Design Method of Observation Window for Full Ocean Depth Manned Submersible

Abstract

The present application relates to a design method for the observation window of a full-depth manned submersible. The method includes: performing size calculation according to the first observation window parameters and a preset observation window size formula to obtain the target size of the observation window; performing force calculation according to the first observation window parameters, the target size of the observation window, the second observation window parameters and a preset stress formula to obtain the theoretical stress of the observation window and check the design of the target size of the observation window; performing numerical calculation according to a numerical calculation model, the third observation window parameters and a pre-designed calculation scheme to obtain the numerical calculation results of the stress and displacement of the observation window, and checking the observation window. Generally, the observation window checked by the above method can pass the hydrostatic external pressure test. However, to ensure the safety of the observation window, it is recommended to carry out the hydrostatic external pressure test to check that the displacement of the observation window does not exceed the allowable value and check that the observation window does not show stress damage. By using this method, the problem of precise design of the core components of a full-depth manned submersible is solved.

Description

Technical Field

[0001] This application relates to the technical field of deep - sea manned submersibles, and particularly to a design method for the observation window of a full - depth manned submersible. Background Art

[0002] The abyssal zone, referring to the area in the ocean with a depth greater than 6000 meters, is one of the most mysterious and extreme environments on Earth. Due to the extremely high pressure, active tectonic activities, frequent earthquakes, and extremely unique ecosystems in this area, it has attracted great attention from scientists. To conduct in - depth research on the abyssal environment, manned submersibles have become important tools for scientific exploration. In particular, full - depth manned submersibles can overcome huge water pressures and carry professional personnel to directly observe and survey the abyssal zone. One of the core components of a manned submersible is the observation window, which plays a crucial role in the extreme deep - sea environment.

[0003] In related technologies, the design of observation windows mostly follows the ASME PVHO standard and uses plexiglass for manufacturing. This standard is divided into grades according to the design pressure and design temperature, and provides methods for obtaining the dimensions of observation windows under different grades. For example, the ASME PVHO standard recommends that when the design pressure exceeds 69 MPa, conical plexiglass is used, and its basic dimensions such as thickness, large - end diameter, and small - end diameter are calculated according to different combinations of pressure and temperature.

[0004] However, as stipulated in the ASME PVHO standard, when designing the observation window, it only requires that the mechanical properties of the plexiglass material used are not lower than the minimum value specified by the index. In fact, the mechanical properties of plexiglass materials vary significantly depending on their sources, thicknesses, and temperatures. And the mechanical properties of materials are necessary inputs for analyzing and evaluating the structural design. Therefore, the method of only specifying the minimum value of material properties results in the sub - optimal design of the observation window structure.

[0005] At the same time, when designing according to the pressure and temperature grades, if there are slight changes in the design pressure or temperature, causing the design to cross into an adjacent grade, the design results will change greatly. This loses the design rationality and will also lead to the sub - optimal design of the observation window structure. At the same time, the ASME PVHO standard only gives four grades of 60°, 90°, 120°, and 150°, and does not provide methods for obtaining the basic dimensions of observation windows for other angles, such as 75° and 105°.

[0006] Using the ASME PVHO standard to design observation windows is a relatively simple method in engineering, and it is also impossible to conduct post - design verification. The fundamental reason is that the design idea of grade - based value - taking and experimental regression cannot establish a one - to - one mapping relationship between design parameters and design results. Summary of the Invention

[0007] Based on this, in view of the above technical problems, it is necessary to provide a design method for the observation window of a full-depth manned submersible, which can check the design results, has relatively optimized design results, and can be manufactured using a variety of glass materials (including plexiglass).

[0008] The present application provides a design method for the observation window of a full-depth manned submersible. The method includes:

[0009] Performing size calculation according to the first observation window parameter and the preset observation window size formula to obtain the target size of the observation window;

[0010] Performing stress calculation according to the first observation window parameter, the target size of the observation window, the second observation window parameter and the preset stress formula to obtain the theoretical stress of the observation window;

[0011] Performing numerical calculation according to the numerical calculation model, the third observation window parameter and the pre-designed calculation scheme to obtain the numerical calculation results of the stress and displacement of the observation window, and checking the observation window.

[0012] In one embodiment, performing size calculation according to the first observation window parameter and the preset observation window size formula to obtain the target size of the observation window, including:

[0013] Determining the target small end diameter based on the light transmission diameter, the included angle, the maximum design pressure of the large end face and the preset small end formula;

[0014] Determining the target observation window thickness based on the target small end diameter, the maximum design pressure of the large end face and the preset thickness formula;

[0015] Determining the target large end diameter based on the target small end diameter, the target observation window thickness, the included angle and the preset large end formula;

[0016] Setting the target small end diameter, the target observation window thickness and the target large end diameter as the target size of the observation window.

[0017] In one embodiment, performing force calculation according to the first observation window parameter, the target size of the observation window, the second observation window parameter and the preset stress formula to obtain the theoretical stress of the observation window, including:

[0018] Performing stress calculation according to the included angle, the maximum design pressure of the large end face, the target size of the observation window, the second observation window parameter and the axial stress formula to obtain the axial stress at each position along the thickness and radius directions of the observation window;

[0019] Performing stress calculation according to the included angle, the second observation window parameter and the radial stress formula to obtain the radial stress at each position along the radial direction of a certain cross section in the axial direction of the observation window;

[0020] Based on the calculated axial stress and radial stress, compare with the compressive yield strength or tensile strength in the third observation window parameters to conduct a theoretical stress check on the observation window.

