Artificial valve leaflet fatigue life evaluation method, system, equipment and medium

Abstract

The invention provides an artificial valve leaflet fatigue life evaluation method, system and device and a medium. The method comprises the steps that stress load spectrums borne by artificial valve leaflet surface fatigue failure risk points in a plurality of cardiac cycles are obtained; obtaining the number of load sequence segments of the stressed load spectrum of any cardiac cycle after the trend of the borne load tends to be stable, and the alternating stress, the average stress and the cycle number of each segment of load sequence; calculating the fatigue failure cycle index of the corresponding artificial valve leaflet material standard sample piece under each section of load sequence; calculating the ratio of the cycle number to the fatigue failure cycle number under each section of load sequence to calculate the fatigue damage under the section of load sequence; and obtaining the sum of the fatigue damages under all the load sequences, and obtaining the reciprocal of the fatigue damages as the expected fatigue life. The method has the advantages of being short in time consumption, low in cost, low in difficulty, high in accuracy, high in precision and few in limitation.

Description

Technical Field

[0001] The present invention belongs to the technical field of artificial valve leaflets, and specifically relates to an artificial valve leaflet fatigue life evaluation method, system, equipment and medium. Background Art

[0002] Valves and leaflets play a vital role in the human circulatory system. When a valve is diseased, minimally invasive interventional surgery becomes an effective, safe and less sequelae treatment method. Through this surgery, a prosthetic valve can be implanted to replace and substitute the diseased valve. The artificial leaflets of these prosthetic valves are usually made of animal pericardium or polymer materials. Although they have excellent performance, they have a certain fatigue limit life. According to FDA regulations, the fatigue life of artificial leaflets should be higher than 200 million times, which is approximately equivalent to a service life of ten years, thereby ensuring that patients can benefit long-term after surgery.

[0003] At present, the evaluation of the overall fatigue life of prosthetic valves is completed through in vitro accelerated fatigue testing (the leaflets open and close 10 times or more per second). This experiment can obtain the overall fatigue life of the valve under ideal working conditions and evaluate whether the valve as a whole meets regulatory standards. However, it has the following problems. For example, it takes a 6-12 month test cycle to complete 200 million fatigue tests; valve fatigue testing equipment is expensive, and the cost of accelerated fatigue testing consumables is high; fatigue testing requires professionals to debug instruments, install prosthetic valve samples, and collect data manually, which makes it difficult; it is a fatigue test of the prosthetic valve as a whole, and it cannot accurately evaluate the fatigue life of the artificial leaflets, resulting in low accuracy; the fatigue test observes whether the leaflets are damaged by the naked eye, but in the experiment, the cracks generated when the leaflets reach the fatigue limit are extremely small and cannot be detected by the naked eye. When the naked eye detects significant cracks, the number of leaflet openings and closings has far exceeded the fatigue limit. At the same time, there is a situation where the leaflet cracks are not detected in time, resulting in low accuracy; the fatigue test is an evaluation of the fatigue life of the artificial leaflets based on the idealized working conditions of the fatigue tester. The working conditions of prosthetic valves after implantation in the human body are very different from the ideal working conditions, and the physiological and anatomical structures of different patients are also completely different. According to the knowledge of fatigue mechanics, the fatigue life of artificial valve leaflets is related to their structure and morphology. Therefore, although the prosthetic valves and artificial valve leaflets meet the regulatory requirements under ideal working conditions through accelerated fatigue testing, due to different working conditions, there are clinical cases where the valve leaflets in the patient's body are damaged before reaching their fatigue life, resulting in many testing restrictions. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a method, system, equipment and medium for evaluating the fatigue life of artificial valve leaflets, so as to reduce the time, cost and difficulty required for evaluating the fatigue life of artificial valve leaflets, reduce the limitations of evaluating the fatigue life of artificial valve leaflets, and improve the accuracy and precision of evaluating the fatigue life of artificial valve leaflets.

[0005] To achieve the above-mentioned and other related purposes, the present invention provides a method for evaluating the fatigue life of an artificial valve leaflet, which is characterized by comprising:

[0006] Obtain the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial valve leaflet;

[0007] The minimum value of the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial valve leaflet is the fatigue life of the artificial valve leaflet;

[0008] The steps for obtaining the expected fatigue life corresponding to each fatigue failure risk point include:

[0009] Obtain the stress load spectrum of the fatigue failure risk point on the artificial valve leaflet surface during several cardiac cycles;

[0010] Obtain the stress load spectrum of any cardiac cycle after the load trend in several cardiac cycles tends to be stable, and obtain the number of load sequence segments, the alternating stress of each load sequence segment, the average stress of each load sequence segment, and the number of cycles of each load sequence segment of the stress load spectrum;

[0011] Calculate and obtain the number of fatigue failure cycles of the standard sample of artificial valve leaflet material corresponding to each load sequence;

[0012] Calculate the ratio of the number of cycles under each load sequence to the number of fatigue failure cycles to obtain the fatigue damage under the load sequence;

[0013] Obtain the sum of fatigue damage under all load sequences, and obtain its inverse as the expected fatigue life.

[0014] In one embodiment of the present invention, the step of obtaining the stress load spectrum of any cardiac cycle after the load trend in several cardiac cycles tends to be stable, and obtaining the number of load sequence segments of the stress load spectrum, the alternating stress of each load sequence, the average stress of each load sequence, and the number of cycles of each load sequence includes:

[0015] Obtaining the stress load spectrum of any cardiac cycle after the load trend in several cardiac cycles tends to be stable, and obtaining the load sequence segment number of the stress load spectrum;

[0016] Obtain the minimum and maximum stresses in each load sequence;

[0017] The alternating stress and the average stress under each load sequence are calculated according to the minimum stress and the maximum stress.

