared detector 408 is used to detect the temperature distribution on the diaphragm valve core, thereby determining the length of the crease on the diaphragm.

[0052] In this embodiment, by adjusting the frequency of the sound wave generator, the tested diaphragm valve core vibrates at different frequencies. Ultrasonic waves propagating in the medium exhibit three vibration modes: longitudinal waves, transverse waves, and surface waves. Longitudinal waves propagate in the same direction as the vibration of the medium particles and have the fastest propagation speed. Transverse waves propagate perpendicular to the vibration of the medium particles. Surface waves can propagate along the surface of an object. The speed of sound propagation in the medium is...

[0053]

[0054] Where E is the elastic modulus of the medium, in Pa; ρ is the density of the medium, in kg·m³. -3 The speed of sound in air at 15℃ is c = 340 m / s. -1 In freshwater, c = 1440 m·s -1 In steel, c = 5000 m·s -1 Sound waves propagate by dispersing the energy of mechanical vibrations in all directions. The sound intensity *l* is defined as the average power transmitted per unit area along the direction of wave propagation, with units of W·m². -2 ,Right now

[0055]

[0056] Where P r It is the effective (root mean square) pressure, with units of N·m. -1 ρ is density, with units of kg·m³. -3 c is the speed of sound, measured in m / s. -1 .

[0057] The stress detection module includes a strain gauge 409, a signal amplifier and receiver 7, and a host computer 5. The signal amplifier and receiver 7 is placed on the work cabinet. The host computer 5 is located above the signal amplifier and receiver 7. The strain gauge 409 is attached to the thin-walled structure of the diaphragm valve core and surrounds it. When the diaphragm valve core deforms due to ultrasonic vibration, it will cause the strain gauge to deform, thereby generating a current. The micro-current is further amplified by the signal amplifier and transmitted to the signal acquisition unit, and the signal is acquired through the PC. When the workpiece is damaged, the current signal detected by the strain gauge will be in an over-range state, which indicates that the workpiece of the diaphragm valve core is broken, and the detection work stops.

[0058] The fluid circulation module includes a valve body assembly 1, a fluid storage tank 2, and a fluid delivery device 3. The fluid storage tank 2 is mounted on top of the fluid delivery device 3; the fluid delivery device 3 is mounted on a work cabinet.

[0059] Valve body assembly 1 includes a third check valve 101, a first differential pressure reducing valve 102, a third differential pressure reducing valve 103, a second differential pressure reducing valve 104, a first check valve 105, and a second check valve 106. The output port of fluid storage tank 2 is connected to the input port of fluid delivery device 3; the output port of fluid delivery device 3 is connected to the input ports of the first differential pressure reducing valve 102 and the second differential pressure reducing valve 104; the output port of the first differential pressure reducing valve 102 is connected to the input port of the first check valve 105; and the output port of the second differential pressure reducing valve 104 is connected to the input port of the second check valve 106. The output ports of both the first check valve 105 and the second check valve 106 are connected to the liquid inlet of the cylinder 401 in the pressure vessel via an input conduit 201. The outlet of the cylinder 401 in the pressure vessel is connected to the inlet of the third differential pressure reducing valve 103 via an output conduit 202; the output of the third differential pressure reducing valve 103 is connected to the inlet of the third check valve 101; the output of the third check valve 101 is connected to the inlet of the fluid storage tank 2; thus forming a fluid circulation loop that provides simulated pressure for the diaphragm valve core, thereby providing a test environment for the diaphragm valve core in the pressure vessel that approximates the real working environment.

[0060] During operation, the fluid conveying device 3 drives the liquid medium to circulate through the pressure vessel, providing flushing for the diaphragm valve core; the first differential pressure reducing valve 102 and the second differential pressure reducing valve 104 can regulate the fluid pressure input to the pressure vessel. When the load of the liquid medium suddenly disappears, it indicates that the diaphragm has ruptured; at this time, the third check valve 101 immediately stops sucking in the liquid medium, and the third differential pressure reducing valve 103 immediately sucks out the remaining liquid medium in the cylinder and stores it in the liquid medium storage tank.

