Metal 3D printing laser based on topological optimization and design method

Abstract

The invention discloses a metal 3D printing laser based on topological optimization and a design method, and belongs to the technical field of design methods, the laser is widely applied to the fields of spaceflight exploration, automobiles and the like, and metal 3D printing becomes a hot spot of laser processing and manufacturing due to high speed and low cost. According to a traditional structure design method, when weight reduction is carried out on a structure, materials are removed firstly, then material force is used for checking the strength, and when the materials are removed, the rigidity and vibration stability of the structure under various working conditions cannot be guaranteed, so that the invention provides a multi-working-condition multi-target topological optimization method. The mass of the laser is reduced, the performance of the structure is optimized, and a good effect is achieved.

Description

Technical Field

[0001] The present invention relates to a design method, in particular to a metal 3D printing laser and a design method based on topology optimization, belonging to the technical field of design methods. Background Art

[0002] The processing of solid-state laser structures often relies on traditional subtractive manufacturing methods. The use of subtractive manufacturing methods will impose some restrictions on the mechanical design of the laser, which is mainly reflected in the following aspects. For some small-volume lasers, the structural components of the laser are small in size and thin in wall thickness, and the distance between the laser structural components is relatively close, which has high requirements for the tools and equipment for processing the laser. Therefore, most subtractive manufacturing solid-state lasers use the traditional method of processing mechanical structures in parts and then assembling them. In order to achieve higher automation and avoid mechanical assembly to the greatest extent, Fabian Kranert proposed a solid-state laser based on deposition fusion molding (FDM) additive manufacturing technology. The optical elements were successfully embedded in the mechanical structure using the print-pause-print method of the FDM printer. Since FDM molding uses filamentous plastic as the material, it has the characteristics of lower melting temperature and higher precision, so that the optical elements can be conveniently placed directly on the molded structure, and continue to print on the optical elements and plastic, so that the optical elements are accurately and firmly embedded in the printed structure. The above methods have great limitations on processing materials. Plastic materials are often easy to degrade, have poor thermal conductivity, and are not as strong as metal materials, which seriously limits the application of additive manufacturing lasers. Therefore, a metal 3D printing laser and design method based on topology optimization are designed to solve the above problems. Summary of the invention

[0003] The main purpose of the present invention is to provide a metal 3D printing laser and design method based on topology optimization.

[0004] The purpose of the present invention can be achieved by adopting the following technical solutions:

[0005] A metal 3D printing laser design method based on topology optimization includes the following steps:

[0006] Step 1: Design the optical base structure;

[0007] Step 2: Perform finite element simulation before optimization to calculate the structural performance parameters of the laser under appropriate given working conditions, mainly obtaining information on structural flexibility and modal frequency;

[0008] Step 3: Topology optimization of the optical base;

[0009] Step 4: Set the objective function of topology optimization to weighted flexibility;

[0010] Step 5: Constrain the feasible solution region of topology optimization;

[0011] Step 6: Reconstruct the laser based on the density cloud map obtained by topology optimization;

[0012] Step 7: Perform finite element analysis on the remodeled laser to verify the structural performance of the laser;

[0013] Step 8: Install the laser's optical components and assemble the entire laser.

[0014] Preferably, in step one, the optical base structure includes a base plate and an optical frame and is designed in one structure.

[0015] Preferably, the mathematical expression of topology optimization in step 3 is as follows: The mathematical model of the optimized design can be expressed as follows:

[0016] Findx=(x1,x2,…,x n ) T ;

[0017]

[0018] Where: x e is the unit relative density design variable, and its value range is 0-1;

[0019] x min is the minimum relative density;

[0020] x is the vector of design variables;

[0021] N is the number of design variables;

[0022] c is the overall flexibility;

[0023] E e is the unit elastic modulus;

[0024] U is the overall displacement matrix;

[0025] F is the overall force matrix;

[0026] K is the overall stiffness matrix;

[0027] k e is the element stiffness matrix.

[0028] Preferably, in step 4, if there are n working conditions, their weights are x1, x2, ... x n , then the objective function of topology optimization becomes the following:

[0029]

[0030] Preferably, in step 2, load analysis and topology optimization analysis are performed according to the acceleration part of GJB150.15A-2009 "Military Equipment Laboratory Environmental Experiment Method".