[0021] In one of the embodiments, stress calculation is performed according to the included angle, the maximum design pressure of the large end face, the target size of the observation window, the second observation window parameters, and the axial stress formula in the first observation window parameters to obtain the axial stress at various positions along the thickness and radius directions of the observation window, including:

[0022] Based on the target observation window thickness, determine the axial deformation increment at various positions along the axis of the observation window;

[0023] Based on the axial deformation increment, determine the first approximate radial strain at various positions along the axis;

[0024] Based on the first approximate radial strain, Poisson's ratio, and compressive elastic modulus, determine the axial stress increment;

[0025] According to the target large end diameter, target small end diameter, included angle, the maximum design pressure of the large end face, and the axial stress formula, conduct stress calculation to obtain the axial stress at various positions along the thickness and radius directions of the observation window;

[0026] In one of the embodiments, stress calculation is performed according to the included angle, the second observation window parameters, and the radial stress formula to obtain the radial stress at various positions along the radius of a certain cross-section in the axis direction of the observation window, including:

[0027] Based on the preset deformation formula, determine the axial deformation at various positions along the radius of a certain cross-section in the axis direction;

[0028] Based on the axial deformation and the included angle, determine the second approximate radial strain at various positions along the radius of a certain cross-section in the axis direction;

[0029] Based on the second approximate radial strain, Poisson's ratio, and compressive elastic modulus, determine the radial stress increment at various positions along the radius of a certain cross-section in the axis direction;

[0030] According to the radial stress increment, the included angle, the friction coefficient between the observation window and the window seat support conical surface, and the radial stress formula, conduct stress calculation to obtain the radial stress at various positions along the radius of a certain cross-section in the axis direction of the observation window;

[0031] In one of the embodiments, numerical calculation is performed according to the numerical calculation model, the third observation window parameters, and the pre-designed calculation scheme to obtain the numerical calculation results of the stress and displacement of the observation window, and conduct a check on the observation window, including:

[0032] Based on the target size of the observation window, the third observation window parameters, and the window seat material parameters, establish a numerical calculation model;

[0033] Based on the numerical calculation model, conduct mesh division, set contact boundaries, and apply load constraints;

[0034] Perform numerical calculations based on the numerical calculation model, the mesh generation, the contact boundary settings, and the application of load constraints to obtain the numerical calculation results of the stress and displacement of the observation window;

[0035] According to the numerical calculation results, perform displacement verification on the observation window, and the displacement value should not exceed 2 / 3 of the reserved displacement threshold;

[0036] Based on the compressive yield strength or tensile strength in the third observation window parameters, perform numerical calculation stress verification on the observation window. The stress in the main part of the observation window should not exceed its material strength, and the stress in the stress concentration part should not exceed 1.25 times its material strength.

[0037] In one embodiment, based on the numerical calculation model, perform mesh generation, contact boundary settings, and apply load constraints, including:

[0038] Set the window body as the target element and the observation window as the contact element;

[0039] Set up a contact pair on the contact boundary between the target element and the contact element;

[0040] The friction coefficient between the target element and the contact element is determined by experiments.

[0041] In one embodiment, after performing numerical calculations according to the numerical calculation model, the third observation window parameters, and the pre-designed calculation scheme to obtain the numerical calculation results, the method further includes:

[0042] Conduct experiments on the observation window according to the experimental scheme. The experimental displacement is not greater than the reserved displacement threshold, and there is no internal or external stress damage to the observation window after the experiment, then the final design of the observation window is completed;

[0043] Otherwise, it is necessary to re-adjust the target size of the observation window until it passes the theoretical stress calculation, numerical calculation, and experiment simultaneously.

[0044] In one embodiment, before calculating the target size of the observation window according to the first observation window parameters and the preset observation window size formula, the method further includes:

[0045] Perform performance testing on the observation window material according to the preset specimen parameters and the preset performance testing scheme to obtain the third observation window parameters.

[0046] In one embodiment, performing performance testing on the observation window material according to the preset specimen parameters and the preset performance testing scheme to obtain the third observation window parameters includes:

[0047] Fabricate specimens of the observation window material according to the preset specimen parameters to obtain multiple groups of specimens;

[0048] Perform performance tests on multiple groups of specimens according to the performance test plan to obtain the third observation window parameters.

[0049] In one embodiment, perform performance tests on each group of specimens according to the performance test plan to obtain the third observation window parameters, including:

[0050] Perform tensile tests on each group of tensile specimens according to the preset tensile test plan to obtain the tensile performance test results;

[0051] Perform compression tests on each group of compression specimens according to the preset compression test plan to obtain the compression performance test results.

[0052] The above-mentioned design method for the observation window of the full-depth manned submersible obtains the target size of the observation window through the preset size design formula, and then combines the second observation window parameters and the preset stress formula to calculate the theoretical stress of the observation window. Compare it with the pre-tested tensile strength or compression yield strength to complete the theoretical stress check of the observation window design; combine the numerical calculation model, the third observation window parameters and the preset calculation plan to perform numerical calculations to obtain the numerical calculation results of the stress and displacement of the observation window, and compare the displacement allowable value, compare the pre-tested tensile strength or compression yield strength, and complete the numerical calculation check of the observation window design; the observation window designed through the above design generally can pass the hydrostatic external pressure test, but to ensure the safety of the observation window, it is still recommended to carry out the hydrostatic external pressure test to check that the displacement of the observation window does not exceed the allowable value and check that the observation window does not have stress damage. Description of the Drawings

[0053] Figure 1 Is a schematic structural diagram of the observation window in the related art;

[0054] Figure 2 Is a selection table of the size ratio coefficient of the observation window in the related art.

[0055] Figure 3 Is a schematic flow chart of the design method for the observation window of the full-depth manned submersible in one embodiment;

[0056] Figure 4 Is a schematic diagram of the size of the tensile specimen in one embodiment;

[0057] Figure 5 Is a schematic diagram of the size of the compression specimen in one embodiment;

[0058] Figure 6 Is a schematic structural diagram of the observation window in one embodiment;

[0059] Figure 7 Is a schematic diagram of the target size of the observation window, the stress calculation coordinate system, and the force in one embodiment;

[0060] Figure 8 At a certain axial cross-section (ordinate is z ) r = 150 mm in an embodiment, the comparison curve of the theoretical radial stress and the experimentally measured radial stress when the pressure on the large end face increases from 0 MPa to 115 MPa; p

[0061] Figure 9 r = 0, Z = h At the center of the small end in an embodiment ( r = 0, Z = h ), the comparison curve of the numerical calculation displacement (compression constitutive simulation in the figure), the experimentally measured displacement, and the numerical calculation displacement obtained using the minimum index of the plexiglass material specified in the ASME PVHO standard (specification index simulation in the figure) when the pressure on the large end face increases from 0 MPa to 115 MPa; p

