A method for analyzing the structural integrity of engines in long-term vertical storage

Abstract

The invention discloses a method for analyzing the structural integrity of a long-term vertical storage engine. The method comprises the following steps: carrying out accelerated aging, relaxation and constant-speed tensile tests of propellants, determining parameters of a constitutive model of propellant aging, determining a development relationship of a maximum elongation of the propellant, carrying out aging and interface separation tests of an engine bonding interface, determining a bilinear cohesive zone model after aging, discretizing the propellant aging constitutive model, deriving its stress increment and tangent stiffness matrix, constructing a three-dimensional eight-node cohesive unit to simulate a bonding interface, deriving its stiffness matrix, assigning a constitutive relationship of propellant aging, assigning an aging cohesive zone model of a propellant / insulating layer bonding interface, carrying out calculations of long-term vertical storage and ignition of the engine, extracting calculation result files, and judging whether a grain column and a bonding interface structure have failed.

Description

Technical Field

[0001] The invention relates to a method for analyzing the structural integrity of a long-term vertically stored engine, and belongs to the technical field of engine structural integrity research. Background Art

[0002] Long-term combat readiness requires that the engine must be stored in a vertical state for a long time. At present, my country's analysis technology for the structural integrity of engines in a vertical storage state is still in its infancy. There is a lack of methods for analyzing the aging mechanism of engine grains and the mechanical behavior of the bonding interface, and it is impossible to timely determine whether the grain and the bonding interface structure have failed. Summary of the invention

[0003] To address the deficiencies of the prior art, the present invention aims to provide a method for analyzing the structural integrity of a long-term vertically stored engine, which solves the problem in the prior art of lacking analysis and prediction of the structural integrity of an engine in a vertically stored state.

[0004] In order to achieve the above object, the present invention adopts the following technical solution:

[0005] A method for analyzing the structural integrity of a long-term vertical storage engine comprises the following steps:

[0006] Carry out accelerated aging, relaxation and constant-rate tensile tests on propellants to determine the parameters of the propellant aging constitutive model and the development relationship of the maximum elongation of propellants;

[0007] Carry out engine bonding interface aging and interface separation tests to determine the bilinear cohesive zone model after aging;

[0008] The propellant aging constitutive model is discretized, its stress increment and tangent stiffness matrix are derived, a three-dimensional eight-node cohesive element is constructed to simulate the bonding interface, and its stiffness matrix is ​​derived.

[0009] Based on the aforementioned stress increment, tangent stiffness matrix and combined with the UMAT technology of ABAQUS software, the finite element application of the propellant aging constitutive model is realized. Based on the aforementioned three-dimensional eight-node cohesive element, stiffness matrix and combined with the UEL technology of ABAQUS software, the finite element application of the bilinear cohesive zone model after aging of the propellant / insulation layer bonding interface is realized, and the long-term vertical storage and ignition calculation of the engine is carried out;

[0010] Extract the calculation result file to determine whether the grain and bonding interface structure have failed.

[0011] Furthermore, the aforementioned steps of conducting accelerated aging, relaxation and constant-speed tensile tests on propellants, determining parameters of the propellant aging constitutive model, and determining the development relationship of the maximum elongation of the propellant include:

[0012] Based on the propellant billet, an accelerated aging test of the propellant is carried out to obtain the propellant billet under different aging time periods, wherein the accelerated aging temperature in the accelerated aging test is ≤70°C;

[0013] Take out the propellant billets at different aging time periods and carry out relaxation test, cross-linking test and constant speed tensile test on the propellant;

[0014] The relaxation modulus E(t, t′) of propellant aging is determined by using the propellant aging development equation controlled by the degree of crosslinking combined with the relaxation test:

[0015] Said Where t' is the aging time, T is the aging temperature, is the activation energy of the aging reaction without stress-strain field, α c is the unknown coefficient of the chemical reaction equation, k B is the Boltzmann constant, h P is the Planck constant, A is the aging reaction rate constant, υ m is the maximum cross-linking density, υ(t′) is the propellant cross-linking density;

[0016] The maximum elongation development equation was fitted using the Arrhenius equation and the maximum elongation data at different stages obtained by constant-speed stretching.