[0031] Beneficial technical effects of the present invention:

[0032] The present invention provides a metal 3D printing laser and design method based on topology optimization. Lasers are widely used in aerospace exploration, automobiles and other fields. Metal 3D printing has become a hot spot in laser processing and manufacturing due to its high speed and low cost. Traditional structural design methods often remove materials first and then use material mechanics to check strength when reducing the weight of the structure, and cannot guarantee the stiffness and vibration stability of the structure under various working conditions when removing materials. This paper proposes a multi-condition and multi-objective topology optimization method for structural optimization and weight reduction of lasers, and has achieved good results. This method can improve the flexibility of the structure under various working conditions, reduce the maximum stress under various working conditions, and improve the modal frequency of the laser at the same time, and avoid the alternation of modal frequencies that are easy to occur in the optimization process involving the high target of improving the modal frequency, which affects the effect of modal frequency optimization. At the same time, the objective function of this method is simple. Through the steepest descent method, this method can easily find the optimal solution to the optimization problem, which is conducive to the engineering realization of laser structure design. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a design diagram of an optical base of a laser according to a preferred embodiment of a metal 3D printing laser and a design method based on topology optimization of the present invention.

[0034] Figure 2 This is a graph of acceleration data of a laser structure performance test according to a preferred embodiment of a metal 3D printing laser and design method based on topology optimization of the present invention.

[0035] Figure 3 This is an upward acceleration stress cloud diagram according to a preferred embodiment of a metal 3D printing laser and design method based on topology optimization of the present invention.

[0036] Figure 4 This is an acceleration stress cloud diagram of a downward acceleration test according to a preferred embodiment of a metal 3D printing laser and design method based on topology optimization of the present invention.

[0037] Figure 5 This is an acceleration stress cloud diagram of a forward acceleration test according to a preferred embodiment of a metal 3D printing laser and design method based on topology optimization of the present invention.

[0038] Figure 6This is an acceleration stress cloud diagram of a backward acceleration test according to a preferred embodiment of a metal 3D printing laser and design method based on topology optimization of the present invention.

[0039] Figure 7 This is an acceleration stress cloud diagram of a leftward acceleration test according to a preferred embodiment of a metal 3D printing laser and design method based on topology optimization of the present invention.

[0040] Figure 8 This is the 7th-order vibration shape diagram of a preferred embodiment of a metal 3D printing laser and design method based on topology optimization according to the present invention.

[0041] Fig. 9 This is the 8th-order vibration shape diagram of a preferred embodiment of a metal 3D printing laser and design method based on topology optimization according to the present invention.

[0042] Fig.10 This is the 9th-order vibration shape diagram of a preferred embodiment of a metal 3D printing laser and design method based on topology optimization according to the present invention.

[0043] Fig.11 It is a density cloud diagram of topology optimization results according to a preferred embodiment of a metal 3D printing laser and design method based on topology optimization of the present invention.

[0044] Fig.12 This is a diagram of a laser model reconstructed after topology optimization according to a preferred embodiment of a metal 3D printing laser and design method based on topology optimization of the present invention.

[0045] Fig.13 This is an upward acceleration stress cloud diagram according to a preferred embodiment of a metal 3D printing laser and design method based on topology optimization of the present invention.

[0046] Fig.14 This is an upward acceleration stress cloud diagram according to a preferred embodiment of a metal 3D printing laser and design method based on topology optimization of the present invention.

[0047] Fig.15 This is an upward acceleration stress cloud diagram according to a preferred embodiment of a metal 3D printing laser and design method based on topology optimization of the present invention.

[0048] Fig.16 This is an upward acceleration stress cloud diagram according to a preferred embodiment of a metal 3D printing laser and design method based on topology optimization of the present invention.

[0049] Fig.17This is an upward acceleration stress cloud diagram according to a preferred embodiment of a metal 3D printing laser and design method based on topology optimization of the present invention.

[0050] Fig.18 This is the 7th-order modal vibration shape diagram of a preferred embodiment of a metal 3D printing laser and design method based on topology optimization according to the present invention.

[0051] Fig.19 This is the 8th-order modal vibration shape diagram of a preferred embodiment of a metal 3D printing laser and design method based on topology optimization according to the present invention.

[0052] Fig. 20 This is the 9th-order modal vibration shape diagram of a preferred embodiment of a metal 3D printing laser and design method based on topology optimization according to the present invention.

