A computational model generation method for high-frequency electromagnetic simulation

Abstract

This invention belongs to the field of preprocessing for high-frequency electromagnetic simulation, specifically a method for generating computational models for high-frequency electromagnetic simulation. The invention first establishes a CAD model, then marks the analytical features and parameters of the CAD model in CAE software, performs geometric processing and Boolean operations on it, and finally retains the vacuum and medium computational domains. By judging the collision relationships between model bodies and performing Boolean operations on five possible complete collision relationships, it ensures that there is no loss of attribute information (zero distortion) during the model conversion, generating a finite element calculation model, which is then applied to electromagnetic simulation software for rapid and accurate modeling, design checking, etc. This avoids the huge workload of traditional manual interactive operations, as well as the enormous workload of modifying and calculating the corresponding CAE model when the CAD model needs frequent modification. It is of great significance for realizing collaborative design and modeling between CAD and CAE software.

Description

Technical Field

[0001] This invention belongs to the field of preprocessing for high-frequency electromagnetic simulation, specifically a method for generating computational models for high-frequency electromagnetic simulation, which achieves efficient and high-precision conversion from CAD geometric models to finite element computational models. Background Technology

[0002] Electromagnetic simulation software can quickly and accurately obtain the electromagnetic design analysis results of a system and simulate the electromagnetic field distribution. Traditional methods that separate CAD and CAE processes, performing tasks such as CAD model to finite element model conversion, mesh generation, and electromagnetic solution within electromagnetic simulation software, are not only extremely inefficient but also fail to guarantee quality. Traditional commercial CAD and CAE software are relatively independent systems. The structural optimization iterations required to complete the CAD model to finite element model conversion within these systems involve a continuous cycle of "modeling – optimization – remodeling." The traditional manual interactive model generation process is extremely labor-intensive, requiring significant time to manually determine model interference (such as model intersections and overlaps) and perform Boolean operations (including Boolean union, Boolean subtraction, and Boolean intersection), leading to inefficiency.

[0003] The CAD / CAE (Computer-Aided Engineering) fusion technology can fully leverage its advantages in electromagnetic simulation software, enabling rapid and accurate modeling and simulation. This ensures the quality and efficiency of the conversion from CAD geometric models to finite element calculation models in CAD / CAE fusion, representing a new breakthrough in improving electromagnetic solution efficiency and simulation quality.

[0004] Currently, CAD / CAE integration mainly focuses on integrating CAD functions with CAE software. Software such as ANSYS (a large-scale general-purpose finite element analysis software) and Abaqus (a finite element software for engineering simulation) have added solid modeling functions. However, these systems have not completely solved the problem of the huge workload of manual interactive calculation model generation faced by independent CAD and CAE systems. There are two common ways to generate calculation models: (1) manual modeling in CAE software; (2) importing CAD models into CAE software using a data interface. The former method requires a lot of manual operation by the user, which is time-consuming and laborious. At the same time, this method cannot share the information of the established CAD model. The design and analysis models are unrelated and prone to errors. The latter method involves exporting the geometric model as a neutral file in the CAD system, then importing the file into the CAE system to generate the geometric model, and then using the automatic mesh generation function to establish a finite element mesh model. In actual operation, this method has many problems: First, it requires a lot of time to simplify the model because the CAD model is design-oriented and has many structural details. These details have little impact on the final analysis results, but consume a lot of calculation time. Some may even lead to incorrect analysis results. Therefore, it is necessary to simplify the model manually. More importantly, this method requires manual reconstruction of the analytical features and their parameters. Therefore, researching how to achieve efficient and high-quality automatic generation from CAD geometric models to finite element calculation models is of great significance. Summary of the Invention

[0005] To address the aforementioned problems and shortcomings, and to solve the issues of low efficiency and low accuracy in generating computational models for existing electromagnetic simulation modeling, this invention proposes a computational model generation method for high-frequency electromagnetic simulation based on the electromagnetic field theory that electromagnetic waves can only propagate in vacuum and media. By reading the established CAD model, marking the analytical features and parameters of the CAD model in CAE software, performing geometric processing and Boolean operations on it, and finally retaining the vacuum and media computational domains, the conversion from the geometric model to the finite element model is realized, and the finite element model is quickly established.