[0017] Furthermore, the aforementioned

[0018]

[0019]

[0020]

[0021]

[0022] Where t is the loading time, E 0 (t) is the tensile and compressive relaxation modulus before aging, is the change in tension and compression relaxation modulus caused by aging, is the dimensionless change in crosslink density.

[0023] Furthermore, the aforementioned engine bonding interface aging and interface separation test was carried out to determine the bilinear cohesive zone model after aging:

[0024] Based on the propellant / insulation layer bonding interface type I and type II fracture test pieces, an accelerated aging test is carried out, wherein the accelerated aging temperature in the accelerated aging test is ≤70°C;

[0025] The bilinear cohesive zone model is combined with the parameter inversion method to obtain the cohesive zone model of the bonding interface:

[0026]

[0027] Among them, T n represents the cohesive force on the bonding interface, σ max Indicates the bonding strength, δ n represents the maximum separation displacement, δ l represents the critical separation displacement, Δ represents the separation displacement on the bonding interface;

[0028] Combining the bilinear cohesive zone model parameters at each aging stage, the bilinear cohesive zone model after aging is determined using the Arrhenius equation:

[0029]

[0030] Among them, T n (t′) represents the cohesive force on the bonding interface after aging, σ max (t′) represents the bonding strength after aging, δ n (t′) represents the maximum separation displacement after aging, δ l (t′) represents the critical separation displacement after aging.

[0031] Furthermore, the above steps of discretizing the propellant aging constitutive model, deriving its stress increment and tangent stiffness matrix, constructing a three-dimensional eight-node cohesive unit to simulate the bonding interface, and deriving its stiffness matrix include:

[0032] The aging constitutive model is discretized, and the numerical expression of stress increment and the corresponding tangent stiffness matrix are derived;

[0033] Construct a three-dimensional eight-node cohesive unit, derive the separation displacement and displacement conversion matrix, and construct the stiffness matrix of the cohesive unit: the stiffness matrix K and the internal force vector F of the cohesive unit are,

[0034]

[0035]

[0036] Where B represents the separation displacement field and node overall displacement conversion matrix, J represents the Jacobian matrix, T c represents the unit cohesion, is the cohesive stiffness matrix, Δ represents the element separation displacement, Γc represents the element mid-surface area, and ξ and η represent the reference coordinate system coordinates.

[0037] Furthermore, the aforementioned step of extracting the calculation result file and determining whether the drug column and the bonding interface structure are invalid includes:

[0038] Extract the calculation result file and directly read the maximum equivalent strain cloud diagram of the grain column component in ABAQUS software. If the maximum equivalent strain is greater than the maximum elongation, it is judged that the grain column structure has failed.

[0039] The calculation result file was extracted and a cloud diagram of the cohesive force distribution of the bonding interface was drawn in the TECPLOT software. If the separation displacement in the bonding interface reached the critical separation displacement in the cohesive zone model, the bonding interface was judged to be failed.

[0040] A computer-readable storage medium stores a computer program / instruction thereon, which, when executed by a processor, implements the steps of any of the aforementioned methods for analyzing the structural integrity of a long-term vertical storage engine.

[0041] An electronic device, comprising:

[0042] Memory, for storing computer programs / instructions;

[0043] A processor is used to execute the computer program / instructions to implement the steps of any one of the aforementioned methods for analyzing the structural integrity of a long-term vertical storage engine.

[0044] The beneficial effects achieved by the present invention are:

[0045] By constructing the propellant aging constitutive relationship and the propellant / insulation layer bonding interface aging cohesive zone model, long-term vertical storage and ignition calculations of the engine are carried out. By reading the maximum equivalent strain cloud map of the grain column component and the cohesive force distribution cloud map of the bonding interface, it is possible to judge whether the grain column and the bonding interface structure have failed. The present invention can analyze and predict the structural integrity of the engine under vertical storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 Schematic diagram of a Type I fracture test piece of the propellant / insulation layer bonding interface of the present invention;

[0047] Figure 2 Schematic diagram of a propellant / insulation layer bonding interface type II fracture test piece of the present invention;

[0048] Figure 3 It is a schematic diagram of the design of a three-dimensional eight-node cohesive unit of the present invention;

[0049] Figure 4 It is a schematic diagram of the cohesive force distribution of the bonding interface displayed by the TECPLOT software of the present invention. DETAILED DESCRIPTION

[0050] The technical solution of the present invention is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present application and the specific features in the embodiments are detailed descriptions of the technical solution of the present application, rather than limitations on the technical solution of the present application. In the absence of conflict, the embodiments of the present application and the technical features in the embodiments can be combined with each other.

