A method and system for closed-loop feedback control of residual stress during propellant curing

Abstract

This application discloses a closed-loop feedback control method and system for residual stress in propellant curing. The method includes setting up a high-energy acoustic beam transducer for control and a high-energy acoustic beam transducer for monitoring; acquiring ultrasonic signals emitted by the transceiver end of the high-energy acoustic beam transducer passing through the propellant; analyzing the acquired ultrasonic signals to obtain the curing state of the propellant, wherein the curing state includes liquid, viscous, and solid states; setting control parameters for the high-energy acoustic beam transducer based on the curing state, wherein the control parameters include control power and control frequency, and the control parameters are set as a first control parameter, a second control parameter, and a third control parameter according to the curing state; and controlling the propellant in different curing states according to the control parameters. This application can reduce cavitation effects and segregation phenomena, adjust control parameters in a timely manner, ensure propellant quality, and effectively reduce residual stress.

Description

Technical Field

[0001] This application relates to the field of propellant performance research technology, specifically to a closed-loop feedback control method for residual stress during propellant solidification. Background Technology

[0002] High-energy ultrasound is one of the most effective and reliable methods for controlling residual stress during propellant curing. The control parameters for propellant residual stress control are subject to strict requirements. However, because the structural state of the propellant continuously changes during curing, the control parameters for high-energy ultrasound also need to be constantly adjusted. Existing techniques generally rely on visual or manual methods to test the propellant curing state, but these methods yield extremely unstable and incomplete results, directly affecting the setting of high-energy ultrasound control parameters and ultimately the control effect.

[0003] The propellant undergoes roughly three stages during solidification: liquid, viscous, and solid. When high-energy ultrasound propagates through the propellant slurry, it generates a series of tiny bubbles, a phenomenon known as cavitation. Under the influence of the high-energy sound beam, these bubbles rapidly expand, vibrate, and collapse, resulting in high-speed liquid micro-jet propagation, impact effects, high pressure, and the release of a large amount of energy. During the generation and collapse of these bubbles, changes in pressure or temperature can introduce porosity defects into the propellant, potentially leading to an explosion in severe cases.

[0004] When the propellant is in the liquid or viscous state, solid particles will settle due to gravity, which is called segregation. This will lead to uneven composition of the propellant, which will seriously affect the combustion performance and mechanical properties of the propellant. Segregation will also generate residual stress. Summary of the Invention

[0005] In view of this, the main objective of this application is to provide a closed-loop feedback control method and system for propellant solidification residual stress.

[0006] This application provides a closed-loop feedback control method for residual stress during propellant curing, comprising:

[0007] Set up a high-energy acoustic beam transducer for regulation and a high-energy acoustic beam transducer for monitoring.

[0008] The ultrasonic signals emitted by the transceiver of the high-energy acoustic beam transducer for monitoring pass through the propellant.

[0009] The solidification state of the propellant is obtained by analyzing the collected ultrasonic signals, which includes liquid, viscous and solid states.

[0010] Based on the curing state, the control parameters for the high-energy acoustic beam transducer are set, including control power and control frequency. The control parameters are set as a first control parameter, a second control parameter, and a third control parameter according to the curing state. The value of the first control parameter is not greater than the value of the second control parameter, and the value of the second control parameter is not greater than the value of the third control parameter.

[0011] The propellant in different solidification states is controlled according to the control parameters.

[0012] As described above, the number and operating frequency settings of the high-energy acoustic beam transducers used for regulation and monitoring differ under different operating modes. The high-energy acoustic beam transducers used for monitoring monitor the solidification state of the propellant during the solidification process, allowing for timely changes in the regulation frequency of the high-energy acoustic beam transducers used for regulation. The solidification states generally include liquid, viscous, and solid states. As the propellant transitions from liquid to solid, the regulation parameters increase in stages. The first regulation parameter corresponding to the liquid state includes at least one combination of regulation power and regulation frequency. Similarly, the second regulation parameter corresponding to the viscous state and the third regulation parameter corresponding to the solid state follow the same principle. Using different regulation parameters for different solidification states of the propellant can avoid cavitation effects, reduce segregation caused by particle sedimentation, and eliminate residual stress within the propellant. This ensures propellant quality while saving human resources.

[0013] Optionally, a high-energy acoustic beam transducer for regulation and a high-energy acoustic beam transducer for monitoring are configured, including:

[0014] Among the multiple high-energy acoustic beam transducers set on the outer wall of the mold where the propellant is cured

[0015] Within the first preset time period, all high-energy acoustic beam transducers are used as high-energy acoustic beam transducers for regulation to control the propellant.

[0016] During the second preset time period, all high-energy acoustic beam transducers are used as high-energy acoustic beam transducers for monitoring to monitor the solidification state inside the propellant.

[0017] The first preset time is longer than the second preset time, and the first preset time and the second preset time are consecutive.

