Dynamic finite element model correction method of multi-dot-matrix integrated structure

Abstract

The invention provides a dynamic finite element model correction method for a multi-dot-matrix integrated structure, and the method comprises the steps: decomposing a complex structure modal test into three states; the three modal tests are an installation structure multi-dot-matrix modal test without internal airborne equipment in a free state, an installation structure multi-dot-matrix modal test with internal airborne equipment in a free state and an installation structure multi-dot-matrix modal test with internal airborne equipment in a constraint state in sequence, and meanwhile, a model correction process is combined into the three modal tests; the installation structure part, the internal airborne equipment part, the internal connection relation and the external connection relation are sequentially corrected, the influence of various factors among all the parts on the whole correction process result is avoided, and the correction efficiency and accuracy of the multi-lattice structure dynamic model can be obviously improved.

Description

Technical Field

[0001] This application belongs to the field of aircraft layout design technology, and specifically relates to a method for correcting the dynamic finite element model of a multi-lattice integrated structure. Background Technology

[0002] Currently, in new aircraft such as aerospace, the installation structure in which multiple airborne equipment are distributed and integrated into one unit is becoming the mainstream design. These multi-point lattice integrated structures are generally large in size, with a large number of airborne equipment inside, varying in quality and unevenly distributed. In addition, the connection relationship between airborne equipment and installation structure, as well as between installation structure and external airframe structure, is complex. When performing dynamic finite element modeling to analyze its modal or vibration stress, it is not only time-consuming and laborious, but the accuracy of the model is also difficult to meet the requirements. Therefore, it is necessary to modify the dynamic finite element model to ensure that it can truly reflect the inherent characteristics of such structures.

[0003] Existing methods for correcting dynamic finite element models rely on modal testing of real structures to obtain their natural frequencies and mode shapes. Conventional modal tests measure the modal parameters of the entire structure through a single impact or excitation point. Modal testing and finite element simulation analysis are independent processes; that is, modal parameters are obtained first through modal testing, and then the dynamic finite element model is corrected based on the simulation results. However, for multi-lattice integrated structures, modal testing at a single excitation point is ineffective. Moreover, even if the modal parameters of the entire structure are obtained through modal testing, the complexity of the overall structure requires significant manpower and time for model modification and simulation calculations, making it difficult to directly use for correcting dynamic finite element models. Summary of the Invention

[0004] The purpose of this application is to provide a method for correcting the dynamic finite element model of a multi-lattice integrated structure to solve or alleviate at least one problem in the background art.

[0005] The technical solution of this application is: a method for correcting the dynamic finite element model of a multi-lattice integrated structure, including:

[0006] Step S1: Perform multi-point excitation modal tests on the installation structure without internal airborne equipment in a free state to obtain the modal parameters of the installation structure without internal airborne equipment in a free state.

[0007] Step S2: Construct a finite element model of the installation structure without internal airborne equipment in a free state. Based on the modal parameters in step S1, modify the finite element model of the installation structure without internal airborne equipment in a free state to obtain a modified finite element model of the installation structure without internal airborne equipment in a free state.

[0008] Step S3: Conduct multi-point excitation modal tests on the installation structure of the internal airborne equipment in a free state to obtain the modal parameters of the installation structure of the internal airborne equipment in a free state.

[0009] Step S4: Construct the finite element model of the internal airborne equipment, establish a connection relationship with the finite element modified model of the installation structure obtained in step S2 to obtain the finite element combined model of the assembled internal airborne equipment, and modify the connection relationship of the finite element combined model of the assembled internal airborne equipment based on the installation structure modal parameters obtained in step S3 to obtain the finite element combined modified model of the assembled internal airborne equipment.

[0010] Step S5: The mounting structure for assembling the internal airborne equipment is fixedly installed on the external connecting structure, and a multi-point excitation modal test is performed on the mounting structure to obtain the modal parameters of the mounting structure when the mounting structure for assembling the internal airborne equipment is fixedly installed on the external connecting structure.

[0011] Step S6: Establish external connections and constraints on the finite element combination correction model of the assembled internal airborne equipment obtained in step S4, and correct the external connections of the constrained finite element correction model of the assembled internal airborne equipment based on the modal parameters obtained in step S5, so as to finally obtain a real and reliable dynamic finite element model of the multi-lattice integrated structure.

