Aviation blade optimization additive manufacturing method based on anisotropy and constraint self-adaption

Abstract

The invention relates to an aviation blade optimization additive manufacturing method based on anisotropy and constraint self-adaption. An adopted 3D printing device is provided with a magnetic field constraint structure and an ultrasonic constraint structure. According to the method, firstly, finite element analysis is carried out on the aero-engine blade based on a model design method, different areas on the aero-engine blade are judged and analyzed to obtain the material stacking direction with the optimal strength, printing is carried out according to the direction, and meanwhile the minimum safety performance needed by the aero-engine blade is compared; and the magnetic field constraining force and the ultrasonic intensity are adaptively changed, and the microstructure in the alloy is refined, so that the machined aero-engine blade meets the strength standard.

Description

Technical Field

[0001] The present invention relates to the field of industrial design and manufacturing, and in particular to an optimized additive manufacturing method for aviation blades based on anisotropy and constraint adaptation. Background Art

[0002] The aircraft engine is the life of the aircraft, providing power for the aircraft and being the core part of the aircraft. Its performance will seriously affect the flight status of the drone. The blades of the aircraft engine rotate at high speed during operation, especially when performing more complex tasks. Since the blades may be affected by loads from all directions, and may be damaged by collisions with other flying objects, their strength and other properties must be taken very seriously. With the rapid update and iteration of aircraft, the performance of aircraft engine blades has been put forward with high standards of high flight reliability, good safety, economical and applicable, lightweight and high thrust, making the development space of aircraft engine blades more stringent. It is mainly reflected in the complex force and high stress of the blades. The shape of the aircraft engine blade presents a complex spatial curved surface. The traditional processing method has a long cycle. The application of additive manufacturing processing methods can not only quickly process products, but also use the advantages of additive manufacturing to optimize their structure. Theoretical research on blade design, the combination of computer technology and fluid mechanics technology, has continuously improved the calculation accuracy of the flow field of the blade. Numerical simulation technology has been widely used in the analysis of propeller aerodynamic characteristics, reducing the dependence on experiments, improving design efficiency, shortening the production cycle, and saving manpower and material resources. The blade mass is minimized by optimizing the design of the blades and has no effect on the dynamic performance of the propeller. With the rapid development of additive manufacturing technology, a new processing method is provided for some complex parts similar to thin-walled parts, especially. The performance parameters of various aspects meet the requirements and the processing cycle is greatly shortened. Since the structural shape of the propeller blade is composed of the bending of the free-form surface in space, the thickness of the blade is changing everywhere, and the thickness is different everywhere. Such a complex geometric shape does not have a true symmetry because there is no symmetry plane. The material thickness decreases from the root to the tip of the blade, and finally the structural shape of the blade is obtained. Traditional processing technology requires many processes to process it, and it wastes a lot of parent materials. If additive manufacturing is used, it can be quickly printed to achieve the purpose of energy saving and material reduction. However, the current additive manufacturing method is too universal. For different structures, a unified printing method is often used, which greatly weakens the strength and other properties of the 3D printed blades. At the same time, because the strength requirements of various parts are not consistent, it is necessary to take strengthening measures for certain key parts to improve the performance of the parts. These key problems are currently difficult to be effectively solved. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide an optimized additive manufacturing method for aviation blades based on anisotropy and constraint adaptation.

[0004] The technical solution adopted by the present invention is as follows: an optimized additive manufacturing method for aviation blades based on anisotropy and constraint adaptation, wherein the 3D printing device used has a magnetic field constraint structure and an ultrasonic constraint structure;

[0005] The method comprises the following steps:

[0006] Step 1: Based on the aircraft engine blade model, perform finite element analysis in the finite element analysis module of the additive manufacturing intelligent system to analyze the strength requirements of each part of the aircraft engine blade and the optimal material stacking direction:

[0007] Step 2: After obtaining the optimal material stacking direction of each part through real-time analysis, three thresholds of each part are calculated, namely, the strength of improved material stacking alone, the strength of integrated improved material stacking and magnetic field constraint, and the strength of integrated improved material stacking, magnetic field constraint and ultrasonic constraint;

[0008] Step 3: After obtaining the three threshold strengths, compare the three threshold strengths with the minimum safety performance required for the aircraft engine blade to determine the additive manufacturing method to be used for this part;

[0009] Step 4: After determining the additive manufacturing method for this part of the aircraft engine blade, perform adaptive printing and manufacturing;

[0010] If the minimum safety performance required for the aero-engine blade is within the first threshold, 3D printing will be started directly to complete the optimized additive manufacturing process;

[0011] If the minimum safety performance required for the aircraft engine blade is between the first threshold strength and the second threshold strength, or between the second threshold strength and the third threshold strength, the required magnetic field confinement strength and / or ultrasonic strength is calculated in real time, and the optimized additive manufacturing process is completed.

