Method and system for evaluating the rollover instability of metal diaphragm cone segment

Abstract

The present invention provides a method and system for evaluating the rollover instability of a metal diaphragm cone segment, including: obtaining the geometric dimensions and material performance parameters of the metal diaphragm to be evaluated; establishing an expression for the plastic instability pressure of the cone shell; constructing a material-related metal diaphragm cone segment rollover instability evaluation diagram and evaluation curve; determining the maximum rollover pressure P of the cone segment of the metal diaphragm to be evaluated. rmax0 ; Determine the equivalent cone shell plastic instability pressure P corresponding to the maximum overturning pressure of the cone section of the metal diaphragm to be evaluated pb0 ; Draw the evaluation points (P pb0 ,P rmax0 ) in the evaluation diagram; the metal diaphragm cone section rollover instability evaluation is performed. The evaluation method of the present invention can realize the prediction of the cone section rollover instability in the metal diaphragm design scheme stage, and can also guide the optimization design of the diaphragm structure.

Description

Technical Field

[0001] The invention relates to the technical field of metal diaphragm rollover instability assessment, and in particular to a metal diaphragm cone section rollover instability assessment method and system. Background Art

[0002] As one of the important types of liquid propellant management devices suitable for space work, metal diaphragm tanks have the characteristics of simple structure, large adjustable flow range and stable center of mass. They are widely used in spacecraft, weapons, satellites and other aircraft.

[0003] Patent document CN109033514A (application number: CN201810626314.0) discloses a method for evaluating the elastic instability of a planar tube bundle fluid, which includes two parts: modal analysis and Connors formula calculation. The modal analysis part is responsible for calculating the natural frequency and corresponding vibration mode of the heat exchange tube; the Connors formula calculation calculates the equivalent flow rate and critical flow rate under different modes based on the modal analysis results.

[0004] In a metal diaphragm tank, the supply of propellant is achieved by the regular flipping of the metal diaphragm. Therefore, the flipping behavior of the metal diaphragm is very important to the working performance of the metal diaphragm tank. The flipping behavior of the metal diaphragm is affected by the combined influence of the diaphragm geometry and material properties. When the material properties are determined, the undesirable geometry will lead to radial instability of the cone section during the diaphragm flipping process, thereby affecting the diaphragm's discharge efficiency and fatigue life. The typical radial instability morphology of the metal diaphragm cone section is as follows: Figure 1 Therefore, it is necessary to propose a method for evaluating the rollover instability of the diaphragm cone segment, predict the rollover instability of the designed diaphragm cone segment in the design stage, and optimize and improve the structure based on the prediction results. Summary of the invention

[0005] In view of the defects in the prior art, the object of the present invention is to provide a method and system for evaluating the rollover instability of a metal diaphragm cone segment.

[0006] The method for evaluating the rollover instability of a metal diaphragm cone section provided by the present invention comprises:

[0007] Step 1: Obtain the geometric dimensions and material performance parameters of the metal diaphragm to be evaluated;

[0008] Step 2: Based on the geometric dimensions and material performance parameters, establish the expression for the plastic instability pressure of the conical shell;

[0009] Step 3: Based on the expression of the plastic instability pressure of the cone shell, construct the material-related metal diaphragm cone section overturning instability assessment diagram and assessment curve;

[0010] Step 4: Determine the maximum overturning pressure P of the cone section of the metal diaphragm to be evaluatedrmax0 ;

[0011] Step 5: Determine the equivalent cone shell plastic instability pressure P corresponding to the maximum overturning pressure of the cone section of the metal diaphragm to be evaluated pb0 ;

[0012] Step 6: Draw the assessment points (P pb0 ,P rmax0 );

[0013] Step 7: Conduct an instability assessment on the metal diaphragm cone segment during rollover. When the assessment point is located in the lower right area of ​​the instability assessment curve, it indicates that the diaphragm cone segment will not experience radial instability during the rollover process. When the assessment point is located in the upper left area of ​​the instability assessment curve, it indicates that the diaphragm cone segment will experience radial instability during the rollover process.