[0018] In one embodiment of the present invention, the alternating stress is half of the difference between the maximum stress and the minimum stress; and the average stress is half of the sum of the maximum stress and the minimum stress.

[0019] In one embodiment of the present invention, the step of calculating and obtaining the number of fatigue failure cycles of the standard sample of the artificial valve leaflet material corresponding to each load sequence includes:

[0020] When the load of the load sequence is a non-pulsating cyclic load and an asymmetric cyclic load, the load of this section of the load sequence is corrected, and the fatigue strength of the artificial valve leaflet material at the fatigue failure risk point is calculated based on the correction result;

[0021] When the load of the load sequence is a pulsating cyclic load or a symmetrical cyclic load, the alternating stress of the load sequence is the fatigue strength of the artificial valve leaflet material at the fatigue failure risk point;

[0022] The number of fatigue failure cycles is obtained by calculation according to a relationship between the fatigue strength and the number of fatigue failure cycles.

[0023] In one embodiment of the present invention, when the load of the load sequence is a non-pulsating cyclic load and an asymmetric cyclic load, the load of the load sequence is corrected by the Goodman equation or the Morrow equation.

[0024] Its Goodman equation is:

[0025] Among them, S a is the alternating stress of each load sequence; S m is the average stress of each load sequence; S Nf is the fatigue strength of the artificial valve leaflet material; S u is the nominal ultimate tensile strength of the artificial valve leaflet material.

[0026] In one embodiment of the present invention, when the load of the load sequence is a non-pulsating cyclic load and an asymmetric cyclic load, the load of the load sequence is corrected by the Morrow equation, and the Morrow equation is:

[0027] Among them, S a is the alternating stress of each load sequence; S m is the average stress of each load sequence; S Nf is the fatigue strength of the artificial valve leaflet material; σ f It is the true ultimate tensile strength of the artificial valve leaflet material.

[0028] In one embodiment of the present invention, when the load of the load sequence is a non-pulsating cyclic load and an asymmetric cyclic load, the load of the load sequence is corrected by the Gerber equation, and the Gerber equation is: S a is the alternating stress of each load sequence; S m is the average stress of each load sequence; S Nf is the fatigue strength of the artificial valve leaflet material; S u is the nominal ultimate tensile strength of the artificial valve leaflet material.

[0029] The present invention also provides an artificial valve leaflet fatigue life evaluation system, which is characterized by comprising:

[0030] An expected fatigue life acquisition module is used to obtain the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial valve leaflet;

[0031] A fatigue life acquisition module is used to obtain the minimum value of the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial valve leaflet, which is the fatigue life of the artificial valve leaflet;

[0032] The expected fatigue life acquisition module includes:

[0033] A stress load spectrum acquisition unit, used to acquire the stress load spectrum of the artificial valve leaflet surface fatigue failure risk point in a number of cardiac cycles;

[0034] A stress load spectrum processing unit is used to obtain the stress load spectrum of any cardiac cycle after the load trend in several cardiac cycles tends to be stable, and obtain the number of load sequence sections of the stress load spectrum, the alternating stress of each load sequence section, the average stress of each load sequence section and the number of cycles of each load sequence section;

[0035] A fatigue failure cycle number calculation unit is used to calculate the fatigue failure cycle number of the artificial valve leaflet material standard sample corresponding to each load sequence;

[0036] The expected fatigue life calculation unit is used to calculate the ratio of the number of cycles under each load sequence to the number of fatigue failure cycles to obtain the fatigue damage under the load sequence; and obtain the sum of the fatigue damage under all load sequences, and obtain its reciprocal as the expected fatigue life.

[0037] The present invention also proposes an electronic device, comprising a processor, a memory and a communication bus; the communication bus is used to connect the processor and the memory; the processor is used to execute a computer program stored in the memory to implement the artificial valve leaflet fatigue life evaluation method as described in any one of the above embodiments.

[0038] The present invention further proposes a computer-readable storage medium having a computer program stored thereon, wherein the computer program is used to enable a computer to execute the artificial valve leaflet fatigue life evaluation method as described in any one of the above embodiments.

[0039] The present invention proposes a method, system, device and medium for evaluating the fatigue life of an artificial valve leaflet, which calculates the fatigue life of typical fatigue failure risk points on the surface of the artificial valve leaflet. During the calculation process, the stress load spectrum of the artificial valve leaflet in the last cardiac cycle among several cardiac cycles is used to obtain the number of load sequence segments of the stress load spectrum, the alternating stress of each load sequence, the average stress of each load sequence and the number of cycles of each load sequence, so as to obtain the fatigue life under each load sequence and accumulate the expected fatigue life. The method has the following advantages: short time consumption, and the fatigue evaluation calculation of the artificial valve leaflet under ideal conditions only takes about 1-10 hours; the fatigue evaluation calculation time of the artificial valve leaflet under extremely complex patient individual conditions is less than 5 days; low cost There is no need to purchase expensive fatigue testing equipment or testing consumables. The fatigue life of artificial valve leaflets can be obtained through virtual valve leaflet simulation technology and evaluation algorithm technology. The difficulty is low. The artificial valve leaflet fatigue evaluation and calculation equipment is simple to debug. It can automatically collect valve leaflet stress, strain and other data, and automatically calculate the fatigue life results of artificial valve leaflets without installing artificial valve leaflet samples. The accuracy is high. The influence of metal stents, skirts and sutures can be excluded. Only the fatigue life of artificial valve leaflets is evaluated and calculated. The precision is high. The evaluation and calculation of the fatigue life of artificial valve leaflets (the number of times the artificial valve leaflets are opened and closed) can be accurate to single digits. There are few restrictions. The fatigue life of artificial valve leaflets under any working conditions can be evaluated and calculated, including the same ideal working conditions as the fatigue tester and the actual complex implantation conditions of different patients. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0041] Figure 1 The figure is a flow chart of a method for evaluating fatigue life of an artificial valve leaflet in one embodiment of the present invention.