[0062] Figure 10 r=0 At the center of the small end in an embodiment ( r=0 ), when the seawater pressure on the large end p = 30 MPa, at each axial position ( Z from 0 to h ), the comparison curve of the axial stress calculated by the existing theory (traditional theory calculation in the figure), the axial stress calculated by the present invention (calculated by the deformation correction formula), and the axial stress numerically calculated by the present invention; Detailed implementation manners

[0063] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0064] The applicant has noticed that currently, the design of the viewing window glass of submersibles mainly refers to the "Safety Standard for Pressure Vessels for Human Occupancy" formulated by the American Society of Mechanical Engineers (hereinafter referred to as the ASME PVHO standard). According to the regulations in the ASME PVHO standard, the design of the viewing window glass is bounded by 69 MPa. When the design pressure exceeds 69 MPa, the ASME PVHO standard recommends using a frustum-shaped plexiglass viewing window, and its structure is as Figure 1 shown, and a selection table of the size ratio coefficient is provided as Figure 2 shown for calculating the basic dimensions of the viewing window glass.

[0065] The above-mentioned ASME PVHO standard design is generally a method of grading and taking values according to design pressure and design temperature and conducting test regression, and the design results are relatively simple and rough. In the actual adoption of this standard design, there are several main problems, such as a wide range of material properties, large differences in cross-grade design, and lack of design analysis and verification, which are specifically elaborated below:

[0066] 1) Wide range of material properties

[0067] According to the provisions in the ASME PVHO standard, when designing the observation window, it is only required that the mechanical properties of its materials are not lower than the lowest value specified by the index. However, in fact, the differences in the mechanical properties of plexiglass materials from different sources, with different thicknesses and at different temperatures are very obvious. According to relevant domestic literature, at 40°C, the tensile strength of domestic thick-plate plexiglass is 67.3% higher than that of thin plates (65.47 MPa → 39.14 MPa). For the same domestic thick-plate plexiglass, the tensile strength of the test piece at 40°C is 35.6% lower than that at 0°C (65.47 MPa → 101.64 MPa). At the same time, there are also significant differences in the elastic modulus of plexiglass materials under different conditions, and the elastic modulus and strength of the material are necessary inputs for analyzing and verifying the design of the observation window. Therefore, the method of only limiting the lowest value of material properties results in the fact that the size design of the observation window cannot be optimized.

[0068] 2) Large differences in cross-grade

[0069] Assume that the light-transmitting diameter of a frustum-shaped observation window is 200 mm, the design temperature ≤ 24°C, and the design cone angle is 150°. When its design pressure is 103.4 MPa, the minimum thickness of the observation window designed according to the ASME PVHO standard is 507 mm. When the design pressure increases by 0.1 MPa, the design thickness will increase by 286.6 mm, and the increase amplitude reaches 56.5%. The differences in the design results brought about by grading and taking values significantly deviate from the reasonable range.

[0070] The differences in the results brought about by grading the design temperature are also large. Taking the frustum-shaped observation window for full-depth diving as an example, if its design temperature is adjusted from ≤ 10°C to ≤ 24°C, the minimum thickness of the observation window will increase by 15.1 mm. The design temperature of the observation window refers to the ambient temperature at the designed depth of the submersible. Obviously, for the frustum-shaped observation window used in full-depth submersibles, its design temperature should be within a relatively stable range. In addition, since the design cone angles in the ASME PVHO standard are divided into four grades: 60° / 90° / 120° / 150°, for some specific angles such as 75° or 105°, there is no applicable design guidance in the standard.

[0071] 3) Lack of analysis and verification

[0072] Using the ASME PVHO standard to design the viewing window is a relatively simple method in engineering, but it cannot be used for post-design verification. The fundamental reason is that the design concept of grading and value-taking, and experimental regression cannot establish a one-to-one mapping relationship between design parameters and design results.

[0073] In one embodiment, as Figure 3 shown, the present application provides a design method for the viewing window of a full-depth manned submersible. In this embodiment, the method includes the following steps:

[0074] Step 302: Calculate the size according to the first viewing window parameter and the preset viewing window size formula to obtain the target size of the viewing window.

[0075] Specifically, by presetting the first viewing window parameter, the first viewing window parameter includes the light-transmitting diameter, the included angle, and the maximum design pressure of the large-end end face. The included angle is the included angle between the support cone surface and the central axis, and the maximum design pressure of the large-end end face is the maximum seawater pressure borne by the large-end end face and a certain safety factor is taken. Then, the first viewing window parameter is input into the preset viewing window size formula for calculation to obtain the target size of the viewing window.

[0076] Step 304: Calculate the force according to the first viewing window parameter, the target size of the viewing window, the second viewing window parameter, and the preset stress formula to obtain the theoretical stress of the viewing window.

[0077] Specifically, obtain the second viewing window parameter, and the second viewing window parameter includes the compression elastic modulus, the Poisson's ratio, and the friction coefficient between the viewing window and the window seat.

[0078] After calculating the target size of the viewing window, the axial stress and the radial stress are calculated in combination with the preset stress formula (i.e., the axial stress formula and the radial stress formula), and then the stress of the viewing window is theoretically calculated, and the strength of the viewing window is checked by using the calculated stress.

[0079] Step 306: Perform numerical calculation according to the numerical calculation model, the third viewing window parameter, and the pre-designed calculation scheme to obtain the numerical calculation results of the stress and displacement of the viewing window, and check the viewing window.

[0080] Specifically, obtain the third viewing window parameter by pre-testing. In addition to the compression elastic modulus and the Poisson's ratio in the second viewing window parameter, the third viewing window parameter also includes the tensile strength, the elongation at break, the tensile elastic modulus, the tensile load-deformation curve, the compression yield strength, and the compression load-deformation curve. After determining the target size of the submersible viewing window, establish a numerical calculation model including the window seat and the viewing window. For example, a two-dimensional axisymmetric model can be used, and this model needs to consider that if the deformation of the viewing window is restricted under pressure, the model should also include a restricted boundary.

