CN114818407B - Virtual heat test method for structural strength analysis - Google Patents

Abstract

The invention discloses a virtual thermal test method for structural strength analysis. First, a Simulink closed-loop control system model is constructed, including a load spectrum given module, a control module, a power conversion module and a Simulink and Comsol interface; and then a Comsol electric field-thermal test method is constructed. The field coupling model converts the electrical signals input from the Simulink and Comsol interfaces into the heat flow information and temperature information of the test piece; the Comsol electric field-thermal field coupling model provides the heat flow information and temperature of the test piece to the control module through the Simulink and Comsol interfaces. Information; the control module selects heat flow information or temperature information as the feedback signal according to the nature of the given load spectrum during the virtual thermal test, and implements the control law in the control module. The present invention adopts software method to realize complete virtualization of thermal test.

Description

A virtual thermal test method for structural strength analysis

Technical field

The invention belongs to the technical field of structural strength thermal testing, and specifically relates to a virtual thermal testing method.

Background technique

During the flight of the aircraft, strong friction occurs between the high-speed airflow and its surface, and the kinetic energy lost by the airflow in the boundary layer is converted into heat energy, causing the temperature of the airflow in the boundary layer to rise, resulting in aerodynamic heating. Aerodynamic heating will weaken the structural strength of the aircraft and produce phenomena such as thermal stress, thermal strain and material ablation, causing internal temperature to rise, worsening the working environment of electronic equipment in the cabin and reducing the performance of electronic equipment. Aerodynamic heating is an issue that must be considered in the design of aircraft structural strength. Thermal testing simulates aerodynamic loads on the ground to assess the performance of the aircraft under aerodynamic heating. It is an effective method to suppress aerodynamic heating problems and has become an important means of structural design, strength and reliability analysis, and product performance inspection. Although there are many ways to simulate aerodynamic heating, considering that the quartz lamp heating source has better efficiency during the implementation of thermal tests, currently the domestic aerospace field mainly uses quartz lamp radiant heaters for thermal environment simulation.

Thermal test is a ground simulation test with large scale, wide coverage, high energy consumption and high requirements on measurement and control technology. Virtual thermal testing based on software simulation technology can greatly improve the technical level of thermal environment ground simulation, and has a predictive and guiding role in actual thermal testing. It can speed up model development progress, improve model product quality, and reduce model development costs. There's important meaning. During thermal testing, control and electric and thermal fields are involved. How to effectively introduce control signals into the electric field and thermal field has hindered the development of virtual thermal test technology.

The document "Technical Research on Structural Thermal Strength Virtual Test Platform" analyzes how to carry out modular virtual thermal tests from the perspective of thermal test system composition, but there is no specific implementation method. The document "Software Architecture and Application of Spacecraft Virtual Thermal Test Platform" realizes the model establishment of the tested product and heater. The document "Design and Implementation of Virtual Thermal Test Program for Quartz Lamp Irradiation" provides a quartz lamp virtual thermal test method based on MSC.Nastran/Patran, which uses finite element analysis technology to realize thermal test virtualization. The patent "A Virtual Thermal Test Method Based on CFD and FEM Technology" uses the computational fluid dynamics method to establish a virtual model of the arc wind tunnel, uses the finite element method to establish the test piece model, and realizes the combined simulation of the two models through fluid-structure coupling technology. The patent "Spacecraft Virtual Thermal Test System and Thermal Test Method Based on Thermal Network Method" uses related numerical methods of numerical heat transfer and computational radiology to analyze the heat transfer process. Looking at the development of virtual thermal tests in China, the public literature mainly focuses on the virtualization of heaters and tested products. In addition to the heater and the product under test, the thermal test system includes a heating power supply and a control system. In the public literature, no relevant information can be found to realize the virtual thermal test method of virtualizing the entire thermal test system.

Contents of the invention

In order to overcome the shortcomings of the existing technology, the present invention provides a virtual thermal test method for structural strength analysis. First, a Simulink closed-loop control system model is constructed, including a load spectrum given module, a control module, a power conversion module, and Simulink and Comsol interface; then build a Comsol electric field-thermal field coupling model to convert the electrical signal input from the Simulink and Comsol interface into the heat flow information and temperature information of the test piece; the Comsol electric field-thermal field coupling model is provided to the control module through the Simulink and Comsol interface Heat flow information and temperature information of the test piece; the control module selects heat flow information or temperature information as the feedback signal according to the nature of the given load spectrum during the virtual thermal test, and implements the control law in the control module. The present invention adopts software method to realize complete virtualization of thermal test.