[0012] Among them, in step one, the optimal stacking direction of each part of the aircraft engine blade is first analyzed on the simulation system, so that the material stacking direction can be adjusted accordingly according to the different structures, which will greatly improve the strength performance of the blade.

[0013] Preferably, the optimal stacking direction is determined based on the Tsai-Hill failure criterion. Anisotropic materials have significant differences in mechanical properties in different directions. The Tsai-Hill failure criterion is developed based on the maximum strain energy theory. It takes into account the strength characteristics of the material in different principal directions and the interaction between different stress components. It uses a comprehensive expression to determine whether the material has failed, accurately evaluates the failure risk of the structure, and can effectively describe the anisotropic mechanical properties of the additively manufactured structure.

[0014] The magnetic field constraint structure is at least one set of excitation coils wound outside the nozzle of the 3D printer; the ultrasonic constraint structure is an ultrasonic constraint instrument installed next to the nozzle of the 3D printer. The integration of magnetic field constraint and ultrasonic constraint can refine the microstructure inside the alloy and enhance the strength performance of the aircraft engine blade.

[0015] Since the minimum safety performance required for each part of the aircraft engine blade is different, each part is calculated separately in steps 2 and 3 to provide a targeted additive manufacturing method to achieve anisotropy and constraint adaptation. Among them, within the first threshold range, it means that the optimized additive manufacturing process of this part can be completed by relying solely on the anisotropic topology optimization additive manufacturing method, so 3D printing can be started directly to complete the optimized additive manufacturing process; between the first threshold and the second threshold strength, it means that relying solely on the anisotropic topology optimization additive manufacturing method cannot meet the strength requirements of the target part, and it is necessary to combine certain magnetic field constraints to enhance the strength performance of the printed part, and the required magnetic field constraint strength is calculated according to the required strength performance to improve the structural strength of the part; between the second threshold strength and the third threshold strength, it means that relying solely on the anisotropic topology optimization additive manufacturing method combined with magnetic field constraints cannot meet the strength requirements of the target part, and it is necessary to comprehensively improve material accumulation, magnetic field constraints and ultrasonic constraints, and calculate the required magnetic field constraint strength and ultrasonic constraint strength according to the required strength performance to improve the structural strength of the part.

[0016] The beneficial effects of the present invention are as follows: the present invention first performs finite element analysis on aircraft engine blades based on a model design method, determines and analyzes the material stacking direction for obtaining optimal strength in different areas on the aircraft blades, and prints in this direction. At the same time, the minimum safety performance required for the aircraft engine blades is compared, the magnetic field constraint force and the ultrasonic intensity are adaptively changed, and the microstructure inside the alloy is refined so that the processed aircraft engine blades meet the strength standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the present invention.

[0018] Figure 1 A schematic diagram of a 3D printing device used in the present invention;

[0019] Figure 2 It is a schematic flow chart of the manufacturing method of the present invention;

[0020] Figure 3 It is a schematic diagram of step three of the present invention;

[0021] In the figure, 1-substrate, 2-nozzle, 3-excitation coil, 4-ultrasonic restraint instrument. DETAILED DESCRIPTION

[0022] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0023] The present invention provides an optimized additive manufacturing method for aviation blades based on anisotropy and constraint adaptation, wherein the 3D printing device used has a magnetic field constraint structure and an ultrasonic constraint structure, specifically, Figure 1 As shown, the magnetic field constraint structure is a set of excitation coils wound outside the nozzle of the 3D printer; the ultrasonic constraint structure is an ultrasonic constraint instrument installed next to the nozzle of the 3D printer. The integration of magnetic field constraint and ultrasonic constraint can refine the microstructure inside the alloy and enhance the strength performance of the aircraft engine blade.