[0061] like Figure 3 As shown, the method for testing using the aforementioned accelerated service life testing device for polymer diaphragm valve cores is illustrated in the attached diagram. Figure 3 As shown, the specific steps include:

[0062] Step 1: Establish a spatial rectangular coordinate system and install the diaphragm valve core workpiece to be tested into the specimen clamping vibration module 4. The installation sequence is as follows: First, place the first sealing ring 411 on the top of the cylinder 401, then place the diaphragm valve core workpiece on the first sealing ring, so that the outer edge of the diaphragm valve core coincides with the outer edge of the first sealing ring. Place the second sealing ring 412 on the outer edge of the diaphragm valve core, so that the outer edge of the second sealing ring coincides with the outer edge of the diaphragm valve core. When installing the acoustic probe 407, use a rangefinder to detect the distance between the diaphragm valve core and the acoustic probe 407, and adjust the distance accordingly. Afterward, thread the fixing sleeve 402 to the cylinder 401 to complete the fixing of the diaphragm valve core.

[0063] Step 2: Conduct a temperature step test. Set the hydraulic pressure of the liquid medium and start the fluid system circulation. The initial value of the fluid pressure is set according to the actual situation. The fluid temperature is divided into two types: high temperature (20℃~80℃) and low temperature (0℃~20℃ (excluding)). The diaphragm life is studied under a relatively extreme environment. The high-temperature fluid is heated by a high-power electric heating wire, and the heating rate is controlled during the subsequent experiment. The low-temperature fluid is cooled by a compressor and condenser, and the cooling rate is controlled during the subsequent experiment.

[0064] The specific process for this step is as follows:

[0065] 2-1. Keep the acoustic vibration parameters constant and set the initial temperature value (e.g., 20°C); in this embodiment, the acceleration of the acoustic generator is 5 GRMS.

[0066] 2-2. Set the temperature test duration and conduct a temperature step experiment. The temperature step experiment involves increasing or decreasing the temperature in steps until the operational and destructive limits of the sample are found. The dwell time at each temperature point is 10-15 minutes; the initial value of the temperature step is 10℃.

[0067] 2-3. After the preset temperature test duration, observe whether the diaphragm valve core is damaged. If it is damaged, use the current temperature step as the critical temperature step. If the diaphragm valve core is not damaged, increase the temperature step, replace the diaphragm valve core, and repeat step 2-2 until the diaphragm valve core is damaged.

[0068] 2-4. Repeat steps 2-2 and 2-3 five times; take the average critical temperature step size obtained from the five trials as the final critical temperature step size T. s .

[0069] 2-5. Based on the critical temperature step size T s Calculate the accelerating temperature stress v T as follows:

[0070] v T =T s / S0 formula (3)

[0071] Where S0 is the diaphragm cross-sectional area of ​​the diaphragm valve core.

[0072] 2-6. Based on the inverse power law model, by accelerating the temperature stress v T Temperature-dependent fatigue factor K T The prediction calculations are as follows:

[0073] K T =Av T c Equation (4)

[0074] In the formula, A and c are constants related to product structure, process, and experimental methods, which are obtained through fitting.

[0075] 2-7. Taking the logarithm of both sides of the equation, we can also obtain the linearized function as follows:

[0076] lnK T =a+b[-lnv T Equation (5)

[0077] In the formula, a and b are both coefficients, a = lnA; b = c;

[0078] 2-8. Obtain the temperature-dependent fatigue factor K from step 2-7. T A value was assigned to characterize the percentile life of the tested diaphragm valve core, using the 50%, 63.2%, and 10% percentiles that are closest to the temperature-induced fatigue factor K. T The calculated quantile lifetime is used as the final temperature-dependent fatigue factor K. T .

[0079] Step 3: Conduct an acoustic vibration step test. Adjust the fluid density, pressure, and motion pattern according to the actual operating conditions. Start the acoustic wave generator assembly and adjust the acoustic vibration level, step size, and state dwell time of the acoustic wave generator to vibrate and excite the diaphragm valve core, causing the diaphragm valve core to exhibit different modes and record them, thus completing the life test of the diaphragm valve core under the given modes.