[0014] Preferably, the geometric dimensions include: pre-bending radius R, cone length L, cone angle α, transition circle radius R t , spherical cap radius R c , diaphragm diameter D, diaphragm height H, diaphragm wall thickness t;

[0015] The material performance parameters include: elastic modulus E, Poisson's ratio ν, and true stress-strain curve;

[0016] The elastic modulus E and Poisson's ratio ν are obtained by measuring raw material samples, and the true stress-strain curve is obtained by directly sampling and measuring the actual diaphragm.

[0017] Preferably, the step 2 comprises:

[0018] Step 2.1: Derive the tangent modulus E based on the true stress-strain relationship expression of the material t expression;

[0019] Step 2.2: Use the tangent modulus E obtained in step 2.1 t Replace the traditional cone shell elastic instability pressure expression P pb (E, L′, R′, r′, t), and the corresponding plastic instability pressure expression P is obtained pb (E t ,L′,R′,r′,t).

[0020] Preferably, step 3 comprises:

[0021] Step 3.1: Select a certain number of reference diaphragm groups (diaphragm X1, diaphragm X2), where X represents the serial number of the diaphragm group, and obtain the corresponding diaphragm geometric dimensions;

[0022] Step 3.2: Determine the maximum overturning pressure P of the cone section of each set of reference diaphragms xrmax1 and P xrmax2 ;

[0023] Step 3.3: Determine the maximum overturning pressure P of each set of reference diaphragms in their respective cone sections xrmax1 and P xrmax2 The corresponding equivalent cone shell plastic instability pressure P xpb1 and P xpb2 ;

[0024] Step 3.4: Take the equivalent conical shell plastic instability pressure P pb is the horizontal axis, the maximum overturning pressure of the cone section P rmax As the ordinate, each set of reference points (P xpb1 ,P xrmax1 ,) and (P xpb2 ,,) are drawn on the same figure to form the instability assessment diagram, and the curve obtained by connecting all reference points constitutes the instability assessment curve.

[0025] Preferably, all reference membrane materials and manufacturing processes in step 3.1 are consistent with those of the membrane to be evaluated.

[0026] Preferably, each group of reference diaphragms in step 3.1 is required to be verified by a flipping test to satisfy the requirement that the transition from instability to stability during the flipping process of the diaphragm cone segment can be achieved by only changing a certain geometric dimension, and at the same time, the change in the geometric dimension is not greater than 20% of the original dimension. At this time, the two reference diaphragms in this group are in a critical state of cone segment instability.

[0027] Preferably, the step 3.2 comprises:

[0028] Step 3.2.1: Based on the material performance parameters obtained in step 1 and the geometric dimensions obtained in step 3.1, a finite element mechanical model of the metal diaphragm is established;

[0029] Step 3.2.2: According to the actual connection mode of the diaphragm, boundary conditions are set and loads are applied to the finite element mechanical model established in step 3.2.1;

[0030] Step 3.2.3: Obtain the overturning pressure curve of the diaphragm cone section during the overturning process through finite element simulation calculation, and thereby determine the maximum overturning pressure P of the diaphragm cone section rmax .

[0031] Preferably, the step 3.3 comprises:

[0032] Step 3.3.1: Determine the maximum overturning pressure P of the diaphragm in the cone section through the stress cloud diagram rmax When the stress exceeds the material yield strength σ 0 The cone section length L', cone major radius R' and cone minor radius r';

[0033] Step 3.3.2: Substitute the geometric dimensions and material performance parameters obtained in step 3.3.1 and step 1 into the cone shell instability pressure expression P obtained in step 2. pb (E t ,L′,R′,r′,t), the equivalent cone shell plastic instability pressure P of the diaphragm is calculated at this time pb .

[0034] Preferably, the maximum overturning pressure P of the diaphragm cone section to be evaluated in step 4 is rmax0 Determine with reference to steps 3.2.1 to 3.2.3, wherein the finite element mechanical model adopts the geometric dimensions of the diaphragm to be evaluated obtained in step 1; the equivalent cone shell instability pressure P of the diaphragm to be evaluated in step 5 pb0 Refer to steps 3.3.1-3.3.2 for determination.

