Parameter optimization method for hydatid endocyst resection cutter

Abstract

The invention relates to a parametric optimization method for a hydatid endocyst resection cutter. The optimization method specifically comprises the following steps: S1, determining simulation model parameters; s2, obtaining two-dimensional simplified model simulation of the cutter; s3, constructing a Box-Behnken response surface method test of three factors and three levels of the cutter; s4, on the basis of the S3, constraint target solving is conducted on the regression model, simulation result optimization prediction is conducted, and optimal knife edge parameters are obtained; the method has the advantages that stress distribution and deformation of different cutter shapes in the simulation process are analyzed, and the stability of the cutting process is ensured; and (2) according to a simulation result, the accuracy of the cutting process during implementation of the operation and the effectiveness of the safe operation process are ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of parameter optimization methods for resection cutters, and particularly relates to a parameter optimization method for an echinococcus inner capsule resection cutter. Background Art

[0002] The laparoscopic surgery method is a minimally invasive surgical method. With the progress of the current medical level and the development of minimally invasive technology, the laparoscopic surgery treatment method is increasingly widely used in the treatment of various surgical diseases. When performing laparoscopic surgery, doctors are highly dependent on laparoscopic equipment, which is required to accurately locate the lesion site and confirm the surrounding tissue conditions of the lesion site. Therefore, the quality of laparoscopic instruments and equipment directly affects the surgical operation effect of doctors.

[0003] As a parasitic disease, hepatic cystic echinococcosis shows expansive growth. The domestic expert consensus recommends complete resection as the main treatment method. Currently, compared with open surgery, although the field of view is clearer during laparoscopic surgery, when performing liver surgery, especially when the lesion is located in the right posterior lobe area of the liver, its exposure is relatively poor. The echinococcus lesion is usually located in the right lobe of the liver, and the lesion volume is relatively large. Its expansive growth mode exacerbates the problem of surgical field exposure. Therefore, during laparoscopic resection surgery, decompression of the echinococcus inner capsule has become the preferred operation method. Decompressing the echinococcus inner capsule is crucial for ensuring the complete resection of echinococcus under laparoscopy.

[0004] Currently, the domestic special instrument methods for echinococcus surgery are as follows: a multifunctional puncture needle for echinococcus (application number 200820062050.2), and an echinococcus inner capsule aspiration cutter (200820062052.1). The former is a surgical instrument for pulmonary echinococcosis and is not applicable to hepatic cystic echinococcosis. The latter device includes a suction tube and a handle. One end of the suction tube is a sharp surface, and the other end is connected to a negative pressure tube connected to a negative pressure bottle. The handle longitudinally penetrates through the suction tube and is hermetically connected to the suction tube. A switch valve is provided inside the handle. The switch valve is composed of a pressure column, a cross bolt with a flow hole, and a spring. The pressure column is fixedly connected to the cross bolt. One end of the spring is fixed to the cross bolt, and the other end is fixed to the inner wall of the handle. The flow hole is located outside the suction tube when the spring is in its natural length. The device structure is too simple, the size is inappropriate, the cutting structure is inconvenient to use, and the design position of the negative pressure suction switch is unreasonable, which is not conducive to popularization and use. Summary of the Invention

[0005] In view of the problems mentioned in the background art, the present invention provides a parameter optimization method for an echinococcus inner capsule resection cutter.

[0006] Existing research shows that the postoperative hospital stay of laparoscopic surgery patients is shorter than that of the laparotomy group, and patients in the laparoscopic group recover faster. Laparoscopic surgery has advantages such as less bleeding and faster postoperative recovery. After strictly mastering the surgical indications, laparoscopic treatment of hepatic cystic echinococcosis is safe and effective. With the rapid development of laparoscopic technology, laparoscopic minimally invasive surgery has currently been used in the treatment of hepatic cystic echinococcosis. Performing an internal capsule resection under direct vision with a laparoscope can effectively improve the surgical efficiency, reduce postoperative complications such as bleeding, bile leakage, and recurrence, and has advantages such as good curative effect, small trauma, and fast recovery. When treating hepatic cystic echinococcosis with minimally invasive surgery, a special instrument is used to assist the surgery, which will improve the surgical efficiency and reduce the operation time. In view of the current clinical needs and the defects and inconveniences of existing methods, we designed a special laparoscopic instrument to assist the surgery and help doctors treat hepatic cystic echinococcosis.

