CN116432491A - Method and system for judging implosion failure mechanism of deep-sea metal pressure-resistant shell based on modal displacement - Google Patents

Abstract

The invention provides a method and a system for judging an implosion failure mechanism of a deep-sea metal pressure housing based on modal displacement, wherein the method comprises the following steps: modeling a finite element model of the deep sea metal pressure shell, and numbering nodes of the finite element model; performing eigenvalue buckling analysis on the finite element model to obtain a front N-order modal displacement result; obtaining initial geometric defects of a local single-mode defect method or a combined-mode defect method based on each-order modal displacement result; scaling the initial geometric defects according to the geometric out-of-roundness requirement of the pressure shell to obtain final geometric defect displacement of the deep sea pressure structure; modeling the results of different final geometric defect displacements to obtain a final structural finite element model, and judging the implosion failure form of the deep sea metal pressure shell by using the obtained final structural finite element model; and carrying out implosion fluid-solid coupling calculation verification on the metal pressure shell in the deep sea environment, and judging the implosion failure mode of the deep sea metal pressure shell by utilizing a final structure finite element model.

Description

Method for judging failure mechanism of deep-sea metal pressure vessel implosion based on modal displacement system

technical field

The invention relates to the field of modeling and evaluation of deep-sea metal pressure-resistant structures, in particular to a method and system for judging the implosion failure mechanism of deep-sea metal pressure-resistant shells based on modal displacement.

Background technique

Deep-sea metal pressure hull is an important part of underwater vehicles and manned submersibles. It needs to withstand the external hydrostatic pressure in different water depth environments and provide an operating environment for internal non-pressure-resistant components. At present, the judgment of the underwater implosion mechanism of the metal pressure vessel is usually directly calculated by the fluid-solid coupling method. This method is based on the interaction between the surface fluid and the structure of the pressure vessel, and is realized through the transfer of force and displacement during the calculation process. Determination of implosion failure mechanism.

However, in actual engineering, it is found that due to the complex structure of the deep-sea metal pressure vessel, there are initial geometric and material defects of various sizes in the design and manufacture. Therefore, when directly using the fluid-solid coupling algorithm for numerical calculation, on the one hand, it needs a strong computing power, which will cause a large calculation cost. On the other hand, the defects of the structure cannot be fully considered, resulting in errors in the numerical simulation results.

The present invention can scientifically judge the failure mechanism of the deep-sea metal pressure-resistant structure by adopting the finite element method to perform modal calculation on the deep-sea metal pressure-resistant structure, and considering the geometric out-of-roundness requirements of the structure. The design and manufacture of submersibles and other deep-sea equipment has important engineering application value.

Contents of the invention

In view of the defects in the prior art, the object of the present invention is to provide a method and system for judging the implosion failure mechanism of deep-sea metal pressure vessel based on modal displacement.

A method for judging the implosion failure mechanism of a deep-sea metal pressure vessel based on modal displacement provided by the present invention includes:

Step S1: Carry out structural finite element model modeling on the deep-sea metal pressure vessel, obtain the finite element model, and number the nodes of the finite element model;

Step S2: Using the finite element method to perform eigenvalue buckling analysis on the finite element model to obtain the first N order modal displacement results;

Step S3: Obtain the initial geometric defects of the local single mode defect method or combined mode defect method based on the results of the modal displacements of each order;

Step S4: Scale the initial geometric defect according to the geometric out-of-roundness requirements of the pressure vessel, and obtain the final geometric defect displacement of the deep-sea pressure structure;

Step S5: Carry out finite element model modeling on the results of different final geometric defect displacements to obtain the final structural finite element model, and use the obtained final structural finite element model to determine the implosion failure mode of the deep-sea metal pressure vessel;

Step S6: Carry out implosion fluid-solid coupling calculation on the metal pressure vessel in the deep sea environment, and verify the implosion failure mode of the deep sea metal pressure vessel by using the final structural finite element model.

Preferably, the step S3 adopts: obtaining a certain order modal result based on the modal displacement results of each order to obtain the initial geometric defect of the single mode defect method; or performing partial or complete superposition based on the modal displacement results of each order to obtain a combined The defect geometry of the modal defect method.