[0018] As described above, the high-energy acoustic beam transducer on the outer wall of the mold where the propellant undergoes a curing reaction is used as a monitoring transducer during the second preset time period to monitor the curing state of the propellant. Based on the monitored curing state, the corresponding control parameters are selected, and the process proceeds to the first preset time period. All high-energy acoustic beam transducers are then used for control, and the propellant is controlled using the selected control parameters. During time-segmented control and monitoring, the second preset time for monitoring is much shorter than the first preset time for control, and this configuration allows for timely adjustment of the control parameters.

[0019] Optionally, the setting of a high-energy acoustic beam transducer for regulation and a high-energy acoustic beam transducer for monitoring further includes: in multiple layers of high-energy acoustic beam transducers disposed on the outer wall of the mold for propellant curing, multiple high-energy acoustic beam transducers in each layer serve as high-energy acoustic beam transducers for regulation, and the remaining high-energy acoustic beam transducers in each layer serve as high-energy acoustic beam transducers for monitoring; the high-energy acoustic beam transducers for regulation and the high-energy acoustic beam transducers for monitoring operate simultaneously.

[0020] Therefore, when the size of the mold for the propellant curing reaction is large enough, that is, each layer of the mold can support many pairs of high-energy acoustic beam transducers, some high-energy acoustic beam transducers can be used as high-energy acoustic beam transducers for regulation, and other high-energy acoustic beam transducers can be used as high-energy acoustic beam transducers for monitoring. The two types of high-energy acoustic beam transducers work at different operating frequencies at the same time, which can realize regulation and real-time monitoring at the same time.

[0021] Optionally, the operating frequency of the high-energy acoustic beam transducer used for regulation is different from the operating frequency of the high-energy acoustic beam transducer used for monitoring.

[0022] As shown above, the different operating frequencies of the two systems ensure that regulation and monitoring do not interfere with each other, thereby improving efficiency.

[0023] Optionally, in the high-energy acoustic beam transducer used for monitoring, the number of high-energy acoustic beam transducers used for transmitting and the number of high-energy acoustic beam transducers used for receiving are one-to-many, multiple-to-one, or multiple-to-multiple.

[0024] Therefore, under different working modes, the high-energy acoustic beam transducer used for monitoring can be set to one transmitter and one receiver, one transmitter and multiple receivers, or multiple transmitters and one receiver, etc. This is an adjustment made according to different needs and actual conditions, making it more flexible to use.

[0025] Optionally, the number of high-energy acoustic beam transducers used for regulation is arranged in pairs and is centrally symmetrically designed on the outer wall of the mold; the number of high-energy acoustic beam transducers used for monitoring is arranged in pairs and is centrally symmetrically designed on the outer wall of the mold.

[0026] As a result, the centrally symmetrical design makes it more convenient for high-energy acoustic beam transducers with different functions to transmit and receive signals.

[0027] This application provides a closed-loop feedback control system for residual stress during propellant curing, comprising:

[0028] Molds used for the propellant curing process;

[0029] Multiple high-energy acoustic beam transducers are evenly arranged in multiple layers around the outer side wall of the mold. One end of each high-energy acoustic beam transducer is electrically connected to the acquisition card via a relay. Each layer of high-energy acoustic beam transducers is pre-set with high-energy acoustic beam transducers for regulation and high-energy acoustic beam transducers for monitoring.

[0030] The computer has an internal controller that is electrically connected to the acquisition card. The controller analyzes the ultrasonic signals acquired by the acquisition card through the high-energy acoustic beam transducer to obtain the solidification state of the propellant, and adjusts the control parameters of the high-energy acoustic beam transducer according to the solidification state.

[0031] Network-controlled ultrasonic power supply provides power to high-energy acoustic beam transducers, relays, and data acquisition cards.

[0032] As described above, multiple high-energy acoustic beam transducers are installed on the outer wall of the mold used for the propellant curing reaction. The acquisition card collects the monitoring signals received by the high-energy acoustic beam transducers, the relay protects the acquisition card, and the computer internal controller analyzes the collected monitoring signals to obtain the curing state of the propellant. The computer adjusts the control parameters according to the curing state, so that the high-energy acoustic beam transducers control the propellant according to the adjusted control parameters, and can achieve the optimal control state for residual stress.

[0033] Optionally, the interface between the controller and the data acquisition card, and the interface between the data acquisition card and the relay, can be a network port, USB, or RS485.

[0034] Therefore, the interfaces between the controller and the acquisition card, and between the acquisition card and the relay, are not limited to network ports, USB, or RS485.

[0035] Optionally, the high-energy acoustic beam transducer used for regulation and the high-energy acoustic beam transducer used for monitoring are excited at their respective frequencies.