[0051] Embodiment 1

[0052] This embodiment discloses a method for analyzing the structural integrity of a long-term vertical storage engine, and the implementation steps include:

[0053] 1) Carry out accelerated aging, relaxation and constant-speed tensile tests on propellants to determine the parameters of the propellant aging constitutive model and the development relationship of the maximum elongation of the propellant.

[0054] 1.1 Prepare propellant billets and conduct accelerated aging tests on the propellants. The accelerated aging temperature is ≤70°C. Take out propellant billets at different aging time periods and conduct relaxation tests, crosslinking tests, and constant speed tensile tests on the propellants. Determine the aging constitutive model parameters using the propellant aging development equation controlled by the crosslinking degree combined with the relaxation test.

[0055] The rate equation for the crosslink density of the propellant is:

[0056]

[0057] Where t' is the aging time, T is the aging temperature, is the activation energy of the aging reaction without stress-strain field, α c is the unknown coefficient of the chemical reaction equation, k B is the Boltzmann constant, h P is the Planck constant, A is the aging reaction rate constant, υ m is the maximum crosslinking density. The coefficients B and β c They have the following forms respectively

[0058]

[0059] For the aging test with a constant storage temperature of T0, β c There are the following forms

[0060]

[0061]

[0062] Where υ0 is the initial crosslink density. The relaxation modulus of the propellant after aging is expressed as

[0063]

[0064] Where t is the loading time, E 0 (t) is the tensile and compressive relaxation modulus before aging, is the change in tension and compression relaxation modulus caused by aging, is the dimensionless change of crosslinking density.

[0065] 1.2 Using the Arrhenius equation and the maximum elongation data of different stages obtained by constant-speed stretching, the maximum elongation development equation was fitted.

[0066] 2) Carry out engine bonding interface aging and interface separation tests to determine the bilinear cohesive zone model after aging.

[0067] Prepare propellant / insulation layer bonding interface Type I and Type II fracture test pieces (such as Figure 1 and 2 As shown), an accelerated aging test is carried out, and the accelerated aging temperature is ≤70℃. The parameters of the bonding interface cohesive zone model are obtained by combining the bilinear cohesive zone model with the parameter inversion method. The bonding interface cohesive zone model refers to the corresponding relationship between the separation displacement and the cohesive force on the bonding interface. The bilinear cohesive zone model here refers to the curve relationship between the separation displacement and the cohesive force in the form of bilinearity:

[0068]

[0069] Among them, T n represents the cohesive force on the bonding interface, σ max Indicates the bonding strength, δ n represents the maximum separation displacement, δ l represents the critical separation displacement, and Δ represents the separation displacement on the bonding interface.

[0070] The bilinear cohesive zone model parameters at each aging stage are combined and the Arrhenius equation is used to determine the bilinear cohesive zone model after aging.

[0071]

[0072] Where Tn(t′) represents the cohesive force on the bonding interface after aging, σ max (t′) represents the bonding strength after aging, δ n (t′) represents the maximum separation displacement after aging, δ l (t′) represents the critical separation displacement after aging.

[0073] 3) Discretize the propellant aging constitutive model and derive its stress increment and tangent stiffness matrix. Construct a three-dimensional eight-node cohesive element to simulate the bonding interface and derive its stiffness matrix.

[0074] The aging constitutive model is discretized, and the numerical expression of the stress increment and the corresponding tangent stiffness matrix are derived. Similarly, a three-dimensional eight-node cohesive element (such as Figure 3 ), derive the separation displacement and displacement transfer matrices, and construct the stiffness matrix of the cohesive element.