Preferably, the step S4 adopts: taking the geometric out-of-roundness requirement of the pressure vessel as a scaling factor to scale the initial geometric defect displacement to obtain the final geometric defect displacement.

Preferably, the step S5 adopts: adding the node number m corresponding to the final node defect displacement to the node number n _i of the structural finite element model to obtain the final structural finite element model;

Among them, considering the node position of the deep-sea metal pressure vessel based on the modal displacement is:

n _{n, i(x, y)} = n _i +m _i

In the formula, n _{n, i(x, y)} represents the position corresponding to the unit node number i after the superimposed displacement based on the first N modes.

Preferably, the step S6 adopts: adopting a fluid-structure coupling algorithm to calculate the implosion fluid-structure coupling for the metal pressure vessel in the deep sea environment.

According to the present invention, a system for judging the implosion failure mechanism of a deep-sea metal pressure vessel based on modal displacement includes:

Module M1: Carry out structural finite element model modeling on the deep-sea metal pressure vessel, obtain the finite element model, and number the nodes of the finite element model;

Module M2: Use the finite element method to perform eigenvalue buckling analysis on the finite element model to obtain the first N order modal displacement results;

Module M3: Obtain the initial geometric defects of the local single mode defect method or the combined mode defect method based on the displacement results of each order of mode;

Module M4: Scale the initial geometric defects according to the geometric out-of-roundness requirements of the pressure vessel, and obtain the final geometric defect displacement of the deep-sea pressure structure;

Module M5: Carry out finite element model modeling on the results of different final geometric defect displacements to obtain the final structural finite element model, and use the obtained final structural finite element model to judge the implosion failure form of deep-sea metal pressure vessel;

Module M6: Carry out fluid-solid coupling calculation of implosion metal pressure vessel in deep sea environment, and verify the use of final structural finite element model to judge the implosion failure mode of deep sea metal pressure vessel.

Preferably, the module M3 adopts: obtaining a certain order modal result based on the modal displacement results of each order to obtain the initial geometric defect of the single mode defect method; or performing partial or complete superposition based on the modal displacement results of each order to obtain a combined The defect geometry of the modal defect method.

Preferably, the module M4 adopts: taking the geometric out-of-roundness requirement of the pressure vessel as a scaling factor to scale the initial geometric defect displacement to obtain the final geometric defect displacement.

Preferably, the module M5 adopts: adding the node number m _i corresponding to the final node defect displacement to the node number n _i of the structural finite element model to obtain the final structural finite element model;

Among them, considering the node position of the deep-sea metal pressure vessel based on the modal displacement is:

n _{n, i(x, y)} = n _i +m _i

In the formula, n _{n, i(x, y)} represents the position corresponding to the unit node number i after the superimposed displacement based on the first N modes.

Preferably, the module M6 adopts: a fluid-structure coupling algorithm for implosion fluid-structure coupling calculations for metal pressure hulls in deep sea environments.

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

1. The present invention considers the initial defects of deep-sea metal pressure hulls based on the single defect mode method and the overall defect mode method, and can meet the design and construction requirements of underwater submersibles.

2. The present invention scales the single mode displacement and the overall mode displacement results based on the out-of-roundness coefficient of the radius, and realizes the rapid judgment of the implosion failure form of the deep-sea metal pressure vessel.

3. The present invention realizes the interrelated inversion control of underwater implosion and modal displacement by calculating the evolution characteristics after implosion failure of the deep-sea metal pressure vessel.

Description of drawings

Other characteristics, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

Fig. 1 is a flowchart of a method for judging the implosion failure mechanism of a deep-sea metal pressure vessel based on modal displacement.

Fig. 2 is a schematic diagram of a finite element model of a deep-sea titanium alloy ring rib cylindrical shell structure.

Fig. 3 is a schematic diagram of the first six modal displacement results of a deep-sea titanium alloy ring-ribbed cylindrical shell.

Fig. 4 is a schematic diagram of the finite element model after the superposition of the single first-order mode and the first six-order modes of the deep-sea titanium alloy ring-ribbed cylindrical shell.

Fig. 5 is a schematic diagram of the ultimate strength of a deep sea titanium alloy ring rib cylindrical shell.

Fig. 6 is a schematic diagram of two implosion failure mechanisms of deep-sea titanium alloy ring-ribbed cylindrical shell poles based on modal displacement.