[0036] As shown above, each high-energy acoustic beam transducer vibrates at its natural frequency. High-energy acoustic beam transducers with the same function are located on different layers. The state of each layer of propellant is not necessarily the same. Therefore, the operating frequencies of high-energy acoustic beam transducers on different layers are not necessarily the same.

[0037] Optionally, the curing state includes liquid, viscous and solid, and the control parameters include control power and control frequency, with different values ​​of the control parameters set according to different curing states.

[0038] As described above, the solidification state of propellant is a process of gradual transformation from liquid to solid. Different solidification states correspond to different values ​​of control parameters. Low control power and low control frequency can reduce the occurrence of cavitation in the liquid state. As the solidification state increases, the control power and control frequency can reduce segregation and also reduce residual stress inside the propellant.

[0039] In summary, the propellant curing residual stress closed-loop feedback control method and system provided in this application have different operating modes, including time-segmented control and monitoring, and simultaneous control and monitoring. The number and operating frequency settings of the high-energy acoustic beam transducers used for control and monitoring differ in each mode. Time-segmented control and monitoring involves all high-energy acoustic beam transducers on the outer wall of the mold performing control or monitoring tasks at different times. Simultaneous control and monitoring involves a portion of the high-energy acoustic beam transducers being used for control and another portion for monitoring, with both working simultaneously, controlling and monitoring in real time. By monitoring the curing state of the propellant during the curing process using the high-energy acoustic beam transducers used for monitoring, the control parameters of the high-energy acoustic beam transducers used for control can be changed in a timely manner. Using different control parameters at different curing states of the propellant can avoid cavitation effects, reduce segregation caused by particle sedimentation, and eliminate residual stress inside the propellant, ensuring propellant quality while saving human resources. Attached Figure Description

[0040] The various technical features of this application and their relationships will be further explained below with reference to the accompanying drawings. The drawings are exemplary; some technical features are not shown to scale, and some drawings may omit technical features commonly used in the art to which this application pertains that are not essential for understanding and implementing this application, or additionally show technical features that are not essential for understanding and implementing this application. In other words, the combination of various technical features shown in the drawings is not intended to limit this application. Furthermore, throughout this application, the same reference numerals refer to the same things. Specific descriptions of the drawings are as follows:

[0041] Figure 1 This is a flowchart of a closed-loop feedback control method for residual stress in propellant curing, as described in this application.

[0042] Figure 2a This is a mold structure diagram of a closed-loop feedback control system for residual stress during propellant curing, as described in this application.

[0043] Figure 2b This is a top view of a mold for a closed-loop feedback control system for residual stress during propellant curing, as described in this application.

[0044] Figure 2c This is a structural block diagram of a closed-loop feedback control system for residual stress in propellant curing, as described in this application.

[0045] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0046] The preferred embodiments of this application will now be described in detail with reference to the accompanying drawings, so that the advantages and features of this application can be more easily understood by those skilled in the art, thereby providing a clearer and more definite definition of the scope of protection of this application.

[0047] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0048] Ultrasonic waves propagate at different speeds in different media. The propagation speed of ultrasound during propellant solidification depends primarily on the propellant's density and viscoelastic properties. During propellant solidification, the solidification state can be determined based on the propagation speed of ultrasound waves and the attenuation of the waveform amplitude. The propagation speed is calculated based on the time taken for the ultrasound waves to propagate through the propellant. Attenuation is due to energy loss (converted into heat) during propagation, primarily caused by the diffusion, scattering, and absorption of ultrasound waves.

[0049] When ultrasound propagates through a material, it is absorbed, scattered, and reflected, all of which cause the ultrasound waves to gradually attenuate. Therefore, the attenuation rate of ultrasound waves in a material becomes an important experimental parameter, reflecting the energy loss of the material to ultrasound waves. As the curing reaction proceeds, amplitude attenuation can reflect the time it takes for the propellant to reach a gel point during curing, and the changes in its phases from liquid to viscous to solid.

[0050] The ultrasonic signal undergoes a series of changes during the curing process. From the liquid to the viscous state, the arrival time of the ultrasonic wave peak decreases, the propagation speed increases, and the amplitude of the peak decreases. This indicates that the propellant exhibits exothermic activity in the early stages of the curing reaction, leading to a decrease in system viscosity. After a period of reaction, the propellant reaches a gel point. Following the gel point, the propellant enters a viscous state, where the arrival time of the ultrasonic wave peak continues to decrease, and the amplitude barely increases. This suggests that the propellant system in the viscous state has a low modulus, resulting in significant energy loss during ultrasonic wave transmission. Upon reaching a solid state, the amplitude gradually increases until the curing reaction is complete. This indicates that as the propellant curing reaction progresses, its internal macromolecules continuously cross-link and polymerize, reaching a solid state. The system viscosity increases dramatically, causing the ultrasonic wave propagation speed to increase continuously, and the system modulus to gradually recover. Therefore, ultrasonic signals can successfully monitor the gel point and phase changes of polymers such as propellants online during the curing process and accurately quantify the time domain of each stage.

