Oxygen mask optimization design method based on finite element simulation technology

Abstract

The invention provides an oxygen mask optimization design method based on a finite element simulation technology. The method comprises the specific steps that S1, an oxygen mask three-dimensional model is constructed based on an obtained face model; s2, simulating the oxygen mask by using a finite element simulation technology to obtain accurate pressure distribution; and S3, optimizing the shape of the oxygen mask based on a numerical gradient method to obtain an optimal shape of the oxygen mask. The oxygen mask can be designed in a customized mode, the pressure distribution of the optimized oxygen mask is more uniform, the area of a high-pressure area is reduced, and the oxygen mask can better adapt to the face shape of a patient, so that the wearing comfort is improved, and the risk of pressure injury is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of medical equipment design, in particular to an oxygen mask optimization design method based on finite element simulation technology. Background Art

[0002] Non-invasive ventilation is a common means of respiratory assistance, but wearing an oxygen mask for a long time may cause pressure injury. Current oxygen masks are usually standardized and often cannot adapt to a variety of facial shapes, resulting in uneven pressure distribution and increasing the risk of pressure injury.

[0003] 3D printing technology has obvious advantages in the personalized customization of products. With the advancement and development of 3D printing technology, its application in the medical industry has become more and more extensive. Chinese invention patent application CN111569296A (application publication date: 2020.08.25) discloses a method for preparing a personalized 3D printed protective mask, including the following steps: S1 collects the user's facial scan data, collects the user's facial scan data, and generates a primary model; S2 retrieves the preset protective mask basic model in the original model library, imports the data of the primary model and the protective mask basic model into the three-dimensional design software, and then uses the three-dimensional design software to process and Boolean the primary model and the protective mask basic model to generate a protective mask base model that fully fits the user's face; S3 performs 3D printing and manufacturing; S4 performs post-processing and assembly. The above invention realizes the personalized customization and rapid manufacturing of protective masks, so that the protective masks have a high degree of fit, comfort, airtightness and safety. However, the above invention does not take into account the flexibility of the mask itself and the impact of uneven distribution of facial stiffness of the human face, and the manufactured mask still has the problem of uneven pressure on the human face when worn. Summary of the invention

[0004] In order to solve the above-mentioned deficiencies in the prior art, the present invention provides an oxygen mask optimization design method based on finite element simulation technology to improve the comfort of the oxygen mask and reduce pressure injuries.

[0005] In order to achieve the above technical purpose, the technical solution adopted by the present invention is:

[0006] An oxygen mask optimization design method based on finite element simulation technology, the specific steps include:

[0007] S1. construct a three-dimensional model of an oxygen mask based on the acquired face model;

[0008] S2. Use finite element simulation technology to simulate oxygen masks and obtain accurate pressure distribution;

[0009] S3. Optimize the oxygen mask shape based on the numerical gradient method to obtain the optimal oxygen mask shape.

[0010] Furthermore, in step S1, the face model is obtained by using magnetic resonance imaging or CT technology or an existing face database.

[0011] Furthermore, in step S2, the specific method of using finite element simulation technology to simulate the oxygen mask and obtain accurate pressure distribution is:

[0012] S21, finite element meshing;

[0013] S22, physical field modeling: assign material properties to the oxygen mask and human face model;

[0014] S23. Determine the boundary conditions and loads of the system: the load is applied by the oxygen mask straps;

[0015] S24. Use numerical methods to solve the physical equations on all units to obtain the stress, displacement and pressure distribution of the oxygen mask and the human face model;

[0016] S25. Analyze simulation results: including pressure distribution, stress distribution and displacement distribution; measure the pressure at certain points on the face in reality and compare it with the simulation results, and adjust the loading load and boundary conditions.

[0017] Further, in step S2, finite element simulation is performed using ANSYS, Abaqus or COMSOL.

[0018] Further, in step S3, the shape of the oxygen mask is optimized based on the numerical gradient method, and the specific method for obtaining the optimal shape of the oxygen mask is:

[0019] S31, initializing design variables, including but not limited to the size and curvature of the oxygen mask;

[0020] S32, establishing an objective function, wherein the objective function is the square of the contact pressure between the oxygen mask and the face;

[0021] S33, calculate gradient: use numerical methods to calculate the gradient of the objective function with respect to the design variables;

[0022] S34, updating the design variables according to the gradient calculated in step S33;

[0023] S35, check convergence. If the value of the objective function or the amplitude of the change of the design variable is less than the set threshold, it is considered that the optimization process has converged. The design variable value obtained after convergence is the optimal design, and the corresponding oxygen mask shape is the optimal oxygen mask shape; otherwise, return to step S33 and continue iterating.