[0007] In summary, in order to obtain better surgical cutting quality and improve surgical efficiency, the cutting edge parameters must be reasonable to achieve better working performance. Unfortunately, existing literature on optimizing cutting edge parameters is not applicable to this special laparoscopic instrument device.

[0008] To solve the above problems, the technical solution adopted by the present invention is:

[0009] To verify the cutting effect of the cutting edge part, this method uses a rigid-flexible coupling model for simulation analysis to ensure the stability of the tool during cutting. By using the response surface method designed by Box-Behnken and combining regression analysis, the cutting edge parameters are optimized to ensure the structural rationality and functional effectiveness of the device.

[0010] A method for optimizing the parameters of a hydatid internal capsule resection cutter, the optimization method is specifically as follows:

[0011] S1: Determine the model parameters of the simulation;

[0012] S2: Obtain the two-dimensional simplified model simulation of the tool;

[0013] S3: Construct a Box-Behnken test with three factors and three levels for the tool;

[0014] S4: Based on S3, solve the constraint objective for the regression model and optimize and predict the simulation results to obtain the optimal cutting edge parameters.

[0015] Further, the S1 is specifically as follows:

[0016] S11 Cutting edge material parameters: To obtain an accurate simulation environment, corresponding material properties need to be assigned to each model, including parameters such as Poisson's ratio, elastic modulus, and density. The cutting device uses the built-in structural steel material in Workbench.

[0017] S12 Tissue elastoplastic parameters: Complex structures in the human liver, such as blood vessels, cavities, and meridians, may interfere with cutting simulations. Therefore, directly conducting research using liver tissue may be affected by these uncertain factors, thereby influencing the study of the cutting process. To exclude the influence brought by the inhomogeneous medium within the tissue, in this paper, a homogeneous hydrogel with mechanical properties similar to those of the real liver is used for cutting simulations. The hydrogel prosthesis has similar elastic parameters and other physical properties, as shown in Tables 1 and 2. The data is sourced from the article: Simulation of the Coupling Process of Flexible Needle Penetrating Soft Tissue Based on ABAQUS.

[0018] Table 1 Elastic parameters and other physical properties

[0019]

[0020] Table 2 Conversion of nominal stress and nominal strain to true stress and true strain

[0021]

[0022] Furthermore, the specific content of S2 is as follows:

[0023] S21 Two-dimensional model simplification: As Figure 2-3 shown, the inner and outer cutting edges are simplified into a planar shell, which can simplify the simulation process, shorten the simulation time, and improve the efficiency of simulation research. The inner cyst of hydatid is simplified into a simple semi-circular structure placed between the cutting edges, facilitating the display of the cutting simulation effect. The opening of the inner and outer cutting edges of the designed device is approximately 17 mm, so the width of the inner cyst of hydatid is set to 15 mm, maintaining a certain gap from the inner and outer cutting edges to ensure the integrity of the cutting action. During the process of cutting the inner cyst of hydatid, the cutting angle of the cutting device will not be adjusted, and the flexure and deflection of the cutting device will be maintained in the same plane. The analysis of the cutting force between the cutting device and the inner cyst of hydatid and the research of the simulation process can be regarded as a study in the plane, and the two-dimensional simulation in ANSYS-LS-DYNA is used to simulate the cutting process and its influence on the displacement and deformation of the inner cyst of hydatid units in the plane. That is, during the cutting process, the inner and outer cutting edges only have a linear motion in the relative axial direction and no axial or radial rotation, so the device is directly simplified into a two-dimensional plane model.

[0024] S22 Two-dimensional model simulation:

[0025] (1) Contact setting

[0026] The contact during the cutting process is mainly the surface-to-surface contact between each cutting edge and the inner cyst of hydatid. Define the contact of all geometries as friction, with a friction coefficient of 0.5, a dynamic coefficient of 0.25, and the attenuation coefficient set to 0.

[0027] The cutting method of this device is that the relative movement of the inner and outer blades produces a shearing effect on the object. Therefore, friction has little influence on the cutting effect of this device, and the friction coefficient refers to the friction coefficient between metal and skin.