[0051] The technical solutions of this application and how they solve the aforementioned technical problems will be described in detail below with specific embodiments. The specific embodiments described below can be combined with each other to form new embodiments. The same or similar ideas or processes described in one embodiment may not be repeated in other embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0052] Figure 1 This is a flowchart of a specific embodiment of the propellant solidification residual stress closed-loop feedback control method of this application.

[0053] This application provides a closed-loop feedback control method for residual stress during propellant curing, comprising:

[0054] S101: Setting up a high-energy acoustic beam transducer for regulation and a high-energy acoustic beam transducer for monitoring.

[0055] S102: Collect ultrasonic signals emitted by the transceiver of the high-energy acoustic beam transducer used for monitoring, which pass through the propellant.

[0056] S103: Analyze the acquired ultrasonic signals to obtain the solidification state of the propellant, which includes liquid, viscous and solid states;

[0057] S104: Based on the curing state, set the control parameters for the high-energy acoustic beam transducer, wherein the control parameters include control power and control frequency. The control parameters are set as a first control parameter, a second control parameter and a third control parameter according to the curing state. The value of the first control parameter is not greater than the value of the second control parameter, and the value of the second control parameter is not greater than the value of the third control parameter.

[0058] S105: The propellant in different solidification states is regulated according to the control parameters. Specifically, the number and operating frequency of the high-energy acoustic beam transducers used for regulation and monitoring are different in different operating modes. The high-energy acoustic beam transducers used for monitoring monitor the solidification state of the propellant during the solidification process, and the control frequency of the high-energy acoustic beam transducers used for regulation is changed in a timely manner. The solidification states generally include liquid, viscous, and solid states. When the propellant changes from liquid to solid, the control parameters also increase in stages. The first control parameter corresponding to the liquid state includes at least one combination of control power and control frequency. Similarly, the second control parameter corresponding to the viscous state and the third control parameter corresponding to the solid state are also like this. By adopting different control parameters for different solidification states of the propellant, cavitation effects can be avoided, segregation caused by particle sedimentation can be reduced, and residual stress inside the propellant can be reduced. This ensures the quality of the propellant while saving human resources.

[0059] Optionally, a high-energy acoustic beam transducer for regulation and a high-energy acoustic beam transducer for monitoring are configured, including:

[0060] Among the multiple high-energy acoustic beam transducers set on the outer wall of the mold where the propellant is cured

[0061] Within the first preset time period, all high-energy acoustic beam transducers are used as high-energy acoustic beam transducers for regulation to control the propellant.

[0062] During the second preset time period, all high-energy acoustic beam transducers are used as high-energy acoustic beam transducers for monitoring to monitor the solidification state inside the propellant.

[0063] The first preset time is longer than the second preset time, and the first preset time and the second preset time are consecutive.

[0064] Specifically, the high-energy acoustic beam transducer on the outer wall of the mold where the propellant undergoes a curing reaction is used as a monitoring transducer for a second preset time period to monitor the curing state of the propellant. Based on the monitored curing state, the corresponding control parameters are selected, and then the process enters the first preset time period. All high-energy acoustic beam transducers are used as control transducers, and the propellant is controlled using the selected control parameters. During time-segmented control and monitoring, the second preset time for monitoring is much shorter than the first preset time for control. This configuration also allows for timely adjustment of the control parameters.

[0065] Optionally, the setting of a high-energy acoustic beam transducer for regulation and a high-energy acoustic beam transducer for monitoring further includes: in multiple layers of high-energy acoustic beam transducers disposed on the outer wall of the mold for propellant curing, multiple high-energy acoustic beam transducers in each layer serve as high-energy acoustic beam transducers for regulation, and the remaining high-energy acoustic beam transducers in each layer serve as high-energy acoustic beam transducers for monitoring; the high-energy acoustic beam transducers for regulation and the high-energy acoustic beam transducers for monitoring operate simultaneously.

[0066] Specifically, when the mold for the propellant curing reaction is large enough, that is, each layer of the mold can support many pairs of high-energy acoustic beam transducers, some high-energy acoustic beam transducers can be used as high-energy acoustic beam transducers for regulation, and other high-energy acoustic beam transducers can be used as high-energy acoustic beam transducers for monitoring. The two types of high-energy acoustic beam transducers operate at different operating frequencies at the same time, which can realize regulation and real-time monitoring at the same time.

[0067] Optionally, the operating frequency of the high-energy acoustic beam transducer used for regulation is different from the operating frequency of the high-energy acoustic beam transducer used for monitoring.

[0068] Specifically, their different operating frequencies allow for independent control and monitoring, thus improving efficiency.