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

Aiming at the problem of judging the failure mechanism of deep-sea metal pressure vessel implosion in deep sea, the purpose of the present invention is to provide a method and system for judging the failure mechanism of deep-sea metal pressure vessel implosion based on modal displacement, which can accurately judge the failure mechanism of deep-sea metal pressure vessel. The implosion failure form of the pressure hull provides a basis for the subsequent evaluation of the structural ultimate strength and structural dynamic response based on this model, aiming to provide a theoretical basis and basis for the design and manufacture of deep-sea underwater vehicles and manned submersibles. Practical basis.

Example 1

A method for judging the implosion failure mechanism of a deep-sea metal pressure vessel based on modal displacement provided by the present invention includes:

Step S1: Carry out structural finite element model modeling on the deep-sea metal pressure vessel, obtain the finite element model, and number the nodes of the finite element model;

Step S2: Using the finite element method to perform eigenvalue buckling analysis on the finite element model to obtain the first N order modal displacement results;

Step S3: Obtain the initial geometric defects of the local single mode defect method or combined mode defect method based on the results of the modal displacements of each order;

Step S4: Scale the initial geometric defect according to the geometric out-of-roundness requirements of the pressure vessel, and obtain the final geometric defect displacement of the deep-sea pressure structure;

Step S5: Carry out finite element model modeling on the results of different final geometric defect displacements to obtain the final structural finite element model, and use the obtained final structural finite element model to determine the implosion failure mode of the deep-sea metal pressure vessel;

Step S6: Carry out implosion fluid-solid coupling calculation on the metal pressure vessel in the deep sea environment, and verify the implosion failure mode of the deep sea metal pressure vessel by using the final structural finite element model.

Specifically, the step S3 adopts: obtaining a certain order modal result based on the modal displacement results of each order to obtain the initial geometric defect of the single mode defect method; or performing partial or complete superposition based on the modal displacement results of each order to obtain a combined The defect geometry of the modal defect method.

Specifically, the step S4 adopts: taking the geometric out-of-roundness requirement of the pressure vessel as a scaling factor to scale the initial geometric defect displacement to obtain the final geometric defect displacement.

Specifically, the step S5 adopts: adding the node number m _i corresponding to the final node defect displacement to the node number n _i of the structural finite element model to obtain the final structural finite element model;

Among them, considering the node position of the deep-sea metal pressure vessel based on the modal displacement is:

n _{n, i(x, y)} = n _i +m _i

In the formula, n _{n, i(x, y)} represents the position corresponding to the unit node number i after the superimposed displacement based on the first N modes.

Specifically, the step S6 adopts: using the fluid-structure coupling algorithm for the metal pressure vessel in the deep sea environment to perform the fluid-structure coupling calculation of the implosion.

According to the present invention, a system for judging the implosion failure mechanism of a deep-sea metal pressure vessel based on modal displacement includes:

Module M1: Carry out structural finite element model modeling on the deep-sea metal pressure vessel, obtain the finite element model, and number the nodes of the finite element model;

Module M2: Use the finite element method to perform eigenvalue buckling analysis on the finite element model to obtain the first N order modal displacement results;

Module M3: Obtain the initial geometric defects of the local single mode defect method or the combined mode defect method based on the displacement results of each order of mode;

Module M4: Scale the initial geometric defects according to the geometric out-of-roundness requirements of the pressure vessel, and obtain the final geometric defect displacement of the deep-sea pressure structure;

Module M5: Carry out finite element model modeling on the results of different final geometric defect displacements to obtain the final structural finite element model, and use the obtained final structural finite element model to judge the implosion failure form of deep-sea metal pressure vessel;

Module M6: Carry out fluid-solid coupling calculation of implosion metal pressure vessel in deep sea environment, and verify the use of final structural finite element model to judge the implosion failure mode of deep sea metal pressure vessel.

Specifically, the module M3 adopts: based on the modal displacement results of each order, a certain order modal result is obtained to obtain the initial geometric defect of the single mode defect method; The defect geometry of the modal defect method.

Specifically, the module M4 adopts: taking the geometric out-of-roundness requirement of the pressure vessel as a scaling factor to scale the initial geometric defect displacement to obtain the final geometric defect displacement.