[0042] Figure 2 The figure is a schematic diagram of a process for calculating fatigue life of any fatigue failure risk point in one embodiment of the present invention.

[0043] Figure 3A schematic diagram of obtaining the stress load spectrum of the integral points on the surface of the artificial valve leaflet during 5 cardiac cycles in one embodiment of the present invention.

[0044] Figure 4 The figure is a schematic diagram of extracting the stress load spectrum of the last cardiac cycle in one embodiment of the present invention.

[0045] Figure 5 FIG. 4 is a schematic diagram of a simplified stress load spectrum of the last cardiac cycle in one embodiment of the present invention.

[0046] Figure 6 The present invention is a structural block diagram of an artificial valve leaflet fatigue life evaluation system in one embodiment.

[0047] Figure 7 The present invention is a structural block diagram of an artificial valve leaflet fatigue life evaluation calculation device in one embodiment. DETAILED DESCRIPTION

[0048] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0049] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner. Therefore, the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0050] See also Figure 1 As shown, in this embodiment, the present invention proposes a method, system, device and medium for evaluating the fatigue life of artificial valve leaflets, so as to reduce the time, cost and difficulty required for evaluating the fatigue life of artificial valve leaflets, reduce the limitations of evaluating the fatigue life of artificial valve leaflets, and improve the accuracy and precision of evaluating the fatigue life of artificial valve leaflets. Specifically, the method for evaluating the fatigue life of artificial valve leaflets includes:

[0051] S1. Obtaining the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial valve leaflet;

[0052] S2. The minimum value of the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial valve leaflet is obtained, which is the fatigue life of the artificial valve leaflet.

[0053] For details, please refer to Figure 2As shown, in this embodiment, the step of obtaining the expected fatigue life corresponding to a fatigue failure risk point on the surface of the artificial valve leaflet includes:

[0054] S11. Obtain the stress load spectrum of the artificial valve leaflet surface fatigue failure risk point during several cardiac cycles; for example, the stress load spectrum of the artificial valve leaflet surface fatigue failure risk point during several cardiac cycles can be obtained by bidirectional fluid-solid coupling finite element simulation.

[0055] It is understandable that in each cardiac cycle, the artificial valve leaflet completes a cyclical movement of opening and closing due to the flow field force, but in one movement cycle, any point on the surface of the artificial valve leaflet is subjected to several changing stress loads. All the stress loads on the artificial valve leaflet in one movement cycle are the stress load spectrum of this point. Figure 3 As shown in the figure, the stress load spectrum of any point on the surface of the artificial valve leaflet within 5 cardiac cycles is obtained. Since the multi-field coupling calculation is affected by the calculation value error generated when it is first started, the stress load spectrum of this point in the 1st to 2nd cardiac cycles has no periodic pattern, but the calculation error is gradually eliminated in the 3rd to 5th cardiac cycles, the fluid dynamics representation of each cardiac cycle tends to be consistent, and the stress load spectrum shows a periodic pattern.

[0056] S12, obtaining a stress load spectrum of any cardiac cycle after the load trend in several cardiac cycles tends to be stable, and obtaining the number of load sequence segments, the alternating stress of each load sequence segment, the average stress of each load sequence segment, and the number of cycles of each load sequence segment of the stress load spectrum;

[0057] It is understandable that the rain flow counting method can be used to extract all sub-cycles in the load spectrum and record the number n of identical sub-cycles. The rain flow counting method refers to rotating the stress-time history data record of the stress load spectrum by 90°, with the time coordinate axis pointing vertically downward. The data record is like a series of roofs, and rainwater flows down along the roofs, so it is called the rain flow counting method. The main function of the rain flow counting method is to simplify the measured load history into several load cycles for fatigue life estimation and preparation of fatigue test load spectra. It is based on the dual parameter method, taking into account the two variables of dynamic strength (amplitude) and static strength (mean), which conforms to the inherent characteristics of the fatigue load itself. Its basic counting principle is:

[0058] The rain flow flows down along the slope from the inner side of the peak position of the load time history;

[0059] The rain flow starts from a certain peak point and stops flowing when it encounters a peak value larger than its initial peak value.

[0060] When the rain stream meets the rain stream flowing down from above, it must stop flowing;

[0061] Take out all the full cycles and write down the amplitude of each cycle;

[0062] The divergent-convergent load time history remaining after the first stage counting is equivalent to a convergent-divergent load time history, and the second stage rain flow counting is performed. The total number of counting cycles is equal to the sum of the counting cycles of the two counting stages.

[0063] In this embodiment, since the calculation error in the 3-5 cardiac cycles is gradually eliminated, the fluid dynamics of each cardiac cycle tends to be consistent, and the stress load spectrum shows a periodic law. Therefore, the stress load spectrum of the last (5th) cardiac cycle of this point can be extracted. For the last cardiac cycle, please refer to Figure 4 As shown in the figure, the number of load sequence segments of the stress load spectrum and the alternating stress S of each load sequence are obtained by the rain flow counting method. a / Mpa, average stress S for each load sequence m / Mpa and the number of cycles n of each load sequence. Of course, if the number of cardiac cycles calculated by multi-field coupling is greater (for example, calculated up to the 10th cardiac cycle), the stress load spectrum of the points within the 10th cardiac cycle should be extracted.