[0053] Fig.21 This is a three-dimensional model diagram of the laser after assembly is completed according to a preferred embodiment of a metal 3D printing laser and design method based on topology optimization of the present invention. DETAILED DESCRIPTION

[0054] In order to make the technical solution of the present invention more clear and specific to those skilled in the art, the present invention is further described in detail below in conjunction with embodiments and drawings, but the implementation manner of the present invention is not limited thereto.

[0055] like Figure 1-Figure 21 As shown, this embodiment provides a metal 3D printing laser design method based on topology optimization, and designs an optical base structure including a base plate and an optical mirror frame in one structure.

[0056] Finite element simulation is performed before optimization to calculate the structural performance parameters of the laser under appropriate given working conditions, mainly obtaining information on structural flexibility and modal frequency.

[0057] The mathematical expression of topology optimization is as follows: The mathematical model of optimization design can be expressed as follows:

[0058] Findx=(x1,x2,…,x n ) T ;

[0059]

[0060] Where x e ——Design variable (unit relative density), its value range (0-1);

[0061] x min - minimum relative density (to avoid singularities);

[0062] x——vector of design variables;

[0063] N is the number of design variables;

[0064] c – overall flexibility;

[0065] E e ——Unit elastic modulus (cell equivalent elastic modulus);

[0066] U——overall displacement matrix;

[0067] F——overall force matrix;

[0068] K——overall stiffness matrix;

[0069] k e ——element stiffness matrix;

[0070] Set the objective function of topology optimization to weighted flexibility. If there are n working conditions, their weights are x1, x2, …x n , then the objective function of topology optimization becomes the following:

[0071]

[0072] Constrain the feasible solution region of topology optimization, constrain the 7th, 8th, 9th or higher order modal frequencies of free modes (the first 6 orders of free modes are rigid body modes, and their modal frequencies are close to 0, which are of no value to structural optimization. The modal frequencies starting from the 7th order are the most important, and the importance decreases with the order. Generally, constraining the first three orders starting from the 7th order can guarantee the performance of the structure). During the optimization process, the modal order decreases with the adjacent frequency interpolation of iterations, and eventually modal exchange occurs, resulting in unstable or non-convergent iterations. Therefore, the mode is not set as the optimization target, but instead constrained in the form of constraints, so that the modal frequency of the feasible solution must be limited to a sufficiently wide range without intersection. This can not only optimize the modal frequency, but also ensure that the iteration does not slow down the mode or the iteration is unstable and non-convergent.

[0073] Reconstruct the laser based on the density cloud map obtained by topology optimization.

[0074] Finite element analysis is performed on the remodeled laser to verify the structural performance of the laser.

[0075] Install the laser's optical components and the entire laser assembly.

[0076] In a specific embodiment;

[0077] First, design the base structure of the laser, such as Figure 1 As shown;

[0078] Pre-finite element simulation was performed. In this case, the load analysis and topology optimization analysis were performed according to the acceleration part of GJB150.15A-2009 "Military Equipment Laboratory Environment Experiment Method", and the structural performance required to meet the experimental requirements was taken as the standard working condition as shown in Table 1 and Figure 2 As specified;

[0079] Table 1 Acceleration data of laser structure performance test

[0080]

[0081] Further upward acceleration test is conducted;

[0082] The upward acceleration test results are as follows: Figure 3 As shown;

[0083] Downward acceleration test;

[0084] The downward acceleration test results are as follows: Figure 4 As shown;

[0085] Forward acceleration test;

[0086] Forward acceleration test results are as follows Figure 5 As shown;

[0087] Backward acceleration test;

[0088] The backward acceleration test results are as follows: Figure 6 As shown;

[0089] Left acceleration test;

[0090] The leftward acceleration test results are as follows: Figure 7 As shown;

[0091] Rightward acceleration test;

[0092] The structure is symmetrical, and the working conditions are symmetrical.

