阅读说明：本技术 水声材料三维几何形貌检测方法及系统 (Method and system for detecting three-dimensional geometric morphology of underwater acoustic material ) 是由 彭锋 尹铫 李超 杨婉雨 张秀娟 杨军 程晓斌 伍世桥 于 2020-06-29 设计创作，主要内容包括：本发明公开了一种水下变温变压模拟环境下水声材料三维几何形貌的检测方法和系统,基于CT扫描和重构技术,对置于一个变温变压容器内的水声材料样品进行CT断层扫描检测,然后对样品的CT断层扫描图像进行三维几何重构,即可准确得到相应工况下水声材料样品的三维几何形貌。基于本发明的检测方法还实现了一种水声材料静态体积压缩模量的检测方法,可准确测量材料在相应工况下的静态体积模量。本发明提出的检测方法实现了水声材料在水下变温变压模拟环境下的表观外形三维几何形貌、内部空腔三维几何形貌、内部微结构/掺杂材料三维几何形貌的直接测量,能为水声材料设计和性能评价提供具有十分重要的参考依据。(The invention discloses a method and a system for detecting the three-dimensional geometric morphology of an underwater acoustic material in an underwater temperature and pressure varying simulation environment. The detection method also realizes a detection method of the static bulk compression modulus of the underwater acoustic material, and can accurately measure the static bulk modulus of the material under corresponding working conditions. The detection method provided by the invention realizes the direct measurement of the apparent appearance three-dimensional geometric morphology, the internal cavity three-dimensional geometric morphology and the internal microstructure/doped material three-dimensional geometric morphology of the underwater acoustic material in the underwater temperature and pressure changing simulation environment, and can provide very important reference basis for the design and performance evaluation of the underwater acoustic material.)

1. A three-dimensional geometric morphology detection system for an underwater acoustic material is characterized by comprising an underwater environment simulation device, a CT scanning system and a detection control system;

the underwater environment simulation device comprises a sample cavity for accommodating and fixing an underwater acoustic material sample and is used for providing an underwater temperature and pressure changing simulation environment for the underwater acoustic material sample;

the CT scanning system comprises a sample table for fixing the underwater environment simulation device, and is used for carrying out CT scanning on an underwater acoustic material sample fixed in the underwater environment simulation device to obtain an underwater acoustic material sample tomography image corresponding to the measured temperature and pressure, and carrying out three-dimensional reconstruction by adopting the tomography image to obtain the three-dimensional geometric morphology of the underwater acoustic material sample corresponding to the measured temperature and pressure;

the detection control system provides a human-computer interaction interface, inputs a detection scheme and outputs a detection result; secondly, controlling the underwater environment simulation device according to the input detection scheme, and controlling and displaying the temperature and the pressure in the sample cavity; and thirdly, controlling a CT scanning system to scan according to the input detection scheme and acquiring the three-dimensional geometric morphology of the underwater acoustic material sample corresponding to the measured temperature and pressure.

2. The detection system for the three-dimensional geometric morphology of the underwater acoustic material as claimed in claim 1, wherein the underwater environment simulation device comprises a temperature and pressure variable container, a temperature and pressure variable environment medium, a pressure variable system, a temperature variable system and a temperature and pressure control system,

the temperature and pressure changing container comprises a sample cavity, an underwater acoustic material sample is fixed in the sample cavity, and the temperature and pressure changing container can be penetrated by X rays so as to scan the underwater acoustic material sample in the underwater temperature and pressure changing simulation environment;

the temperature and pressure changing environment medium enters and exits the sample cavity through the opening on the temperature and pressure changing container, is used for realizing the underwater temperature and pressure changing simulation environment in the sample cavity, and has enough contrast on the boundary contacted with the underwater sound material sample so as to ensure the reconstruction precision of the outer boundary of the underwater sound material sample;

the variable pressure system is used for pressurizing, decompressing and maintaining the medium in the variable temperature and variable pressure environment;

the temperature-changing system is used for heating, cooling and preserving the temperature of the temperature-changing and pressure-changing environment medium;

the temperature and pressure control system acquires the temperature in the sample cavity through the temperature sensor under the control of the detection control system, acquires the pressure in the sample cavity through the pressure sensor, and controls the variable pressure system and the variable temperature system so as to control the temperature and the pressure in the sample cavity.

3. The detection system for the three-dimensional geometrical morphology of the underwater acoustic material according to claim 2,

the sample cavity of the temperature and pressure changing container is enclosed by a pressure resistant wall, an upper cover and a bottom plate, and the upper cover, the bottom plate and the pressure resistant wall are sealed by sealing rings;

the temperature and pressure changing environment medium adopts a gas medium, or adopts seawater added with a tracer or an artificial simulated seawater medium;

the pressure varying system comprises a pressurizing device, a pressure relief device, a pressure regulating valve and a pressure regulating valve controller; the pressure control system comprises a pressure regulating valve, a pressure regulating valve controller, a temperature and pressure control system, a pressure regulating valve controller, a pressure regulating valve controller and a pressure regulating valve controller, wherein the pressure regulating valve controller is connected with the sample cavity; the pressure relief device is connected with the sample cavity through a pipeline and is used for relieving the pressure of the sample cavity under the control of a temperature and pressure control system;

the temperature changing system adopts an internal circulation mode or an external circulation mode; when an internal circulation mode is adopted, the heated or cooled temperature and pressure changing environment medium is driven by a circulating pump to circularly flow in a sample cavity and a circulating pipeline in a temperature and pressure changing container, and heat exchange is carried out on a heat exchange pipe part in the circulating pipeline to finally realize circulating heat exchange, so that the temperature change in the sample cavity is realized; when an external circulation mode is adopted, the temperature and pressure changing environment container is arranged in the heat insulation sleeve, a heat exchange medium is arranged in a gap between the temperature and pressure changing environment container and the heat insulation sleeve, the heat exchange medium exchanges heat with the temperature and pressure changing environment medium in the sample cavity through the temperature and pressure changing container, the heat exchange medium is driven by the circulating pump to circularly flow in the gap between the temperature and pressure changing environment container and the heat insulation sleeve and the circulating pipeline, and the heat exchange of a heat exchange pipe part in the circulating pipeline is carried out; the circulating pump is controlled by a temperature and pressure control system;

the temperature and pressure control system comprises an acquisition card and a controller, wherein the acquisition card is used for acquiring signals of the pressure sensor and the temperature sensor; the controller is used for controlling the variable pressure system and the variable temperature system.