[0006] A computational model generation method for high-frequency electromagnetic simulation, comprising the following steps:

[0007] Step 1: Perform CAD modeling of the target electronic device, including setting boundary conditions, excitations, and materials. The program reads the created CAD (Computer-Aided Design) model file (SAT file, 3D CAD design file format); creates a model body list ENTITYLIST, and saves all bodies in the model into ENTITYLIST.

[0008] The established CAD model files, except for the air box, do not allow two metal bodies of different materials to intersect / overlap / include / include each other, nor do they allow two non-metal bodies of different materials to intersect / overlap / include / include each other; the wave port excitation is that one side is completely backed by a metal body and the other side is not completely backed by a metal body.

[0009] Step 2: Mark the attributes of the bodies in the ENTITYLIST obtained in Step 1 using the attribute manipulation functions of ACIS (a 3D geometry modeling engine for object-oriented software technology), remove useless (without boundary or encrypted attributes) pieces from the list, and update the model body list ENTITYLIST.

[0010] Sheet: A thin-walled shell with a surface structure; all faces of a sheet are bidirectional. Solid: All bodies other than sheet bodies; all faces of a solid are unidirectional. Since the index of the removed body is not removed after removing a useless sheet body, it will point to an empty body; therefore, the original model list needs to be updated after removing a useless sheet body.

[0011] Step 3: For the updated list ENTITYLIST from Step 2, use the collision function in ACIS to determine the pairwise relationships and record them.

[0012] The pairwise relationships output by the collision function include: unknown relationship, no collision, unclassified, contain, contain and connect, connect, coincide, and intersect.

[0013] Step 4: For the two bodies in Step 3 whose pairwise relationships are containment, containment connection, connection, intersection, and overlap, use the single / double-sided function in ACIS to determine whether they are solid bodies or sheet bodies, and record the results.

[0014] Get all faces of two bodies that are in a collision relationship. Use the ACIS function to determine whether the obtained faces are one-way or two-way. If there are one-way faces in the body, it is a solid; otherwise, if all faces in the body are two-way, the body is a sheet.

[0015] Step 5: If both bodies recorded in Step 4 are solids, obtain their collision relationship and perform corresponding Boolean operations based on their collision relationship; if one of the two bodies recorded in Step 4 is a sheet body, obtain the boundary determination to determine whether the sheet body is a waveport excitation or another boundary sheet body, and perform corresponding Boolean operations.

[0016] Boolean operations are used to process the model while transferring its analytical features and parameters, thereby updating the ENTITYLIST list.

[0017] The underlying principle of Boolean operations for different types of relationships is that electromagnetic waves can only propagate in a vacuum and in a medium, all metal bodies need to be removed, and the skin effect inside the conductor needs to be considered. Therefore, Boolean operations are needed to complete the model processing while transferring the analytical features and parameters of the model.

[0018] Since useless pieces have been removed in step 2, and pieces are only created for cases where there are stimuli, there will be no cases where two different pieces of stimuli contain / are connected / intersect / coincide (the boundary correctness has been determined in the model check boundary check before the calculation model is generated). The case of connection does not need to be processed. Therefore, the case where both are pieces is not considered.

[0019] Step 6: Mark all pieces in the updated list ENTITYLIST from Step 5 as non-metallic bodies, create a computational model list ENTITYLIST1, and store all non-metallic bodies from the list ENTITYLIST into the newly created computational model list ENTITYLIST1.

[0020] Step 7: Write out the finite element calculation model from the ENTITYLIST1 list of calculation models obtained in Step 6, thus obtaining the calculation model applicable to high-frequency electromagnetic simulation.