[0064] It is understandable that in order to reduce the amount of rainflow counting calculations, the stress load spectrum can also be simplified, see Figure 5 As shown, Figure 5 Yes Figure 4 The stress load spectrum of the last cardiac cycle is simplified by considering the similar peak values ​​in the load spectrum as equal and taking them as the average value, thereby simplifying the load spectrum and reducing the amount of calculation.

[0065] In this embodiment, the step of obtaining the number of load sequence segments of the stress load spectrum, the alternating stress of each load sequence, the average stress of each load sequence, and the number of cycles of each load sequence according to the stress load spectrum of the last cardiac cycle in the stress load spectrum of n cardiac cycles includes:

[0066] S121, obtaining a stress load spectrum of any cardiac cycle after the load trend in several cardiac cycles tends to be stable, and obtaining the load sequence segment number of the stress load spectrum;

[0067] S122. Obtain the minimum stress S in each load sequence min / Mpa and maximum stress S max / Mpa;

[0068] S123, calculating the alternating stress and average stress under each load sequence according to the minimum stress and the maximum stress. a is the maximum stress S maxand the minimum stress S min The average stress S m is the maximum stress S max With minimum stress S min One half of the sum.

[0069] According to the rain flow counting method, Figure 5 The stress load spectrum of this point has 8 load orders, each of which has a minimum stress S min / Mpa and maximum stress S max / Mpa, then according to the formula The alternating stress S of each load sequence a / Mpa, according to the formula Calculate the mean stress S for each load sequence m / Mpa, the cycle number n in each load sequence can be obtained by counting the total cycle number of the force value. In this embodiment, the cycle numbers of the 8 load sequences are respectively recorded as n1, n2, ....., n8.

[0070] S13, calculating and obtaining the number of fatigue failure cycles of the standard sample of the artificial valve leaflet material corresponding to each load sequence; in this embodiment, the step of calculating and obtaining the number of fatigue failure cycles of the standard sample of the artificial valve leaflet material corresponding to each load sequence includes:

[0071] When the load of the load sequence is a non-pulsating cyclic load and an asymmetric cyclic load, the load of this section of the load sequence is corrected, and the fatigue strength of the artificial valve leaflet material at the fatigue failure risk point is calculated based on the correction result;

[0072] The number of fatigue failure cycles is obtained by calculation according to a relationship between the fatigue strength and the number of fatigue failure cycles.

[0073] In this embodiment, when the fatigue SN curve of the material describes the number of symmetrical cycles required for fatigue failure of the material at different stress levels, the load of the load sequence of the asymmetric cycle can be corrected by using the Goodman equation, or the load of the load sequence of the asymmetric cycle can be corrected by using the Morrow equation.

[0074] Its Goodman equation is:

[0075] Among them, S u It is the nominal ultimate tensile strength of the artificial valve leaflet material, which is an inherent material constant and can be obtained through mechanical experiments on artificial valve leaflet materials.

[0076] Its Morrow equation is:

[0077] Among them, σ f It is the true ultimate tensile strength of the artificial valve leaflet material and is an inherent material constant.

[0078] In another embodiment, when the fatigue SN curve of the material describes the number of pulsating cycles required for fatigue failure of the material at different stress levels, the Gerber equation is preferably used to correct all load cycles in the load sequence to pulsating cycles in a unified load form, and the correction equation is:

[0079] At this time, S Nf That is the fatigue strength of the material under a complete pulsation cycle.

[0080] In this embodiment, when the working time of the artificial valve leaflet exceeds 10 years, the number of cyclic movements is expected to exceed 10 to the 8th power, which is ultra-high cycle fatigue. Therefore, the fatigue strength and the number of fatigue failure cycles have the following relationship:

[0081] S Nf =σ' f (2N f1 ) b , where S Nf The artificial valve leaflet material is completely symmetrical and under 2N f1 Fatigue strength under 2N f1 N f1 Refers to the number of half cycles of fatigue failure of artificial valve leaflet materials under full symmetrical cyclic tension. A full cycle refers to the number of complete cycles of the material from maximum stress to minimum stress and then back to maximum stress, while a half cycle refers to the number of unidirectional stress changes from maximum stress to minimum stress (or vice versa). In this case, two half cycles are the number of full cycles. 2N f1 is an inherent material constant and can be obtained from the fatigue life curve of the artificial valve leaflet material. σ' f is the single fatigue strength coefficient of the artificial valve leaflet material, which is an inherent material constant and can be obtained through the fatigue life curve of the artificial valve leaflet material. b is the fatigue life index, which is an inherent material constant and is used to describe the relationship between fatigue life and stress level, that is, the slope of the fatigue life curve, which can be obtained through the fatigue life curve of the artificial valve leaflet material. It can be understood that the fatigue life index b is preferably the slope k of the high cycle fatigue segment of the asquin type SN curve.

[0082] In this embodiment, the fatigue life curve of the artificial valve leaflet material can be obtained first, the fatigue life index can be obtained based on the fatigue life curve, and the corresponding correction equation described in the above embodiment can be selected according to the method of obtaining the fatigue life curve.

[0083] In this embodiment, according to the Goodman correction equation and the above formula S Nf =σ' f (2N f1 ) b Taking the example as an example, the fatigue failure cycle number can be calculated.