[0028] (2) Boundary condition setting

[0029] The boundary conditions of the device cutting simulation model are mainly the settings of the positions and motion parameters of each part. Set the remote displacement of the inner blade to 25 mm, the lower edge of the echinococcus inner cyst is a fixed support, and the outer blade is a fixed support.

[0030] (3) Analysis setting

[0031] The device cutting simulation is mainly to observe whether the tool can cut open the echinococcus inner cyst, and there is only one cutting action in the simulation. The inner blade pushes the echinococcus inner cyst towards the outer blade, and the outer blade blocks it for the cutting action to complete the fragmentation of the echinococcus inner cyst.

[0032] Therefore, in the 2D simulation, the contact characteristic is designed as geometric body interaction, the contact type is only a single surface, and the calculation formula is AUTOMATIC_SINGLE_SURFACE.

[0033] Further, the specific content of S3 is as follows:

[0034] S31: Response surface analysis experiment: Take the maximum equivalent stress when the echinococcus inner cyst undergoes shear failure as the evaluation index for the cutting effect. Conduct experimental design. From the 2D simulation results above, it can be seen that the cutting angle, tool gap, and tool configuration will all affect the cutting effect of the echinococcus inner cyst. Define the maximum equivalent stress generated when the echinococcus inner cyst contacts the tool as the cutting effect index, take the cutting inclination angle of the outer blade, the cutting inclination angle of the inner blade, and the tool gap as influencing factors, and the cutting effect index reflected by the maximum equivalent stress as the response index. Select the cutting inclination angle of the outer blade to be -45° to +45°, the cutting inclination angle of the inner blade to be -45° to +45°, and the tool gap to be 0 to 1 mm. To explore the influence of each influencing factor and the interaction between factors on the evaluation index and obtain the optimal parameter combination, conduct a three-factor three-level Box-Behnken test, with a total of 17 groups of experiments. The experimental factor coding is shown in Table 3-4.

[0035] Table 3 Experimental factor coding

[0036]

[0037] Further, the specific content of S4 is as follows:

[0038] S41: Determination of the device blade shape: To obtain the optimal working parameter combination of the blade of the hydatid inner capsule cutting device, the Design-Expert software is used to solve the constraint objective of the regression model and optimize and predict the simulation results.

[0039] The beneficial effects of the present invention are as follows:

[0040] In this design scheme, by precisely setting the cutting inclination angles of the outer blade and the inner blade and controlling the size of the tool gap, the maximum equivalent stress is limited to a relatively low level, thereby achieving the optimal cutting effect. In actual operation, such a design can significantly improve the cutting effect of the device and effectively enhance the surgical efficiency. At the same time, by avoiding situations such as continuous cutting and inability to cut during the cutting process, it also ensures the smooth progress of the surgical procedure and provides a more reliable operating environment for doctors. This scheme can not only improve work efficiency but also ensure the safety of patients and the quality of the surgery, and is a very beneficial innovative design.

[0041] (1) It analyzes the stress distribution and deformation of different tool shapes during the simulation process to ensure the stability of the cutting process.

[0042] (2) Based on the simulation results, it ensures the accuracy of the cutting process during actual operation and the effectiveness during a safe surgical procedure.

[0043] The shear stress changes generated by the three-dimensional model and the two-dimensional model during cutting are similar. Therefore, a two-dimensional model is selected for subsequent design simulation. At the same time, when using ANSYS Workbench for simulation, choosing a two-dimensional model has some advantages over a three-dimensional model:

[0044] 1. Fast calculation speed: The geometry and the number of meshes of the two-dimensional model are usually much less than those of the three-dimensional model, and the amount of data to be processed during the calculation process is smaller. Therefore, the simulation speed of the two-dimensional model is usually much faster than that of the three-dimensional model, which is convenient for

[0045] the initial research stage that requires verifying the design concept.

[0046] For the initial research stage that requires verifying the design concept.

[0047] 2. Applicability: The data and results generated by the two-dimensional model are easier to interpret and understand. For some types

[0048] of problems, such as structures like plates, films, and long pipes, the two-dimensional assumption is very reasonable, and the error introduced by effectively approximating the actual three-dimensional behavior is very small.

