Wide-temperature-range force and heat load cooperative loading device

Abstract

The invention discloses a wide-temperature-range force and heat load in-situ collaborative loading device, and belongs to the technical field of spacecraft structures. Comprising a hollow frame, a sample is arranged in the hollow frame, a liquid nitrogen cooling module is arranged below the sample, and a resistance heating sheet and a hydraulic loading module are arranged above the sample; the above modules are electrically connected to a multi-physics field coupling control system, and through the above device, an alternating force thermal load environment faced by a storage tank shell structure is approximately simulated, and time-space cooperative accurate regulation and control of an extreme temperature range (-196 DEG C to + 200 DEG C) and a complex mechanical load (static / dynamic pressure) are realized. And a synergistic effect scene of high-frequency alternating thermal shock and unsteady pressure fluctuation faced by the storage tank shell in on-orbit service can be reproduced. The temperature domain which can be simulated by the test is improved, the damage of the test sample is reduced, and dynamic regulation and control and accurate temperature field generation of an extreme temperature environment as well as time-space collaborative accurate regulation and control of temperature and mechanical load are realized.

Description

Technical Field

[0001] The present invention belongs to the field of spacecraft structure technology, and specifically relates to a loading device and control method that can realize multi-physical field coupling experiments of spacecraft composite materials structures under the synergistic action of extreme temperatures (-196°C to +300°C) and complex mechanical loads (static / dynamic pressure). Background Art

[0002] With advancements in on-orbit servicing technology, spacecraft are developing toward long-life, high-reliability, and reusable features. Propellant tanks, as the core structure of on-orbit servicing spacecraft, differ from traditional launch vehicle tanks, which only require short-term storage and single refueling. New tanks for on-orbit servicing spacecraft must possess three core characteristics: reusability, high reliability, and lightweight. Research and development of composite tanks for on-orbit servicing spacecraft is still in the early stages of technological exploration. The relevant basic theories and design methods are not yet fully developed, and a mature engineering solution has yet to be established. The core contradiction of this research gap lies in the following: while traditional metal tanks have mature manufacturing processes and reliability verification systems, their structural efficiency is low, making it difficult to meet the core lightweighting requirements of spacecraft systems. Composite tanks have significant lightweighting potential, but their performance degradation patterns in the long-term complex aerospace environment have not been systematically revealed, becoming a key bottleneck restricting the reusable design and reliability assessment of tanks.

[0003] Reusability requires that the tank maintain near-zero leakage and structural stability under the temperature shocks and multi-source force loads generated during multiple filling / emptying processes, supporting the continuous replenishment of cryogenic propellants during multiple mission cycles; high reliability requires overcoming the thermal cycle fatigue caused by the large temperature difference alternating loads formed by multiple fillings and the space environment temperature, and adapting to the needs of on-orbit residence for several years or even longer; lightweighting requires reducing the tank's own weight through composite materials, structural topology design and other technologies to improve the structural efficiency of the spacecraft. Therefore, the tanks of on-orbit servicing spacecraft face a coupled service environment with a wide temperature range and synergistic effects of force and thermal loads, which poses a challenge to the service performance of composite materials in this environment. Therefore, the development of a wide-temperature range force and thermal load synergistic loading device to form the ability to simulate the coupled service environment of spacecraft tanks is of great value to the structural design of on-orbit servicing spacecraft.

[0004] The existing composite material environment simulation device has the following shortcomings:

[0005] Narrow temperature range: Traditional refrigeration technology is difficult to achieve ultra-low temperature environments below -196°C, and the high-temperature heating rate and temperature control accuracy are insufficient.

[0006] Load uniformity: Mechanical loading systems are mostly single-actuator structures, which cannot achieve dynamic uniform pressure loading.

[0007] Poor structural reliability: The specimen is prone to damage due to thermal stress concentration or mechanical shock under extreme temperatures.