[0035] The metal diaphragm cone section rollover instability assessment system provided by the present invention comprises:

[0036] Module M1: Obtain the geometric dimensions and material performance parameters of the metal diaphragm to be evaluated;

[0037] Module M2: Establish the expression of plastic instability pressure of cone shell according to geometric dimensions and material performance parameters;

[0038] Module M3: Based on the expression of the plastic instability pressure of the cone shell, the material-related metal diaphragm cone section rollover instability assessment diagram and assessment curve are constructed;

[0039] Module M4: Determine the maximum overturning pressure P of the cone section of the metal diaphragm to be evaluated based on the evaluation diagram and evaluation curve rmax0 ;

[0040] Module M5: Obtain the equivalent cone shell plastic instability pressure P corresponding to the maximum overturning pressure of the cone section of the metal diaphragm to be evaluated pb0 ;

[0041] Module M6: Plotting Assessment Points (P pb0 ,P rmax0 );

[0042] Module M7: Perform rollover instability assessment on the metal diaphragm cone segment. When the assessment point is located in the lower right area of ​​the instability assessment curve, it indicates that the diaphragm cone segment will not experience radial instability during the rollover process; when the assessment point is located in the upper left area of ​​the instability assessment curve, it indicates that the diaphragm cone segment will experience radial instability during the rollover process.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] 1. The present invention can realize the prediction of cone segment flipping instability in the metal diaphragm design stage, and can also guide the optimization design of the diaphragm structure;

[0045] 2. The construction process of the metal diaphragm cone section failure assessment diagram of the present invention is simple, convenient and low-cost;

[0046] 3. The failure assessment diagram constructed by the present invention has a wide range of applications and is suitable for the assessment of all metal diaphragms with the same material and manufacturing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0048] Figure 1 It is a schematic diagram of the radial instability profile of a typical metal diaphragm cone section involved in the patent of the present invention;

[0049] Figure 2 The schematic diagram of the metal diaphragm cone section rollover instability assessment method provided by the present invention;

[0050] Figure 3 A diagram showing a diaphragm structure according to an embodiment of the present invention;

[0051] Figure 4 is a true stress-strain curve diagram of high-purity titanium according to an embodiment of the present invention;

[0052] Figure 5 A stress cloud diagram of a diaphragm according to an embodiment of the present invention;

[0053] Figure 6 This is a diagram for evaluating the rollover instability of a cone section of a high-purity titanium diaphragm according to an embodiment of the present invention. DETAILED DESCRIPTION

[0054] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0055] Example:

[0056] The present invention provides a method for evaluating the rollover instability of a metal diaphragm cone segment, comprising the following steps:

[0057] Step 1: Obtain the geometric dimensions and material performance parameters of the metal diaphragm to be evaluated;

[0058] Among them, the geometric dimensions mainly include: pre-bending radius R, cone length L, cone angle α, transition circle radius R t , spherical cap radius R c , diaphragm diameter D, diaphragm height H, diaphragm wall thickness t; material performance parameters mainly include: elastic modulus E, Poisson's ratio ν, true stress-strain curve;

[0059] In addition, the elastic modulus E and Poisson's ratio ν of the diaphragm material to be evaluated are obtained by measuring the raw material sample, and the true stress-strain curve needs to be obtained by directly sampling and measuring the actual diaphragm;

[0060] Step 2: Establish the expression of plastic instability pressure of conical shell, including:

[0061] Step 2.1: Derive the tangent modulus E from the material stress-strain relationship expression t expression;

[0062] Step 2.2: Use the tangent modulus E obtained in step 2.1 t Replace the traditional cone shell elastic instability pressure expression P pb (E, L′, R′, r′, t), and the corresponding plastic instability pressure expression P is obtained pb (E t ,L′,R′,r′,t);

[0063] Step 3: Construct material-related metal diaphragm cone section rollover instability assessment diagram and assessment curve, such as Figure 1 As shown, specifically including:

[0064] Step 3.1: Select a certain number of reference metal diaphragm groups (diaphragm X1, diaphragm X2), where X represents the serial number of the diaphragm group, and obtain the corresponding diaphragm geometric dimensions;

[0065] Among them, all reference diaphragm materials and manufacturing processes should be consistent with the diaphragm to be evaluated;

[0066] In addition, each set of reference diaphragms must be verified by a rollover test to satisfy the requirement that the transition from instability to stability during the rollover of the diaphragm cone segment can be achieved by simply changing a certain geometric dimension, and the change in the geometric dimension should not be greater than 20% of the original dimension. At this time, the two reference diaphragms in this set are in a critical state of cone segment instability.

[0067] Step 3.2: Determine the maximum overturning pressure P of the cone section of each set of reference diaphragms xrmax1 and P xrmax2 , including:

[0068] Step 3.2.1: Based on the material properties obtained in step 1 and the geometric dimensions obtained in step 3.1, a finite element mechanical model of the metal diaphragm is established;

[0069] Step 3.2.2: Set boundary conditions and apply loads to the finite element mechanical model established in step 3.2.1 according to the actual connection method of the diaphragm;

[0070] Step 3.2.3: Obtain the overturning pressure curve of the diaphragm cone section during the overturning process through finite element simulation calculation, and thereby determine the maximum overturning pressure P of the diaphragm cone section rmax ;

[0071] Step 3.3: Determine the maximum overturning pressure P of each set of reference diaphragms in their respective cone sections xrmax1 and P xrmax2 The corresponding equivalent cone shell plastic instability pressure P xpb1 and P xpb2 , including:

[0072] Step 3.3.1: Determine the maximum overturning pressure P of the diaphragm in the cone section through the stress cloud diagram rmax When the stress exceeds the material yield strength σ 0 The cone section length L', cone major radius R' and cone minor radius r';

[0073] Step 3.3.2: Substitute the geometric dimensions and material performance parameters obtained in step 3.3.1 and step 1 into the cone shell instability pressure expression P obtained in step 2. pb (E t ,L′,R′,r′,t), the equivalent cone shell plastic instability pressure P of the diaphragm is calculated at this time pb ;

[0074] Step 3.4: Take the equivalent conical shell plastic instability pressure as P pb Abscissa, maximum overturning pressure of cone section P rmax As the ordinate, each set of reference points (P xpb1 ,P xrmax1 ) and (P xpb2 ,P xrmax2 ) are drawn on the same graph to form an instability assessment graph, and the curve obtained by connecting all reference points constitutes an instability assessment curve;

[0075] Step 4: Determine the maximum overturning pressure P of the cone section of the metal diaphragm to be evaluated rmax0 ;

[0076] Step 5: Determine the equivalent cone shell plastic instability pressure P corresponding to the maximum overturning pressure of the cone section of the metal diaphragm to be evaluated pb0 ;

[0077] Among them, the maximum overturning pressure P of the diaphragm cone section to be evaluated in step 4 is rmax0Refer to steps 3.2.1-3.2.3 to determine that the finite element mechanical model adopts the geometric dimensions of the diaphragm to be evaluated obtained in step 1; the equivalent cone shell instability pressure P of the diaphragm to be evaluated in step 5 pb0 Refer to steps 3.3.1-3.3.2 to determine;

[0078] Step 6: Draw the evaluation points (P pb0 ,P rmax0 ) in the assessment diagram;

[0079] Step 7: Figure 2 As shown, the rollover instability assessment of the metal diaphragm cone section is performed; when the assessment point is located in the lower right area of ​​the instability assessment curve, it indicates that the diaphragm cone section will not be radially unstable during the rollover process; when the assessment point is located in the upper left area of ​​the instability assessment curve, it indicates that the diaphragm cone section will be radially unstable during the rollover process;

[0080] Assessment methods and results

[0081] A high-purity titanium metal diaphragm is taken as an example of the diaphragm to be evaluated, and a specific embodiment of the present invention is given below to specifically illustrate a metal diaphragm cone segment rollover instability evaluation method and results of the present invention.