[0012] This application differs from conventional modal testing methods by decomposing the modal testing of complex structures into three states: a free state with no internal onboard equipment, a free state with internal onboard equipment, and a constrained state with internal onboard equipment. Furthermore, unlike conventional dynamic finite element model correction methods, this application integrates the model correction process into the three modal tests, sequentially correcting the installation structure, the internal onboard equipment and its internal connections, and the external connections. This process allows for a multi-dimensional understanding of the structure's inherent characteristics and enables gradual correction of such complex models, avoiding the influence of various factors on the overall correction process. This significantly improves the efficiency and accuracy of multi-point structure dynamic model correction. Attached Figure Description

[0013] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.

[0014] Figure 1 This is a schematic diagram of the method for correcting the dynamic finite element model of the multi-lattice integrated structure in this application.

[0015] Figure 2This is a schematic diagram of the multi-point excitation modal test and finite element modeling for the three states in this application. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings.

[0017] To overcome the problems mentioned in the background art, this application provides a method for correcting the dynamic finite element model of multi-lattice integrated structures.

[0018] like Figure 1 As shown, this application provides a method for correcting the dynamic finite element model of a multi-lattice integrated structure, including the following steps:

[0019] Step S1: Perform multi-point excitation modal tests on the installation structure without internal airborne equipment in a free state to obtain the modal parameters of the installation structure without internal airborne equipment in a free state.

[0020] like Figure 2 Figure a shows a schematic diagram of the installation structure in the free state without the internal airborne equipment in this embodiment of the application. By conducting multi-point excitation modal tests on it, the modal parameters of the installation structure in this state can be obtained. The modal parameters generally include natural frequency, damping ratio, mode shape, etc.

[0021] Step S2: Construct a finite element model of the installation structure without internal airborne equipment in a free state. Based on the modal parameters of the installation structure obtained in step S1, modify the finite element model of the installation structure to obtain a modified finite element model of the installation structure without internal airborne equipment in a free state, thereby achieving modification only of the installation structure part.

[0022] like Figure 2 Figure b shows a schematic diagram of the finite element model of the installation structure without internal airborne equipment in a free state, established in this embodiment of the application. By correcting the finite element model using the modal parameters of the installation structure obtained in step S1, a corrected finite element model with only the installation structure modified can be obtained in this state. In some embodiments of the application, the finite element model is established using CAE software, commonly used CAE software includes Abaqus, Nastran, etc.

[0023] Step S3: Perform multi-point vibration modal tests on the installation structure of the internal airborne equipment in the free state to obtain the modal parameters of the installation structure of the internal airborne equipment in the free state.

[0024] like Figure 2Figure c shows a schematic diagram of the installation structure of the internal airborne equipment in a free state in this embodiment of the application. The modal parameters of the installation structure in this state can be obtained by conducting multi-point excitation modal tests. It should be noted that since the internal airborne equipment and the installation structure are mutually fixed through connectors during this process, the obtained modal parameters include the contents of the internal airborne equipment; that is, the modal parameters of the installation structure obtained in this state include the overall structural modal parameters of the internal airborne equipment.

[0025] Step S4: Construct the finite element model of the internal airborne equipment and establish a connection relationship with the finite element modified model of the installation structure obtained in step S2 to obtain the finite element combined model of the assembled internal airborne equipment. Based on the modal parameters of the installation structure obtained in step S3, modify the connection relationship of the finite element combined model of the assembled internal airborne equipment to obtain the finite element combined modified model of the assembled internal airborne equipment, thereby realizing that only the internal airborne equipment part and the internal connection relationship need to be modified.

[0026] like Figure 2 Figure d shows the finite element assembly model of the internal airborne equipment in this embodiment of the present application. By correcting the connection relationship between the internal airborne equipment and the installation structure, the correction result of the connection between the internal airborne equipment and the installation structure in the finite element model can be obtained.

[0027] Step S5: The mounting structure for assembling internal equipment is fixedly installed on the external connecting structure, and a multi-point excitation modal test is performed on the mounting structure to obtain the modal parameters of the mounting structure when the mounting structure for assembling internal equipment is fixedly installed on the external connecting structure.