4. A system for detecting the three-dimensional geometry of an underwater acoustic material according to claims 1-3, wherein the underwater acoustic material is a viscoelastic material, and the sample of the underwater acoustic material has an embedded cavity structure or a foam structure.

5. The underwater acoustic material three-dimensional geometric shape detection method based on the system of any one of claims 1 to 4 is characterized in that an underwater acoustic material sample is fixed in an underwater environment simulation device, the underwater environment simulation device provides an underwater temperature and pressure changing simulation environment, then the underwater acoustic material sample fixed in the underwater environment simulation device is subjected to tomography CT scanning, and finally, a tomography image of the underwater acoustic material sample is subjected to three-dimensional reconstruction processing to obtain the three-dimensional geometric shape of the underwater acoustic material sample in the underwater temperature and pressure changing simulation environment.

6. The method for detecting the three-dimensional geometric morphology of the underwater acoustic material as claimed in claim 5, characterized by comprising the steps of:

step 1, sample installation and fixation: fixing an underwater acoustic material sample in a sample cavity of an underwater environment simulation device, and then installing and fixing the underwater environment simulation device on a sample table of a CT scanning system;

step 2, controlling the temperature change of the sample cavity: carrying out variable temperature control on the underwater environment simulation device until the temperature in the sample cavity reaches a set temperature state;

step 3, controlling the variable pressure in the sample cavity: after the temperature in the sample cavity is stable, carrying out variable pressure control on the underwater environment simulation device until the pressure in the sample cavity reaches a set pressure state;

step 4, controlling the heat preservation and pressure maintaining in the sample cavity: when the temperature and the pressure in the sample cavity reach set values, heat preservation and pressure maintaining control is carried out, and the temperature and the pressure in the sample cavity need to be stable for a long time to ensure that the integral temperature of the underwater acoustic material sample is stable and consistent and the deformation is stable;

step 5, CT scanning and three-dimensional reconstruction of the sample: and carrying out CT scanning on the underwater environment simulation device containing the underwater acoustic material sample by adopting a CT scanning system, wherein the temperature and pressure changing environment simulation device is in a heat preservation and pressure maintaining state during the whole CT scanning period, acquiring an underwater acoustic material sample tomography image corresponding to the set temperature and pressure through CT scanning, storing the tomography image result and carrying out three-dimensional reconstruction to obtain the three-dimensional geometric morphology of the underwater acoustic material sample corresponding to the set temperature and pressure.

7. The method for detecting the three-dimensional geometrical morphology of the underwater acoustic material as claimed in claim 6, further comprising:

step 6, changing the underwater variable temperature and pressure simulation environment for multiple measurements: changing an underwater temperature and pressure changing simulation environment, and repeating the steps 1 to 5 until CT scanning and three-dimensional reconstruction of the underwater acoustic material sample in a plurality of underwater temperature and pressure changing simulation environments are completed; the changing of the underwater temperature and pressure varying simulation environment refers to changing of the pressure of the underwater temperature and pressure varying simulation, or changing of the temperature of the underwater temperature and pressure varying simulation, or changing of the pressure and the temperature of the underwater temperature and pressure varying simulation.

8. The method for detecting the three-dimensional geometric morphology of the underwater acoustic material in the underwater temperature and pressure varying simulation environment as claimed in claim 6 or 7, further comprising:

and 7, replacing the sample to repeat the measurement: and replacing the underwater sound material samples to repeatedly measure until the CT scanning and the three-dimensional reconstruction of all the underwater sound material samples are completed.

9. A method for detecting the static volume compression modulus of an underwater acoustic material is characterized by comprising the following steps: the method for detecting the three-dimensional geometric morphology of the underwater acoustic material according to claim 6, wherein a pressure increment is set on the basis of a reference pressure and a reference temperature, the total volume change of the material before and after pressurization is measured, and the static volume compression modulus of the underwater acoustic material is calculated and obtained, and the method comprises the following steps:

step one, CT scanning of a sample under a reference pressure and a reference temperature: the method for detecting the three-dimensional geometrical morphology of the underwater acoustic material as claimed in claim 6, wherein the method comprises the steps of firstly detecting the three-dimensional geometrical morphology of an underwater acoustic material sample under a reference pressure and a reference temperature;

step two, the step of pressurized sample CT scanning: setting a pressure increment delta P on the basis of the reference pressure and the reference temperature, then carrying out heat preservation and pressure maintaining control, and carrying out a three-dimensional geometric shape detection method of the underwater acoustic material sample after stabilization;

step three, acquiring the volume of the sample before and after pressurization: respectively obtaining the total volumes V1 and V2 of the underwater sound material sample before and after pressurization according to the obtained three-dimensional geometric shapes of the underwater sound material sample before and after pressurization;

step four, calculating the static volume compression modulus of the sample: obtaining the total volume change DeltaV of the underwater acoustic material sample before and after pressurization as V1-V2 by defining the formulaCalculating to obtain the static volume compression modulus of the underwater acoustic material;

step five, detecting the static volume compression modulus under different reference pressures and reference temperatures: and changing the temperature and the pressure, and repeating the first step to the fourth step at different reference pressures and reference temperatures to obtain the static volume compression modulus of the underwater acoustic material at different reference pressures and reference temperatures.