[0024] Furthermore, in step S34, the gradient descent method is used to update the design variables.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention constructs a three-dimensional model of an oxygen mask based on the acquired human face model, uses finite element simulation technology to simulate the oxygen mask to obtain accurate pressure distribution, and then optimizes the shape of the mask based on a digital gradient method to ultimately obtain an optimal oxygen mask shape, thereby making the pressure distribution more uniform and reducing the area of ​​the high-pressure zone. The present invention can customize the design of the oxygen mask to better adapt to the patient's facial shape, thereby improving wearing comfort and reducing the risk of pressure injuries. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 It is a schematic diagram of the process of the present invention;

[0029] Figure 2 This is a schematic diagram of finite element mesh division of the face model. DETAILED DESCRIPTION

[0030] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians of the art without making creative work are within the scope of protection of the present application.

[0031] An oxygen mask optimization design method based on finite element simulation technology, such as Figure 1 As shown in the flowchart, the specific steps include:

[0032] S1. Construct an oxygen mask three-dimensional model based on the acquired face model; the face model can be acquired through magnetic resonance imaging or CT technology (or using an existing face database), and the oxygen mask three-dimensional model can be created through computer-aided design (CAD, SolidWorks) tools.

[0033] S2. Use finite element simulation technology to simulate oxygen masks and obtain accurate pressure distribution; specifically:

[0034] S21. Finite element mesh division: The smaller the unit of the finite element mesh, the higher the calculation accuracy, but the greater the amount of calculation. In order to strike a balance between accuracy and calculation efficiency, smaller mesh units can be used in the contact area between the face and the oxygen mask as needed. The schematic diagram of finite element mesh division is as follows: Figure 2 shown.

[0035] S22. Physical field modeling: The material properties of the oxygen mask need to take into account its flexibility, such as elastic modulus and Poisson's ratio; the material properties of the face model need to take into account the uneven distribution of facial stiffness, which may involve a mixed model of multiple materials such as bones, muscles, and skin.

[0036] S23. Determine the boundary conditions and loads of the system: The load is applied by the oxygen mask straps.

[0037] S24. Use numerical methods to solve the physical equations on all units to obtain the stress, displacement, and pressure distribution of the oxygen mask and human face model.

[0038] The balanced differential equation is as follows:

[0039]

[0040] where ρ is the density, d a is the damping coefficient, is stress, is the displacement, t is the time, is the divergence operator is the force. By solving the partial differential equation using the finite element method, we can get the pressure distribution.

[0041] S25. Analyze the simulation results, including pressure distribution, stress distribution and displacement distribution.

[0042] In order to further improve the simulation accuracy, it is necessary to measure the pressure at certain points on the face in reality, and adjust the loading load and boundary conditions by comparing with the simulation results.

[0043] The above simulation process using finite element analysis (FEA) requires a lot of computing resources, so you may need to use a high-performance computer or cloud computing service. In addition, you may also need to use specialized finite element analysis software such as ANSYS, Abaqus or COMSOL.

[0044] S3. Optimizing the oxygen mask shape based on the numerical gradient method to obtain the optimal oxygen mask shape, specifically including:

[0045] S31. Initialize design variables.

[0046] Design variables are a set of parameters that describe the shape of the oxygen mask, including but not limited to the size and curvature of the oxygen mask. In order to speed up the optimization process, a mask design that has been tested is selected as the initial value of the optimization process (in this example, the High Concentration Oxygen Mask of Salter Labs, model Salter 8140) is selected.

[0047] S32. Establish an objective function. The objective function is the quantity we want to minimize (or maximize). In this embodiment, the objective function is the square of the contact pressure between the oxygen mask and the human face.

[0048] S33. Calculate gradient: Use numerical methods to calculate the gradient of the objective function relative to the design variables.

[0049] The gradient is a vector that points to the direction in which the objective function increases fastest at the current point. For a multivariable function f(x1,x2,...,x n ), its gradient at point x is defined as:

[0050]

[0051] Since the function f is complex, the gradient cannot be calculated directly. We can use numerical methods to estimate the gradient. For each variable x, we can calculate its numerical gradient at point x:

[0052] df / dx i ≈[f(x1,...,x i +h,...,x n )-f(x1,...,x i -h,...,x n )] / (2h)

[0053] where h is a small number, such as 1e-5 or 1e-6. We can then combine the numerical gradients of all variables into a vector as an estimate of the gradient:

[0054]

[0055] S34. Update the design variables based on the calculated gradient. In the gradient descent method, we subtract an amount in the same direction as the gradient in the expectation that the value of the objective function will decrease. This amount is usually the gradient multiplied by a small step size factor.