[0081] Input the third observation window parameters into the numerical calculation model, perform mesh generation, contact boundary setting, and load constraint application, and then obtain the numerical calculation results. Among them, in the contact boundary setting, the observation window is defined as the contact element, and the window seat is defined as the target element, and a contact pair is set on the contact boundary between the two. The numerical calculation results include the stress and displacement of the observation window. Among them, the displacement value should not exceed 2 / 3 of the reserved displacement threshold, and the numerically calculated stress of the main part of the observation window should not exceed the compressive yield strength (when the observation window only bears pressure) or the tensile strength (when the observation window bears tension) in the third observation window parameters, and the emergency concentration part should not exceed 1.25 times the compressive yield strength (when the observation window only bears pressure) or the tensile strength (when the observation window bears tension) in the third observation window parameters; thus, the verification of the target size design of the observation window is completed.

[0082] The above-mentioned design method of the full-depth manned submersible observation window obtains the target size of the observation window through a preset size design formula, and then combines the second observation window parameters and the preset stress formula to calculate the theoretical stress of the observation window, and compares it with the tensile strength or compressive yield strength obtained by pre-testing to complete the theoretical stress verification of the observation window design; combines the numerical calculation model, the third observation window parameters and the preset calculation scheme to perform numerical calculation, obtains the numerical calculation results of the stress and displacement of the observation window, and completes the numerical calculation verification of the observation window design by comparing the displacement allowable value and comparing the tensile strength or compressive yield strength obtained by pre-testing; the observation window designed through the above design generally can pass the hydrostatic external pressure test, but to ensure the safety of the observation window, it is still recommended to carry out the hydrostatic external pressure test to verify that the displacement of the observation window does not exceed the allowable value and verify that the observation window does not show stress damage.

[0083] In one embodiment, before calculating the target size of the observation window according to the first observation window parameters and the preset observation window size formula, the method further includes:

[0084] Perform performance testing on the observation window material according to the preset specimen parameters and the preset performance testing scheme to obtain the third observation window parameters.

[0085] Among them, the preset specimen parameters include the specimen size parameters for making tensile tests and the sizes for making compression specimens, and the preset performance testing scheme includes a tensile testing scheme and a compression testing scheme.

[0086] Specifically, multiple groups of test specimens for obtaining the third observation window parameters are made from the blank with the same manufacturing process as the observation window. After determining the size parameters of the tensile specimens and the size parameters of the compression specimens, the blank is processed to obtain multiple groups of tensile specimens and multiple groups of compression specimens.

[0087] Then, according to the tensile test plan and the compression test plan, each group of tensile specimens and each group of compression specimens are tested respectively to obtain the third observation window parameters.

[0088] In one embodiment, according to the preset specimen parameters and the preset performance test plan, the performance of the observation window material is tested to obtain the third observation window parameters, including:

[0089] Specimens are made from the observation window material according to the preset specimen parameters to obtain multiple groups of specimens; the performance of the multiple groups of specimens is tested according to the performance test plan to obtain the third observation window parameters.

[0090] Specifically, specimens are prepared from the blank with the same preparation process as the observation window. If the thickness of the blank is less than 150 mm, samples are taken from the middle of the blank; otherwise, samples are taken from the surface layer and the middle of the blank respectively.

[0091] And the sampled blank is processed according to the size parameters of the specimens and the production plan, so as to obtain multiple groups of specimens for testing the material performance. Then, each group of specimens is tested accordingly based on the performance test plan.

[0092] For example, the specimens include tensile specimens and compression specimens.

[0093] Refer to Figure 4 , Figure 4 which shows the relevant production parameters of the tensile specimens. Based on these production parameters, the blank is processed, specifically:

[0094] During the processing of the specimens, the starting processing position should avoid the arc section or the 50 - mm - long gauge section to prevent local defects caused by the tool staying for too long; after processing, the specimens need to be polished to ensure a smooth surface, no visible cracks, scratches or other defects; in addition, before the tensile test, the specimens should be heat - treated to eliminate the residual stress.

[0095] Refer to Figure 5 , Figure 5 which shows the relevant production parameters of the compression specimens. Based on these production parameters, the blank is processed, specifically:

[0096] The processed specimens need to be polished to ensure a smooth surface, no visible cracks, scratches or other defects, and at the same time ensure that both end faces are flat and the edges are clear and sharp; before the compression test, the specimens should also be heat - treated to effectively eliminate the residual stress, so as to ensure the stability and reliability of the specimens during the test and avoid unnecessary deformation or damage caused by stress.

[0097] In one embodiment, according to the performance test plan, each group of specimens is tested to obtain the third observation window parameters, including:

[0098] Tensile tests are performed on each group of tensile specimens according to a preset tensile test plan to obtain tensile property test results; compression tests are performed on each group of compression specimens according to a preset compression test plan to obtain compression property test results; the tensile property test results and the compression property test results constitute the third observation window parameters.

[0099] Among them, the multiple groups of specimens include multiple groups of tensile specimens and multiple groups of compression specimens, and the preset property test plan includes a preset tensile test plan and a preset compression test plan.

[0100] Exemplarily, after the tensile specimens are manufactured and before the tensile test, coarse sandpaper is attached to both ends of the specimens to prevent fracture or slipping during the test. The specimens need to be placed for more than 24 hours under standard environmental conditions (23°C ± 2°C, humidity 50% ± 5%); the width and height at the middle of the gauge section and 20 mm on both sides are measured, and the cross-sectional area is calculated; when the specimens are clamped, the fixture design needs to ensure no eccentricity during loading, and the clamping area is not less than 2 / 3 of the area of the large end; tensile tests are carried out at a loading rate of 5 mm / min, and the strain is measured at constant intervals until the specimens break.

[0101] Before the compression test, the specimens are placed for more than 24 hours under standard environmental conditions (23°C ± 2°C, humidity 50% ± 5%), and the width and height at different positions of the specimens are measured to calculate the minimum cross-sectional area; the specimens are placed in the middle of the pressure plate of the testing machine to ensure that the center line of the specimens coincides with the center of the pressure plate and the end faces are parallel; compression tests are carried out at a loading rate of 1.3 mm / min, and the strain is measured at constant time intervals during the loading process until the specimens yield.