[0084] It can be understood that since the inverse of the number of fatigue failures of the standard sample material is fatigue damage, in this embodiment, when the load of the load sequence is a non-pulsating cyclic load and an asymmetric cyclic load, it is necessary to correct the load of this load sequence, and use the corrected fatigue strength to obtain the number of fatigue failures of the standard sample material of the artificial valve leaflet corresponding to the artificial valve leaflet material, thereby calculating its fatigue damage.

[0085] Of course, in some other embodiments, if the fatigue life curve used is obtained based on a full cycle tensile test, S Nf =σ' f (2N f1 ) b Change to S Nf =σ' f (N f2 ) b , at this time N f2 It refers to the number of full cycles of fatigue failure of artificial valve leaflet materials under fully symmetrical cyclic stretching;

[0086] When the load of the load sequence is a pulsating cyclic load or a symmetrical cyclic load, the alternating stress S of the load sequence is a It is the fatigue strength S of the artificial valve leaflet material at the fatigue failure risk point. Nf ,at this time,

[0087] S14, calculating the ratio of the number of cycles under each load sequence to the number of cycles to fatigue failure to obtain the fatigue damage under the load sequence; specifically, the number of cycles under each load sequence n and the number of cycles to fatigue failure N f Ratio That is the fatigue damage under this load sequence.

[0088] S15. Obtain the sum of fatigue damage under all load sequences, and obtain its reciprocal as the expected fatigue life. It can be understood that when the total cumulative damage is equal to 1, it is considered that the material has reached its fatigue life, so the expected fatigue life L can be deduced to be Where N fi is the number of fatigue failure cycles under the i-th load sequence, n i Number of cycles for the i-th load sequence.

[0089] It is understandable that, according to the knowledge of material mechanics and fracture mechanics, the point with a larger maximum stress value is a fatigue failure risk point, that is, the fatigue life of this point is poor and it is more prone to tearing and breakage. Therefore, preferably, the selected point should be a point with a larger maximum stress value, and the stress concentration area is a high-risk area for fatigue failure. The fatigue life of the material at the maximum stress integral point is the total life of the artificial valve leaf as a whole, and the load spectrum of the integral point where the maximum stress appears on the surface of the artificial valve leaf in a complete cardiac cycle can be extracted. Of course, except for the point with a large maximum stress value, any other point of concern can be used as a stress load spectrum extraction point.

[0090] It should be understood that the order of execution of the steps in the above embodiment does not necessarily mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention.

[0091] See also Figure 6 As shown, the present invention provides a system for evaluating the fatigue life of an artificial valve leaflet, and the system for evaluating the fatigue life of an artificial valve leaflet corresponds to the method for evaluating the fatigue life of an artificial valve leaflet in the above-mentioned embodiment. Figure 6 This is a structural block diagram of an artificial valve leaflet fatigue life evaluation system proposed by the present invention. The artificial valve leaflet fatigue life evaluation system 100 includes an expected fatigue life acquisition module 10 and a fatigue life acquisition module 20. The functional modules are described in detail as follows:

[0092] The expected fatigue life acquisition module 10 is used to acquire the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial valve leaflet;

[0093] The fatigue life acquisition module 20 acquires the minimum value of the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial valve leaflet, which is the fatigue life of the artificial valve leaflet;

[0094] The expected fatigue life acquisition module 10 includes a stress load spectrum acquisition unit 11, a stress load spectrum processing unit 12, a fatigue failure cycle number calculation unit 13 and an expected fatigue life calculation unit 14. The detailed description of each functional module is as follows:

[0095] The stress load spectrum acquisition unit 11 is used to acquire the stress load spectrum of the artificial valve leaflet surface fatigue failure risk point in a number of cardiac cycles;

[0096] The stress load spectrum processing unit 12 is used to obtain the stress load spectrum of any cardiac cycle after the load trend in several cardiac cycles tends to be stable, and obtain the number of load sequence sections of the stress load spectrum, the alternating stress of each load sequence, the average stress of each load sequence and the number of cycles of each load sequence;

[0097] The fatigue failure cycle number calculation unit 13 is used to calculate the fatigue failure cycle number of the artificial valve leaflet material standard sample corresponding to each load sequence;

[0098] The expected fatigue life calculation unit 14 is used to calculate the fatigue damage under each load sequence according to the number of fatigue failure cycles and the number of cycles under each load sequence; and to obtain the sum of the fatigue damage under all load sequences, and obtain its reciprocal as the expected fatigue life.

[0099] For the specific limitations of the artificial valve leaflet fatigue life evaluation system, please refer to the limitations of the artificial valve leaflet fatigue life evaluation method above, which will not be repeated here. Each module in the above-mentioned artificial valve leaflet fatigue life evaluation system can be implemented in whole or in part through software, hardware and a combination thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

[0100] See also Figure 7 As shown, the present invention also proposes an artificial valve leaflet fatigue life evaluation calculation device, which can evaluate and calculate the service life of the artificial valve leaflets of a prosthetic valve that needs to undergo long-term in vitro fatigue testing, or evaluate and calculate the service life of the artificial valve leaflets of a prosthetic valve implanted in the body through the input of prosthetic valve product data, in vitro experimental data and clinical data. Specifically, a data intersection module 101, a three-dimensional modeling module 102, a virtual experiment & virtual surgery module 103, a multi-field coupling calculation module 104, a fatigue life evaluation module 105 and a human-computer interaction module 106. The functional modules are described in detail as follows:

[0101] The data exchange module 101 is used to collect and store prosthetic valve product data, in vitro experimental data and clinical data, and transmit these data to the three-dimensional modeling module 102 and the human-computer interaction module 106 .