[0080] The specific process for this step is as follows:

[0081] 3-1. Keep the temperature constant (20℃ in this embodiment); set the initial acceleration to the acoustic vibration parameter set in step two; in this embodiment, the initial acceleration is 5 GRMS.

[0082] 3-2. Conduct an acoustic vibration stepping experiment until the diaphragm valve core ruptures. Specifically, the acoustic vibration stepping experiment involves gradually increasing the acceleration of the diaphragm valve core with increasing acceleration step size; infrared detector 408 continuously captures infrared images of the diaphragm valve core, thereby obtaining the change in the crease length 'a' on the diaphragm as the number of stress cycles increases; simultaneously, strain gauge 409 detects the change in the stress amplitude σ of the diaphragm as the number of stress cycles increases. The acceleration step size is 5 GRMS to 15 GRMS; the dwell time at the same acceleration is 10 minutes.

[0083] 3-3. Record the time of diaphragm rupture and the stress changes throughout the entire acoustic vibration step experiment.

[0084] Step 4: Based on the experimental results of Steps 2 and 3, determine the predicted service life N of the polymer diaphragm valve core. s

[0085] In this embodiment, the crease propagation rate caused by fatigue damage is used as the basis. To predict the service life N of polymer diaphragm valve cores s This embodiment uses the Paris formula to describe the crease propagation rate. As shown in the following formula:

[0086]

[0087] In the formula, a is the crease length, N is the number of stress cycles; C and m are material constants, and environmental factors such as temperature, humidity, medium, and loading frequency are implicit in the constants C and m, whose specific values ​​are obtained by fitting experimental data. ΔK is the stress intensity factor amplitude. The expression for ΔK is as follows:

[0088]

[0089] In the formula, f is the estimated fatigue damage of the structure under load within time t; K max K min These are the maximum and minimum values ​​of the stress intensity factor at the crease, respectively; Δσ is the stress amplitude at the crease.

[0090] According to PM cumulative damage theory, the total fatigue damage of a structure under random loading is equal to the sum of the damage caused by each stress cycle in the random stress response, regardless of the order in which the stress cycles occur. The fatigue damage estimate f of the structure under random loading within time t is defined as...

[0091]

[0092] In the formula, S rThe stress range is represented by the value obtained through the acoustic vibration stepping experiment in step 3-2, specifically the interval formed by the maximum and minimum stress values ​​in the experiment; P(·) is the stress range probability density function.

[0093] N f The stress range S r The number of cycles at which the structure fails; F p This represents the expected number of stress peak occurrences per unit time. When the structural fatigue damage amount f = 1, the structure can be considered to have failed.

[0094] As shown by the Paris formula, the stress intensity factor amplitude ΔK is the driving factor in fatigue crease propagation; ΔK is the core of the Paris formula, and calculating ΔK is the basis for predicting the fatigue life of the specimen. This embodiment introduces the temperature fatigue factor K. T The lifetime prediction calculation is expressed as follows:

[0095]

[0096] Where n, p, and q are empirical constants obtained by fitting experimental data; R is the stress ratio, which is the ratio of the maximum stress to the minimum stress of the diaphragm in the acoustic vibration stepping test; ΔK th It is the critical stress at which the diaphragm begins to show creases and expand in step three; K T It is a temperature-dependent fatigue factor.