[0102] In one embodiment, size calculations are performed according to the first observation window parameters and a preset observation window size formula to obtain the target size of the observation window, including:

[0103] Determine the target small end diameter based on the light transmission diameter, included angle, maximum design pressure on the large end face, and a preset small end formula; determine the target observation window thickness based on the target small end diameter, maximum design pressure on the large end face, and a preset thickness formula; determine the target large end diameter based on the target small end diameter, target observation window thickness, included angle, and a preset large end formula; set the target small end diameter, target observation window thickness, and target large end diameter as the target size of the observation window.

[0104] Among them, the first observation window parameters include the light transmission diameter, included angle, and maximum design pressure on the large end face.

[0105] Specifically, after determining the light transmission diameter of the observation window, the included angle between the support conical surface and the central axis, and the maximum design pressure borne by the large end face, calculate the size of the observation window, and the size of the observation window includes the small end diameter, the observation window thickness, and the large end diameter.

[0106] The small end diameter is positively correlated with the maximum design pressure borne by the large end face, the angle between the support conical surface and the central axis, and the light-transmitting diameter. The specific formula for calculating the small end diameter is:

[0107]

[0108] Wherein, is the maximum design pressure borne by the large end face, is the angle between the support conical surface and the central axis, is the light-transmitting diameter.

[0109] The thickness of the observation window is positively correlated with the maximum design pressure borne by the large end face and the small end diameter. The specific formula for calculating the thickness of the observation window is:

[0110]

[0111] Wherein, is the small end diameter.

[0112] The large end diameter can be obtained by geometric calculation. The specific formula for calculating the large end diameter is:

[0113]

[0114] Wherein, is the thickness of the observation window, is the large end diameter.

[0115] Based on the above formulas, the target dimensions of the observation window are calculated and determined. The schematic diagrams of each dimension are as shown in Figure 7 and the structure of the observation window is as shown in Figure 6 as shown.

[0116] In one embodiment, according to the angle and the maximum design pressure of the large end face in the first observation window parameters, the target dimensions of the observation window, the second observation window parameters, and the preset stress formula, the stress of the observation window is calculated to obtain the theoretical stress of the observation window, including:

[0117] According to the angle and the maximum design pressure of the large end face in the first observation window parameters, the target dimensions of the observation window, the second observation window parameters, and the axial stress formula, the stress is calculated to obtain the axial stress at each point ( Figure 7 in the Z direction of Figure 7 ) along the thickness (i.e., 0 - h, 0 - R ) and the radial direction (i.e., z at the cross-section of the observation window along the radial direction at each point ( r , in the range 0-RThe radial stress; after calculating the axial theoretical stress and the radial theoretical stress, according to the tensile strength or the compressive yield strength in the third observation window parameters, the theoretical stress check and evaluation of the observation window are carried out.

[0118] In one embodiment, stress calculation is performed according to the included angle and the maximum design pressure of the large end face, the target size of the observation window, the second observation window parameters, and the axial stress formula in the first observation window parameters, to obtain the axial stress at each position along the thickness (i.e., Figure 7 the Z direction in Figure 7 ) and the radial direction (i.e.,

[0119] the R direction in z ) of the observation window, including: z Determine the axial 0 - h axial deformation increment at the position (

[0120]

[0121] ) based on the thickness of the observation window, specifically: where is the axial distance from the large end face, and

[0122]

[0123] is the thickness of the observation window; z Determine the first approximate radial strain at the axial z position, which is negatively correlated with the diameter at the

[0124]

[0125] position and positively correlated with the axial deformation increment, specifically: where z is the cross-sectional diameter at the

[0126] position and can be obtained by geometric calculation, specifically:

[0127] Determine the axial stress increment based on the first approximate radial strain, Poisson's ratio, and compressive elastic modulus; the first approximate radial strain and the compressive elastic modulus are both positively correlated with the axial stress increment, specifically:

[0128]

[0129] where is the Poisson's ratio of the observation window material, and E is the compressive elastic modulus of the observation window material.

[0130] After calculating the axial stress increment, combined with zDiameter at this point , the maximum design pressure borne by the large end face p , large end diameter and small end diameter , calculate and determine the radius r at this point, the axial theoretical stress, and the specific calculation formula is:

[0131]

[0132] Among them, the parameters of the first observation window include the light-transmitting diameter, the included angle, and the maximum design pressure of the large end face, and the parameters of the second observation window include the compression elastic modulus, the Poisson's ratio, and the friction coefficient between the observation window and the window seat.

[0133] In one embodiment, stress calculation is performed according to the included angle in the parameters of the first observation window, the parameters of the second observation window, and the radial stress formula, and the radial stress at each point along the radial direction ( z at this point) of a certain cross-section in the axial direction of the observation window ( r at this point, the range is 0-R ) is obtained, including:

[0134] Determine the axial z axial deformation at this point of the cross-section in the radial direction r , and the specific formula is:

[0135]

[0136] In the formula, .

[0137] Based on the axial deformation and the included angle, determine the second approximate radial strain z at this point of the cross-section in the radial direction r , the axial deformation, the radial coordinate , the included angle between the support conical surface and the central axis are all positively correlated with the second approximate radial strain, and the second approximate radial strain and the axial r、 diameter at this point are negatively correlated, and the specific calculation formula is: z

[0138]

[0139] Based on the second approximate radial strain, the Poisson's ratio, and the compression elastic modulus, determine the radial stress increment at this point of the cross-section in the radial direction z r ; the second approximate radial strain and the compression elastic modulus are both positively correlated with the radial stress increment, and the specific calculation formula is:

[0140]

[0141]

[0141] Among them, is the Poisson's ratio of the observation window material,E The compression elastic modulus of the viewing window material.

[0142] After calculating the obtained radial stress increment, in combination with the friction coefficient between the window seat and the support conical surface of the viewing window, the included angle between the support conical surface and the central axis, the axial theoretical stress and the radial stress increment, calculate and determine the radial stress at each point along the radial direction of a certain cross-section ( z at the location), within the range ( r at the location), the specific calculation formula is: 0-R )

[0143]

[0144] Wherein, is the friction coefficient between the window seat and the support conical surface of the viewing window, is the included angle between the support conical surface and the central axis.