The technical solution adopted by the present invention to solve the technical problems includes the following steps:

Step 1: Build a Simulink closed-loop control system model;

The Simulink closed-loop control system model includes a load spectrum given module, a control module, a power conversion module and Simulink and Comsol interfaces;

The load spectrum given module is implemented through the signal builder module in Simulink; the signalbuilder module sets the load spectrum of the virtual thermal test in a time-numeric given manner;

The control module generates control quantities based on feedback and given information to achieve closed-loop control; the input signal of the control module is the load spectrum given signal set by the load spectrum given module; the output of the control module is to control the conduction of the power conversion module horn;

The power conversion module is an AC/AC converter or an AC/DC converter, which uses AC power to provide original energy. According to the conduction angle output by the control module, the power conversion module outputs an effective value of AC power corresponding to the conduction angle. or direct current;

The Simulink and Comsol interface provides the output information of the power conversion module to the Comsol model;

Step 2: Construct the Comsol electric field-thermal field coupling model;

The Comsol electric field-thermal field coupling model functions to convert electrical signals input from the Simulink and Comsol interfaces into heat flow information and temperature information of the test piece;

Step 3: The Comsol electric field-thermal field coupling model provides the heat flow information and temperature information of the test piece to the control module through the Simulink and Comsol interface; the control module selects heat flow information or temperature information according to the nature of the given load spectrum during the virtual thermal test process. The temperature information is a feedback signal, and the control law is implemented in the control module.

Preferably, the load spectrum is heat flow or temperature.

Preferably, the control law is PID control or fuzzy control.

Preferably, the AC power in the power conversion module is three-phase AC or single-phase AC.

Preferably, the Comsol electric field-thermal field coupling model uses tungsten wire to transfer the input electric energy to the test piece through radiation.

Preferably, the Comsol electric field-thermal field coupling model needs to be meshed, and the specific settings are as follows: the mesh is a free quadrilateral mesh, and the size is ultra-fine.

The beneficial effects of the present invention are as follows:

1) This invention uses software to achieve complete virtualization of thermal tests;

2) This invention uses joint simulation technology to realize comprehensive simulation analysis of the control system, electric field, and thermal field;

3) The thermal test load spectrum of the present invention can be set arbitrarily, and at the same time, the data status of each observation point can be directly observed at one time, including the power amplifier output status information, the heater output status information, and the thermal status information of the test piece.

Description of the drawings

Figure 1 is the overall structural block diagram of the virtual thermal test method based on Simulink and Comsol multi-field coupling.

Figure 2 is a block diagram of the model structure based on Simulink.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and examples.

In order to realize the virtualization of the entire thermal test system, the present invention provides a virtual thermal test method based on Simulink and Comsol multi-field coupling, using Simulink to realize control system virtualization; using Comsol to realize thermal field and electric field virtualization; using Simulink and Comsol Joint simulation technology realizes data interaction between the control system and the electric field and thermal field.

Step 1: Build a Simulink closed-loop control system model;

The Simulink closed-loop control system model includes a load spectrum given module, a control module, a power conversion module and Simulink and Comsol interfaces;

The load spectrum given module is implemented through the signal builder module in Simulink; the signalbuilder module sets the load spectrum of the virtual thermal test in a time-numeric given manner;

The control module generates control quantities based on feedback and given information to achieve closed-loop control; the input signal of the control module is the load spectrum given signal set by the load spectrum given module; the output of the control module is to control the conduction of the power conversion module horn;

The power conversion module is an AC/AC converter or an AC/DC converter, which uses AC power to provide original energy. According to the conduction angle output by the control module, the power conversion module outputs an effective value of AC power corresponding to the conduction angle. or direct current;

The Simulink and Comsol interface provides the output information of the power conversion module to the Comsol model;

Step 2: Construct the Comsol electric field-thermal field coupling model;

The Comsol electric field-thermal field coupling model functions to convert electrical signals input from the Simulink and Comsol interfaces into heat flow information and temperature information of the test piece;

Step 3: The Comsol electric field-thermal field coupling model provides the heat flow information and temperature information of the test piece to the control module through the Simulink and Comsol interface; the control module selects heat flow information or temperature information according to the nature of the given load spectrum during the virtual thermal test process. The temperature information is a feedback signal, and the control law is implemented in the control module.

Preferably, the load spectrum is heat flow or temperature.

Preferably, the control law is PID control or fuzzy control.

Preferably, the AC power in the power conversion module is three-phase AC or single-phase AC.

Preferably, the Comsol electric field-thermal field coupling model uses tungsten wire to transfer the input electric energy to the test piece through radiation.

Preferably, the Comsol electric field-thermal field coupling model needs to be meshed, and the specific settings are as follows: the mesh is a free quadrilateral mesh, and the size is ultra-fine.

Specific examples:

Figure 1 is an overall structural diagram of the present invention, which consists of a Simlink-based control model, a Simulink and Comsol interface, and a Comsol-based electric field-thermal field model.

Figure 2 is a block diagram of the Simulink-based model structure of the present invention. It consists of load spectrum given module, control module, power conversion module, Simulink and Comsol interface.

In the Simulink-based model, the load spectrum is given through the signal builder module. The module sets the load spectrum required during the virtual thermal test in a time-value given manner.

In the model based on Simulink, the control module is designed based on the PID module that comes with Simulink. The module input signal is the load spectrum given signal; the module output is the conduction angle corresponding to the power conversion device. During the control process, the required control parameters such as proportion, integral, and differential can be set freely before the implementation of the virtual thermal test.