[0069] Optionally, in the high-energy acoustic beam transducer used for monitoring, the number of high-energy acoustic beam transducers used for transmitting and the number of high-energy acoustic beam transducers used for receiving are one-to-many, multiple-to-one, or multiple-to-multiple.

[0070] Specifically, in different working modes, the high-energy acoustic beam transducers used for monitoring can be configured as one transmitter and one receiver, one transmitter and multiple receivers, or multiple transmitters and one receiver, etc. This is an adjustment made according to different needs and actual situations, making it more flexible to use.

[0071] Optionally, the number of high-energy acoustic beam transducers used for regulation is arranged in pairs and is centrally symmetrically designed on the outer wall of the mold; the number of high-energy acoustic beam transducers used for monitoring is arranged in pairs and is centrally symmetrically designed on the outer wall of the mold.

[0072] Specifically, the centrally symmetrical design makes it easier for high-energy acoustic beam transducers with different functions to transmit and receive signals.

[0073] This application provides a closed-loop feedback control system for residual stress during propellant curing, comprising:

[0074] Molds used for the propellant curing process;

[0075] Multiple high-energy acoustic beam transducers are evenly arranged in multiple layers around the outer side wall of the mold. One end of each high-energy acoustic beam transducer is electrically connected to the acquisition card via a relay. Each layer of high-energy acoustic beam transducers is pre-set with high-energy acoustic beam transducers for regulation and high-energy acoustic beam transducers for monitoring.

[0076] The computer has an internal controller that is electrically connected to the acquisition card. The controller analyzes the ultrasonic signals acquired by the acquisition card through the high-energy acoustic beam transducer to obtain the solidification state of the propellant, and adjusts the control parameters of the high-energy acoustic beam transducer according to the solidification state.

[0077] Network-controlled ultrasonic power supply provides power to high-energy acoustic beam transducers, relays, and data acquisition cards.

[0078] Specifically, multiple high-energy acoustic beam transducers are installed on the outer wall of the mold used for the propellant curing reaction. A data acquisition card collects the monitoring signals received by the high-energy acoustic beam transducers. A relay protects the data acquisition card. The computer's internal controller analyzes the collected monitoring signals to obtain the curing state of the propellant. The computer adjusts the control parameters according to the curing state, so that the high-energy acoustic beam transducers can control the propellant according to the adjusted control parameters, thereby achieving the optimal control state for residual stress.

[0079] Optionally, the interface between the controller and the data acquisition card, and the interface between the data acquisition card and the relay, can be a network port, USB, or RS485.

[0080] Specifically, the interfaces between the controller and the data acquisition card, and between the data acquisition card and the relay, are not limited to network ports, USB, or RS485.

[0081] Optionally, the high-energy acoustic beam transducer used for regulation and the high-energy acoustic beam transducer used for monitoring are excited at their respective frequencies.

[0082] Specifically, each high-energy acoustic beam transducer vibrates at its natural frequency. High-energy acoustic beam transducers with the same function are located on different layers. The state of each layer of propellant is not necessarily the same, so the operating frequencies of high-energy acoustic beam transducers on different layers are not necessarily the same.

[0083] Optionally, the curing state includes liquid, viscous and solid, and the control parameters include control power and control frequency, with different values ​​of the control parameters set according to different curing states.

[0084] Specifically, the solidification state of the propellant is a process of gradual transformation from liquid to solid. Different solidification states correspond to different values ​​of control parameters. Low control power and low control frequency can reduce the occurrence of cavitation in the liquid state. As the solidification state increases, the control power and control frequency can reduce segregation and also reduce residual stress inside the propellant.

[0085] Figures 2a-2c This paper illustrates a specific embodiment of the propellant solidification residual stress closed-loop feedback control system of this application. For example... Figures 2a-2b As shown, this example has three layers of high-energy acoustic beam transducers on the outer wall of the mold. Each layer has three high-energy acoustic beam transducers, which are evenly distributed along its circumference. The high-energy acoustic beam transducers in each layer are pre-set to be used for regulation and monitoring. A high-energy acoustic beam transducer is set at the bottom of the mold, which is only used to regulate residual stress.

[0086] exist Figure 2c In the diagram, 0-9 simply represent the number of items. The 10 high-energy acoustic beam transducers are electrically connected to the 10 acquisition cards via 10 relay switches, and the acquisition cards are electrically connected to the controller.

[0087] As the propellant solidification reaction proceeds, the propellant first transforms from a liquid state to a viscous state, and then from a viscous state to a solid state. These processes can be observed through the changes in the propagation speed and amplitude attenuation curves of the ultrasonic waves.

[0088] Residual stress in the propellant affects the propagation speed of ultrasonic waves. When the direction of residual stress is consistent with the longitudinal wave direction, tensile stress slows down the propagation speed of ultrasonic waves or prolongs the propagation time T, while compressive stress speeds up the propagation speed or shortens the propagation time T. Therefore, under the condition that the distance between the excitation and receiving transducers is fixed, if the ultrasonic propagation time T0 corresponding to zero stress σ0 is known, the residual stress in the propellant can be calculated based on the time difference ΔT by detecting the ultrasonic propagation time T corresponding to the measured stress state σ.