[0145] In one embodiment, according to the numerical calculation model, the parameters of the third viewing window and the pre-designed calculation scheme, perform numerical calculations to obtain the numerical calculation results of the stress and displacement of the viewing window, and check the viewing window, including:

[0146] Based on the target size of the viewing window, the parameters of the third viewing window and the material parameters of the window seat, establish a numerical calculation model; based on the numerical calculation model, perform mesh division, contact boundary setting, and apply load constraints; according to the numerical calculation model, the mesh division, contact boundary setting, and load constraint application, perform numerical calculations to obtain the numerical calculation results of the stress and displacement of the viewing window; according to the numerical calculation results, check the displacement of the viewing window, and the displacement value should not exceed 2 / 3 of the reserved displacement threshold; based on the compressive yield strength in the parameters of the third viewing window, check the numerical calculation stress of the viewing window, the stress of the main part of the viewing window should not exceed its compressive yield strength, and the stress of the stress concentration part should not exceed 1.25 times of its compressive yield strength.

[0147] Exemplarily, the numerical calculation model of the viewing window can adopt a two-dimensional axisymmetric model, and if there are deformation limitations when the viewing window is under pressure, the calculation model should include corresponding limiting boundaries; when inputting the parameters of the third viewing window into the numerical calculation model, the multi-linear kinematic hardening (MKIN) or multi-linear isotropic hardening (MISO) model is usually adopted.

[0148] In addition, when applying the constraint load, the maximum working pressure should be applied to the outer side of the window seat and the large end face of the viewing window; if there is a pre-tightening force between the window seat and the viewing window, the pre-tightening force load should also be set in the relevant area.

[0149] After the above settings are completed, numerical calculations are performed using the model to obtain the numerical calculation results of the model, and the numerical calculation stress in the numerical calculation results is compared and analyzed with the compressive yield strength. Among them, due to the structural design of the observation window and the window seat in this embodiment, the observation window only bears pressure, and thus the compressive yield strength is used to judge the stress. The stress in the main part of the observation window should not exceed the compressive yield strength, and the ratio of the stress in the stress concentration part to the compressive yield strength does not exceed 1.25.

[0150] In one embodiment, based on the numerical calculation model, mesh generation, contact boundary setting, and load constraints are performed, including:

[0151] The window body is set as the target element, and the observation window is set as the contact element;

[0152] Contact pairs are set on the contact boundary between the target element and the contact element;

[0153] The friction coefficient between the target element and the contact element is determined by experiments.

[0154] In one embodiment, after performing numerical calculations according to the numerical calculation model, the third observation window parameters, and the pre-designed calculation scheme to obtain the numerical calculation results, the method further includes:

[0155] The observation window is tested according to the test scheme to obtain the test results; among them, the test scheme includes a hydrostatic external pressure test.

[0156] In one embodiment, testing the observation window according to the test scheme to obtain the test results includes:

[0157] Prepare and install accessories according to the observation window design scheme to obtain the test observation window; perform a hydrostatic external pressure test on the test observation window to obtain the hydrostatic external pressure test results.

[0158] Specifically, before the test, strain gauges need to be pasted at relevant positions on the inner and outer surfaces of the observation window, and displacement sensors need to be installed at places where the displacement needs to be measured; then, lubricant is evenly sprayed on the support surface of the window seat, and the observation window is installed in place on the window seat. During this process, the fasteners need to be tightened according to the specified torque, and at the same time, an anti-collision frame is set outside the observation window.

[0159] Then, the installed observation window assembly is subjected to a hydrostatic external pressure test. The test water temperature is controlled within the designed required water temperature. The maximum test pressure shall be the maximum design pressure, and the maximum design pressure takes into account the margin coefficient based on the maximum seawater pressure, and ensures that the pressure increase and decrease rate and the pressure holding time simulate the actual service conditions of the observation window as much as possible; among them, the pressure holding time under the maximum test pressure shall not be less than 15 minutes. In one embodiment, when the maximum seawater pressure does not exceed 60 MPa, the margin coefficient is not less than 1.25, and after the maximum seawater pressure exceeds 60 MPa, the margin coefficient is not less than 1.1.

[0160] During the hydrostatic external pressure test, the displacement-pressure and strain-pressure curves need to be recorded synchronously, and the time and temperature information shall be marked. In one embodiment, at a certain cross-section r = 150 mm axially, the comparison curve of the theoretical radial stress and the measured radial stress during the test when the test pressure increases from 0 MPa to 115 MPa is as Figure 8 shown.

[0161] In one embodiment, after performing the hydrostatic external pressure test on the observation window and obtaining the hydrostatic external pressure test results, the method further includes:

[0162] Inspecting the observation window after the test to obtain the observation window inspection results.

[0163] Specifically, if the test displacement is not greater than the reserved displacement threshold and there are no internal and external stress damages such as cracks and crazes on the observation window after the test, then the observation window completes the final design;

[0164] Otherwise, the target size of the observation window needs to be readjusted until it passes the theoretical stress calculation, numerical calculation, and test simultaneously.

[0165] For example, remove the observation window from the window seat, place it on a dark blue background cloth, and carefully check the end face, conical surface, and interior of the observation window for surface abrasions, crazes, or cracks from different angles with appropriate lighting. If there are none, it can be judged as passing the stress check test verification.

[0166] In one embodiment, at the center of the small end of the observation window ( r = 0, Z = h ), when the test pressure increases from 0 MPa to 115 MPa, the comparison curve of the numerically calculated displacement (compression constitutive simulation in the figure), the measured displacement during the test, and the numerically calculated displacement obtained using the minimum index of the plexiglass material specified in the ASME PVHO standard (specification index simulation in the figure) is as Figure 9 shown.

[0167] In one embodiment, at the center of the small end of the observation window ( r=0 ), the seawater pressure at the large end p = 30 MPa, at each axial position ( z from 0 to h), the comparison curves of the axial stress calculated by the existing theory (traditional theory calculation in the figure), the axial stress calculated in the embodiments of the present invention (calculated by the deformation correction formula), and the axial stress numerically calculated in the embodiments of the present invention are as Figure 10 shown.