[0049] 3. Parameter optimization: Two-dimensional simulation can provide quick feedback. The cutting angle, blade diameter, and

[0050] Tool geometry, and quickly evaluate the impact of these changes on the cutting effect through a two-dimensional model. Description of the Drawings

[0051] The present invention will be further described below in conjunction with the drawings and embodiments;

[0052] Figure 1 It is the process intention diagram of the present invention;

[0053] Figure 2 It is a simplified two-dimensional simulation diagram;

[0054] Figure 3 It is the two-dimensional simulation result;

[0055] Figure 4 and Figure 5 It is the Box-Behnken test with three factors and three levels;

[0056] Figure 6 Schematic diagram of the influence of different factors on the cutting effect;

[0057] Figure 7 It is the overall schematic diagram of the device;

[0058] In the figure: 1. Outer catheter, 2. Inner catheter, 3. Front handle, 4. Rear handle, 5. Link, 6. Spring, 7. Connecting axle pin (front handle), 8. Connecting axle pin (inner catheter), 9. Connecting axle pin (outer catheter). Detailed Description of the Invention

[0059] Example 1, in order to more deeply understand the objectives, technical content and advantages of the present invention, the following content will elaborate on the implementation manner of the present invention by combining the drawings of the embodiments. It should be noted that the embodiments introduced here only represent some ways of the present invention, not all. The purpose of understanding these specific implementation manners is to explain the present invention, not to limit its scope. Based on the present invention, those of ordinary skill in the art can derive all other possible implementation manners without creative labor, and these manners are also covered by the protection scope of the present invention.

[0060] This embodiment proposes a tool attitude optimization method, as Figure 1 shown, specifically:

[0061] Since the cutting effect is an important indicator for measuring this device, which affects the safety and efficiency of the operation, the cutting effect should be as good as possible. And the tool edge parameters are the main factors affecting the cutting effect. When the tool is determined, different tool edge parameters will have a great impact on the cutting effect. Therefore, there is a correlation between the edge parameters of the workpiece and the cutting effect.

[0062] To verify this conclusion, a Box-Behnken test was designed for analysis, and the experiment is as follows:

[0063] Table 4 Test Results

[0064]

[0065] A, B, and C are the factor coding values. Response surface regression analysis was performed on the simulation data using Design-Expert software, and the fitting equation between each influencing factor and the evaluation index was obtained through calculation as

[0066] Y = 0.1583 - 0.0365A + 0.0122B

[0067] - 0.0091C + 0.0341AB

[0068] - 0.0195AC - 0.0596BC

[0069] To ensure the effectiveness of the fitting equation, an analysis of variance of the regression equation was performed on the experimental results. The P value of the rigid-flexible coupling model of the device cutting action is less than 0.01, indicating that the regression equation is extremely significant. The P value of the lack-of-fit term is greater than 0.05, indicating that the lack-of-fit term is not significant, indicating that the fitting degree of this regression model is good and can be used for analyzing the influence of each test factor on the evaluation index.

[0070] Table 5 Analysis of Variance of the Regression Equation

[0071]

[0072]

[0073] To obtain the optimal working parameter combination of the blade of the hydatid inner capsule cutting device, Design-Expert software was used to solve the constraint objective of the regression model and optimize and predict the simulation results. The obtained optimization results are shown in Table 6.

[0074] Table 6 Simulation Optimization and Prediction Results

[0075]

[0076] The optimal tool parameters obtained by the method of the present invention effectively improve and verify the cutting effect of the device, ensuring the structural rationality and functional effectiveness of the device. It improves the surgical safety and efficiency and has high clinical application value.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the present technical solution, and they should all be covered within the scope of the claims of the present invention.

[0078] A device for inner capsule cutting includes a cutting part, a catheter part, and a control handle part.

[0079] The cutting part is composed of the front end of the inner catheter 2 and the front end opening of the outer catheter 1, which cooperate with each other. The catheter part includes the inner catheter 2, the outer catheter 1, and the inner catheter rear spring 6. The control handle part includes the front handle 3, the rear handle 4, the connecting rod 5, and the connecting shaft pins (front handle) 7, the connecting shaft pin (inner catheter) 8, and the connecting shaft pin (outer catheter) 9. The movement of the front handle 3 is transmitted to the inner catheter 1 through the connecting rod 5, converting the opening and closing movement of the palm and fingers into the sliding of the inner catheter 2.