Technical Field

The invention belongs to the field of detection and design of underwater acoustic materials, and particularly relates to a detection method and a detection system for simulating three-dimensional geometric morphology of an underwater acoustic material in an underwater temperature and pressure changing simulation environment, and a detection method for static volume compression modulus based on the detection method for the three-dimensional geometric morphology of the underwater acoustic material.

Background

The underwater acoustic material is mainly used for vibration and acoustic treatment of an underwater vehicle, such as a sound absorption covering layer laid on the surface of a hull of the vehicle and used for reducing sonar echoes, a sound insulation decoupling covering layer used for reducing radiation noise of the hull to the water, and the like, and is widely applied at present.

The traditional underwater acoustic material mainly takes a viscoelastic material as a main material, and a main base material adopts a rubber material and a polyurethane material. In order to meet various practical application occasions, a cavity structure (shown in figure 1) or a structure containing foam (shown in figure 2) is often embedded in the material, so that the effects of internal scattering, resonance and the like are enhanced, the loss in the material is further increased, and the damping and absorption performances of vibration and sound of the material layer are improved.

In order to design and prepare the underwater acoustic material meeting the actual application conditions, basic physical parameters and geometric parameters of the material are needed firstly, and then the corresponding underwater acoustic material is predicted and optimally designed by using methods such as finite elements and the like. The acoustic parameters of the material mainly comprise density, dynamic modulus, loss factor and the like, and corresponding commercial equipment and experimental devices are used for testing at present; the geometrical parameters of the material mainly comprise the thickness of the material layer and the geometrical shapes of structures such as cavities or scatterers.

Because the actual underwater acoustic material usually works in the environment of different underwater temperatures (the variation range is usually 4-40 ℃) and hydrostatic pressures (the variation range is usually 0-3 MPa depending on the working water depth) and the factors such as water areas, water depths, seasonal time and the like, the physical parameters and the geometric parameters of the underwater acoustic material can correspondingly change along with the temperature and the pressure, and particularly for the underwater acoustic material with the cavity structure, the bubble and the like, the internal geometric structure of the underwater acoustic material can obviously change along with the change of the hydrostatic pressure. At present, physical parameters under different pressures are measured by corresponding methods through experiments, but the geometric change of the physical parameters is not measured by a direct detection method, and only numerical simulation prediction can be carried out through statics analysis. The static modulus, poisson ratio and the like of the material required in the simulation calculation are generally obtained by testing or empirical estimation of a universal material testing machine, the modulus measured by the material testing machine is not a real mechanical parameter of the underwater acoustic material under the corresponding temperature and hydrostatic pressure (or called environmental pressure or confining pressure), and in addition, the actual viscoelastic underwater acoustic material may have nonlinearity under the larger hydrostatic pressure, so that the nonlinear parameter (to be measured) is added to the accurate simulation of direct static deformation and additional difficulty is brought. Meanwhile, some oversimplified boundary conditions are often introduced in the statics numerical prediction, the three-dimensional geometry of the material layer under the corresponding working condition obtained through numerical simulation analysis is often greatly different from the result under the real condition, the accuracy of the simulation result is not checked by the current direct test result, and the reliability of the final design result is further influenced to a great extent. In addition, for some cavity-containing structures, the internal cavities are stressed under actual hydrostatic pressure to significantly deform, thereby resulting in an increase in apparent equivalent density throughout the material layer. If the three-dimensional geometric deformation of underwater sound under corresponding working conditions cannot be detected in advance, hidden danger can even be brought to the safety of the aircraft. At present, due to the lack of a method and a device for directly and accurately detecting the three-dimensional geometry of an underwater acoustic material in an underwater temperature and pressure changing simulation environment, the design and development of the underwater acoustic material are severely restricted.

Disclosure of Invention

In view of the above, the present invention provides a method for directly and accurately detecting three-dimensional geometry of underwater acoustic material under an underwater temperature and pressure varying simulation environment; based on the method, a method for detecting the static volume compression modulus of the material at the corresponding reference temperature and reference pressure is provided; meanwhile, the underwater acoustic material three-dimensional geometric morphology detection system under the underwater temperature and pressure changing simulation environment is provided, which is required by the detection, so that the defects of the current detection technology in the background technology are overcome.

In order to solve the technical problem, the invention provides a three-dimensional geometric morphology detection system for an underwater acoustic material, which is characterized by comprising an underwater environment simulation device, a CT scanning system and a detection control system; the underwater environment simulation device comprises a sample cavity for accommodating and fixing an underwater acoustic material sample and is used for providing an underwater temperature and pressure changing simulation environment for the underwater acoustic material sample; the CT scanning system comprises a sample table for fixing the underwater environment simulation device, and is used for carrying out CT scanning on an underwater acoustic material sample fixed in the underwater environment simulation device to obtain an underwater acoustic material sample tomography image corresponding to the measured temperature and pressure, and carrying out three-dimensional reconstruction by adopting the tomography image to obtain the three-dimensional geometric morphology of the underwater acoustic material sample corresponding to the measured temperature and pressure; the detection control system provides a human-computer interaction interface, inputs a detection scheme and outputs a detection result; secondly, controlling the underwater environment simulation device according to the input detection scheme, and controlling and displaying the temperature and the pressure in the sample cavity; and thirdly, controlling a CT scanning system to scan according to the input detection scheme and acquiring the three-dimensional geometric morphology of the underwater acoustic material sample corresponding to the measured temperature and pressure.