[0021] Furthermore, the specific Boolean operation rules for different situations in step 5 are as follows:

[0022] A. For the case where both entities are solids:

[0023] a) If the collision type of the two bodies is containment / containment connection: perform a Boolean operation to subtract the smaller body from the larger body, and retain the smaller body; if the larger body is metallic and the smaller body is non-metallic, then, following the above rules, the surface of the smaller non-metallic body should be (manually) assigned a metallic boundary.

[0024] b) If the collision type of the two bodies is intersecting / coincident: non-metallic body and metallic body, then the non-metallic body is subtracted from the metallic body, and the metallic body is retained; if they are of the same material, choose one body as the minuend and subtract the other body as the subtrahend, and retain the subtrahend.

[0025] c) If the collision type of the two bodies is contact: subtract the metal body from the non-metal body, and retain the metal body.

[0026] B. For cases where one of the bodies is a slice, obtain the properties of that slice:

[0027] a) If it is a waveport excitation, determine whether both sides are completely backed by the metal: In the correct model, the waveport excitation is that one side is completely backed by the metal body and the other side is not completely backed by the metal body. Subtract the metal body on the side that is not completely backed by the metal body from the waveport surface, and retain the metal body. No processing is done on the side that is completely backed by the metal body.

[0028] b) If there are other boundary conditions, subtract the metal body from the sheet body and retain the metal body.

[0029] In summary, this invention ensures the correct transmission of model boundary excitation and other attributes by judging collision relationships between model bodies and performing Boolean operations on five possible complete collision relationships. This means that no attribute information is lost before and after model conversion, achieving a "zero-distortion" conversion. This enables the generation of finite element calculation models in electromagnetic simulation preprocessing, which can then be applied to electromagnetic simulation software for rapid and accurate modeling and design checks. It avoids the enormous workload of traditional manual interactive operation modes and the significant workload of modifying and calculating the corresponding CAE model when frequent modifications are needed to the CAD model. This improves the efficiency of electromagnetic simulation and is of great significance for enabling collaborative design and modeling using CAD and CAE software. Attached Figure Description

[0030] Figure 1 This is a flowchart of the present invention;

[0031] Figure 2 This is a model diagram of an embodiment;

[0032] Figure 3 This is the finite element calculation model generated from the example;

[0033] Figure 4 This is a comparison chart of electromagnetic simulation characteristic parameters of the embodiment. Detailed Implementation

[0034] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0035] Reference Figure 1 A computational model generation method for high-frequency electromagnetic simulation includes the following steps:

[0036] Step 1: Perform CAD modeling of the target electronic device, set boundary conditions, excitations, and materials, and the program reads the created CAD model file; create a model body list ENTITYLIST and store all bodies in the model into ENTITYLIST.

[0037] The established CAD model files, except for the air box, do not allow two metal bodies of different materials to intersect / overlap / include / include each other, nor do they allow two non-metal bodies of different materials to intersect / overlap / include / include each other; the wave port excitation is that one side is completely backed by a metal body and the other side is not completely backed by a metal body.

[0038] This embodiment takes the electromagnetic transmission analysis of a horn antenna as an example to establish, as follows: Figure 2 The model structure shown has a vacuum region as the electromagnetic computation domain. The outermost cuboid is an air box with the material set to vacuum, and a radiation boundary is set on the outer surface, denoted as volume (4); the inner cuboid ring and trapezoidal ring are rectangular waveguide feed patches and radiation patches, denoted as volume (1); the lower cuboid is a metal substrate, denoted as volume (2), and the material is set to PEC (ideal conductor); the volume formed by the rectangular surfaces is a sheet body, denoted as volume (3), and a waveport excitation is set. Then, the SAT file (3D CAD design file format) is output. The program reads the SAT model file and creates a model body list ENTITYLIST, storing all the bodies in the model into the list ENTITYLIST.