[0075] The stiffness matrix and internal force vector of the element are

[0076]

[0077]

[0078] Where B represents the separation displacement field and node overall displacement conversion matrix, J represents the Jacobian matrix, T c represents the unit cohesion, is the cohesive stiffness matrix, Δ represents the element separation displacement, Γc represents the element mid-surface area, and ξ and η represent the reference coordinate system coordinates.

[0079] 4) Assign the propellant aging constitutive relationship and the propellant / insulation layer bonding interface aging cohesive zone model to carry out long-term vertical storage and ignition calculations of the engine.

[0080] The stress increment and tangent stiffness matrix in step 3) are used in combination with the UMAT technology of ABAQUS software to realize the finite element application of the propellant aging constitutive model.

[0081] The three-dimensional eight-node cohesive element and stiffness matrix in step 3) are used in combination with the UEL technology of ABAQUS software to realize the finite element application of the bilinear cohesive zone model after aging of the propellant / insulation layer bonding interface.

[0082] The modeling technology of other engine components is consistent with conventional calculations, and the long-term vertical storage and ignition calculations of the engine are carried out in combination with actual engineering needs.

[0083] 5) Extract the calculation result file to determine whether the projectile and the bonding interface structure have failed.

[0084] Extract the calculation result file, directly read the maximum equivalent strain cloud diagram of the grain component in ABAQUS software, and compare it with the maximum elongation. If the maximum equivalent strain is greater than the maximum elongation, it is judged that the grain structure has failed.

[0085] In the TECPLOT software, draw the distribution cloud diagram of the cohesive force of the bonding interface (such as Figure 4 ). The separation displacement in the bonding interface reaches the critical separation displacement in the cohesive zone model, and the bonding interface fails.

[0086] Embodiment 2

[0087] Based on the same inventive concept as the first embodiment, this embodiment introduces a computer storage medium, in which at least one instruction, at least one program, code set or instruction set is stored. The at least one instruction, at least one program, code set or instruction set is loaded and executed by a processor to implement the long-term vertical storage engine structural integrity analysis method provided in the first embodiment.

[0088] Embodiment 3

[0089] Based on the same inventive concept as the first embodiment, this embodiment discloses an electronic device, which includes a processor and a memory, wherein the memory stores at least one instruction, at least one program, code set or instruction set, and the at least one instruction, at least one program, code set or instruction set is loaded and executed by the processor to implement the above-mentioned long-term vertical storage engine structural integrity analysis method.

[0090] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0091] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0092] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0093] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0094] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for analyzing the structural integrity of a long-term vertical storage engine, characterized in that: The steps include: Based on the accelerated aging, relaxation and constant-speed tensile tests of propellants, the parameters of the propellant aging constitutive model are determined, and the development relationship of the maximum elongation of the propellant is determined; Based on the engine bonding interface aging and interface separation test, the bilinear cohesive zone model after aging is determined; The propellant aging constitutive model is discretized, its stress increment and tangent stiffness matrix are derived, a three-dimensional eight-node cohesive element is constructed to simulate the bonding interface, and its stiffness matrix is ​​derived. Based on the aforementioned stress increment, tangent stiffness matrix and combined with the UMAT technology of ABAQUS software, the finite element application of the propellant aging constitutive model is realized. Based on the aforementioned three-dimensional eight-node cohesive element, stiffness matrix and combined with the UEL technology of ABAQUS software, the finite element application of the bilinear cohesive zone model after aging of the propellant / insulation layer bonding interface is realized, and the long-term vertical storage and ignition calculation of the engine is carried out; Extract the calculation result file to determine whether the grain and bonding interface structure are failed; The method of determining the bilinear cohesive zone model after aging based on the engine bonding interface aging and interface separation test includes: Based on the propellant / insulation layer bonding interface type I and type II fracture test pieces, an accelerated aging test is carried out, wherein the accelerated aging temperature in the accelerated aging test is ≤70°C; The bilinear cohesive zone model is combined with the parameter inversion method to obtain the cohesive zone model of the bonding interface: Among them, T n represents the cohesive force on the bonding interface, σ max Indicates the bonding strength, δ n represents the maximum separation displacement, δ l represents the critical separation displacement, Δ represents the separation displacement on the bonding interface; Combining the bilinear cohesive zone model parameters at each aging stage, the bilinear cohesive zone model after aging is determined using the Arrhenius equation: Among them, T n (t′) represents the cohesive force on the bonding interface after aging, σ max (t′) represents the bonding strength after aging, δ n (t′) represents the maximum separation displacement after aging, δ l (t′) represents the critical separation displacement after aging.