[0024] like Figure 2 As shown, the method comprises the following steps:

[0025] Step 1: Based on the aircraft engine blade model, perform finite element analysis in the finite element analysis module of the additive manufacturing intelligent system to analyze the strength requirements of each part of the aircraft engine blade and the optimal material stacking direction:

[0026] In the finite element analysis module of the additive manufacturing intelligent system, after meshing and loading the imported model, the stress state of each unit of the model, including normal stress and shear stress, can be obtained. Substitute these stress values ​​into the expression of the Tsai-Hill failure criterion to determine whether each unit meets the failure condition, thereby determining the area in the model where failure may occur. According to the calculation results of the Tsai-Hill failure criterion, the model is optimized. If the stress state of certain areas is close to or exceeds the threshold of the failure criterion, the stress level of these areas is reduced by adjusting the material stacking direction so that they meet the requirements of the failure criterion.

[0027] Specifically,

[0028] min ρ F=F(u(ρ),ρ)=∫ Ω f(u(ρ),ρ)dV,

[0029] satisfy,

[0030] G0(ρ)=∫ Ω ρdV-V0≤0,

[0031] G j (u(ρ), ρ)≤0, and H i (u(ρ), ρ)=0, with j=1,...,m, and i=0,...,n;

[0032] The objective function F(u(ρ), ρ) usually corresponds to flexibility, and when the flexibility is minimized, it equivalently leads to maximization of the structural stiffness.

[0033] Among the other symbols, ρ(x) is an unknown variable, indicating whether there is a substance at the x position. 1 indicates that there is a substance, and 0 indicates that there is no substance. This variable can also be regarded as a pseudo-density and is assumed to be any value in [0, 1], thereby simplifying the solution of the optimization problem.

[0034] The symbol u(ρ) denotes the relevant state domain that depends on the unknown variables, while V corresponds to the design space, which can be defined by additional constraints that determine the allowed volume, fixed model area, and other factors.

[0035] About the function H i , G j , i = 0, ..., n, j = 0, ... m, corresponding to functional constraints (equalities and inequalities), the first inequality constraint (j = 0) corresponds to a given volume constraint (V0). The finite element method (FEM) is often used to estimate the value of u(r), since differential equations in general domains usually do not have analytical solutions corresponding to u.

[0036] Step 2: After obtaining the optimal material stacking direction of each part through real-time analysis, three thresholds of each part are calculated at the same time, namely, the strength of improved material stacking only, the strength of integrated improved material stacking and magnetic field constraint, and the strength of integrated improved material stacking, magnetic field constraint and ultrasonic constraint;

[0037]

[0038] Where σ is the von Mises strength, σ1, σ2, and σ3 are the strength of improved material stacking alone, the strength of the fusion of improved material stacking and magnetic field constraint, and the strength under the comprehensive improved material stacking, magnetic field constraint, and ultrasonic constraint, respectively.

[0039] Energy required E V =P L / (v s *h s *D S );

[0040] Where E V : energy value; P: power; L: length; v s : speed; h s : Height; D S : Layer thickness.

[0041] In the deposition process of additive manufacturing, the single heat source model can be simplified to a point heat source. The analytical expression of the temperature field can be expressed as follows:

[0042]

[0043] Where T0 is the ambient temperature, Q is the heat input, λ is the thermal conductivity, R is the distance from the target point to the center of the heat source, v0 is the heat source velocity, and a is the thermal diffusion coefficient.

[0044] The following is the analytical solution of the dimensionless distribution:

[0045]

[0046] In the formula,

[0047]

[0048] Dimensionless coordinates:

[0049] Dimensionless distance:

[0050] The current distribution in the molten pool is as follows:

[0051]

[0052] In the formula, Jz is the Z component of the current density, J r is the r component of current density, I is the welding current, σ c0 is the current density distribution coefficient when Z = 0, σ c is the current density distribution coefficient at any height, d is the arc distribution coefficient, which is 0.5 under the axisymmetric model, L is the arc height, r is the wire radius, and ζ is the molten pool distribution coefficient.

[0053] The magnetic field distribution in the molten pool is as follows:

[0054]

[0055] The longitudinal coil is energized to generate external LMF in the molten pool, where B am is the external LMF intensity and μ0 is the conductivity.