[0089] σ-σ0=K×(T-T0), that is, Δσ=K×ΔT

[0090] Among them, K stress coefficient needs to be obtained through calibration for specific transducer configuration and test material, Δσ is the change in residual stress, and ΔT is the change in ultrasonic wave propagation time.

[0091] Based on the above, the changes in residual stress inside the propellant can be plotted using methods such as cloud maps.

[0092] Taking a mold for propellant curing, consisting of multiple vertically stacked circular die sections, as an example, the bottom of the mold is equipped with one or more high-energy acoustic beam transducers, which are used only to reduce residual stress inside the propellant. Each die section is equipped with multiple high-energy acoustic beam transducers, which can be used as both exciters and signal sensors. The following embodiments use this mold as an example to illustrate its working principle:

[0093] Example 1

[0094] This embodiment takes the residual stress regulation and ultrasonic signal monitoring of multiple high-energy acoustic beam transducers on each module section in different time periods as an example. It is assumed that there are three high-energy acoustic beam transducers on each module section, and based on the empirical values ​​of human experiments, all three high-energy acoustic beam transducers on each module section are excited for 1 hour, and then ultrasonic signal monitoring is performed for 10 seconds. In this case, all three high-energy acoustic beam transducers on each module section are excited simultaneously, and the high-energy acoustic beam transducers are used to reduce and homogenize residual stress. When the high-energy acoustic beam transducers are not excited to regulate residual stress, the number of high-energy acoustic beam transducers used for transmitting and receiving on each module section can be flexibly configured, including one transmitter and multiple receivers, multiple transmitters and one receiver, or multiple transmitters and multiple receivers (the number of high-energy acoustic beam transducers on each module section is not less than four).

[0095] Taking a single-transmitter, multiple-receiver configuration as an example, on each propellant section, one high-energy acoustic beam transducer emits ultrasonic signals, while the other two high-energy acoustic beam transducers receive the ultrasonic signals passing through the propellant. During the propellant's solidification process—the transformation from liquid to viscous to solid—ultrasonic signals are monitored for 10 seconds. Based on the overall liquid state and stress state of the propellant, the control parameters of each high-energy acoustic beam transducer are adjusted (these values ​​are pre-set based on empirical values ​​from human experiments, and then the controller adjusts the control parameters according to the propellant's solidification state and stress changes). Control then begins. Every hour, a 10-second ultrasonic signal monitoring is performed. Based on the monitored propellant solidification state and stress changes, the controller adjusts the pre-set control parameters and continues to control the propellant to achieve the optimal control state, ultimately reducing and homogenizing the residual stress after propellant solidification.

[0096] During the liquid-viscous-solid transformation of the propellant, the propellant is intermittently regulated and its state monitored. The regulation parameters of the high-energy acoustic beam transducer are increased sequentially. In the liquid state, with a fixed input power, cavitation is more likely to occur at lower frequencies. To avoid cavitation and ensure that the regulation parameters of the high-energy acoustic beam transducer are as low as possible, the regulation frequency should not be lower than 20 kHz (the lowest regulation frequency when the propellant is in the liquid state). Reducing the regulation power can reduce the occurrence of cavitation. In the transition from liquid to viscous state and then to solid state, to avoid segregation caused by the sedimentation of solid particles, the regulation parameters of the high-energy acoustic beam transducer should be increased, but the regulation frequency should not exceed 50 kHz (the highest regulation frequency when the propellant is in the solid state).

[0097] Each high-energy acoustic beam transducer mounted on the outer wall of the mold is electrically connected to a data acquisition card via a relay multiplexer. Each data acquisition card is electrically connected to a computer with a controller. A network-controlled ultrasonic power supply provides power to the high-energy acoustic beam transducers, relays, and data acquisition cards. When the high-energy acoustic beam transducers switch between control and monitoring states at different time intervals, the computer controls the relays to disconnect the power supply to the high-energy acoustic beam transducers and data acquisition cards, thus protecting the multiplex data acquisition cards. The data acquisition cards send the ultrasonic signal data monitored by the high-energy acoustic beam transducers to the computer. The controller performs calculations and, based on the propagation speed of the ultrasonic signal and the amplitude attenuation curve of the waveform, derives a step graph of the solidification state, with time as the horizontal axis and solidification state as the vertical axis. That is, the solidification state of the propellant remains basically unchanged within a certain time interval, maintaining a horizontal line state; in the next time interval, the solidification state of the propellant is another step-like horizontal line.