[0039] Step 2: Mark the properties of the bodies in the ENTITYLIST from Step 1 using the ACIS property manipulation function, remove the useless pieces from the list, and update the model body list ENTITYLIST.

[0040] Since the index of the removed body is not removed after removing a useless body, it will point to an empty body. Therefore, the original model list needs to be updated after removing a useless body.

[0041] Taking the electromagnetic transmission analysis of the horn antenna in this embodiment as an example, the attributes of the radiation boundary and the wave port excitation are marked by the ACIS attribute operation function, and the attributeless pieces are removed. Then the original model list ENTITYLIST is updated (there are no attributeless pieces in this example, so there is no need to remove or update them).

[0042] Step 3: For the updated list ENTITYLIST from Step 2, use the collision function in ACIS to determine the pairwise relationships and record them.

[0043] In this embodiment, the collision function determines that the relationship between body (1) and body (2) in the horn antenna model is connected, the relationship between body (1) and body (3) is connected, the relationship between body (1) and body (4) is contained, the relationship between body (2) and body (3) is contained connected, the relationship between body (2) and body (4) is contained, and the relationship between body (3) and body (4) is contained, and records it.

[0044] Step 4: For the two bodies in Step 3 whose pairwise relationships are containment, connection, containment and connection, intersection, and overlap, use the single / double-sided function in ACIS to determine whether they are solid bodies or sheet bodies, and record the results.

[0045] In this embodiment of the horn antenna model, both bodies (1) and (2) are solids, one of bodies (1) and (3) is a sheet, both bodies (1) and (4) are solids, one of bodies (2) and (3) is a sheet, both bodies (2) and (4) are solids, one of bodies (3) and (4) is a sheet, and these are recorded.

[0046] Step 5: For cases where both bodies recorded in Step 4 are solids, obtain their collision relationship and perform corresponding Boolean operations based on the collision relationship. If one of the two bodies recorded in Step 4 is a sheet body, obtain the boundary condition to determine whether the sheet body is a waveport excitation or another boundary sheet body, and perform corresponding Boolean operations. Boolean operations are used to complete model processing while simultaneously transferring the model's analytical features and parameters, thereby updating the ENTITYLIST list.

[0047] The specific Boolean operation rules for different situations are as follows:

[0048] A. For cases where both entities are real entities.

[0049] a) If the collision type of the two bodies is containment / containment connection: perform a Boolean operation to subtract the smaller body from the larger body, and keep the smaller body; if the larger body is metallic and the smaller body is non-metallic, the surface of the smaller non-metallic body needs to be manually assigned a metallic boundary while following the above rules.

[0050] b) If the collision type of the two bodies is intersecting / coincident: non-metallic body and metallic body, then the non-metallic body is subtracted from the metallic body, and the metallic body is retained; if they are of the same material, choose one body as the minuend and subtract the other body as the subtrahend, and retain the subtrahend.

[0051] c) If the collision type of the two bodies is contact: subtract the metal body from the non-metal body, and retain the metal body.

[0052] B. If one of the objects is a slice, obtain the properties of that slice.

[0053] a) If it is a waveport excitation, determine whether both sides are completely backed by metal (one side is completely backed by metal and the other side is not completely backed by metal, which is correct; otherwise, report an error). Subtract the metal body on the side that is not completely backed by metal from the waveport surface, and retain the metal body. Do not process the side that is completely backed by metal.

[0054] b) If there are other boundary conditions, subtract the metal body from the sheet body and retain the metal body.

[0055] In this embodiment, the target electronic device is a horn antenna. Both bodies (1) and (2) in the horn antenna are solid objects, their collision relationship is that they are in contact, and both are metallic, so no calculation is performed.

[0056] In this horn antenna, one of the two bodies (1) and body (3) is a sheet body. The properties of the sheet body are obtained as wave port excitation, and it is a metal body with one side completely backed by metal and the other side not completely backed by metal. Body (1) is a metal body with the side not completely backed by metal. Therefore, Boolean subtraction of body (3) is used with body (1), and body (3) is retained.