[0008] Multi-field coupling failure: The co-control precision of the temperature field and the mechanical field is low, lacking the ability of spatio-temporal synchronous regulation. Summary of the Invention

[0009] In order to solve the above technical problems, the present invention provides a wide-temperature-range force-thermal load collaborative loading device. The present invention integrates the dual-mode coupling of liquid nitrogen spraying refrigeration and high-response resistance heating, realizes the dynamic regulation and precise temperature field generation of the extreme temperature environment (-196°C to +300°C) in a wide temperature range, and breaks through the limit temperature range boundary of the existing technology; the present invention proposes a multi-actuator collaborative uniform loading architecture, which converts the single-point load into a uniform load through a high-rigidity pressure transfer plate, and realizes the precise application of quasi-static and dynamic uniform loads; the present invention introduces a flexible fluorinated rubber water belt between the high-response thermal resistance heating sheet and the high-rigidity pressure transfer plate, which enhances the load distribution uniformity and prevents the heat loss of the resistance heating plate at the same time. The present invention introduces a quartz flexible buffer layer, and suppresses the damage induced by the hard contact between the composite material specimen and the hollow frame through structural design; the present invention develops a control program based on multi-field collaborative logic, and realizes the precise spatio-temporal synchronous loading of temperature and pressure through the phase compensation control of the actuator. Compared with the existing technology, the present invention has achieved a technical breakthrough in "wide temperature range - multi-load - high reliability".

[0010] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0011] A wide-temperature-range force-thermal load in-situ collaborative loading device, comprising: a hollow frame.

[0012] A specimen is arranged inside the frame, a liquid nitrogen cooling module is arranged below the specimen, and a resistance heating sheet and a hydraulic loading module are arranged above the specimen.

[0013] The liquid nitrogen cooling module, the resistance heating module and the hydraulic loading module are all electrically connected to a control computer.

[0014] Further, the liquid nitrogen cooling module includes a liquid nitrogen nozzle installed at the bottom of the hollow frame, and an adiabatic pipeline, a solenoid valve and a liquid nitrogen dewar outside the frame.

[0015] Further, the hydraulic loading module includes a plurality of actuators, a high-rigidity pressure transfer plate, a hydraulic pump and a hydraulic controller.

[0016] Further, a quartz sand buffer layer is arranged between the specimen and the hollow frame, and a fluorinated rubber water belt is arranged between the resistance heating sheet and the high-rigidity pressure transfer plate.

[0017] Further, temperature sensors are arranged on both the upper and lower surfaces of the specimen.

[0018] A multi-physical-field coupling experimental method integrates a temperature-field feedback and a dynamic load spectrum tracking algorithm based on the LabVIEW platform to achieve spatio-temporal synchronous control of temperature and pressure. The tracking algorithm is used to track the changing thermo-mechanical load target in real time. Its core is to make the system output (such as temperature, force, displacement, acceleration) accurately follow the preset dynamic load spectrum through a control algorithm. The input of the tracking algorithm is the time-varying thermo-mechanical load target set in the experiment; the output is the real-time response of the system, that is, the measurement data of the temperature sensors set on the upper and lower surfaces of the specimen and the pressure sensors built in the hydraulic pump; the goal is to minimize the tracking error by adjusting the solenoid valve opening, the power of the resistance heating element, and the flow rate of the hydraulic pump in real time. By combining feedforward compensation, feedback regulation, and online learning, the dynamic load spectrum tracking algorithm can achieve high-precision tracking.

[0019] The liquid nitrogen cooling module dynamically adjusts the solenoid valve opening through the PID algorithm. The temperature data collected by the temperature sensor set on the lower surface of the specimen is the input of the PID system; the computer runs the PID algorithm to output an execution signal, and controls the liquid nitrogen spraying amount on the lower surface of the specimen by adjusting the solenoid valve opening. Combining technologies such as integral anti-windup and derivative filtering, precise control of the specimen surface temperature is achieved.

[0020] The resistance heating element realizes closed-loop control of the target temperature through the PID algorithm. The temperature data collected by the temperature sensor set on the upper surface of the specimen is the input of the PID system; the computer outputs an execution signal by running the PID algorithm to control the power of the resistance heating element. Combining technologies such as integral anti-windup and derivative filtering, precise control of the specimen upper surface temperature is achieved. The hydraulic loading module realizes dynamic uniform pressure loading through uniformly distributed actuators and high-rigidity transfer plates.