Furthermore, the underwater environment simulation device comprises a temperature and pressure changing container, a temperature and pressure changing environment medium, a pressure changing system, a temperature changing system and a temperature and pressure control system, wherein the temperature and pressure changing container comprises a sample cavity, the underwater acoustic material sample is fixed in the sample cavity, and the temperature and pressure changing container can be penetrated by X rays so as to scan the underwater acoustic material sample in the underwater temperature and pressure changing simulation environment; the temperature and pressure changing environment medium enters and exits the sample cavity through the opening on the temperature and pressure changing container, is used for realizing the underwater temperature and pressure changing simulation environment in the sample cavity, and has enough contrast on the boundary contacted with the underwater sound material sample so as to ensure the reconstruction precision of the outer boundary of the underwater sound material sample; the variable pressure system is used for pressurizing, decompressing and maintaining the medium in the variable temperature and variable pressure environment; the temperature-changing system is used for heating, cooling and preserving the temperature of the temperature-changing and pressure-changing environment medium; the temperature and pressure control system acquires the temperature in the sample cavity through the temperature sensor under the control of the detection control system, acquires the pressure in the sample cavity through the pressure sensor, and controls the variable pressure system and the variable temperature system so as to control the temperature and the pressure in the sample cavity.

Furthermore, a sample cavity of the temperature and pressure changing container is enclosed by a pressure resistant wall, an upper cover and a bottom plate, and the upper cover, the bottom plate and the pressure resistant wall are sealed by sealing rings; the temperature and pressure changing environment medium adopts a gas medium, or adopts a seawater medium added with a tracer or an artificial simulated seawater medium; the pressure varying system comprises a pressurizing device, a pressure relief device, a pressure regulating valve and a pressure regulating valve controller; the pressure control system comprises a pressure regulating valve, a pressure regulating valve controller, a temperature and pressure control system, a pressure regulating valve controller, a pressure regulating valve controller and a pressure regulating valve controller, wherein the pressure regulating valve controller is connected with the sample cavity; the pressure relief device is connected with the sample cavity through a pipeline and is used for relieving the pressure of the sample cavity under the control of a temperature and pressure control system; the temperature changing system adopts an internal circulation mode or an external circulation mode; when an internal circulation mode is adopted, the heated or cooled temperature and pressure changing environment medium is driven by a circulating pump to circularly flow in a sample cavity and a circulating pipeline in a temperature and pressure changing container, and heat exchange is carried out on a heat exchange pipe part in the circulating pipeline to finally realize circulating heat exchange, so that the temperature change in the sample cavity is realized; when an external circulation mode is adopted, the temperature and pressure changing environment container is arranged in the heat insulation sleeve, a heat exchange medium is arranged in a gap between the temperature and pressure changing environment container and the heat insulation sleeve, the heat exchange medium exchanges heat with the temperature and pressure changing environment medium in the sample cavity through the temperature and pressure changing container, the heat exchange medium is driven by the circulating pump to circularly flow in the gap between the temperature and pressure changing environment container and the heat insulation sleeve and the circulating pipeline, and the heat exchange of a heat exchange pipe part in the circulating pipeline is carried out; the circulating pump is controlled by a temperature and pressure control system; the temperature and pressure control system comprises an acquisition card and a controller, wherein the acquisition card is used for acquiring signals of the pressure sensor and the temperature sensor; the controller is used for controlling the variable pressure system and the variable temperature system.

Further, the underwater acoustic material is a viscoelastic material, and the underwater acoustic material sample has an embedded cavity structure or a foaming structure.

The invention also provides a detection method of the three-dimensional geometrical morphology of the underwater acoustic material based on the system, which is characterized in that the underwater acoustic material sample is fixed in the underwater environment simulation device, the underwater environment simulation device provides an underwater temperature and pressure changing simulation environment, then the underwater acoustic material sample fixed in the underwater environment simulation device is subjected to tomography CT scanning, and finally, the tomography image of the underwater acoustic material sample is subjected to three-dimensional reconstruction processing to obtain the three-dimensional geometrical morphology of the underwater acoustic material sample in the underwater temperature and pressure changing simulation environment.

Further, the detection method of the three-dimensional geometrical morphology of the underwater acoustic material comprises the following steps:

step 1, sample installation and fixation: fixing an underwater acoustic material sample in a sample cavity of an underwater environment simulation device, and then installing and fixing the underwater environment simulation device on a sample table of a CT scanning system;

step 2, controlling the temperature change of the sample cavity: carrying out variable temperature control on the underwater environment simulation device until the temperature in the sample cavity reaches a set temperature state;

step 3, controlling the variable pressure in the sample cavity: after the temperature in the sample cavity is stable, carrying out variable pressure control on the underwater environment simulation device until the pressure in the sample cavity reaches a set pressure state;

step 4, controlling the heat preservation and pressure maintaining in the sample cavity: when the temperature and the pressure in the sample cavity reach set values, heat preservation and pressure maintaining control is carried out, and the temperature and the pressure in the sample cavity need to be stable for a long time to ensure that the integral temperature of the underwater acoustic material sample is stable and consistent and the deformation is stable;

step 5, CT scanning and three-dimensional reconstruction of the sample: and carrying out CT scanning on the underwater environment simulation device containing the underwater acoustic material sample by adopting a CT scanning system, wherein the temperature and pressure changing environment simulation device is in a heat preservation and pressure maintaining state during the whole CT scanning period, acquiring an underwater acoustic material sample tomography image corresponding to the set temperature and pressure through CT scanning, storing the tomography image result and carrying out three-dimensional reconstruction to obtain the three-dimensional geometric morphology of the underwater acoustic material sample corresponding to the set temperature and pressure.