[0057] In this horn antenna, both bodies (1) and (4) are solids, and their collision relationship is inclusion. Body (1) is a metal body and is the smaller body, while body (4) is a non-metal body and is the larger body. The larger body is subtracted from the smaller body, and the smaller body is retained.

[0058] In this horn antenna, one of the two bodies (2) and (3) is a sheet body. The properties of the sheet body are obtained as wave port excitation, and one side is completely backed by metal while the other side is not completely backed by metal. Body (2) is a metal body with one side completely backed by metal, so no processing is required.

[0059] In this horn antenna, both bodies (2) and (4) are solids, and their collision relationship is inclusion. Body (2) is a metal body and is the smaller body, while body (4) is a non-metal body and is the larger body. The larger body is subtracted from the smaller body, and the smaller body is retained.

[0060] In this horn antenna, one of the two bodies (3) and (4) is a sheet body. The properties of the sheet body are obtained as wave port excitation, and one side is completely backed by metal while the other side is not completely backed by metal. Body (4) is a non-metallic body and is not processed.

[0061] Update the ENTITYLIST list.

[0062] Step 6: Mark all pieces in the updated list ENTITYLIST from Step 5 as non-metallic bodies, create a computational model list ENTITYLIST1, and store all non-metallic bodies from the list ENTITYLIST into the newly created computational model list ENTITYLIST1.

[0063] In this embodiment, the sheet body (3) is marked as a non-metallic body, a computational model list ENTITYLIST1 is established, and all non-metallic bodies in the list ENTITYLIST are stored in the newly established computational model list ENTITYLIST1.

[0064] Step 7: Based on the calculation model list established in Step 6, write out the finite element calculation model to obtain the calculation model applicable to high-frequency electromagnetic simulation. Figure 3This is the finite element calculation model generated in this embodiment.

[0065] In this embodiment, the finite element calculation model of the calculation model list ENTITYLIST1 is written out, and the written finite element calculation model of the horn antenna is compared with the initial CAD model in step 1 to verify the correctness of the above Boolean operation. (Refer to...) Figure 3 Only the sheet body (body 1) and the air box (body 2) after Boolean subtraction with the metal are correct.

[0066] Based on the finite element calculation model written in step 7, a non-manifold model was generated. After mesh construction, the finite element solver was used for solving, and the calculation results were compared and analyzed with HFSS (a 3D radio frequency simulation software). (Refer to...) Figure 4 , Figure 4 This is a comparison chart of electromagnetic simulation characteristic parameters in this embodiment. A non-manifold model was generated from the written finite element calculation model, and after mesh construction, the finite element solver was used for solving. The radiation pattern of the finite element solver at a solving frequency of 10 GHz is consistent with the radiation pattern results of the commercial software HFSS, indicating that the solution result is correct, meaning the calculation model was generated correctly.

[0067] As can be seen from the above embodiments, this invention reads the established CAD model, marks the analytical features and parameters of the CAD model in CAE software, performs geometric processing and Boolean operations on it, and ultimately retains the vacuum and medium calculation domains. By judging the collision relationships between model bodies and performing Boolean operations on the six possible complete collision relationships, it ensures the correct transfer of model boundary excitation and other attributes, that is, no attribute information is lost before and after the model conversion, achieving "zero distortion" conversion. This realizes the generation of finite element calculation models in electromagnetic simulation preprocessing, and then applies them to electromagnetic simulation software for rapid and accurate modeling, design checking, etc. It avoids the huge workload of traditional manual interactive operation mode, and also avoids the huge workload of modifying and calculating the corresponding CAE model when the CAD model needs to be frequently modified. It improves the efficiency of electromagnetic simulation and is of great significance for realizing collaborative design and modeling between CAD and CAE software.