[0080] When in use, the user holds the rear handle 4 and inserts the fingers into the opening of the front handle 3. The outer catheter 1 is inserted into the outer capsule of the hepatic hydatid cyst to contact the inner capsule, and the blade of the outer catheter 1 is aligned with the inner capsule of the hepatic hydatid cyst. The fingers are inserted into the opening of the front handle 3, and the palm is pinched to drive the inner catheter 2 to slide backward, opening the blade. The inner capsule of the hepatic hydatid cyst is clamped into the blade of the outer catheter 1, and then the palm is extended to drive the inner catheter 2 to slide forward, and the inner and outer blades slide relative to each other to perform inner capsule cutting. At the same time, during cutting, the negative pressure connected to the tail end of the inner catheter 2 will aspirate the inner capsule fluid of the hepatic hydatid cyst.

[0081] The design of this device makes the inner capsule cutting operation more accurate and convenient, and at the same time realizes the aspiration function of the inner capsule fluid, which is helpful for the treatment of hepatic hydatid cyst.

[0082] Box-Behnken

[0083] The response surface method (Box-Behnken) is a synthesis of statistical design of experiment techniques, using the experimental design of Box-Behnken

[0084] And a certain amount of data is obtained through experiments. A multiple quadratic equation is used to fit the functional relationship between factors and response values. By analyzing the regression equation, the optimal process parameters are sought, which is a statistical method for solving multi-variable problems. In this method, a three-factor and three-level experiment is carried out using this method, and a fitting equation regarding the cutting effect of the blade is obtained.

[0085] Workbench

[0086] It is a software within the engineering simulation software Ansys. The ANSYS Workbench simulation platform can analyze and simulate the structural statics, structural dynamics, rigid body dynamics, fluid dynamics, structural heat, electromagnetic field, and coupled fields of complex mechanical systems. This method uses the workbench software for simulation operations.

[0087] ABAQUS

[0088] It is the name of another commonly used engineering simulation software, similar to Ansys. The reference data paper uses the abques software, while this method uses the ansys workbench software.

[0089] ANSYS LS-DYNA

[0090] LS-DYNA is a simulation module within ansys workbench, specifically applicable to explicit dynamics such as cutting penetration and explosion.

[0091] For the simulation, the module used in this method's simulation experiment is the ANSYS LS-DYNA module;

[0092] AUTOMATIC_SINGLE_SURFACE

[0093] It is the contact function defined during the simulation calculation of the LS-DYNA module. Literally, it defines cutting penetration as "automatic single surface contact".

[0094] Y = 0.1583 - 0.0365A + 0.0122B

[0095] -0.0091C + 0.0341AB

[0096] -0.0195AC - 0.0596BC

[0097] In this formula, Y represents the "maximum equivalent stress" of the explicit cutting effect. A, B, and C are the individual effects of the three experimental factors in the method respectively, and AB, AC, and BC are the combined effects of two of the factors. This fitting equation reflects the relationship between the cutting effect and the influencing factors.

[0098] Because under theoretical conditions, in-plane shear stress (such as shear stress in plates or thin-walled structures) is usually different from in-body shear stress (such as shear stress in thick-walled structures or three-dimensional bodies). In-plane shear stress is mainly affected by the material surface conditions and the external loading method, while in-body shear stress is more related to the internal force balance and three-dimensional stress state of the material.

[0099] However, to a certain extent, these two stress curves show similar characteristics. (1) Both curves exhibit obvious fluctuating behavior, that is, the stress values change drastically over time, increasing and decreasing, indicating that the stress response is dynamically changing due to the severe plastic deformation and plastic failure of the inner cyst of hydatid. (2) The distributions of the peak values (local maximum points) and valley values (local minimum points) of the two curves on the time axis have a certain similarity. This indicates that at similar time points, the simulated cutting action system experiences similar stress states. (3) Within a specific time interval, from the start to approximately 0.0025 seconds, both curves show a relatively stable growth. After that, although the volatility increases, the two curves show a general upward or downward trend in the subsequent stages.