[0056] S35, check convergence. If the value of the objective function or the amplitude of the change in the design variable is less than the set threshold, it can be considered that the optimization process has converged. The design variable value obtained after convergence is the optimal design, and the corresponding oxygen mask shape is the desired optimal oxygen mask shape; otherwise, return to step S33 and continue iterating.

[0057] It should be noted that this process may fall into a local optimal solution, because the numerical gradient method can usually only find the nearest local optimal solution. In addition, when there are many design variables or the objective function is complex, it may be very difficult to calculate the gradient. In practical applications, it may be necessary to combine other global optimization algorithms or use more complex gradient estimation methods.

[0058] After the oxygen mask optimization design is completed, the oxygen mask can be prepared by 3D printing, including:

[0059] Generate 3D printing files: First, export the optimized oxygen mask design from the finite element simulation software and generate the file format required for 3D printing, generally .STL or .OBJ files, which will describe the geometry of the mask.

[0060] Prepare a 3D printer: Choose a suitable 3D printer and materials. Considering that the oxygen mask needs to be in contact with the human face, the material should be safe, non-toxic, comfortable, and have sufficient strength and elasticity. Some possible options include plastics (such as PLA, ABS), elastic materials (such as TPU), or specialized biomedical 3D printing materials.

[0061] Set 3D printing parameters: According to the characteristics of the 3D printer and the selected material, set appropriate 3D printing parameters, including but not limited to printing speed, layer thickness, filling density, printing temperature, etc.

[0062] Start 3D printing: Load the 3D printing file into the printer and start printing. During the printing process, the printer will add materials layer by layer according to the 3D model to form a three-dimensional object.

[0063] Post-processing: After printing is complete, some post-processing steps may be required, such as removing support structures, smoothing surfaces, disinfection, etc., to ensure the safety and comfort of the mask.

[0064] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. An oxygen mask optimization design method based on finite element simulation technology, characterized in that: The specific steps include: S1. constructing a three-dimensional model of an oxygen mask based on the acquired face model; S2. Use finite element simulation technology to simulate oxygen masks and obtain accurate pressure distribution; S3. Optimize the oxygen mask shape based on the numerical gradient method to obtain the optimal oxygen mask shape.

2. The oxygen mask optimization design method based on finite element simulation technology according to claim 1 is characterized in that: In step S1, the face model is obtained by using magnetic resonance imaging or CT technology or an existing face database.

3. The oxygen mask optimization design method based on finite element simulation technology according to claim 1 is characterized in that: In step S2, the finite element simulation technology is used to simulate the oxygen mask, and the specific method of obtaining accurate pressure distribution is as follows: S21, finite element meshing; S22, physical field modeling: assign material properties to the oxygen mask and human face model; S23. Determine the boundary conditions and loads of the system: the load is applied by the oxygen mask straps; S24. Use numerical methods to solve the physical equations on all units to obtain the stress, displacement and pressure distribution of the oxygen mask and the human face model; S25. Analyze simulation results: including pressure distribution, stress distribution and displacement distribution; measure the pressure at certain points on the face in reality and compare it with the simulation results, and adjust the loading load and boundary conditions.

4. The oxygen mask optimization design method based on finite element simulation technology according to claim 3 is characterized in that: In step S2, finite element simulation is performed using ANSYS, Abaqus or COMSOL.

5. The oxygen mask optimization design method based on finite element simulation technology according to claim 1 is characterized in that: In step S3, the shape of the oxygen mask is optimized based on the numerical gradient method, and the specific method for obtaining the optimal shape of the oxygen mask is: S31, initializing design variables, including but not limited to the size and curvature of the oxygen mask; S32, establishing an objective function, wherein the objective function is the square of the contact pressure between the oxygen mask and the face; S33, calculate gradient: use numerical methods to calculate the gradient of the objective function with respect to the design variables; S34, updating the design variables according to the gradient calculated in step S33; S35, checking convergence. If the value of the objective function or the amplitude of the change of the design variable is less than the set threshold, it is considered that the optimization process has converged. The design variable value obtained after convergence is the optimal design, and the corresponding oxygen mask shape is the optimal oxygen mask shape. Otherwise, return to step S33 and continue iterating.

6. The oxygen mask optimization design method based on finite element simulation technology according to claim 5 is characterized in that: In step S34, the gradient descent method is used to update the design variables.

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