[0102] Prosthetic valves usually consist of a metal stent, artificial valve leaflets and skirts. Metal stents are mostly made of metals such as cobalt-chromium alloys and nickel-titanium alloys. Artificial valve leaflets can be made of biological tissues such as pig pericardium and bovine pericardium or polymer materials such as expanded polytetrafluoroethylene and polyethylene terephthalate, imitating the original valve leaflets of the human body. The skirts are mostly made of polymer materials such as expanded polytetrafluoroethylene and polyethylene terephthalate, which play a sealing role.

[0103] The valve product data of the present invention includes the size and structure parameters of the metal stent, artificial valve leaflet and skirt (such as the diameter of the metal stent, the height of the artificial valve leaflet, etc.) and material parameters (such as the elastic modulus of the metal stent material, the fatigue life curve of the artificial valve leaflet material, etc.). The above data can be input into the product parameters according to the actual situation of the structural style of the prosthetic valve actually used to ensure the integrity of these size and structure parameters and material parameters.

[0104] In the in vitro bionic circulation test of the prosthetic valve, the prosthetic valve is loaded and fixed in a containing structure. The liquid flows in from the inlet end and then flows out from the outlet end to simulate the flow of blood in the body, causing the artificial valve leaflets to open and close.

[0105] The in vitro experimental data described in the present invention refers to the internal space size parameters of the prosthetic valve, the liquid pressure parameters applied at the inflow end, and the liquid parameters applied at the outflow end in the in vitro bionic circulation test of the prosthetic valve. The size parameters of the containment structure are used to clarify the area where the liquid can flow in the experiment, and the pressure parameters at both ends are used as the load input for the subsequent multi-field coupling calculation. It is understandable that if other structural experimental instruments are used, the size parameters of the containment structure should be input according to the actual situation to ensure the integrity of these size structures.

[0106] In vitro experimental data may also include experimental result data, such as liquid flow rate, liquid pressure, etc., which can be used as a comparison and verification of the subsequent multi-field coupling calculation results.

[0107] The clinical data described in the present invention includes multimodal imaging data of the valvular valve, including but not limited to valve ultrasound imaging data, valve CTA imaging data, valve magnetic resonance imaging data, valve bilateral pressure, etc. The clinical data can be divided into preoperative data and postoperative data. The preoperative data can be used as parameter input for later three-dimensional model reconstruction and virtual surgery boundary conditions, and the postoperative data can be used as a comparative verification of later virtual surgery and multi-field coupling calculation results.

[0108] The clinical data described in the present invention 9 only takes the aortic valve as an example. If other valves (such as mitral valve, tricuspid valve, pulmonary valve, lower limb venous valve, etc.) are used, the multimodal imaging data of the corresponding parts should be input according to the actual situation, and it should be ensured that the three-dimensional modeling of the native valve tissue and its surrounding tissues can be completed through one influencing data.

[0109] The three-dimensional modeling module 102 uses the prosthetic valve product data, in vitro experimental data and clinical data in the data intersection module 101 to construct a three-dimensional model of a prosthetic valve, a three-dimensional flow field model of an in vitro experiment and a three-dimensional model of an individualized tissue structure, and can communicate with the human-computer interaction module 106 to provide feedback on the construction progress and results of the three-dimensional model.

[0110] Taking the preoperative aortic valve as an example, the three-dimensional modeling module 102 first constructs a three-dimensional tissue model directly based on the impact data through the impact data, but this type of model is relatively rough. Then the three-dimensional modeling module 102 performs operations such as smoothing and repairing on the rough three-dimensional model, and further refines the model into a preoperative three-dimensional model that can be used for virtual surgery and multi-field coupling calculations. At the same time, the internal space of the preoperative three-dimensional model is an individualized flow field three-dimensional model.

[0111] The virtual experiment & virtual surgery module 103 can simulate real experimental operations and real surgical operations based on the finite element algorithm, and implant the three-dimensional model of the prosthetic valve product constructed by the three-dimensional modeling module 102 into the containing structure in the in vitro experiment or the preoperative three-dimensional model according to actual experimental operations or actual surgical operations.

[0112] The three-dimensional model of the prosthetic valve product is implanted into the preoperative three-dimensional model through the same compression, intervention, release, and balloon expansion operations as the actual procedure, thereby completing the virtual surgical process and obtaining a virtual postoperative three-dimensional model (different from the postoperative three-dimensional model obtained based on the impact data in the three-dimensional modeling module 102).

[0113] The three-dimensional model of the prosthetic valve product is implanted into the containing structure in the in vitro experiment, completing the virtual experiment implantation process, thereby obtaining the virtual experiment implantation model. The virtual experiment implantation process is similar to the virtual surgery implantation process, which will not be described in detail here.

[0114] The multi-field coupling calculation module 104 is based on the computational fluid dynamics theory, adaptive grid theory, immersed boundary theory and arbitrary Lagrangian-Euler theory, and obtains a virtual experimental implantation model or a virtual surgery postoperative three-dimensional model based on the virtual experiment & virtual surgery module 103, embeds the aortic vascular constitutive equation inverted based on multimodal imaging data, the leaflet constitutive equation based on uniaxial / biaxial tensile test and Bayesian inference fitting of the Mooney-Rivlin constitutive equation, embeds the patient's left ventricle and ascending aorta dynamic pressure curve measured by Doppler ultrasound as load input, and uses the ascending aorta blood flow velocity based on 4D Flow as a verification condition, applies a bidirectional fluid-solid coupling algorithm to perform fluid dynamics reconstruction, wall and leaflet kinematics reconstruction, and constructs a blood flow-wall-valve multi-field coupling calculation model (i.e., simulating liquid flow and driving the opening and closing movement of artificial leaflets), and outputs multivariate information such as leaflet morphological parameters, leaflet mechanical function parameters, liquid ejection angle, and liquid flow trend.