[0100] Analysis of Cutting Stability with Different Knife Edges

[0101] Taking the maximum equivalent stress when the inner cyst of hydatid undergoes shear failure as the evaluation index for the quality of cutting effect, the experimental design is carried out. From the two-dimensional simulation results in the previous text, it can be seen that the cutting angle, tool gap, and tool configuration will all affect the cutting effect of the inner cyst of hydatid. Defining the maximum equivalent stress generated when the inner cyst of hydatid contacts the tool as the cutting effect index, taking the outer knife-edge cutting inclination angle, inner knife-edge cutting inclination angle, and tool gap as influencing factors, and the cutting effect index reflected by the maximum equivalent stress as the response index, the outer knife-edge cutting inclination angle is selected as -45° to +45°, the inner knife-edge cutting inclination angle is selected as -45° to +45°, and the tool gap is 0 to 1 mm. To explore the influence of each influencing factor and the interaction between factors on the evaluation index and obtain the optimal parameter combination, a three-factor and three-level Box-Behnken experiment is carried out, with a total of 17 groups of experiments. The experimental factor coding is shown in Table 5.

[0102] According to the experimental design scheme in Table 5 and the experimental factor coding table, the rigid-flexible coupling model of the device's cutting action is simulated to obtain the maximum equivalent stress under different working conditions, that is, the cutting effect index. The experimental results are shown in Table 5.

[0103] In Table 6, A, B, and C are the factor coding values. Through the response surface regression analysis of the simulation data by Design-Expert software, and after calculation, the fitting equation between each influencing factor and the evaluation index is obtained as

[0104] Y = 0.1583 - 0.0365A + 0.0122B

[0105] -0.0091C + 0.0341AB

[0106] -0.0195AC - 0.0596BC

[0107] The variance analysis of the regression equation is shown in Table 6. The software calculation results are analyzed. The P value of the rigid-flexible coupling model of the device cutting action is less than 0.01, indicating that the regression equation is extremely significant. The P value of the lack-of-fit term is greater than 0.05, indicating that the lack-of-fit term is not significant, indicating that the regression model has a good degree of fit and can be used to analyze the impact of various experimental factors on the evaluation indicators.

[0108] It can be seen from Table 7 that the P values ​​of the first-order term A and the interaction term BC of the equation are both less than 0.05, and the difference is significant, while the other terms are not significant. In the regression equation, the single factor coefficient represents the influence of the influencing factors on the evaluation index. The regression equation shows that the influence is from large to small, followed by the outer blade cutting inclination angle, the inner blade cutting inclination angle, and the tool gap.

[0109] The response surface of the effect of two-factor interaction on the maximum equivalent stress is as follows: Figure 6 As shown. Among them, Figure 6 The interaction between the inner cutting angle (c) and the tool clearance has a significant effect on the maximum equivalent stress. Figure 6 a shows that when the outer blade cutting angle increases and the inner blade cutting angle decreases, the maximum equivalent stress decreases. Figure 6 b shows that when the cutting inclination angle of the outer knife edge increases and the tool gap increases, the maximum equivalent stress decreases.

[0110] The cutting inclination angle of the outer blade is 27.349°, the cutting inclination angle of the inner blade is 42.7°, the tool gap is 0.006mm, and the maximum equivalent stress is 0.244MPa. Using this optimal value can improve the cutting effect when the device is cutting, improve the surgical efficiency, and try to avoid the situation of continuous cutting and continuous cutting similar to cutting meat.

[0111] The device of the present invention is used in conjunction with a laparoscope.

Claims

1. A method for optimizing parameters of a hydatid cystectomy knife, characterized in that: The optimization method is: S1: Determine the model parameters for simulation; S2: Get the two-dimensional simplified model simulation of the tool; S3: Construct a three-factor, three-level Box-Behnken response surface method experiment for the tool; S4: Based on S3, the constraint target of the regression model is solved and the simulation results are optimized and predicted to obtain the optimal blade parameters; the outer blade cutting angle is 27.349°, the inner blade cutting angle is 42.7°, the tool gap is 0.006mm, and the maximum equivalent stress is 0.244MPa.