[0098] The controller can also determine the changes in residual stress inside the propellant by analyzing the monitored ultrasonic signals. The computer retrieves the corresponding control parameters based on the solidification state and stress changes of the propellant, enabling the high-energy acoustic beam transducer to achieve optimal control.

[0099] Example 2

[0100] This embodiment takes the simultaneous control and monitoring of multiple high-energy acoustic beam transducers on each mold section as an example. In this case, the number of high-energy acoustic beam transducers on each mold section is arranged in pairs, and the high-energy acoustic beam transducers used for control and those used for monitoring are spaced apart on each mold section. Furthermore, among the high-energy acoustic beam transducers used for monitoring, the high-energy acoustic beam transducers used for transmitting and those used for receiving are arranged opposite each other on the outer wall of the mold section. This facilitates the reception of the transmitted ultrasonic signals that have passed through the propellant, so as to monitor the solidification state of the propellant in a timely manner and adjust the control parameters of the high-energy acoustic beam transducers.

[0101] Only when the mold is large enough to accommodate multiple pairs of high-energy acoustic beam transducers can the propellant be simultaneously regulated and monitored. In order to ensure the efficiency of regulation and monitoring, each mold section has at least four high-energy acoustic beam transducers for regulation and at least four for monitoring.

[0102] During the liquid-viscous-solid transformation of the propellant, both the high-energy acoustic beam transducer used for regulation and the high-energy acoustic beam transducer used for monitoring operate simultaneously. The frequency of the high-energy acoustic beam transducer used for regulation is different from that of the high-energy acoustic beam transducer used for monitoring. For example, when the propellant is in a liquid state, the regulation frequency of the high-energy acoustic beam transducer used for regulation is set to 20 kHz, while the monitoring frequency of the high-energy acoustic beam transducer used for monitoring is set to 50 kHz, so that the two high-energy acoustic beam transducers do not experience signal interference.

[0103] Each high-energy acoustic beam transducer mounted on the outer wall of the mold is electrically connected to a data acquisition card via a relay multiplexer. Each data acquisition card is electrically connected to a computer with a controller. A network-controlled ultrasonic power supply provides power to the high-energy acoustic beam transducers, relays, and data acquisition cards. The relays can disconnect the high-voltage electrical signal when the high-energy acoustic beam transducers are under high-power excitation, thus protecting the multiplexer data acquisition cards.

[0104] The controller in the computer analyzes the ultrasonic signal data acquired in real time by the acquisition card, and can plot the changes in the peak arrival time and amplitude of the ultrasonic waves, as well as the changes in the propagation speed and attenuation of the ultrasonic waves as the propellant solidifies. The controller judges the solidification state of the propellant based on information such as the phase, amplitude, and velocity of the ultrasonic waves. Since the solidification process of the propellant is slow, it generally takes 7-9 days to complete. Therefore, under normal circumstances, the solidification state of the propellant presents a step-like change graph. At the same time, the computer can also display the stress change state of the residual stress inside the propellant. Based on the solidification state and stress change state of the propellant, the computer adjusts the control parameters of the high-energy acoustic beam transducer. When changing the control parameters of the high-energy acoustic beam transducer, a relay is used to instantly complete the power-off and power-on of the high-energy acoustic beam transducer when changing the control parameters.

[0105] In summary, the propellant curing residual stress closed-loop feedback control method and system provided in this application have different operating modes, including time-segmented control and monitoring, and simultaneous control and monitoring. The number and operating frequency settings of the high-energy acoustic beam transducers used for control and monitoring differ in each mode. Time-segmented control and monitoring involves all high-energy acoustic beam transducers on the outer wall of the mold performing control or monitoring tasks at different times. Simultaneous control and monitoring involves a portion of the high-energy acoustic beam transducers being used for control and another portion for monitoring, with both working simultaneously, controlling and monitoring in real time. By monitoring the curing state of the propellant during the curing process using the high-energy acoustic beam transducers used for monitoring, the control parameters of the high-energy acoustic beam transducers used for control can be changed in a timely manner. Using different control parameters at different curing states of the propellant can avoid cavitation effects, reduce segregation caused by particle sedimentation, and eliminate residual stress inside the propellant, ensuring propellant quality while saving human resources.

[0106] Unless otherwise defined, all technical and scientific terms used throughout this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. In case of any inconsistency, the meaning as stated in this application or derived from the content described herein shall prevail. Furthermore, the terminology used in this description is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0107] Note that the above are merely preferred embodiments and the technical principles employed in this application. Those skilled in the art will understand that this application is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of this application. Therefore, although this application has been described in detail through the above embodiments, this application is not limited to the above embodiments. Many other equivalent embodiments may be included without departing from the technical concept of this application, all of which fall within the scope of protection of this application.