[0021] For the hollow frame described above, exhaust holes are provided on its side surface.

[0022] The beneficial effects of the present invention are as follows:

[0023] In the present invention, by installing a resistance heating element and a liquid nitrogen cooling module on the upper and lower surfaces of the composite material specimen respectively, and applying dynamic uniform pressure to it through the hydraulic loading module, the alternating force and heat load environment faced by the tank shell structure is approximately simulated, realizing spatio-temporal coordinated and precise regulation of the extreme temperature range (-196°C to +200°C) and complex mechanical loads (static / dynamic pressure), and reproducing the scenario of the combined action of high-frequency alternating thermal shock and unsteady pressure fluctuation faced by the tank shell during on-orbit service.

[0024] The temperature range that can be simulated by the experiment is significantly improved. During the experiment, specimen damage is not likely to occur, realizing dynamic regulation of the extreme temperature environment and precise temperature field generation, and realizing spatio-temporal coordinated and precise regulation of temperature and mechanical loads. Description of the Drawings

[0025] Figure 1 It is the overall framework diagram of the wide-temperature-range force-thermal load collaborative loading device provided by the present invention.

[0026] Figure 2 It is the structural schematic diagram of the composite material multi-physical-field coupling experimental platform provided by the present invention.

[0027] Reference numerals: 1, hollow frame; 2, exhaust hole; 3, high-rigidity pressure transmission plate; 4, actuator cylinder; 5, power regulator; 6, hydraulic pump; 7, hydraulic controller; 8, data collector; 9, control computer; 10, controller; 11, solenoid valve; 12, liquid nitrogen dewar; 13, temperature sensor; 14, fluorinated rubber water hose; 15, resistance heating sheet; 16, specimen; 17, quartz sand buffer layer; 18, liquid nitrogen nozzle; 19, liquid nitrogen spraying and sweeping; 20, adiabatic pipeline. Specific embodiments

[0028] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention will be further described in detail below with reference to the drawings and embodiments. It can be understood that the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The following embodiments are only used to explain the present invention, rather than limiting the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0029] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Terms such as "connected" and "linked" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Terms such as "include" and "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, the elements defined by the statement "include..." do not exclude the existence of additional identical elements in the process, method, article or device including the said elements.

[0030] An embodiment provided by the present invention, as Figure 1As shown in the figure, a wide-temperature-range in-situ collaborative loading device for force and thermal loads includes: a hollow frame 1.

[0031] As Figure 2 shown, a specimen 16 is arranged inside the hollow frame 1. A liquid nitrogen cooling module is arranged below the specimen 16, and a resistance heating sheet 15 and a hydraulic loading module are arranged above the specimen 16.

[0032] The liquid nitrogen cooling module, the resistance heating sheet 15, and the hydraulic loading module are all electrically connected to a control computer 9.

[0033] The liquid nitrogen cooling module includes a liquid nitrogen nozzle 18 installed at the bottom of the hollow frame 1, an adiabatic pipeline 20 outside the frame, a solenoid valve 11, and a liquid nitrogen dewar 12.

[0034] The hydraulic loading module includes a high-rigidity pressure transfer plate 3, a plurality of actuating cylinders 4, a hydraulic pump 6, and a hydraulic controller 7.

[0035] A quartz sand buffer layer 17 is arranged between the specimen 16 and the hollow frame 1, and a fluorinated rubber water belt 14 is arranged between the resistance heating sheet 15 and the high-rigidity pressure transfer plate 3. Its functions are to buffer mechanical shocks, form a uniform load, and reduce heat conduction.

[0036] Temperature sensors 13 are arranged on the upper and lower surfaces of the specimen 16.

[0037] A multi-physical-field coupling experiment method integrates a temperature field feedback and a dynamic load spectrum tracking algorithm based on the LabVIEW platform to achieve spatio-temporal synchronous control of temperature and pressure.

[0038] The liquid nitrogen cooling module dynamically adjusts the opening degree of the solenoid valve through a PID algorithm.

[0039] The resistance heating sheet 15 uses a serpentine nickel-chromium alloy wire.