[0082] Step 1: Obtain the geometric dimensions and material performance parameters of the metal diaphragm to be evaluated.

[0083] In this embodiment, the diaphragm is spherical, and its specific structure is as follows: Figure 3 The detailed geometrical dimension parameters are shown in Table 1.

[0084] Table 1 Geometric parameters of the diaphragm to be evaluated

[0085]

[0086] The material of the diaphragm to be evaluated is high-purity titanium. The elastic modulus E = 110000 MPa and Poisson's ratio ν = 0.3 are measured through raw material samples. At the same time, the true stress-strain curve is obtained by converting the load-displacement curve of the tensile test, such as Figure 4 shown.

[0087] Step 2: Establish the expression of plastic instability pressure of conical shell. The specific steps are as follows:

[0088] Step 2.1: Derive the tangent modulus E from the material stress-strain relationship expression t expression;

[0089] In this embodiment, the high-purity titanium material has no obvious yield platform and has a certain toughness. Its stress-strain relationship complies with the Ramberg-Osgood relationship, from which the tangent modulus expression E is obtained: t=(0.0083+0.00022(σ / 120) 3.57 ) -1 ;

[0090] Step 2.2: Use the tangent modulus E obtained in step 2.1 t Replace the traditional cone shell elastic instability pressure expression P pb (E, L′, R′, r′, t), and the corresponding plastic instability pressure expression P is obtained pb (E t ,L′,R′,r′,t);

[0091] In this embodiment, the elastic buckling pressure expression of cone shell provided in the literature [Blachut J. On elastic-plastic buckling of cones. Thin-walled Structures, 2011 (49): 45-52] is used to replace the elastic modulus E in the expression with the tangential modulus E t Substitute, and get the instability pressure expression of the conical shell P pb = pE t (t / r e ) 2 / 1.65, where p is the dimensionless instability pressure, r e is the effective radius. The calculation formulas for both are detailed in the literature.

[0092] Step 3: Construct the high-purity titanium diaphragm cone section rollover instability assessment diagram and assessment curve. The specific steps are as follows:

[0093] Step 3.1: Select a certain number of reference metal diaphragm groups (diaphragm X1, diaphragm X2) and obtain the corresponding diaphragm geometric dimensions;

[0094] In this embodiment, two groups of high-purity titanium diaphragms with the same materials and manufacturing processes as the diaphragms to be evaluated are selected as reference diaphragms. At the same time, each group is verified by the flip test to meet the requirement that the transition from instability to stability during the flipping process of the diaphragm cone section can be achieved by only changing the cone section wall thickness by 20%. The specific geometric parameters of the two high-purity titanium reference diaphragms are shown in Table 2.

[0095] Table 2 Geometric parameters of two reference diaphragms

[0096]

[0097] Step 3.2: Determine the maximum overturning pressure P of the cone section of each set of reference diaphragms xrmax1 and P xrmax2 In this embodiment, the specific steps are as follows:

[0098] Step 3.2.1: Using the two sets of high-purity titanium reference diaphragm geometric size parameters obtained in step 2.1 and the high-purity titanium performance parameters obtained in step 1, a three-dimensional model is established in ABAQUS finite element software and a mesh is divided;

[0099] Step 3.2.2: Set fixed constraints at the outer connection of the model flange and set a uniform load on the outer surface of the diaphragm;

[0100] Step 3.2.3: The overturning pressure curve is obtained through simulation, and then the maximum overturning pressures of the cone sections of the two sets of high-purity titanium reference diaphragms are obtained, respectively: P 1rmax1 =0.16MPa, P 1rmax2 =0.22MPa and P 2rmax1 =0.15MPa, P 2rmax2 =0.17MPa;

[0101] Step 3.3: Determine the equivalent cone shell plastic instability pressure P for each set of reference diaphragms xb1 and P xb2 , the specific steps are as follows:

[0102] Step 3.3.1: Obtain the stress distribution cloud diagram of the two reference diaphragms at the maximum overturning pressure of the cone section, such as Figure 5 As shown in the cloud diagram, the length of the cone section L' at which the stress exceeds the yield strength of the diaphragm material is measured. 11 =15.6mm, L′ 12 =18.6mm and L′ 21 =9.9mm, L′ 22 =10.9mm; cone radius R' 11 =197.2mm, R′ 12 =197.1mm and R′ 21 =102.2mm, R′ 22 =102.1mm; small cone radius r' 11 =196.4, r′ 12 =196.1mm and r′ 21 =101.7mm, r′ 22 =101.6mm;

[0103] Step 3.3.2: Substitute the geometric dimensions and material performance parameters obtained in step 3.3.1 and step 1 into the cone shell instability pressure expression obtained in step 2.2, and calculate the equivalent cone shell instability pressures of the two groups of reference diaphragms to be P and 1pb1 =0.088MPa, P 1pb2 =0.116MPa and P 2pb1 =0.082MPa, P 2pb2 =0.093MPa;

[0104] Step 3.4: Take the equivalent conical shell plastic instability pressure as P pb Abscissa, maximum overturning pressure of cone section P rmax As the ordinate, each set of reference points (P xrmax1 , P xpb1 ) and (P xrmax2 , P xpb2 ) are drawn on the same graph to form an instability assessment graph, and the curve obtained by connecting all reference points constitutes an instability assessment curve;

[0105] In this embodiment, two groups of reference points (0.088, 0.16), (0.116, 0.22) and (0.082, 0.15), (0.093, 0.17) are plotted on the same graph to obtain a high-purity titanium diaphragm cone segment rollover instability assessment graph, as shown in FIG. Figure 6 As shown; connecting the above four reference points to obtain the instability assessment curve;

[0106] Step 4: Determine the maximum overturning pressure P of the cone section of the metal diaphragm to be evaluated rmax0 ;

[0107] In this embodiment, the same method as in step 3.2 is used to obtain the maximum overturning pressure P of the cone section of the diaphragm to be evaluated. rmax0 =0.26MPa;

[0108] Step 5: Determine the equivalent cone shell plastic instability pressure P corresponding to the maximum overturning pressure of the cone section of the metal diaphragm to be evaluated pb0 ;

[0109] In this embodiment, the same method as in step 3.3 is used to obtain the equivalent cone shell instability pressures of the diaphragm to be evaluated, which are P pb0 =0.1MPa;

[0110] Step 6: Draw the evaluation points (P rmax0 , P pb0 ) in the assessment diagram;

[0111] In this embodiment, the evaluation points (0.1, 0.26) consisting of the maximum cone segment overturning pressure and the equivalent cone segment plastic instability pressure obtained in steps 4 and 6 are plotted in the high-purity titanium diaphragm cone segment overturning instability evaluation diagram obtained in step 3.

[0112] Step 7: Conduct instability assessment and prediction;

[0113] In this embodiment, since the evaluation point (0.1, 0.26) is located in the upper left area of ​​the instability evaluation curve, it indicates that the evaluation diaphragm cone segment will experience radial instability during the flipping process.

[0114] The metal diaphragm cone section rollover instability assessment system provided by the present invention comprises: module M1: obtaining the geometric dimensions and material performance parameters of the metal diaphragm to be assessed; module M2: establishing the cone shell plastic instability pressure expression according to the geometric dimensions and material performance parameters; module M3: constructing the material-related metal diaphragm cone section rollover instability assessment diagram and assessment curve according to the cone shell plastic instability pressure expression; module M4: determining the cone section maximum rollover pressure P of the metal diaphragm to be assessed rmax0 Module M5: Determine the equivalent cone shell plastic instability pressure P corresponding to the maximum overturning pressure of the cone section of the metal diaphragm to be evaluated pb0 Module M6: Draw the evaluation points (P pb0 ,P rmax0 ) Module M7: Perform rollover instability assessment on the metal diaphragm cone segment. When the assessment point is located in the lower right area of ​​the instability assessment curve, it indicates that the diaphragm cone segment will not experience radial instability during the rollover process; when the assessment point is located in the upper left area of ​​the instability assessment curve, it indicates that the diaphragm cone segment will experience radial instability during the rollover process.