[0028] like Figure 2 Figure e shows a schematic diagram of the mounting structure for assembling internal equipment fixedly installed on an external connection structure in this embodiment of the present application. The external connection structure is usually an aircraft fuselage structure or a support structure, etc. By conducting multi-point excitation modal tests on the mounting structure in this state, its modal parameters can be obtained.

[0029] Step S6: Establish external connections and constraints on the finite element combination correction model of the assembled internal airborne equipment obtained in step S4, and correct the external connections of the constrained finite element combination correction model of the assembled internal airborne equipment based on the modal parameters obtained in step S5. Only the external connection relationships are corrected, and finally a real and reliable dynamic finite element model of the multi-lattice integrated structure is obtained.

[0030] like Figure 2 f represents the finite element combination correction model of the internal airborne equipment in this embodiment of the application and its external connection relationship. Based on the modal parameters obtained in step S5, the external connection is corrected to obtain a true and reliable dynamic finite element model of the multi-lattice integrated structure.

[0031] This application differs from conventional modal testing methods by decomposing the complex structure into three states: a free state with no internal onboard equipment, a free state with internal onboard equipment, and a constrained state with internal onboard equipment. Furthermore, unlike conventional dynamic finite element model correction methods, this application integrates the model correction process into the three modal tests, sequentially correcting the installation structure, the internal onboard equipment and its internal connections, and the external connections. This process allows for a multi-dimensional understanding of the structure's inherent characteristics and enables gradual correction of such complex models, avoiding the influence of various factors on the overall correction process. This significantly improves the efficiency and accuracy of multi-point structure dynamic model correction.

[0032] This application solves the problem of correcting the finite element model of a multi-lattice structure through modal testing. By combining experimental, simulation calculation and model correction techniques, the correction efficiency is improved, and reliable experimental data and accurate dynamic models are obtained, providing a foundation for subsequent vibration characteristic analysis and structural optimization design.

[0033] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for correcting the dynamic finite element model of a multi-lattice integrated structure, characterized in that, The method comprises the following steps: S1, performing a multi-point excitation modal test on the mounting structure without assembling the internal airborne equipment in a free state to obtain the modal parameters of the mounting structure without assembling the internal airborne equipment in the free state; S2, constructing a finite element model of the mounting structure without assembling the internal airborne equipment in the free state, correcting the finite element model of the mounting structure without assembling the internal airborne equipment in the free state based on the modal parameters in step S1 to obtain a finite element corrected model of the mounting structure without assembling the internal airborne equipment in the free state; S3, performing a multi-point excitation modal test on the mounting structure with assembling the internal airborne equipment in the free state to obtain the modal parameters of the mounting structure with assembling the internal airborne equipment in the free state; S4, constructing a finite element model of the internal airborne equipment, establishing a connection relationship between the finite element corrected model of the mounting structure obtained in step S2 and the finite element model of the internal airborne equipment to obtain a finite element combined model of the mounting structure with assembling the internal airborne equipment, correcting the connection relationship of the finite element combined model of the mounting structure with assembling the internal airborne equipment based on the modal parameters of the mounting structure obtained in step S3 to obtain a finite element combined corrected model of the mounting structure with assembling the internal airborne equipment; S5, fixing the mounting structure with assembling the internal airborne equipment on the external connection structure and performing a multi-point excitation modal test on the mounting structure to obtain the modal parameters of the mounting structure with assembling the internal airborne equipment in the state of being fixedly installed on the external connection structure; S6, establishing an external connection and constraint for the finite element combined corrected model of the mounting structure with assembling the internal airborne equipment obtained in step S4 and correcting the external connection of the finite element corrected model of the mounting structure with assembling the internal airborne equipment based on the modal parameters obtained in step S5 to finally obtain a reliable dynamic finite element model of the multi-point array integrated structure.

2. The dynamics finite element model updating method of a multi-point array integrated structure according to claim 1, wherein, The modal parameters include a fixed frequency, a damping ratio and a vibration mode.

3. The dynamics finite element model updating method of a multi-point array integrated structure according to claim 1, wherein, The finite element model is constructed by a CAE software, and the CAE software includes Abaqus and Nastran.

Images