Further, the method for detecting the three-dimensional geometric morphology of the underwater acoustic material further comprises the following steps:

step 6, changing the underwater variable temperature and pressure simulation environment for multiple measurements: changing an underwater temperature and pressure changing simulation environment, and repeating the steps 1 to 5 until CT scanning and three-dimensional reconstruction of the underwater acoustic material sample in a plurality of underwater temperature and pressure changing simulation environments are completed; the changing of the underwater temperature and pressure varying simulation environment refers to changing of the pressure of the underwater temperature and pressure varying simulation, or changing of the temperature of the underwater temperature and pressure varying simulation, or changing of the pressure and the temperature of the underwater temperature and pressure varying simulation.

Further, the method for detecting the three-dimensional geometric morphology of the underwater acoustic material further comprises the following steps:

and 7, replacing the sample to repeat the measurement: and replacing the underwater sound material samples to repeatedly measure until the CT scanning and the three-dimensional reconstruction of all the underwater sound material samples are completed.

The invention also provides a method for detecting the static volume compression modulus of the underwater acoustic material, which is characterized by comprising the following steps: based on the three-dimensional geometric morphology detection method for the underwater acoustic material, on the basis of the reference pressure and the reference temperature, the pressure increment is set, the total volume change of the material before and after pressurization is measured, and the static volume compression modulus of the underwater acoustic material is further calculated and obtained, and the method comprises the following steps:

step one, CT scanning of a sample under a reference pressure and a reference temperature: according to the three-dimensional geometrical morphology detection method for the underwater acoustic material, firstly, the three-dimensional geometrical morphology of the underwater acoustic material sample is detected under the reference pressure and the reference temperature;

step two, the step of pressurized sample CT scanning: setting a pressure increment delta P on the basis of the reference pressure and the reference temperature, then carrying out heat preservation and pressure maintaining control, and carrying out a three-dimensional geometric shape detection method of the underwater acoustic material sample after stabilization;

step three, acquiring the volume of the sample before and after pressurization: respectively obtaining the total volumes V1 and V2 of the underwater sound material sample before and after pressurization according to the obtained three-dimensional geometric shapes of the underwater sound material sample before and after pressurization;

step four, calculating the static volume compression modulus of the sample: obtaining the total volume change DeltaV of the underwater acoustic material sample before and after pressurization as V1-V2 by defining the formula

Calculating to obtain the static volume compression modulus of the underwater acoustic material;

step five, detecting the static volume compression modulus under different reference pressures and reference temperatures: and changing the temperature and the pressure, and repeating the first step to the fourth step at different reference pressures and reference temperatures to obtain the static volume compression modulus of the underwater acoustic material at different reference pressures and reference temperatures.

Advantageous effects

The detection method and the system can detect the three-dimensional geometric morphology of the underwater acoustic material in the underwater temperature and pressure varying simulation environment, obtain the geometric morphologies such as the apparent appearance geometric morphology, the internal cavity geometric morphology, the internal microstructure/doped material and the like of the underwater acoustic material at different temperatures and static pressures, can be directly used for finite element analysis and design in the aspects of acoustics and vibration of the underwater acoustic material, and provide an accurate geometric model under corresponding working conditions for numerical simulation; the three-dimensional geometric morphology of the directly detected material can also be used for verifying the deformation result of the hydrostatic simulation of the underwater acoustic material so as to improve the reliability of the hydrostatic design of the underwater acoustic material. Meanwhile, the directly measured static volume compression modulus of the material can provide basic material parameters for relevant statics analysis.

The detection method provided by the invention breaks through the limitation that the traditional method can not directly test the three-dimensional geometric morphology of the underwater acoustic material in the underwater temperature and pressure changing simulation environment, particularly the geometric and microstructure deformation of the cavity in the material, and the geometric morphology and the structural deformation are very important references for the design and performance evaluation of the underwater acoustic material. The detection method is based on three-dimensional CT scanning and reconstruction technology, and the measured geometric structure of the material can reach high precision (mainly depending on the size of a CT machine and a sample, for the size of industrial CT, the diameter of the sample is 10cm, and the precision of the reconstructed three-dimensional geometric size can reach 50um magnitude or even higher).

The method for detecting the static volume compression modulus of the material, which is provided by the detection method based on the invention, is a new method for directly obtaining the static volume compression modulus of the material, and has the advantages of simple operation and calculation process and high test precision; meanwhile, the static volume compression modulus under different reference pressures and temperatures can be obtained through testing, and a series of material basic parameters can be provided for related researches.

The underwater sound material three-dimensional geometric morphology detection system under the underwater temperature and pressure changing simulation environment can simultaneously meet the requirements of three-dimensional CT scanning of the underwater sound material and actual working conditions of the simulated underwater sound material, can adopt automatic control equipment with high integration level to perform functions of data acquisition, control, monitoring and the like, and is simple to operate, safe and efficient.

Drawings

FIG. 1 is a schematic view of an underwater acoustic material containing a cavity structure;

FIG. 2 is a schematic view of a foamed polymer underwater acoustic material;

FIG. 3 is a schematic diagram of the principle of an underwater environment simulation device for simulating the actual working conditions of an underwater acoustic material;

FIG. 4 is a schematic diagram of a system for detecting the three-dimensional geometrical morphology of an underwater acoustic material in an underwater temperature and pressure varying simulation environment;

FIG. 5 is a flow chart of the three-dimensional geometrical morphology detection of the underwater acoustic material in an underwater temperature and pressure varying simulation environment;

fig. 6 is a flow chart of the detection work flow of the static volume compression modulus of the underwater acoustic material in the underwater temperature and pressure varying simulation environment.