[0056] By comprehensively improving the strength under material accumulation, magnetic field confinement and ultrasonic confinement, the interaction between the external LMF and the divergence of the welding current will generate electromagnetic force, and the magnetic force distribution is shown in the following formula:

[0057]

[0058] When ultrasonic additive manufacturing is used, the stress σ is:

[0059]

[0060] Where ε is the equivalent plastic strain, is the dimensionless plastic strain rate, T* is the homologous temperature, where T* = (TT room ) / (T melt -T room ). T is the actual temperature, T room is the ambient temperature, T melt is the melting point of the material. The five material constants are A, B, t, C, and m, where A is the yield stress, B and t are the strain hardening effect, and C is the strain rate constant.

[0061] Step 3: After obtaining the three threshold intensities, Figure 3 As shown, the three threshold strengths are compared with the minimum safety performance required for the aero-engine blade to determine the additive manufacturing method to be used for this part;

[0062] Step 4: After determining the additive manufacturing method for this part of the aircraft engine blade, perform adaptive printing and manufacturing;

[0063] If the minimum safety performance required for the aero-engine blade is within the first threshold, 3D printing will be started directly to complete the optimized additive manufacturing process;

[0064] If the minimum safety performance required for an aircraft engine blade is between the first threshold and the second threshold strength, or between the second threshold strength and the third threshold strength, the required magnetic field constraint strength and / or ultrasonic strength can be calculated in real time by solving the approximate solution of the boundary value problem of the partial differential equation using the FEM finite element method, and the additive manufacturing process can be optimized.

[0065] The magnetic field confinement strength is shown in the formula.

[0066]

[0067] J=σE+J e ;

[0068]

[0069] Where B is the magnetic induction intensity, J is the magnetic polarization intensity, H is the magnetic field intensity, A is the magnetic vector potential, and E is the electric field intensity.

[0070] The ultrasonic intensity is shown in the formula.

[0071]

[0072] Where p is the sound pressure intensity, u represents the particle velocity, c represents the propagation velocity, ρ represents the medium density, and the product ρc is called the acoustic impedance of the medium.

[0073] A person skilled in the art can understand that all or part of the steps in the above-mentioned embodiment method can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, such as ROM / RAM, disk, CD-ROM, etc.

[0074] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. An optimized additive manufacturing method for aviation blades based on anisotropy and constraint adaptation, characterized in that: The 3D printing device it uses has a magnetic field constraint structure and an ultrasonic constraint structure; The method comprises the following steps: Step 1: Based on the aircraft engine blade model, perform finite element analysis in the finite element analysis module of the additive manufacturing intelligent system to analyze the strength requirements of each part of the aircraft engine blade and the optimal material stacking direction: Step 2: After obtaining the optimal material stacking direction of each part through real-time analysis, three thresholds of each part are calculated, namely, the strength of improved material stacking alone, the strength of integrated improved material stacking and magnetic field constraint, and the strength of integrated improved material stacking, magnetic field constraint and ultrasonic constraint; Step 3: After obtaining the three threshold strengths, compare the three threshold strengths with the minimum safety performance required for the aircraft engine blade to determine the additive manufacturing method to be used for this part; Step 4: After determining the additive manufacturing method for this part of the aircraft engine blade, perform adaptive printing and manufacturing; If the minimum safety performance required for the aero-engine blade is within the first threshold, 3D printing will be started directly to complete the optimized additive manufacturing process; If the minimum safety performance required for the aircraft engine blade is between the first threshold strength and the second threshold strength, or between the second threshold strength and the third threshold strength, the required magnetic field confinement strength and / or ultrasonic strength is calculated in real time, and the optimized additive manufacturing process is completed.

2. The optimized additive manufacturing method for aviation blades based on anisotropy and constraint adaptation according to claim 1, characterized in that: The optimal stacking direction is determined based on the Tsai-Hill failure criterion.

3. The optimized additive manufacturing method for aviation blades based on anisotropy and constraint adaptation according to claim 1, characterized in that: The magnetic field confinement structure is at least one group of excitation coils wound outside the nozzle of the 3D printer.

4. The optimized additive manufacturing method for aviation blades based on anisotropy and constraint adaptation according to claim 1, characterized in that: The ultrasonic constraint structure is an ultrasonic constraint instrument installed next to the nozzle of the 3D printer.

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