[0040] The hydraulic loading module realizes dynamic uniform pressure loading through the uniform actuating cylinders 4 and the high-rigidity pressure transfer plate 3.

[0041] A number of exhaust holes 2 are arranged on the side surface of the hollow frame 1.

[0042] In this embodiment, the hollow frame 1 is made of 304 stainless steel by welding, with a hollow design inside. A number of exhaust holes 2 are arranged around it, which are used for discharging the cold air after the liquid nitrogen vaporizes during the test. A liquid nitrogen nozzle 18 is installed at the center of the bottom. Through the liquid nitrogen spraying 19, a low-temperature test environment is provided for the specimen 16. The liquid nitrogen nozzle 18 is connected to the solenoid valve 11 and the liquid nitrogen dewar 12 through the adiabatic pipeline 20. A temperature sensor 13 is arranged at the center of the lower surface of the specimen 16. The electrical signal of the temperature sensor 13 is converted by the data collector 8 and transmitted back to the control computer 9. The control computer 9 dynamically adjusts the opening degree of the solenoid valve 11 through the controller 10 in combination with the PID control algorithm, and adjusts the liquid nitrogen spraying 19 amount on the lower surface of the specimen 16 in real time to achieve precise temperature control from -196°C to room temperature. A quartz sand buffer layer 17 is laid between the specimen 16 and the hollow frame 1, whose function is to evenly disperse the contact stress, and at the same time isolate the direct contact between the hollow frame 1 and the specimen 16, avoid the propagation of microcracks caused by low-temperature brittleness, and reduce the possibility of damage to the specimen 16.

[0043] The resistance heating sheet 15 is made of nickel-chromium alloy wire with a diameter of 0.2 mm embedded in the substrate in a serpentine arrangement. The surface of the alloy wire is wrapped with a silicone rubber insulation layer resistant to 300°C, and the power density is not less than 5 W / cm 2 , and the heating rate > 10°C / s. A temperature sensor 13 is arranged between the resistance heating sheet 15 and the specimen 16. The electrical signal of the temperature sensor 13 is converted by the data collector 8 and transmitted back to the control computer 9. The control computer 9 dynamically adjusts the temperature of the resistance heating sheet 15 through the power regulator 5 in combination with the PID algorithm to achieve closed-loop control of the target temperature. A fluorinated rubber water belt 14 is laid between the high-rigidity alloy pressure plate 3 and the resistance heating sheet 15. The fluorinated rubber water belt 14 is made of fluorinated rubber that can withstand a high temperature of 450°C and is filled with pure water inside. Its function is to buffer the mechanical impact from the actuator 4 and the high-rigidity pressure plate 3, form a uniform distributed force load conforming to the specimen 16, and reduce the upward transfer of the heat of the resistance heating sheet 15.

[0044] The hydraulic loading module adopts a multi-actuator evenly distributed hydraulic loading structure. The hydraulic actuators 4 are evenly distributed and closely attached to the high-rigidity alloy pressure plate 3 with a certain thickness. Through the high-rigidity alloy pressure plate 3, the output force of the distributed actuators 4 is converted into a quasi-static / dynamic uniform pressure on the surface of the test piece and applied to the surface of the test piece. During the test, the pressure sensor built in the hydraulic pump 6 transmits the pressure data to the control computer 9 in real time. The control computer 9 adjusts the flow rate of the hydraulic pump 6 in real time through the hydraulic controller 7 to achieve closed-loop control of the target force load. The high-precision servo hydraulic pump 6 synchronously drives three groups of actuators 4, and the servo hydraulic pump 6 supports various loading modes such as static load, sinusoidal fluctuation and random shock.

[0045] In this embodiment, a multi-physical-field coupling experiment method is proposed. Based on the LabVIEW platform, the temperature field feedback and dynamic load spectrum tracking algorithms are integrated to achieve the spatio-temporal synchronous control of temperature and pressure, with a phase error < 5 ms.

[0046] The above is not a limitation of the present invention. Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments. Those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Modifications or replacements made without departing from the spirit of the present invention all fall within the scope of the present invention claimed.