Reference numerals:

1. underwater environment simulation device 2 and underwater acoustic material sample

3. CT detector plane 4, CT sample platform

5. CT X-ray light source

101. Thermocouple 102, sample chamber

103. Pressure-resistant wall 104 and control monitoring system

105. Heat exchange bottom plate 106, bottom cover

107. Circulating pump 108 and constant-temperature water tank

109. Compressed gas cylinder (supercharging device) 110 and pressure regulating valve

111. Controller 112, pressure sensor

113. Thermal insulation cover

Detailed Description

The following describes in detail embodiments of the present invention with reference to the drawings.

An underwater environment simulation apparatus according to an embodiment of the present invention is shown in fig. 3. The temperature and pressure changing environment simulation device is used for simulating the actual working conditions of an underwater acoustic material and providing an underwater simulation environment and comprises a temperature and pressure changing container, a temperature and pressure changing environment medium, a pressure changing system, a temperature and pressure changing system and a temperature and pressure control system.

A temperature and pressure changing container: the underwater acoustic material sample chamber is used for placing an underwater acoustic material sample and provides a chamber, namely a sample chamber, which can simulate the actual working condition. The size of the sample cavity is determined according to the maximum size of the sample, and meanwhile, the fault scanning can penetrate all parts of the sample without shielding in the CT scanning process. The sample cavity is enclosed by withstand voltage wall, upper cover, bottom plate and closes and forms, and in order to guarantee the gas tightness, the junction between upper cover and withstand voltage wall, bottom plate and withstand voltage wall must adopt the sealing washer mode to seal tightly. The pressure-resistant wall or the upper cover is provided with an opening, so that the medium in the temperature and pressure changing environment can conveniently enter and exit the sample cavity. The temperature sensor adopts a thermocouple, and the thermocouple is inserted into the sample cavity through an opening on the upper cover so as to test the internal temperature. The pressure-resistant wall of the sample cavity needs to meet the requirement of bearing the maximum hydrostatic pressure of corresponding working conditions and also needs to ensure that X rays emitted by a CT scanning system can penetrate through the pressure-resistant wall, so that the material of the pressure-resistant wall is preferably high-strength non-metal material (such as carbon fiber composite material), and the wall thickness and the external dimension of the pressure-resistant wall need to be determined by comprehensively considering the penetrating power of the X rays and the scanning visual field range; if a metal material (such as duralumin) is adopted, a thin-wall structure is adopted as far as possible on the premise of meeting the structural strength, so that the X-ray can penetrate through the structure. The pressure-resistant wall is externally designed with a heat-insulating sleeve, and a heat-insulating material with good heat-insulating property is adopted, so that the heat-insulating property of the internal sample cavity is improved. The pressure-resistant wall of the sample cavity and the cavity of the heat-insulating sleeve room are used for heat exchange of circulating water. A bottom cover is arranged below the bottom plate, the bottom plate and the bottom cover are tightly sealed through a sealing ring to form a heat exchange cavity, so that an external circulation medium can flow for heat exchange, and the bottom cover is provided with a hole for the heat exchange medium to flow in and out. The temperature and pressure changing container is supported by a support, and the support needs to be designed with corresponding bolt holes and other modes so as to fix the whole temperature and pressure changing container on a CT sample table during CT scanning. The total weight of the underwater environment simulation container can not exceed the maximum bearing of the CT sample table during testing.

Temperature and pressure changing environment medium: namely the environment medium used for temperature and pressure change around the sample in the sample cavity. If the mechanical and thermophysical characteristics of the underwater acoustic material sample are insensitive to the environment medium in practical application, such as seawater, a gas medium is preferably adopted to improve the penetration force of CT, such as air or helium, and the density contrast or density difference between the environment medium and the material sample can be improved, so that the imaging contrast at the outer boundary of the sample can be improved, and the reconstruction precision at the boundary can be improved. If the mechanical and thermal physical characteristics of the underwater acoustic material sample are sensitive to the actual application environment medium, a corresponding environment medium, such as seawater or an artificial simulated seawater medium, needs to be selected. In this case, in order to improve the contrast of the image at the interface between the ambient medium and the material sample, a tracer is added to the ambient medium liquid.

A voltage transformation system: the system is used for pressurizing, depressurizing and maintaining the environment medium in the sample cavity. Based on the selected temperature and pressure changing environment medium, a corresponding air pressure or hydraulic control system is adopted. The pressure transformation system comprises a pressurizing device and a pressure relief device, wherein the pressurizing device adopts a compressed gas cylinder or a hydraulic pump and the like. The pressure regulating valve is arranged on the outlet pipeline of the supercharging device, and a corresponding controller is preferably configured, so that the pressure regulation can be accurately controlled, the outlet pressure of the supercharging device can be regulated, and the pressure in the sample cavity can be controlled. In order to detect the ambient medium pressure in the sample chamber, or in an inlet line connected to the underwater environment simulation device, a corresponding pressure sensor is installed, preferably a sensor with a pressure transducer, in order to convert the detected pressure signal into an electrical or digital signal for transmission to the control computer. The control adopts PID and other industrial general pressure control modes to accurately control the outlet pressure of the pressure regulating valve. In fig. 3, the temperature and pressure control system is connected to the controller associated with the pressure reducing valve at the outlet of the pressure boosting device through a control line, the pressure sensor is connected to the corresponding port of the temperature and pressure control system through a data line, and the solenoid valve controlling the air release device (air release valve) is connected to the corresponding port of the control system through a control line. The high-pressure port of the pressure regulating valve is arranged at the outlet of the pressurizing system, the low-pressure port is connected with one end of a pipeline leading to the sample cavity, the other end of the pipeline is connected with the inlet end of the temperature and pressure variable environment medium entering the sample cavity, the outlet end of the temperature and pressure variable environment medium of the sample cavity is connected with the air leakage device, and the external temperature and pressure variable environment medium supply device supplies the temperature and pressure variable environment medium in the sample cavity through the inlet end and the outlet end of the sample cavity.