[0115] Those skilled in the art know that, in addition to implementing the system, device and its various modules provided by the present invention in a purely computer-readable program code, it is entirely possible to implement the same program in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers and embedded microcontrollers by logically programming the method steps. Therefore, the system, device and its various modules provided by the present invention can be considered as a hardware component, and the modules included therein for implementing various programs can also be considered as structures within the hardware component; the modules for implementing various functions can also be considered as both software programs for implementing the method and structures within the hardware component.

[0116] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A method for evaluating the rollover instability of a metal diaphragm cone segment, characterized in that: include: Step 1: Obtain the geometric dimensions and material performance parameters of the metal diaphragm to be evaluated; Step 2: Based on the geometric dimensions and material performance parameters, establish the expression for the plastic instability pressure of the conical shell; Step 3: Based on the expression of the plastic instability pressure of the cone shell, construct the material-related metal diaphragm cone section overturning instability assessment diagram and assessment curve; Step 4: Determine the maximum overturning pressure of the cone section of the metal diaphragm to be evaluated ; Step 5: Determine the equivalent cone shell plastic instability pressure corresponding to the maximum overturning pressure of the cone section of the metal diaphragm to be evaluated ; Step 6: Draw the rating points on the rating chart ; Step 7: Carry out the rollover instability assessment of the metal diaphragm cone segment. When the assessment point is located in the lower right area of ​​the instability assessment curve, it indicates that the diaphragm cone segment will not experience radial instability during the rollover process; when the assessment point is located in the upper left area of ​​the instability assessment curve, it indicates that the diaphragm cone segment will experience radial instability during the rollover process. The step 2 comprises: Step 2.1: Derive the tangent modulus based on the true stress-strain relationship expression of the material expression; Step 2.2: Use the tangent modulus obtained in step 2.1 Replace the traditional elastic instability pressure expression of conical shell , the corresponding plastic instability pressure expression is obtained ; Where E is the elastic modulus, is the cone length, is the cone major radius, is the small radius of the cone, t is the thickness of the diaphragm wall; The step 3 comprises: Step 3.1: Select a certain number of reference diaphragm groups (diaphragm X1, diaphragm X2), where X represents the serial number of the diaphragm group, and obtain the corresponding diaphragm geometric dimensions; Step 3.2: Determine the maximum cone-segment inversion pressure for each set of reference diaphragms and ; Step 3.3: Determine the maximum overturning pressure of each reference diaphragm in its respective cone section and The equivalent conical shell plastic instability pressure corresponding to and ; Step 3.4: Equivalent conical shell plastic instability pressure is the horizontal axis, the maximum overturning pressure of the cone section As the ordinate, each set of reference points obtained in step 3.2 and step 3.3 is and( Drawing them on the same graph constitutes an instability assessment graph, and the curve obtained by connecting all reference points constitutes an instability assessment curve.

2. The method for evaluating the rollover instability of a metal diaphragm cone section according to claim 1 is characterized in that: The geometric dimensions include: pre-bending radius R, cone length L, cone angle α, transition circle radius , spherical cap radius , diaphragm diameter D, diaphragm height H, diaphragm wall thickness t; The material performance parameters include: elastic modulus E, Poisson's ratio ν and true stress-strain curve; The elastic modulus E and Poisson's ratio ν are obtained by measuring the diaphragm raw material sample, and the true stress-strain curve is obtained by directly sampling and measuring the actual diaphragm.

3. The method for evaluating the rollover instability of a metal diaphragm cone section according to claim 1, characterized in that: All reference membrane materials and manufacturing processes in step 3.1 are consistent with the membrane to be evaluated.

4. The method for evaluating the rollover instability of a metal diaphragm cone section according to claim 1 is characterized in that: In step 3.1, each group of reference diaphragms must be verified by a flip test to satisfy the requirement that the diaphragm cone segment flipping process can be achieved from instability to stability by simply changing a certain geometric dimension, and at the same time, the change in the geometric dimension is no more than 20% of the original dimension. At this time, the two reference diaphragms in this group are in a critical state of cone segment instability.