[0097] Based on the crack propagation principle, the service life is predicted and calculated using a formula. Integrating the formula yields the fatigue life of the diaphragm valve core, where a1 is the critical crease length at which the diaphragm is about to rupture, as shown in the formula below:

[0098]

Claims

1. A method for accelerating the service life testing of a polymer diaphragm valve core, characterized in that: Includes the following steps: Step 1: Install the diaphragm valve core to be tested into the pressure vessel; One side of the diaphragm valve core under test and the inner wall of the pressure vessel together form a filling chamber with an inlet and an outlet; ultrasonic generators are installed at intervals on the other side of the diaphragm valve core under test. Step 2: Temperature step test; Step 2-1. Set the initial temperature value, basic acceleration, temperature test duration, temperature step size, and temperature dwell time; Step 2-2. Introduce liquid medium into the filling chamber; release ultrasonic waves from the ultrasonic generator to drive the tested diaphragm valve core to vibrate non-contactly; the acceleration of the ultrasonic generator is the basic acceleration set in Step 2-1; the temperature of the liquid medium introduced into the filling chamber is the initial temperature value, and is gradually increased according to the temperature step and temperature dwell time. Step 2-3. After the preset temperature test duration, observe whether the diaphragm valve core is damaged; if it is damaged, use the current temperature step as the critical temperature step; if the diaphragm valve core is not damaged, increase the temperature step, replace the diaphragm valve core, and repeat step 2-2 until the diaphragm valve core is damaged. Steps 2-4. Calculate the accelerating temperature stress. ;in, This refers to the diaphragm cross-sectional area of ​​the diaphragm valve core. Steps 2-5. Calculate the temperature-dependent fatigue factor. Where A and c are preset coefficients; Step 3: Acoustic vibration step test; Step 3-1. Set the base temperature value, initial acceleration, acceleration step size, and acceleration dwell time; Step 3-2. Introduce a liquid medium into the filling chamber; the ultrasonic generator releases ultrasonic waves to non-contactly drive the tested diaphragm valve core to vibrate; the temperature of the liquid medium introduced into the filling chamber is the base temperature value; the acceleration of the ultrasonic generator is the initial acceleration set in step 2-1, and is gradually increased according to the acceleration step size and acceleration dwell time; infrared images of the diaphragm valve core are continuously acquired by an infrared detector to obtain the crease length a on the diaphragm at different stress cycle numbers N; at the same time, the diaphragm stress and strain of the tested diaphragm valve core are acquired by a strain gauge. Step 4: Predict the service life of the polymer diaphragm valve core. s as follows: Where C, n, p, and q are all fitted parameters; f is the fatigue damage estimate; R is the stress ratio; ΔK is the stress intensity factor amplitude; ΔK th It is the critical stress when the diaphragm begins to show creases in step three; a1 is the crease length when the tested diaphragm valve core breaks; The expression for the fatigue damage estimate f is: Among them, S r Represents the stress range; P(·) is the stress range probability density function; F p This represents the expected number of times the stress peak occurs per unit time. For time; N f The stress range S r The number of cycles in which the structure fails; The expression for the stress intensity factor amplitude ΔK is: Where Δσ is the stress amplitude at the crease.

2. The method for accelerating the service life testing of a polymer diaphragm valve core according to claim 1, characterized in that: The temperature dwell time is 10 min to 15 min; the temperature step size is 10 °C; the base acceleration is 5 GRMS; and the acceleration step size is 5 GRMS to 15 GRMS.

3. The method for accelerating the service life testing of a polymer diaphragm valve core according to claim 1, characterized in that: In step two, the accelerating temperature stress v is calculated. T The critical temperature step used at that time The average value of the critical temperature step obtained from multiple experiments is taken.

4. The method for accelerating the service life testing of a polymer diaphragm valve core according to claim 1, characterized in that: In step two, the final temperature-dependent fatigue factor K T The final temperature-dependent fatigue factor K is obtained by assigning values ​​to the calculated values ​​of the temperature-dependent fatigue factor. T Take the value that is closest to the temperature-induced fatigue factor among 50%, 63.2%, and 10%.