2. The method for analyzing the structural integrity of a long-term vertical storage engine according to claim 1, characterized in that: The steps of determining the parameters of the propellant aging constitutive model and the development relationship of the maximum elongation of the propellant based on the accelerated aging, relaxation and constant-speed tensile tests of the propellant include: Based on the propellant billet, an accelerated aging test of the propellant is carried out to obtain the propellant billet under different aging time periods, wherein the accelerated aging temperature in the accelerated aging test is ≤70°C; Take out the propellant billets at different aging time periods and carry out relaxation test, cross-linking test and constant speed tensile test on the propellant; The relaxation modulus E(t, t′) of propellant aging is determined by using the propellant aging development equation controlled by the degree of crosslinking combined with the relaxation test: Said Among them, t′ is the aging time, t is the loading time, E 0 (t) is the tensile and compressive relaxation modulus before aging, is the change in tension and compression relaxation modulus caused by aging, is the dimensionless change in crosslink density, υ m is the maximum cross-linking density, υ(t′) is the propellant cross-linking density; The maximum elongation development equation was fitted using the Arrhenius equation and the maximum elongation data at different stages obtained by constant-speed stretching.

3. The method for analyzing the structural integrity of a long-term vertical storage engine according to claim 2, characterized in that: Said Where T is the aging temperature, is the activation energy of the aging reaction without stress-strain field, α c is the unknown coefficient of the chemical reaction equation, k B is the Boltzmann constant, h P is the Planck constant, A is the aging reaction rate constant, and T0 is the constant aging temperature.

4. The method for analyzing the structural integrity of a long-term vertical storage engine according to claim 1, characterized in that: The steps of discretizing the propellant aging constitutive model, deriving its stress increment and tangent stiffness matrix, constructing a three-dimensional eight-node cohesive unit to simulate the bonding interface, and deriving its stiffness matrix include: The aging constitutive model is discretized, and the numerical expression of stress increment and the corresponding tangent stiffness matrix are derived; Construct a three-dimensional eight-node cohesive element, derive the separation displacement and displacement conversion matrix, and construct the stiffness matrix of the cohesive element: The stiffness matrix K and internal force vector F of the cohesive unit are: Where B represents the separation displacement field and node overall displacement conversion matrix, J represents the Jacobian matrix, T c represents the unit cohesion, is the cohesive stiffness matrix, Δ represents the element separation displacement, Γc represents the element mid-surface area, and ξ and η represent the reference coordinate system coordinates.

5. The method for analyzing the structural integrity of a long-term vertical storage engine according to claim 1, characterized in that: The step of extracting the calculation result file and judging whether the drug column and the bonding interface structure are invalid comprises: Extract the calculation result file and directly read the maximum equivalent strain cloud diagram of the grain column component in ABAQUS software. If the maximum equivalent strain is greater than the maximum elongation, it is judged that the grain column structure has failed. The calculation result file was extracted and a cloud diagram of the cohesive force distribution of the bonding interface was drawn in the TECPLOT software. If the separation displacement in the bonding interface reached the critical separation displacement in the cohesive zone model, the bonding interface was judged to be failed.

6. A computer-readable storage medium having a computer program / instruction stored thereon, characterized in that: When the computer program / instructions are executed by a processor, the steps of the method for analyzing the structural integrity of a long-term vertical storage engine as claimed in any one of claims 1 to 5 are implemented.

7. An electronic device, characterized in that: include: Memory, for storing computer programs / instructions; A processor for executing the computer program / instructions to implement the steps of the long-term vertical storage engine structural integrity analysis method according to any one of claims 1-5.

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