A temperature changing system: the system is used for heating, cooling and preserving heat for the medium in the environment with variable temperature and pressure. The temperature changing system has two forms of internal circulation and external circulation. 1) An internal circulation mode: the circulating pump drives the temperature and pressure changing environment medium to circulate in the sample cavity and the circulating pipeline. The heat exchange pipe parts in the circulating pipelines are arranged in the corresponding heat exchange boxes. The heat exchange tube can be designed into structural forms such as a coil and the like so as to enhance the heat exchange efficiency. The heat exchange tank can adopt a circulating heat exchange water tank, and the temperature control range of the circulating heat exchange water tank covers the temperature range of the simulation working condition. All externally disposed circulation lines need to be covered with insulation to reduce heat exchange between the intermediate lines and the surrounding atmosphere. And the heated or cooled temperature and pressure changing environment medium performs circulating flow heat exchange to realize temperature change in the sample cavity. And an internal circulation mode is adopted, and the pressure regulating valve and the exhaust valve are closed in the temperature changing process so as to reduce the influence caused by the change of the external environment. The internal circulation heat exchange efficiency is high, but the system is relatively complex. 2) In the external circulation mode, a heat exchange cavity is arranged in an interlayer between a shell (a pressure-resistant wall and a bottom plate shown in fig. 3) of the container in the temperature and pressure changing environment and the external heat-insulating sleeve room, and the temperature change of the internal sample cavity is realized by exchanging heat through a heat exchange medium in the heat exchange cavity. The heat exchange medium is water or antifreeze liquid. The heat exchange medium realizes heat exchange by adopting modes such as a constant-temperature water tank and the like, and then flows and circulates through the circulating pump to realize circulating heat exchange of the sample cavity. The constant temperature water tank is a circulating water tank, and the temperature control range covers the temperature range of the simulation working condition. The bottom of the sample cavity is heat exchanged by a bottom plate made of metal material with high heat conductivity, such as a copper plate, and the lower part of the sample cavity is provided with a heat exchange plate structure. And a bottom cover is used for sealing under the bottom plate, and the heat exchange medium can exchange heat with the environment medium in the sample cavity through the heat exchange cavity between the bottom plate and the bottom cover. The external circulation system is relatively simple, but the heat exchange efficiency is relatively low. The internal circulation and external circulation modes are selected and need to be balanced and selected according to actual application. And a thermocouple is arranged in the sample cavity, the measured temperature value is transmitted to a corresponding control system in real time, and the temperature control adopts PID and other industrial general temperature control modes to accurately control the temperature and the circulating flow rate of the heat exchange box and the constant-temperature water tank. In fig. 3, the temperature varying system adopts an external circulation mode, and the temperature and pressure control system is connected with the thermocouple through a data line and is connected with a control port of the constant temperature water tank and a control line of the circulating pump through a control line. The circulating pump drives the heat exchange medium to circulate, the heat exchange medium circulates in the heat exchange cavity, the constant-temperature water tank and the circulating pipeline, and the heat exchange medium exchanges heat in the constant-temperature water tank.

Temperature and pressure control system: the system is mainly used for monitoring the temperature and the pressure inside a sample cavity in real time and comprises an acquisition card and a controller, wherein the acquisition card is used for acquiring signals of a pressure sensor and a temperature sensor; the controller is used for controlling the variable pressure system and the variable temperature system and controlling various valves, heaters, refrigerators and the like in the pipeline to work normally.

Based on an underwater environment simulation device, the invention provides a three-dimensional geometric morphology detection system for an underwater acoustic material, which comprises the underwater environment simulation device, a CT scanning system and a detection control system, as shown in figure 4.

The CT scanning system comprises a sample table for fixing the underwater environment simulation device, and is used for carrying out CT scanning on an underwater acoustic material sample fixed in the underwater environment simulation device to obtain an underwater acoustic material sample tomography image corresponding to the measured temperature and pressure, and carrying out three-dimensional reconstruction by adopting the tomography image to obtain the three-dimensional geometric morphology of the underwater acoustic material sample corresponding to the measured temperature and pressure;

the detection control system provides a human-computer interaction interface, inputs a detection scheme and outputs a detection result; secondly, controlling the underwater environment simulation device according to the input detection scheme, and controlling and displaying the temperature and the pressure in the sample cavity; and thirdly, controlling a CT scanning system to scan according to the input detection scheme and acquiring the three-dimensional geometric morphology of the underwater acoustic material sample corresponding to the measured temperature and pressure.

In order to facilitate corresponding operation of operators, the temperature and pressure control system and the detection control system can be integrated together, so that centralized control and real-time monitoring are facilitated.