[0168] In an exemplary embodiment, a design method for the observation window of a full-depth manned submersible is provided, and the method includes the following steps:

[0169] Fabricate specimens of the observation window material according to the preset specimen parameters to obtain multiple groups of specimens.

[0170] Conduct tensile tests on each group of tensile specimens according to the preset tensile test plan to obtain tensile property test results.

[0171] Conduct compression tests on each group of compression specimens according to the preset compression test plan to obtain compression property test results.

[0172] Determine the compression elastic modulus, Poisson's ratio, tensile strength, elongation at break, tensile elastic modulus, tensile load-deformation curve, compression yield strength, and compression load-deformation curve based on the tensile property test results and the compression property test results.

[0173] Determine the target small-end diameter based on the light-transmitting diameter, included angle, maximum design pressure at the large-end end face, and the preset small-end formula.

[0174] Determine the target observation window thickness based on the target small-end diameter, maximum design pressure at the large-end end face, and the preset thickness formula.

[0175] Determine the target large-end diameter based on the target small-end diameter, target observation window thickness, included angle, and the preset large-end formula.

[0176] Set the target small-end diameter, target observation window thickness, and target large-end diameter as the target dimensions of the observation window.

[0177] Determine the axial deformation increments at each axial position of the observation window based on the target observation window thickness.

[0178] Determine the first approximate radial strain at each axial position based on the axial deformation increments.

[0179] Determine the axial stress increments based on the first approximate radial strain, Poisson's ratio, and compression elastic modulus.

[0180] Conduct stress calculations according to the target large-end diameter, target small-end diameter, included angle, maximum design pressure at the large-end end face, and the axial stress formula to obtain the axial stresses at each position along the thickness and radius directions of the observation window.

[0181] Determine the axial deformations at each radial position of a certain axial cross-section based on the preset formula.

[0182] Determine the second approximate radial strain at various radial positions of a certain cross-section along the axis based on the axial deformation and the included angle.

[0183] Determine the radial stress increment at various radial positions of a certain cross-section along the axis based on the second approximate radial strain, Poisson's ratio, and compressive elastic modulus.

[0184] Conduct stress calculations according to the radial stress increment, included angle, observation window, friction coefficient of the window seat support conical surface, and radial stress formula to obtain the radial stress at various radial positions of a certain cross-section along the axis of the observation window.

[0185] According to the calculated axial stress and radial stress, compare the tensile strength and compressive yield strength to conduct stress checking on the observation window.

[0186] Establish a numerical calculation model based on the target size of the observation window, the compressive elastic modulus, Poisson's ratio, compressive load-deformation curve of the observation window, and the material parameters of the window seat.

[0187] Perform mesh division on the numerical calculation model, and locally refine the mesh on the contact boundary between the window seat and the observation window. The refined area should be no less than two layers of mesh in the normal direction of the contact boundary.

[0188] Set the window body as the target element and the observation window as the contact element.

[0189] Set up a contact pair on the contact boundary between the target element and the contact element.

[0190] The friction coefficient between the target element and the contact element is determined by experiments.

[0191] Apply the maximum working pressure on the outer side of the window seat and the large-end end face of the observation window. The load application should include the positions in contact with the sealing ring; if there is an installation pre-tightening force, the corresponding pre-tightening force load should be applied to the corresponding areas of the window seat and the observation window.

[0192] Based on the numerical calculation model and the above settings, conduct numerical calculations to obtain the numerical calculation results of the stress and displacement of the observation window.

[0193] According to the numerical calculation results, conduct displacement checking on the observation window. The displacement value should not exceed 2 / 3 of the reserved displacement threshold; at the same time, compare the compressive yield strength to conduct numerical calculation stress checking on the observation window. The stress of the main part of the observation window should not exceed its compressive yield strength, and the stress of the stress concentration part should not exceed 1.25 times its compressive yield strength.

[0194] When the theoretical calculation stress, numerical calculation stress, and numerical calculation displacement all meet the requirements, manufacture accessories such as the observation window and the test window seat, and conduct a hydrostatic external pressure test for experimental verification.

[0195] After the test, remove the observation window and carefully check whether there are stress-induced damages, such as crazing or cracks, on its surface and inside. If there is no damage, verify it through the stress check test; at the same time, if the displacement measured in the test is not greater than the reserved displacement threshold, the observation window passes the test verification.

[0196] If it fails to pass the test verification, it is necessary to readjust the target size of the observation window until it passes the theoretical stress check, numerical stress and displacement check, and test verification.

[0197] It should be understood that although the steps in the flowcharts involved in the above-described embodiments are shown in sequence according to the arrows, these steps do not necessarily have to be executed in the order indicated by the arrows. Unless there is a clear description in this article, there is no strict order limit for the execution of these steps, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-described embodiments may include multiple steps or multiple stages. These steps or stages do not necessarily have to be executed at the same time, but can be executed at different times. The execution order of these steps or stages does not necessarily have to be sequential, but can be executed alternately or in turn with at least a part of the steps or stages in other steps or other steps.