5. The method for evaluating the rollover instability of a metal diaphragm cone section according to claim 1, characterized in that: The step 3.2 comprises: Step 3.2.1: Based on the material performance parameters obtained in step 1 and the geometric dimensions obtained in step 3.1, a finite element mechanical model of the metal diaphragm is established; Step 3.2.2: According to the actual connection mode of the diaphragm, boundary conditions are set and loads are applied to the finite element mechanical model established in step 3.2.1; Step 3.2.3: Obtain the rollover pressure curve during the rollover of the diaphragm cone segment through finite element simulation calculation, and thereby determine the maximum rollover pressure of the diaphragm cone segment .

6. The method for evaluating the rollover instability of a metal diaphragm cone section according to claim 5, characterized in that: The step 3.3 comprises: Step 3.3.1: Determine the maximum overturning pressure of the diaphragm in the cone section through the stress cloud diagram When the stress exceeds the yield strength of the material The length of the cone , cone radius and cone small radius ; Step 3.3.2: Substitute the geometric dimensions and material performance parameters obtained in step 3.3.1 and step 1 into the cone shell instability pressure expression obtained in step 2: The equivalent cone shell plastic instability pressure of the diaphragm is calculated as .

7. The method for evaluating the rollover instability of a metal diaphragm cone section according to claim 6, characterized in that: The maximum overturning pressure of the diaphragm cone section to be evaluated in step 4 Determine with reference to steps 3.2.1 to 3.2.3, wherein the finite element mechanical model adopts the geometric dimensions of the diaphragm to be evaluated obtained in step 1; the equivalent cone shell plastic instability pressure of the diaphragm to be evaluated in step 5 Refer to steps 3.3.1-3.3.2 for determination.

8. A metal diaphragm cone section rollover instability assessment system, characterized in that: The method for evaluating the rollover instability of a metal diaphragm cone section according to any one of claims 1 to 7 comprises: Module M1: Obtain the geometric dimensions and material performance parameters of the metal diaphragm to be evaluated; Module M2: Based on geometric dimensions and material performance parameters, establish the expression for the plastic instability pressure of the conical shell; Module M3: Based on the expression of plastic instability pressure of cone shell, construct the material-related metal diaphragm cone section rollover instability assessment diagram and assessment curve; Module M4: Determine the maximum overturning pressure of the cone section of the metal diaphragm to be evaluated based on the evaluation diagram and evaluation curve ; Module M5: Obtain the equivalent cone shell plastic instability pressure corresponding to the maximum overturning pressure of the cone section of the metal diaphragm to be evaluated ; Module M6: Plotting rating points on rating charts ; Module M7: Perform rollover instability assessment on the metal diaphragm cone segment. When the assessment point is located in the lower right area of ​​the instability assessment curve, it indicates that the diaphragm cone segment will not experience radial instability during the rollover process; when the assessment point is located in the upper left area of ​​the instability assessment curve, it indicates that the diaphragm cone segment will experience radial instability during the rollover process. The module M2 comprises: The tangent modulus is derived from the true stress-strain relationship expression of the material. expression; Using tangent modulus Replace the traditional elastic instability pressure expression of conical shell , the corresponding plastic instability pressure expression is obtained ; Where E is the elastic modulus, is the cone length, is the cone major radius, is the small radius of the cone, t is the thickness of the diaphragm wall; The module M3 comprises: Select a certain number of reference diaphragm groups (diaphragm X1, diaphragm X2), where X represents the serial number of the diaphragm group, and obtain the corresponding diaphragm geometric dimensions; Determine the maximum overturning pressure of the cone section of each set of reference diaphragms and ; Determine the maximum overturning pressure of each set of reference diaphragms in their respective cone sections and The equivalent conical shell plastic instability pressure corresponding to and ; The equivalent conical shell plastic instability pressure is the horizontal axis, the maximum overturning pressure of the cone section As the vertical coordinate, each set of reference points and( Drawing them on the same graph constitutes an instability assessment graph, and the curve obtained by connecting all reference points constitutes an instability assessment curve.

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