Claims

1. A method for generating computational models for high-frequency electromagnetic simulation, characterized in that, The specific steps are as follows: Step 1: Perform CAD modeling of the target electronic device, including setting boundary conditions, excitations, and materials. The program reads the created CAD model file; creates a model body list ENTITYLIST, and saves all bodies in the model into ENTITYLIST. The established CAD model files are as follows: except for the air box, two metal bodies of different materials are not allowed to intersect / overlap / include / include and connect, nor are two non-metal bodies of different materials allowed to intersect / overlap / include / include and connect; the wave port excitation is that one side is completely backed by a metal body and the other side is not completely backed by a metal body. Step 2: Mark the attributes of the bodies in the ENTITYLIST obtained in Step 1 using the ACIS attribute manipulation function, remove useless body pieces that do not have boundary or encryption attributes from the list, and update the model body list ENTITYLIST. Sheet body: A thin-walled shell with a surface structure; all surfaces of a sheet body are bidirectional. Solid body: All bodies other than sheet bodies; all surfaces of a solid body are unidirectional. Step 3: For the updated list ENTITYLIST from Step 2, use the collision function in ACIS to determine the pairwise relationships and record them; The pairwise relationships output by the collision function include: unknown relationship, no collision, unclassified, contain, contain and connect, connect, coincide, and intersect. Step 4: For the two bodies in Step 3 whose pairwise relationships are containment, containment connection, connection, intersection, and overlap, use the single / double-sided function in ACIS to determine whether they are solid bodies or sheet bodies, and record the results. Get all faces of two bodies that are in a collision relationship. Use the ACIS function to determine whether the obtained faces are one-way or two-way. If there are one-way faces in the body, it is a solid. Otherwise, if all faces of the body are two-way, the body is a sheet. Step 5: If both bodies recorded in Step 4 are solids, obtain their collision relationship and perform corresponding Boolean operations based on their collision relationship; if one of the two bodies recorded in Step 4 is a sheet body, obtain the boundary to determine whether the sheet body is a waveport excitation or another boundary sheet body, and perform corresponding Boolean operations. Boolean operations are used to process the model while transferring the model's analytical features and parameters, thereby updating the ENTITYLIST list. Step 6: Mark all pieces in the updated list ENTITYLIST of Step 5 as non-metallic bodies, create a computational model list ENTITYLIST1, and store all non-metallic bodies in the list ENTITYLIST into the newly created computational model list ENTITYLIST1. Step 7: Write out the finite element calculation model from the ENTITYLIST1 list of calculation models obtained in Step 6, thus obtaining the calculation model applicable to high-frequency electromagnetic simulation.

2. The computational model generation method for high-frequency electromagnetic simulation as described in claim 1, characterized in that, The specific Boolean operation rules for different situations in step 5 are as follows: A. For cases where both entities are solids; a) If the collision type of the two bodies is containment / containment connection: perform a Boolean operation to subtract the smaller body from the larger body, and retain the smaller body; if the larger body is a metallic body and the smaller body is a non-metallic body, the surface of the smaller non-metallic body should be given a metallic boundary while following the above rules. b) If the collision type of the two bodies is intersecting / coincident: non-metallic body and metallic body, then the non-metallic body is subtracted from the metallic body, and the metallic body is retained; if they are of the same material, choose one body as the minuend and subtract the other body as the subtrahend, and retain the subtrahend. c) If the collision type of the two bodies is contact: subtract the metal body from the non-metal body, and retain the metal body in addition; B. If one of the objects is a sheet, obtain the properties of that sheet; a) If it is a waveport excitation, determine whether both sides are completely backed by the metal: In the correct model, the waveport excitation is that one side is completely backed by the metal body and the other side is not completely backed by the metal body. Subtract the metal body on the side that is not completely backed by the metal body from the waveport surface, and retain the metal body. No processing is done on the side that is completely backed by the metal body. b) If there are other boundary conditions, subtract the metal body from the sheet body and retain the metal body.

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