[0115] The fatigue life evaluation module 105 first obtains the stress load spectrum of the fatigue failure risk point on the surface of the artificial valve leaflet based on the multivariate information such as the morphological parameters of the artificial valve leaflet, the mechanical function parameters of the valve leaflet, and the blood flow trend output by the multi-field coupling calculation module 104, and then calculates the fatigue strength of each load sequence in the stress load spectrum by the rain flow counting method and the Goodman criterion, and then calculates the fatigue life of the point by the superposition principle, and finally completes the calculation of the expected fatigue life of the artificial valve leaflet. It can be understood that the fatigue life evaluation module 105 is the same as the artificial valve leaflet fatigue life evaluation system described in the above embodiment, and corresponds to the artificial valve leaflet fatigue life evaluation method in the above embodiment.

[0116] See also Figure 1 and Figure 2 As shown, the present application also proposes an electronic device, including a processor, a memory and a communication bus; the communication bus is used to connect the processor and the memory; the processor is used to execute a computer program stored in the memory, and the processor implements the following steps when executing the computer program:

[0117] Obtain the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial valve leaflet;

[0118] The minimum value of the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial valve leaflet is the fatigue life of the artificial valve leaflet;

[0119] The steps for obtaining the expected fatigue life corresponding to each fatigue failure risk point include:

[0120] Obtain the stress load spectrum of the fatigue failure risk point on the artificial valve leaflet surface during several cardiac cycles;

[0121] Obtain the stress load spectrum of any cardiac cycle after the load trend in several cardiac cycles tends to be stable, and obtain the number of load sequence segments, the alternating stress of each load sequence segment, the average stress of each load sequence segment, and the number of cycles of each load sequence segment of the stress load spectrum;

[0122] Calculate and obtain the number of fatigue failure cycles of the standard sample of artificial valve leaflet material corresponding to each load sequence;

[0123] Calculate the ratio of the number of cycles under each load sequence to the number of fatigue failure cycles to obtain the fatigue damage under the load sequence;

[0124] Obtain the sum of fatigue damage under all load sequences, and obtain its inverse as the expected fatigue life.

[0125] See also Figure 1 and Figure 2As shown, the present invention also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the following steps are implemented:

[0126] Obtain the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial valve leaflet;

[0127] The minimum value of the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial valve leaflet is the fatigue life of the artificial valve leaflet;

[0128] The steps for obtaining the expected fatigue life corresponding to each fatigue failure risk point include:

[0129] Obtain the stress load spectrum of the fatigue failure risk point on the artificial valve leaflet surface during several cardiac cycles;

[0130] Obtain the stress load spectrum of any cardiac cycle after the load trend in several cardiac cycles tends to be stable, and obtain the number of load sequence segments, the alternating stress of each load sequence segment, the average stress of each load sequence segment, and the number of cycles of each load sequence segment of the stress load spectrum;

[0131] Calculate and obtain the number of fatigue failure cycles of the standard sample of artificial valve leaflet material corresponding to each load sequence;

[0132] Calculate the ratio of the number of cycles under each load sequence to the number of fatigue failure cycles to obtain the fatigue damage under the load sequence;

[0133] Obtain the sum of fatigue damage under all load sequences, and obtain its inverse as the expected fatigue life.

[0134] It should be noted that the functions or steps that can be implemented by the computer-readable storage medium or computer device can be found in the aforementioned method embodiments. To avoid repetition, they will not be described one by one here.

[0135] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0136] Those skilled in the art can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0137] The present invention proposes a method, system, device and medium for evaluating the fatigue life of an artificial valve leaflet, which calculates the fatigue life of typical fatigue failure risk points on the surface of the artificial valve leaflet. During the calculation process, the stress load spectrum of the artificial valve leaflet in the last cardiac cycle among several cardiac cycles is used to obtain the number of load sequence segments of the stress load spectrum, the alternating stress of each load sequence, the average stress of each load sequence and the number of cycles of each load sequence, so as to obtain the fatigue life under each load sequence and accumulate the expected fatigue life. The method has the following advantages: short time consumption, and the fatigue evaluation calculation of the artificial valve leaflet under ideal conditions only takes about 1-10 hours; the fatigue evaluation calculation time of the artificial valve leaflet under extremely complex patient individual conditions is less than 5 days; low cost There is no need to purchase expensive fatigue testing equipment or testing consumables. The fatigue life of artificial valve leaflets can be obtained through virtual valve leaflet simulation technology and evaluation algorithm technology. The difficulty is low. The artificial valve leaflet fatigue evaluation and calculation equipment is simple to debug. It can automatically collect valve leaflet stress, strain and other data, and automatically calculate the fatigue life results of artificial valve leaflets without installing artificial valve leaflet samples. The accuracy is high. The influence of metal stents, skirts and sutures can be excluded. Only the fatigue life of artificial valve leaflets is evaluated and calculated. The precision is high. The evaluation and calculation of the fatigue life of artificial valve leaflets (the number of times the artificial valve leaflets are opened and closed) can be accurate to single digits. There are few restrictions. The fatigue life of artificial valve leaflets under any working conditions can be evaluated and calculated, including the same ideal working conditions as the fatigue tester and the actual complex implantation conditions of different patients.

[0138] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

[0139] Except for the technical features described in the specification, the remaining technical features are known technologies to those skilled in the art. In order to highlight the innovative features of the present invention, the remaining technical features will not be described here in detail.