Specifically, the module M5 adopts: adding the node number _mi corresponding to the final node defect displacement to the node number n _i of the structural finite element model to obtain the final structural finite element model;

Among them, considering the node position of the deep-sea metal pressure vessel based on the modal displacement is:

n _{n, i(x, y)} = n _i +m _i

In the formula, n _{n, i(x, y)} represents the position corresponding to the unit node number i after the superimposed displacement based on the first N modes.

Specifically, the module M6 adopts: a fluid-structure coupling algorithm is used for implosion fluid-structure coupling calculations for metal pressure-resistant shells in deep-sea environments.

Example 2

Embodiment 2 is a preferred example of embodiment 1

According to the present invention, a method for judging the implosion failure mechanism of a deep-sea metal pressure vessel based on modal displacement, as shown in Figure 1, includes:

Step 1: Carry out finite element model modeling on the deep-sea metal pressure vessel;

Structural finite element modeling of deep-sea metal pressure hulls, since the application objects are usually spherical or cylindrical thin shell structures, shell elements are usually used. The finite element model of cylindrical titanium alloy pressure hulls is shown in Figure 2. Let the node number of the finite element model be recorded as n _i .

Step 2: Perform eigenvalue buckling analysis on the finite element model to obtain the first N order modal displacement results of the structure;

The eigenvalue buckling analysis of the finite element model is carried out by using the finite element method, and the results of the first six modal displacements are obtained, as shown in Figure 3. And record the total node numbers corresponding to the modal displacement results respectively as m _1,i , m _2,i ,m _3,i ,m _4,i ,m _5,i ,m _6,i . Among them, the subscripts 1 to 6 represent the corresponding modal orders, and the subscript i represents the node number of the finite element model.

Step 3: Superimpose part or all of the modal displacement results of each order to obtain the initial geometric defects of the local single mode defect method and the overall combined mode defect method;

The result of single-mode defect displacement is to use a certain order in the analysis of eigenvalue buckling as the initial defect of the structure, while the result of defect displacement combined by multi-mode superposition is to introduce multiple eigenvalue buckling modal results into one model at the same time. A finite element structural model with a multi-mode displacement defect form is thus formed. The python self-compiled program is used to superimpose the modal results m _{1, i} ~ m _{6, i} of the cylindrical pressure shell corresponding to the finite element node number, and the initial geometric defect based on the modal displacement result is obtained:

m _n,i =m _1,i +m _2,i +...+m _N-1,i +m _N,i

In the formula, m _{n, i} represent the sum of the modal displacement superposition of all nodes in the first N order modes.

Step 4: Scale the initial geometric defect according to the geometric out-of-roundness requirements of the pressure hull, and the numerical result is used as the final geometric defect displacement of the deep-sea pressure structure;

For deep-sea metal pressure vessels, the influence of manufacturing errors needs to be considered. For cylindrical ring-ribbed cylindrical shells, 0.5% is taken as the initial out-of-roundness. Using the python self-compiled program, the out-of-roundness requirement is used as a scaling factor to scale the initial geometric defect displacement based on the mode superposition method to obtain the final geometric defect displacement of the deep-sea titanium alloy pressure hull, so that the final defect displacement corresponds to The node number is m _i .

m _i =0.5%×m _n,i

In the formula, m _i represents the node number of the unit after considering the initial out-of-roundness and superimposing displacement based on the first N order modes.

Step 5: According to the order of calculation, the finite element model is modeled on the results of different final geometric defect displacements to obtain the final finite element model, and the implosion failure form of the deep-sea metal pressure vessel is judged by the final finite element model;

Using the python self-compiler program, the node number _mi corresponding to the final node defect displacement of the deep-sea ring-ribbed cylindrical shell is sequentially added to the node number _ni of the structural finite element model, and the final implosion calculation structural model of the ring-ribbed cylindrical shell is obtained. Among them, the node position of the deep-sea metal pressure vessel based on the modal displacement is considered as:

n _{n, i(x, y)} = n _i +m _i

In the formula, n _{n, i(x, y)} represents the position corresponding to the unit node number i after the superimposed displacement based on the first N modes.