Claims

1. An in-situ collaborative loading device for wide-temperature-range force and thermal loads, characterized in that, It includes a hollow frame; a specimen is arranged inside the hollow frame, a liquid nitrogen cooling module is arranged below the specimen, and a resistance heating sheet and a hydraulic loading module are arranged above the specimen; The liquid nitrogen cooling module, the resistance heating sheet and the hydraulic loading module are all electrically connected to a control computer; the liquid nitrogen cooling module includes a liquid nitrogen nozzle installed at the bottom of the hollow frame, an adiabatic pipeline, a solenoid valve and a liquid nitrogen dewar outside the frame; the hydraulic loading module includes a plurality of actuators, a high-rigidity pressure transfer plate, a hydraulic pump and a hydraulic controller; a quartz sand buffer layer is arranged between the specimen and the hollow frame; a fluorinated rubber water belt is arranged between the resistance heating sheet and the high-rigidity pressure transfer plate; temperature sensors are arranged on both the upper and lower surfaces of the specimen.

2. The in-situ collaborative loading device for wide-temperature-range force and thermal loads according to claim 1, wherein: The liquid nitrogen cooling module dynamically adjusts the opening of the solenoid valve through a PID algorithm.

3. The in-situ collaborative loading device for wide-temperature-range force and thermal loads according to claim 1, wherein: The resistance heating sheet realizes closed-loop control of the target temperature through a PID algorithm.

4. The in-situ collaborative loading device for wide-temperature-range force and thermal loads according to claim 1, wherein: The hydraulic loading module realizes dynamic uniform pressure loading through a plurality of uniformly distributed actuators and a high-rigidity pressure transfer plate.

5. The in-situ co-loading device for wide-temperature-range force and thermal loads according to claim 1, characterized in that: Exhaust holes are arranged on the side surface of the hollow frame.

6. The in-situ collaborative loading device for wide-temperature-range force and thermal loads according to claim 1, characterized in that: A multi-physical-field coupling experiment method, based on the LabVIEW platform, integrates a temperature field feedback and a dynamic load spectrum tracking algorithm to realize spatio-temporal synchronous control of temperature-pressure.

7. The in-situ collaborative loading device for wide-temperature-range force and thermal loads according to claim 6, characterized in that: The tracking algorithm is used to track the changing thermal-mechanical load target in real time, and enables the system output to accurately follow the preset dynamic load spectrum through a control algorithm; the input of the tracking algorithm is the time-varying thermal-mechanical load target set in the experiment; the output is the real-time response of the system, that is, the measurement data of the temperature sensors arranged on the upper and lower surfaces of the specimen and the internal pressure sensor of the hydraulic pump; the goal is to minimize the tracking error by adjusting the opening of the solenoid valve, the power of the resistance heating sheet and the flow rate of the hydraulic pump in real time; through the combination of feedforward compensation, feedback regulation and online learning, the dynamic load spectrum tracking algorithm realizes high-precision tracking.

8. The in-situ collaborative loading device for wide-temperature-range force and thermal loads according to claim 1, characterized in that: The liquid nitrogen cooling module dynamically adjusts the opening of the solenoid valve through a PID algorithm; the temperature data collected by the temperature sensor arranged on the lower surface of the specimen is the input of the PID system; the computer runs the PID algorithm to output an execution signal, controls the liquid nitrogen spraying amount on the lower surface of the specimen by adjusting the opening of the solenoid valve, and combines integral anti-windup and differential filtering techniques to realize precise control of the specimen surface temperature.

9. The in-situ collaborative loading device for wide-temperature-range force and thermal loads according to claim 1, characterized in that: The resistance heating sheet realizes closed-loop control of the target temperature through a PID algorithm; the temperature data collected by the temperature sensor arranged on the upper surface of the specimen is the input of the PID system; the computer outputs an execution signal by running the PID algorithm, controls the power of the resistance heating sheet, and combines integral anti-windup and differential filtering techniques to realize precise control of the specimen upper surface temperature; the hydraulic loading module realizes dynamic uniform pressure loading through uniformly distributed actuators and a high-rigidity pressure transfer plate.

10. The in-situ collaborative loading device for wide-temperature-range force and thermal loads according to claim 1, wherein: Exhaust holes are arranged on the side surface of the hollow frame.

Images