2. The method for optimizing the parameters of a hydatid cystectomy knife according to claim 1, characterized in that: The S1 is specifically: S11 blade material parameters: To obtain an accurate simulation environment, each model needs to be given corresponding material properties, namely Poisson's ratio, elastic modulus and density parameters; the cutting device uses Workbench, which is a software built-in structural steel material in the engineering simulation software Ansys; S12 Tissue elastic-plastic parameters: The complex structures in the human liver, such as blood vessels, cavities and meridians, may interfere with the cutting simulation. In order to eliminate the influence of the inhomogeneous medium in the tissue, the cutting simulation is carried out using a homogeneous hydrogel with mechanical properties similar to those of the real liver. The hydrogel prosthesis has similar elastic parameters and other physical properties. Based on ABAQUS, another commonly used engineering simulation software, the soft tissue coupling process of the flexible needle puncture is simulated similar to Ansys Workbench.

3. The method for optimizing parameters of a hydatid cystectomy knife according to claim 1, characterized in that: The S2 is specifically: S21 2D model simplification: The inner and outer blades are simplified into a flat shell, which can simplify the simulation process and shorten the simulation time; the hydatid cyst is simplified into a simple semicircular structure placed between the blades to facilitate the display of the cutting simulation effect; the inner and outer blade openings of the designed device are 17mm, and the width of the hydatid cyst is set to 15mm, with a gap of 1mm between the inner and outer blades to ensure the integrity of the cutting action; The cutting device will not adjust the cutting angle of the cutting device during the process of cutting the hydatid cyst, and the bending and deflection of the cutting device will be maintained in the same plane; the research on the cutting force analysis and simulation process between the cutting device and the hydatid cyst can be regarded as the research in the plane; S22 2D model simulation: (1) Contact settings The contact during the cutting process is mainly the surface-to-surface contact between each blade and the cyst. The contact of all geometric bodies is defined as friction, with a friction coefficient of 0.5, a dynamic coefficient of 0.25, and a decay coefficient of 0. The cutting method of the device is that the relative movement of the inner and outer blades produces a shearing effect on the object, so friction has little effect on the cutting effect of the device. The friction coefficient refers to the friction coefficient between metal and skin; (2) Boundary condition setting The boundary conditions of the device cutting simulation model are mainly the settings of the positions of each part and the motion parameters. The inner blade remote displacement is set to 25mm, the lower side of the hydatid cyst is a fixed support, and the outer blade is a fixed support; (3) Analysis settings The device cutting simulation is mainly to observe whether the tool can cut the hydatid cyst. The simulation action has only one cutting action. The inner blade pushes the hydatid cyst to move toward the outer blade, and the outer blade blocks it to perform the cutting action, thus completing the crushing of the hydatid cyst. In the two-dimensional simulation, the contact characteristics are designed to be geometric interaction, the contact type is single surface only, and the calculation formula is AUTOMATIC_SINGLE_SURFACE, which is the contact function defined during the LS-DYNA module simulation calculation.

4. The method for optimizing parameters of a hydatid cystectomy knife according to claim 1, characterized in that: The S3 is specifically: S31: Response surface analysis experiment: The maximum equivalent stress when the hydatid cyst is sheared is used as an evaluation index of the cutting effect, and the experiment is designed. The two-dimensional simulation results show that the cutting angle, tool gap and tool configuration will affect the cutting effect of the hydatid cyst. The maximum equivalent stress generated when the hydatid cyst contacts the tool is defined as the cutting effect index. The outer blade cutting inclination angle, inner blade cutting inclination angle and tool gap are used as influencing factors. The cutting effect index reflected by the maximum equivalent stress is used as the response index. The outer blade cutting inclination angle is -45°~+45°, the inner blade cutting inclination angle is -45°~+45°, and the tool gap is 0~1mm. In order to explore the influence of various influencing factors and the interaction between factors on the evaluation index and obtain the optimal parameter combination, a three-factor three-level Box-Behnken test is carried out, and a total of 17 groups of experiments are conducted.

5. The method for optimizing parameters of a hydatid cystectomy knife according to claim 1, characterized in that: The S4 is specifically: S41: Determination of the shape of the device blade: In order to obtain the optimal parameter combination of the blade of the hydatid cyst cutting device, the Design-Expert design expert software is used to solve the constraint objectives of the regression model and optimize the prediction of the simulation results.

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