According to the superimposed displacement results of the modes of each order, a structural finite element model considering the initial defects is obtained, as shown in Fig. 4 . When the first-order buckling mode results are used as the initial defects of the ring-ribbed cylindrical shell to obtain the finite element structural model, the ring-ribbed cylindrical shell only has a slight depression at the central surface position, while other positions are basically unchanged. Therefore, it is predicted that when the deep-sea ring-ribbed cylindrical shell implodes, it will first sink inward at the center and fail at the center first. As the implosion evolved, the collapse at the center gradually expanded to both ends, eventually leading to the failure of the entire structure. However, it can be predicted that for the ring-ribbed cylindrical shell with the first-order buckling mode displacement as the initial defect, the final stage can still maintain a relatively complete structure.

When the modal number of the initial geometric defect is 6th order, the strength near the buckling limit increases, and the surface of the structure presents defect displacement characteristics of multi-order modes, and a slight depression appears on the surface. Therefore, it can be predicted that in the implosion failure mechanism of the superposition of the first six modal displacements, the surface of the ring-ribbed cylindrical shell structure will present a multi-mode concave feature, and with the development of the implosion, the middle section of the cylindrical shell will fail at almost the same time Broken, relatively intact structure is not preserved.

In addition, based on the finite element model considering the structural and geometric initial defects, the arc length method is used to carry out the ultimate bearing calculation results for this model, as shown in Fig. 5. This proves that the results obtained by using the single mode defect method and the overall mode defect method are different, and the correctness of the mode superposition is verified.

Step 6: Carry out fluid-solid coupling calculation of implosion metal pressure vessel in deep sea environment, and verify the result of implosion structural deformation of deep sea metal pressure vessel based on modal displacement

The fluid-solid coupling algorithm is used to simulate the implosion failure mechanism of the final finite element model in step five, and verify the correctness of the judgment method of the ring-ribbed cylindrical shell based on the modal displacement results. The implosion failure process based on the displacement of the single mode and the first six superimposed modes is shown in Fig. 6.

For the results of introducing the first-order buckling mode results as initial defects into the structural finite element model, the deep-sea ring-ribbed cylindrical shell starts to sag inward at the center and fails at the center first. As the implosion evolved, the collapse at the center gradually extended to both ends, eventually leading to the failure of the entire structure. However, in the implosion failure mechanism of the superposition of the first six modal displacements, the ring-ribbed cylindrical shell structure presents multi-mode deformation characteristics at the surface position, and with the development of the implosion, the middle section of the cylindrical shell basically completely fails and breaks . It can be seen that the underwater implosion failure mechanism of the ring-ribbed cylindrical shell is consistent with the single and superposition results based on the modal displacement. Therefore, the invention can quickly obtain the implosion failure mechanism of the deep-sea metal pressure vessel based on the modal displacement, which has important engineering significance for the design and manufacture of the pressure vessel of the deep-sea submersible.

Those skilled in the art know that, in addition to realizing the system, device and each module thereof provided by the present invention in a purely computer-readable program code mode, the system, device and each module thereof provided by the present invention can be completely programmed by logically programming the method steps. The same program is implemented in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, and embedded microcontrollers, among others. Therefore, the system, device and each module provided by the present invention can be regarded as a hardware component, and the modules included in it for realizing various programs can also be regarded as the structure in the hardware component; A module for realizing various functions can be regarded as either a software program realizing a method or a structure within a hardware component.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. In the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims (10)