5. A device for accelerating the service life testing of a polymer diaphragm valve core, characterized in that: The device is used to perform the accelerated service life testing method for a polymer diaphragm valve core as described in claim 1. The device includes a testing module, a stress detection module, and a fluid circulation module. The testing module includes a specimen clamping vibration module (4). The specimen clamping vibration module (4) includes a sound wave generating component and a pressure vessel. The pressure vessel is used to clamp the diaphragm valve core under test. The sound wave generating component is aligned with the position of the diaphragm valve core under test installed on the pressure vessel. When the diaphragm valve core under test is installed in the pressure vessel, a filling chamber for simulating the working environment of the diaphragm valve core is formed inside the pressure vessel, and the sound wave generating component is aligned with the diaphragm valve core under test, so that the sound wave generating component can drive the diaphragm valve core under test to reciprocate. An infrared detector (408) is installed inside the pressure vessel. The infrared detector (408) is used to detect the temperature distribution on the diaphragm valve core. The fluid circulation module is used to drive the liquid medium through the filling chamber in the pressure vessel during the testing process to simulate the working environment of the diaphragm valve core.

6. The device for accelerating the service life testing of a polymer diaphragm valve core according to claim 5, characterized in that: The pressure vessel includes a cylinder (401), a fixed sleeve (402), a lower sealing ring (411), and an upper sealing ring (412); the cylinder (401) is fixed inside the temperature chamber (6); the inner circumferential surface of the fixed sleeve (402) is connected to the outer circumferential surface of the cylinder (401) by a thread; a clamping flange is provided at the end of the inner circumferential surface of the fixed sleeve (402); the clamping flange of the fixed sleeve (402) is aligned with the end of the cylinder (401); an upper sealing ring (412) and a lower sealing ring (411) are provided between the clamping flange of the fixed sleeve (402) and the end of the cylinder (401); during the testing process, the edge of the diaphragm valve core is clamped between the upper sealing ring (412) and the lower sealing ring (411); The side wall of the cylinder (401) is provided with an inlet and an outlet.

7. The device for accelerating the service life testing of a polymer diaphragm valve core according to claim 5, characterized in that: The specimen clamping vibration module (4) further includes a vibration guiding component; the vibration guiding component includes a support base (403), a guide cylinder (404), and a constant pressure spring (405); the support base (403) is fixed inside the cylinder (401); The guide cylinder (404) is sleeved on the support base (403) and forms a sliding pair; the constant pressure spring (405) is set inside the guide cylinder (404) and its two ends abut against the support base (403) and the guide cylinder (404) respectively; the top center of the guide cylinder (404) is provided with an internal thread structure that matches the external thread on the diaphragm valve core.

8. The device for accelerating the service life testing of a polymer diaphragm valve core according to claim 5, characterized in that: The acoustic wave generating assembly includes an acoustic wave generator (406) and an acoustic wave probe (407); the acoustic wave probe (407) is installed at the bottom of the acoustic wave generator (406); during the detection process, the acoustic wave probe (407) is aligned with the diaphragm valve core under test and is spaced apart; the infrared detector (408) is in the shape of a ring and surrounds the acoustic wave probe (407).

9. The device for accelerating the service life testing of a polymer diaphragm valve core according to claim 5, characterized in that: The fluid circulation module includes a valve body assembly (1), a fluid storage tank (2), and a fluid delivery device (3); the fluid storage tank (2) is installed on the upper side of the fluid delivery device (3); the fluid delivery device (3) is installed on the work cabinet; the valve body assembly (1) includes a third check valve (101), a first differential pressure reducing valve (102), a third differential pressure reducing valve (103), a second differential pressure reducing valve (104), a first check valve (105), and a second check valve (106); the output port of the fluid storage tank (2) is connected to the input port of the fluid delivery device (3); the output port of the fluid delivery device (3) is connected to the first differential pressure reducing valve (102) and the second differential pressure reducing valve (106). The input port of (104) is connected; the output port of the first differential pressure reducing valve (102) is connected to the input port of the first check valve (105); the output port of the second differential pressure reducing valve (104) is connected to the input port of the second check valve (106); the output ports of the first check valve (105) and the second check valve (106) are both connected to the inlet of the cylinder (401) in the pressure vessel; the outlet of the cylinder (401) in the pressure vessel is connected to the input port of the third differential pressure reducing valve (103); the output port of the third differential pressure reducing valve (103) is connected to the input port of the third check valve (101); the output port of the third check valve (101) is connected to the input port of the fluid storage tank (2).

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