[0093] Modal analysis;

[0094] The 7th, 8th and 9th order modal vibration shapes are as high as 1408HZ, 2319HZ and 2851HZ respectively. Figure 8 , Fig. 9 and Fig.10 As shown;

[0095] The present invention determines the weight according to the flexibility of various working conditions, so that the working conditions with large flexibility can be optimized as much as possible. Therefore, the weight of each working condition is directly taken as 1. At the same time, according to the modal frequency constraint method in the method, the modal analysis results constrain the 7th, 8th, and 9th order modes, making them higher than 1400HZ, 2300HZ, and 2800HZ respectively. The density cloud diagram of the topology optimization results is as follows: Fig.11 As shown;

[0096] Reconstruct the laser structure based on the topology optimization results;

[0097] After topology optimization, the laser base structure lost 24.39% of its weight. The reconstructed structure is as follows: Fig.12 As shown;

[0098] Simulation comparison after topology optimization;

[0099] Upward acceleration test;

[0100] Under this condition, the maximum stress of the laser decreased by 19.66%. The upward acceleration test results are as follows: Fig.13 As shown;

[0101] Downward acceleration test Under this condition, the maximum stress of the laser decreased by 19.67%. The results of the downward acceleration test are as follows Fig.14 As shown;

[0102] Forward acceleration test;

[0103] Under this condition, the maximum stress of the laser decreased by 4.48%. The forward acceleration test results are as follows: Fig.15 As shown;

[0104] Backward acceleration test;

[0105] Under this condition, the maximum stress of the laser decreased by 4.52%. The forward acceleration test results are as follows: Fig.16 As shown;

[0106] Left acceleration test;

[0107] Under this condition, the maximum stress of the laser decreased by 9.55%;

[0108] Rightward acceleration test;

[0109] Since the structure is completely symmetrical on both sides and the working conditions are exactly the same;

[0110] Modal analysis;

[0111] After optimization, the 7th and 8th order modal frequencies of the laser are slightly increased, while the 9th order is slightly decreased by Hz, reaching 1420HZ, 2321HZ and 2850HZ respectively, and there is no alternation of modal orders. In fact, the constraints on modal frequencies can be further improved to make the feasible solution in the range that increases the modal frequencies of key orders (if such a solution exists). The vibration shape diagram of the key order modal is shown in the figure below: Fig.18 , Fig.19 and Fig. 20 shown.

[0112] Printing laser;

[0113] By simulating the structural performance of the laser to meet the requirements, the various parts of the laser are 3D printed and assembled. The entire laser processing and manufacturing is completed. The assembled laser is Fig.21 As shown;

[0114] The above description is only a further embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and concepts of the present invention within the scope disclosed by the present invention, which belong to the protection scope of the present invention.

Claims

1. A metal 3D printing laser design method based on topology optimization, characterized in that: The steps include: Step 1: Design the optical base structure; Step 2: Perform finite element simulation before optimization to calculate the structural performance parameters of the laser under appropriate given working conditions, mainly obtaining information on structural flexibility and modal frequency; Step 3: Topology optimization of the optical base; Step 4: Set the objective function of topology optimization to weighted flexibility; Step 5: Constrain the feasible solution region of topology optimization; Step 6: Reconstruct the laser based on the density cloud map obtained by topology optimization; Step 7: Perform finite element analysis on the remodeled laser to verify the structural performance of the laser; Step 8: Install the laser's optical components and assemble the entire laser.

2. A metal 3D printing laser design method based on topology optimization according to claim 1, characterized in that: In step one, the optical base structure includes a base plate and an optical frame and is designed in one structure.

3. The metal 3D printing laser design method based on topology optimization according to claim 1, characterized in that: The mathematical expression of topology optimization in step 3 is as follows: The mathematical model of the optimization design can be expressed as follows: Findx=(x1,x2,…,x n ) T ; Where: x e is the unit relative density design variable, and its value range is 0-1; x min is the minimum relative density; x is the vector of design variables; N is the number of design variables; c is the overall flexibility; E e is the unit elastic modulus; U is the overall displacement matrix; F is the overall force matrix; K is the overall stiffness matrix; k e is the element stiffness matrix; u e is the unit displacement vector.

4. The metal 3D printing laser design method based on topology optimization according to claim 1, characterized in that: In step 4, if there are n working conditions, their weights are x1, x2, … x n , then the objective function of topology optimization becomes the following: Where: x1…x n is the weight; E e is the unit elastic modulus; k e is the element stiffness matrix; u e is the unit displacement vector.

5. The metal 3D printing laser design method based on topology optimization according to claim 1, characterized in that: In step 2, load analysis and topology optimization analysis are performed according to the acceleration part of GJB150.15A-2009 Military Equipment Laboratory Environmental Experiment Method.

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