The method for detecting the three-dimensional geometric morphology of the underwater acoustic material in the specific embodiment of the invention has a work flow chart shown in fig. 5, and comprises the following steps:

(1) selection of a CT scanning system: according to the information such as the material and the size of the underwater acoustic material sample, selecting or customizing a CT scanning system with corresponding function and performance, wherein the focal spot of a CT light source is required to be far smaller than the minimum microstructure/doping size in the underwater acoustic material, and meanwhile, the highest working voltage of the light source is required to ensure that the X-ray emitted under corresponding conditions can penetrate through the whole clamp containing the material sample;

(2) designing and manufacturing the underwater environment simulation device: on the basis of the step (1), the corresponding underwater environment simulation device for simulating the actual working condition of the underwater acoustic material is designed and manufactured by comprehensively considering the actual working condition conditions (such as the temperature variation range of 4-40 ℃ and the pressure variation range of 0-3 MPa) and the performance of the CT scanning system. The temperature and pressure control precision of the sample cavity of the underwater environment simulation device needs to meet corresponding requirements, such as: the temperature fluctuation is less than +/-1 ℃, and the pressure fluctuation is less than +/-0.1 MPa;

(3) installation and fixation of the underwater acoustic material sample: the underwater environment simulation device for simulating the actual working condition of the underwater acoustic material is installed and fixed on a sample table of a CT scanning system, a prepared underwater acoustic material sample is placed in a sample cavity of the underwater environment simulation device, and a sealing cover is closed to ensure the tightness of the sample cavity;

(4) temperature change control in the sample chamber: starting to heat or cool the temperature and pressure changing environment medium in the sample cavity, and preserving the temperature after the temperature in the cavity reaches a set temperature, wherein the step can be omitted if the test is carried out at the ambient temperature (namely room temperature);

(5) pressure swing control in the sample chamber: after the temperature in the sample cavity is stable, the environmental medium in the sample cavity is pressurized, and the pressure is maintained after reaching the set pressure, if the test is required under the environmental pressure (namely the atmospheric pressure), the step can be omitted;

(6) and (3) controlling the heat preservation and pressure maintaining in the sample cavity: in the pressurizing process in the step (5), the temperature of the environment medium in the sample cavity fluctuates, at this time, a temperature and pressure control system is required to accurately control the temperature and the pressure in the sample cavity, and the temperature and the pressure in the sample cavity are monitored by pressure and temperature monitoring software, and when the temperature and the pressure are stabilized at set values (the temperature fluctuation is less than +/-1 ℃, and the pressure fluctuation is less than +/-0.1 MPa), the temperature and the pressure are waited for at least more than half an hour to ensure that the whole temperature of the underwater acoustic material sample is stable and consistent and the deformation is stable;

(7) CT scanning of material samples: and (3) starting to adopt a CT scanning system to carry out CT scanning test on the temperature and pressure variable container containing the sample, and storing the results of the tomography test images in a computer. During the whole scanning test period, the sample cavity is in a heat preservation and pressure maintaining state, and the temperature and the pressure in the clamp holder are monitored in real time. If the internal temperature and the pressure fluctuation exceed the specified allowable fluctuation range, stopping the test, invalidating the test data, re-executing the heat preservation and pressure maintaining process, and starting the scanning test after stabilization;

(8) CT scanning of samples under different working conditions: continuously repeating the processes (3) to (7), carrying out CT tomography test on the sample under different temperatures (such as 6 temperatures equally divided in the range of 4-40 ℃) and pressures (4 pressures equally divided in the range of 0-3 MPa) under preset simulation working conditions, closing the CT system after the test is finished, and opening the pressure release valve;

(9) CT scan of different samples: and closing the CT system, opening the pressure relief valve and releasing the pressure in the clamp. Opening the clamp, replacing the samples, repeating the processes (3) to (8), completing CT tomography tests of all samples to be tested under different preset simulation working conditions, closing the CT system after the tests are completed, opening the pressure release valve, and closing all control systems;

(10) three-dimensional geometrical reconstruction of a material sample: and (3) carrying out post-processing on the CT scanning test result by adopting a three-dimensional reconstruction program, reconstructing to obtain the three-dimensional geometric appearance of the underwater acoustic material sample under the corresponding working condition, outputting the three-dimensional geometric appearance into a corresponding file (such as an STL file in a three-dimensional patch format) containing geometric data, further converting into a file in a general CAD format (computer-aided design) such as igs containing three-dimensional entity geometric data, and providing an input material entity model for three-dimensional geometric analysis and related finite element analysis required by subsequent design. This step may be performed after a single scan is completed, or after some data has been accumulated after a partial scan has been completed, or after all data has been acquired after all scans have been completed.

Based on the detection method of the three-dimensional geometry of the underwater acoustic material, the detection method of the static volume compression modulus of the underwater acoustic material under the corresponding reference temperature and reference pressure can be realized, and a working flow chart is shown in fig. 6 and comprises the following steps:

(a) three-dimensional CT scanning of samples at baseline pressure and temperature: according to the steps (3) to (7), CT scanning test of the sample under the reference pressure and the reference temperature is firstly carried out, wherein the reference pressure is 2MPa, and the reference temperature is 25 ℃;

(b) and (3) pressurized sample CT scanning: setting a pressure increment delta P (which is a small quantity relative to the reference pressure and can be a negative value, such as-0.1 MPa) on the basis of the reference pressure and the reference temperature, then performing heat preservation and pressure maintaining control, and performing CT scanning test on the sample after the sample is stabilized;

(c) three-dimensional geometrical reconstruction of a sample before and after pressurization: three-dimensional reconstruction is carried out on the scanning results before and after pressurization, and the total volumes V1 and V2 of the samples before and after pressurization can be obtained respectively by utilizing CAD tool analysis;

(d) calculating the static volume compression modulus of the sample: the change of the total volume of the material before and after pressurization is V1-V2, and the static volume compression modulus can be obtained by the definition formulaCalculating to obtain;

(e) detection at different reference temperatures and pressures: and (d) repeating the steps (a) to (d) under different reference temperature and pressure working conditions, so that the static volume compression modulus of the material under different temperatures and pressures can be obtained.

The present invention is not limited to the above preferred embodiments, and any modifications, equivalents, improvements, etc. made within the principle of the present invention are included in the scope of the present invention.