[0108] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A closed-loop feedback control method for residual stress during propellant curing, characterized in that, include: Set up a high-energy acoustic beam transducer for regulation and a high-energy acoustic beam transducer for monitoring. The ultrasonic signals emitted by the transceiver of the high-energy acoustic beam transducer used for monitoring, passing through the propellant, are collected. The solidification state of the propellant is obtained by analyzing the collected ultrasonic signals, wherein the solidification state includes liquid, viscous and solid states; Based on the solidification state, the control parameters of the high-energy acoustic beam transducer for regulation are set, wherein the control parameters include control power and control frequency. The control parameters are set according to the solidification state as a first control parameter for regulating the liquid state, a second control parameter for regulating the viscous state, and a third control parameter for regulating the solid state. The value of the first control parameter is not greater than the value of the second control parameter, and the value of the second control parameter is not greater than the value of the third control parameter. The propellant in different solidification states is controlled according to the control parameters; The high-energy acoustic beam transducer set for regulation and the high-energy acoustic beam transducer set for monitoring include: Among the multiple high-energy acoustic beam transducers set on the outer wall of the mold where the propellant is cured Within a first preset time period, all high-energy acoustic beam transducers are used as the high-energy acoustic beam transducers for regulation to regulate the propellant. During the second preset time period, all high-energy acoustic beam transducers are used as the high-energy acoustic beam transducers for monitoring to monitor the solidification state inside the propellant. Wherein, the first preset time is longer than the second preset time, and the first preset time and the second preset time are continuous.

2. The propellant curing residual stress closed-loop feedback control method according to claim 1, characterized in that, The high-energy acoustic beam transducer set for regulation and the high-energy acoustic beam transducer set for monitoring also include: In multiple high-energy acoustic beam transducers set on the outer wall of the mold where the propellant is cured. Multiple high-energy acoustic beam transducers in each layer serve as the high-energy acoustic beam transducers used for regulation, and the remaining high-energy acoustic beam transducers in each layer serve as the high-energy acoustic beam transducers used for monitoring. The high-energy acoustic beam transducer used for regulation and the high-energy acoustic beam transducer used for monitoring operate simultaneously.

3. The propellant curing residual stress closed-loop feedback control method according to claim 2, characterized in that, Also includes: The operating frequency of the high-energy acoustic beam transducer used for regulation is different from the operating frequency of the high-energy acoustic beam transducer used for monitoring.

4. The closed-loop feedback control method for residual stress during propellant curing according to claim 1, characterized in that, Also includes: In the high-energy acoustic beam transducer used for monitoring, the number of high-energy acoustic beam transducers used for transmitting and the number of high-energy acoustic beam transducers used for receiving are one-to-many, multiple-to-one, or multiple-to-multiple.

5. The closed-loop feedback control method for residual stress during propellant curing according to claim 2, characterized in that, Also includes: The number of high-energy acoustic beam transducers used for regulation are arranged in pairs and are designed in a centrally symmetrical manner on the outer wall of the mold. The high-energy acoustic beam transducers used for monitoring are arranged in pairs and are designed in a centrally symmetrical manner on the outer wall of the mold.

6. A closed-loop feedback control system for residual stress during propellant curing, characterized in that, include: Molds used for the propellant curing process; Multiple high-energy acoustic beam transducers are evenly and circumferentially arranged in multiple layers on the outer side wall of the mold. One end of each high-energy acoustic beam transducer is electrically connected to a data acquisition card via a relay. Each layer of high-energy acoustic beam transducers is pre-set with high-energy acoustic beam transducers for regulation and high-energy acoustic beam transducers for monitoring. The high-energy acoustic beam transducers for regulation and monitoring include: within a first preset time period, all high-energy acoustic beam transducers act as the high-energy acoustic beam transducers for regulation to regulate the propellant; within a second preset time period, all high-energy acoustic beam transducers act as the high-energy acoustic beam transducers for monitoring to monitor the solidification state inside the propellant. The first preset time period is longer than the second preset time period, and the first preset time period and the second preset time period are continuous. A computer, whose internal controller is electrically connected to the acquisition card, analyzes the ultrasonic signals acquired by the acquisition card through the high-energy acoustic beam transducer to obtain the solidification state of the propellant, and adjusts the control parameters of the high-energy acoustic beam transducer according to the solidification state. The solidification state includes liquid, viscous and solid states, and the control parameters include control power and control frequency, and the control parameters are set to different values ​​according to different solidification states. A network-controlled ultrasonic power supply provides power to the high-energy acoustic beam transducer, the relay, and the acquisition card.

7. The propellant curing residual stress closed-loop feedback control system according to claim 6, characterized in that, The interface between the controller and the acquisition card, and the interface between the acquisition card and the relay, adopt a network port, USB, or RS485.

8. The propellant curing residual stress closed-loop feedback control system according to claim 6, characterized in that, The high-energy acoustic beam transducer used for regulation and the high-energy acoustic beam transducer used for monitoring are respectively excited at their respective frequencies.

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