1. A method for judging the implosion failure mechanism of a deep-sea metal pressure vessel based on modal displacement, characterized in that it comprises: Step S1: Carry out structural finite element model modeling on the deep-sea metal pressure vessel, obtain the finite element model, and number the nodes of the finite element model; Step S2: Using the finite element method to perform eigenvalue buckling analysis on the finite element model to obtain the first N order modal displacement results; Step S3: Obtain the initial geometric defects of the local single mode defect method or combined mode defect method based on the results of the modal displacements of each order; Step S4: Scale the initial geometric defect according to the geometric out-of-roundness requirements of the pressure vessel, and obtain the final geometric defect displacement of the deep-sea pressure structure; Step S5: Carry out finite element model modeling on the results of different final geometric defect displacements to obtain the final structural finite element model, and use the obtained final structural finite element model to determine the implosion failure mode of the deep-sea metal pressure vessel; Step S6: Carry out implosion fluid-solid coupling calculation on the metal pressure vessel in the deep sea environment, and verify the implosion failure mode of the deep sea metal pressure vessel by using the final structural finite element model. 2. The method for judging the implosion failure mechanism of deep-sea metal pressure vessel based on modal displacement according to claim 1, characterized in that, the step S3 adopts: obtaining a certain order modal result based on each order modal displacement result Obtain the initial geometric defects of the single mode defect method; or perform partial or complete superposition based on the displacement results of each order mode to obtain the defect geometric defects of the combined mode defect method. 3. The method for judging the implosion failure mechanism of a deep-sea metal pressure vessel based on modal displacement according to claim 1, wherein said step S4 adopts: taking the geometric out-of-roundness requirement of the pressure vessel as a scaling factor, The initial geometric defect displacement is scaled to obtain the final geometric defect displacement. 4. The method for judging the implosion failure mechanism of deep-sea metal pressure vessel based on modal displacement according to claim 1, characterized in that, the step S5 adopts: adding the node number _mi corresponding to the final node defect displacement to the structure On the finite element model node number n _i , the final structural finite element model is obtained; Among them, considering the node position of the deep-sea metal pressure vessel based on the modal displacement is: n _n,(x,) =n _i +m _i In the formula, n _n,(x,) represents the position corresponding to the unit node number i after superimposed displacement based on the first N order modes. 5. The method for judging the implosion failure mechanism of deep-sea metal pressure vessel based on modal displacement according to claim 1, characterized in that, said step S6 adopts: adopting a fluid-solid coupling algorithm for the metal pressure vessel in the deep-sea environment Perform implosion fluid-structure interaction calculations. 6. A system for judging the implosion failure mechanism of a deep-sea metal pressure vessel based on modal displacement, characterized in that it includes: Module M1: Carry out structural finite element model modeling on the deep-sea metal pressure vessel, obtain the finite element model, and number the nodes of the finite element model; Module M2: Use the finite element method to perform eigenvalue buckling analysis on the finite element model to obtain the first N order modal displacement results; Module M3: Obtain the initial geometric defects of the local single mode defect method or the combined mode defect method based on the displacement results of each order of mode; Module M4: Scale the initial geometric defects according to the geometric out-of-roundness requirements of the pressure vessel, and obtain the final geometric defect displacement of the deep-sea pressure structure; Module M5: Carry out finite element model modeling on the results of different final geometric defect displacements to obtain the final structural finite element model, and use the obtained final structural finite element model to judge the implosion failure form of deep-sea metal pressure vessel; Module M6: Carry out fluid-solid coupling calculation of implosion metal pressure vessel in deep sea environment, and verify the use of final structural finite element model to judge the implosion failure mode of deep sea metal pressure vessel. 7. The system for judging the implosion failure mechanism of deep-sea metal pressure vessel based on modal displacement according to claim 6, wherein the module M3 adopts: obtaining a certain order modal result based on each order modal displacement result Obtain the initial geometric defects of the single mode defect method; or perform partial or complete superposition based on the displacement results of each order mode to obtain the defect geometric defects of the combined mode defect method. 8. The system for judging the implosion failure mechanism of deep-sea metal pressure vessel based on modal displacement according to claim 6, characterized in that, said module M4 adopts: taking the geometric out-of-roundness requirement of the pressure vessel as a scaling factor, The initial geometric defect displacement is scaled to obtain the final geometric defect displacement. 9. The system for judging the failure mechanism of deep-sea metal pressure vessel implosion based on modal displacement according to claim 6, wherein the module M5 adopts: adding the node number _mi corresponding to the final node defect displacement to the structure On the finite element model node number n _i , the final structural finite element model is obtained; Among them, considering the node position of the deep-sea metal pressure vessel based on the modal displacement is: n _n,(x,) =n _i +m _i In the formula, n _n,(x,) represents the position corresponding to the unit node number i after superimposed displacement based on the first N order modes. 10. The system for judging the implosion failure mechanism of deep-sea metal pressure vessel based on modal displacement according to claim 6, characterized in that, said module M6 adopts: fluid-solid coupling algorithm for metal pressure vessel in deep-sea environment Perform implosion fluid-structure interaction calculations.

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