Claims

1. A method for evaluating fatigue life of artificial valve leaflets, characterized in that: include: Obtain the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial valve leaflet; The minimum value of the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial valve leaflet is the fatigue life of the artificial valve leaflet; The steps for obtaining the expected fatigue life corresponding to each fatigue failure risk point include: Obtain the stress load spectrum of the fatigue failure risk point on the artificial valve leaflet surface during several cardiac cycles; Obtain the stress load spectrum of any cardiac cycle after the load trend in several cardiac cycles tends to be stable, and obtain the number of load sequence segments, the alternating stress of each load sequence segment, the average stress of each load sequence segment, and the number of cycles of each load sequence segment of the stress load spectrum; Calculate and obtain the number of fatigue failure cycles of the standard sample of artificial valve leaflet material corresponding to each load sequence; Calculate the ratio of the number of cycles under each load sequence to the number of fatigue failure cycles to obtain the fatigue damage under the load sequence; Obtain the sum of fatigue damage under all load sequences, and obtain its inverse as the expected fatigue life.

2. The artificial valve leaflet fatigue life evaluation method according to claim 1, characterized in that: The steps of obtaining the stress load spectrum of any cardiac cycle after the load trend in several cardiac cycles tends to be stable, and obtaining the number of load sequence segments, the alternating stress of each load sequence, the average stress of each load sequence and the number of cycles of each load sequence of the stress load spectrum include: Obtaining the stress load spectrum of any cardiac cycle after the load trend in several cardiac cycles tends to be stable, and obtaining the load sequence segment number of the stress load spectrum; Obtain the minimum and maximum stresses in each load sequence; The alternating stress and the average stress under each load sequence are calculated according to the minimum stress and the maximum stress.

3. The artificial valve leaflet fatigue life evaluation method according to claim 2, characterized in that: The alternating stress is half of the difference between the maximum stress and the minimum stress; and the average stress is half of the sum of the maximum stress and the minimum stress.

4. The method for evaluating fatigue life of artificial valve leaflets according to claim 1, characterized in that: The step of calculating and obtaining the number of fatigue failure cycles of the standard sample of artificial valve leaflet material corresponding to each load sequence includes: When the load of the load sequence is a non-pulsating cyclic load and an asymmetric cyclic load, the load of this section of the load sequence is corrected, and the fatigue strength of the artificial valve leaflet material at the fatigue failure risk point is calculated based on the correction result; When the load of the load sequence is a pulsating cyclic load or a symmetrical cyclic load, the alternating stress of the load sequence is the fatigue strength of the artificial valve leaflet material at the fatigue failure risk point; The number of fatigue failure cycles is obtained by calculation according to a relationship between the fatigue strength and the number of fatigue failure cycles.

5. The method for evaluating fatigue life of artificial valve leaflets according to claim 4, characterized in that: When the load of the load sequence is a non-pulsating cyclic load and an asymmetric cyclic load, the load of this load sequence is corrected by the Goodman equation or the Morrow equation. Its Goodman equation is: Among them, S a is the alternating stress of each load sequence; S m is the average stress of each load sequence; S Nf is the fatigue strength of the artificial valve leaflet material; S u is the nominal ultimate tensile strength of the artificial valve leaflet material.

6. The method for evaluating fatigue life of artificial valve leaflets according to claim 4, characterized in that: When the load of the load sequence is a non-pulsating cyclic load and an asymmetric cyclic load, the load of this load sequence is corrected by the Morrow equation, and the Morrow equation is: Among them, S a is the alternating stress of each load sequence; S m is the average stress of each load sequence; S Nf is the fatigue strength of the artificial valve leaflet material; σ f It is the true ultimate tensile strength of the artificial valve leaflet material.

7. The method for evaluating fatigue life of an artificial valve leaflet according to claim 4, characterized in that: When the load of the load sequence is a non-pulsating cyclic load and an asymmetric cyclic load, the load of this load sequence is corrected by the Gerber equation, and the Gerber equation is: S a is the alternating stress of each load sequence; S m is the average stress of each load sequence; S Nf is the fatigue strength of the artificial valve leaflet material; S u is the nominal ultimate tensile strength of the artificial valve leaflet material.

8. An artificial valve leaflet fatigue life evaluation system, characterized in that: include: An expected fatigue life acquisition module is used to obtain the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial valve leaflet; A fatigue life acquisition module is used to obtain the minimum value of the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial valve leaflet, which is the fatigue life of the artificial valve leaflet; The expected fatigue life acquisition module includes: A stress load spectrum acquisition unit, used to acquire the stress load spectrum of the artificial valve leaflet surface fatigue failure risk point in a number of cardiac cycles; A stress load spectrum processing unit is used to obtain the stress load spectrum of any cardiac cycle after the load trend in several cardiac cycles tends to be stable, and obtain the number of load sequence sections of the stress load spectrum, the alternating stress of each load sequence section, the average stress of each load sequence section and the number of cycles of each load sequence section; A fatigue failure cycle number calculation unit is used to calculate the fatigue failure cycle number of the artificial valve leaflet material standard sample corresponding to each load sequence; The expected fatigue life calculation unit is used to calculate the ratio of the number of cycles under each load sequence to the number of fatigue failure cycles to obtain the fatigue damage under the load sequence; and obtain the sum of the fatigue damage under all load sequences, and obtain its reciprocal as the expected fatigue life.

9. An electronic device, characterized in that: It comprises a processor, a memory and a communication bus; the communication bus is used to connect the processor and the memory; the processor is used to execute the computer program stored in the memory to implement the artificial valve leaflet fatigue life evaluation method as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that: A computer program is stored thereon, and the computer program is used to enable a computer to execute the artificial valve leaflet fatigue life evaluation method as described in any one of claims 1-7.

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