In the Simulink-based model, the power conversion module provides raw energy with AC power. The AC power supply can choose between single-phase AC power supply and three-phase AC power supply. The phase voltage of the AC power supply should be set to 220V, 50Hz. The power conversion part is an AC/AC converter or AC/DC converter constructed through power electronic devices such as thyristors, IGBTs, and MOSFETs. The conduction control of power electronic devices is controlled by the output of the control module.

In the Simulink-based model, the Simulink and Comsol interface provides the output information of the power conversion module to the Comsol model, based on the effective value. The Simulink and Comsol interfaces provide Simulink with temperature and heat flow information of thermal field feedback. Depending on the nature of the given load spectrum during the virtual thermal test, the signal used for feedback is selected as heat flow information, or temperature information.

In the electric field and thermal field model based on Comsol, the energy transfer from the electric field to the thermal field is realized through tungsten wire. Combined with the characteristics of the quartz lamp used in engineering thermal testing, the tungsten filament characteristic parameters are set. Create a two-dimensional geometric figure in Comsol. From top to bottom, they are the tungsten filament heat source, air layer, and receiving plane. For the tungsten filament heat source and receiving plane, parameters such as constant pressure heat capacity, thermal conductivity, and surface radiance need to be set. For various parameters of air, use the air data in Comsol’s built-in material library.

In the Comsol-based electric field and thermal field model, physical fields need to be set, including surface-to-surface radiation between the tungsten filament heat source and the receiving plane, solid and fluid heat transfer between the tungsten filament heat source, the receiving plane and the air, and the layer of air flow. After adding and setting these three physical fields, they can perform multi-physics coupling characteristic analysis on them.

In the Comsol-based electric field and thermal field model, model meshing is required. The specific settings are: the grid is a free quadrilateral grid, the size is ultra-fine, the maximum unit size is 4mm, and the minimum unit size is 0.015mm.

The software required to set up the interface between Simulink and Comsol is: MATLAB version 2020 and Comsol version 5.6. During installation, you must first install MATLAB, and then install Comsol in the MATLAB installation path. If the installation is successful, the Comsol with Simulink icon will appear. By clicking the Comsol with Simulink icon, set the basic information of the relevant server. In the Comsol software environment, set related server information through the Connect to Server function in the Comsol Multiphysics Server menu.

In the Comsol model, using the Comsol external interface function to package the model requires settings such as input port, output port, name, and save path. Open Simulink in MATLAB with a server connection established. Find the Comsol module in the Simulink library and change the path in the module settings to the path when the Comsol module is exported.

During the joint simulation process, when running the Simlink-based control model, the Comsol-based electric field and thermal field models will automatically run in the background. At any Simulink observation point, by adding an oscilloscope observation module, you can observe the signal changes at each observation point during the virtual thermal test.

Claims (6)

1. A virtual thermal test method for structural strength analysis, characterized in that it includes the following steps: Step 1: Build a Simulink closed-loop control system model; The Simulink closed-loop control system model includes a load spectrum given module, a control module, a power conversion module and Simulink and Comsol interfaces; The load spectrum given module is implemented through the signalbuilder module in Simulink; the signalbuilder module sets the load spectrum of the virtual thermal test in a time-numeric given manner; The control module generates control quantities based on feedback and given information to achieve closed-loop control; the input signal of the control module is the load spectrum given signal set by the load spectrum given module; the output of the control module is to control the conduction of the power conversion module horn; The power conversion module is an AC/AC converter or an AC/DC converter, which uses AC power to provide original energy. According to the conduction angle output by the control module, the power conversion module outputs an effective value of AC power corresponding to the conduction angle. or direct current; The Simulink and Comsol interface provides the output information of the power conversion module to the Comsol model; Step 2: Construct the Comsol electric field-thermal field coupling model; The Comsol electric field-thermal field coupling model functions to convert electrical signals input from the Simulink and Comsol interfaces into heat flow information and temperature information of the test piece; Step 3: The Comsol electric field-thermal field coupling model provides the heat flow information and temperature information of the test piece to the control module through the Simulink and Comsol interface; the control module selects heat flow information or temperature information according to the nature of the given load spectrum during the virtual thermal test process. The temperature information is a feedback signal, and the control law is implemented in the control module. 2. A virtual thermal test method for structural strength analysis according to claim 1, characterized in that the load spectrum is heat flow or temperature. 3. A virtual thermal test method for structural strength analysis according to claim 1, characterized in that the control law is PID control or fuzzy control. 4. A virtual thermal test method for structural strength analysis according to claim 1, characterized in that the AC power supply in the power conversion module is three-phase alternating current or single-phase alternating current. 5. A virtual thermal test method for structural strength analysis according to claim 1, characterized in that the Comsol electric field-thermal field coupling model uses tungsten wire to transfer the input electric energy through radiation. to the test piece. 6. A virtual thermal test method for structural strength analysis according to claim 1, characterized in that the Comsol electric field-thermal field coupling model needs to be model meshed, and the specific setting is: the mesh is free Quadrilateral mesh, size ultrafine.