[0198] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0199] The above-described embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the patent scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A method for designing an observation window for a full-sea-depth manned submersible, characterized in that: The method comprises: Calculate the size of the observation window according to the first observation window parameters and the preset observation window size formula to obtain the target size of the observation window; wherein the first observation window parameters include the light transmission diameter, the angle and the maximum design pressure of the large end face; Stress calculation is performed according to the first observation window parameter, the observation window target size, the second observation window parameter and the preset stress formula to obtain the observation window theoretical stress; wherein, stress calculation is performed according to the included angle, the maximum design pressure of the large end face, the observation window target size, the second observation window parameter and the axial stress formula to obtain the axial stress at various locations along the thickness and radius directions of the observation window; stress calculation is performed according to the included angle, the second observation window parameter and the radial stress formula to obtain the radial stress at various locations along the radial direction of a certain axial section of the observation window; and according to the calculated axial stress and radial stress, the compressive yield strength or tensile strength in the third observation window parameter is compared to perform theoretical stress check on the observation window; Numerical calculation is performed according to the numerical calculation model, the third observation window parameters and the preset calculation scheme to obtain the numerical calculation results of the observation window stress and displacement, and the observation window is checked; wherein, a numerical calculation model is established based on the target size of the observation window, the third observation window parameters and the window seat material parameters; based on the numerical calculation model, meshing, contact boundary setting and load constraints are performed; numerical calculation is performed according to the numerical calculation model to obtain the numerical calculation results of the observation window stress and displacement; The step of performing size calculation according to the first observation window parameter and a preset observation window size formula to obtain the observation window target size includes: Determine the target small end diameter based on the light transmission diameter, the included angle, the maximum design pressure of the large end face and the preset small end diameter formula; Determine the target observation window thickness based on the target small end diameter, the maximum design pressure of the large end face and a preset thickness formula; Determine the target large end diameter based on the target small end diameter, the target observation window thickness, the included angle and a preset large end formula; The target small end diameter, the target observation window thickness and the target large end diameter are set as the observation window target dimensions.

2. The method for designing an observation window for a full-sea-depth manned submersible according to claim 1, characterized in that: The first observation window parameters also include the light transmission diameter; the second observation window parameters include the compressive elastic modulus, Poisson's ratio, and the friction coefficient of the observation window and the window seat support cone surface; the observation window target size includes the target small end diameter, the target observation window thickness, and the target large end diameter; Stress calculation is performed according to the included angle, the maximum design pressure of the large end face, the target size of the observation window, the parameters of the second observation window and the axial stress formula to obtain the axial stress at each location of the observation window along the thickness and radius directions, including: Determine the axial deformation increment of the observation window at each location along the axial direction based on the target observation window thickness; Determine a first approximate radial strain at each axial location based on the axial deformation increment; determining an axial stress increment based on the first approximate radial strain, Poisson's ratio, and compressive elastic modulus; Stress calculation is performed based on the target large end diameter, the target small end diameter, the included angle, the maximum design pressure of the large end face and the axial stress formula to obtain the axial stress at various locations along the thickness and radius directions of the observation window.

3. The method for designing an observation window for a full-sea-depth manned submersible according to claim 1, characterized in that: The second observation window parameters include compressive elastic modulus, Poisson's ratio, and friction coefficient between the observation window and the supporting cone surface of the window seat; Stress calculation is performed according to the angle, the second observation window parameter, and the radial stress formula to obtain radial stress at various locations along the radial direction of a certain axial section of the observation window, including: Based on the preset deformation formula, determine the axial deformation of a certain axial section at various radial locations; Determine a second approximate radial strain of a certain axial cross section at various radial locations based on the axial deformation and the included angle; Determine radial stress increments of a certain axial cross section at various locations in the radial direction based on the second approximate radial strain, Poisson's ratio and compressive elastic modulus; Stress calculation is performed based on the radial stress increment, the included angle, the friction coefficient of the observation window and the window seat supporting cone surface, and the radial stress formula to obtain the radial stress at various locations along the radial direction of a certain axial section of the observation window.

4. The method for designing an observation window for a full-sea-depth manned submersible according to claim 1, characterized in that: The third observation window parameters include not only the compressive elastic modulus and Poisson's ratio in the second observation window parameters, but also tensile strength, elongation at break, tensile elastic modulus, tensile load-deformation curve, compressive yield strength and compressive load-deformation curve; the checking of the observation window includes: According to the numerical calculation results, the observation window is displaced and the displacement value should not exceed 2 / 3 of the reserved displacement threshold; Based on the compressive yield strength or tensile strength in the third observation window parameter, the stress of the observation window is stress-checked. The stress of the main part of the observation window should not exceed its material strength, and the stress of the stress concentration part should not exceed 1.25 times of its material strength.

5. The method for designing an observation window for a full-sea-depth manned submersible according to claim 4, characterized in that: Based on the numerical calculation model, meshing, contact boundary setting, and load constraints are applied, including: Set the window seat as the target unit and the observation window as the contact unit; Setting a contact pair on a contact boundary between the target unit and the contact unit; The friction coefficient between the target unit and the contact unit is determined by experiments.

6. The method for designing an observation window for a full-sea-depth manned submersible according to claim 1, characterized in that: After performing numerical calculation according to the numerical calculation model, the third observation window parameters and the preset calculation scheme to obtain the numerical calculation results of the observation window stress and displacement, and checking the observation window, the method further includes: The observation window is tested according to the test plan. If the test displacement is not greater than the reserved displacement threshold, and there is no internal or external stress damage to the observation window after the test, the final design of the observation window is completed. Otherwise, the target size of the observation window needs to be readjusted until the theoretical stress calculation, numerical calculation and test are all passed simultaneously.

7. The method for designing an observation window for a full-sea-depth manned submersible according to claim 1, characterized in that: Before calculating the size of the observation window according to the first observation window parameter and the preset observation window size formula to obtain the target size of the observation window, the method further includes: The performance test of the observation window material is performed according to the preset specimen parameters and the preset performance test scheme to obtain the third observation window parameters.

8. The method for designing an observation window for a full-sea-depth manned submersible according to claim 7, characterized in that: The method of performing a performance test on the observation window material according to the preset specimen parameters and the preset performance test scheme to obtain the third observation window parameters includes: Making specimens of the observation window material according to the preset specimen parameters to obtain multiple groups of specimens; According to the performance test scheme, performance tests are performed on multiple groups of the test pieces to obtain the third observation window parameters.

9. The method for designing an observation window for a full-sea-depth manned submersible according to claim 8, characterized in that: The plurality of groups of test specimens include a plurality of groups of tensile test specimens and a plurality of groups of compression test specimens; the preset performance test scheme includes a preset tensile test scheme and a preset compression test scheme; The step of performing performance tests on a plurality of groups of test pieces according to the performance test scheme to obtain the third observation window parameters includes: Perform a tensile test on each group of tensile test pieces according to a preset tensile test plan to obtain tensile performance test results; A compression test is performed on each group of compression specimens according to a preset compression test scheme to obtain compression performance test results.

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