A calculation method for parameters of the propellant cohesion zone model

Abstract

The present invention discloses a method for calculating the cohesive zone model parameters of a propellant, belonging to the technical fields of experimental mechanics and computational fracture mechanics. The method includes: calculating and obtaining the cohesive zone model parameters of the propellant by using a pre-constructed master curve of the cohesive zone model of the propellant; wherein, the master curve of the cohesive zone model of the propellant is constructed by conducting a number of groups of tests under different temperature conditions, obtaining the cohesive zone model parameters of the propellant specimens under each temperature condition, and based on the cohesive zone model parameters of the propellant specimens under each temperature condition. This method can calculate and obtain the cohesive zone model parameters of the propellant under any loading time and temperature conditions.

Description

Technical Field

[0001] The present invention relates to a method for calculating parameters of a cohesive zone model of a propellant, belonging to the technical fields of experimental mechanics and computational fracture mechanics. Background Art

[0002] The time- and temperature-dependent mechanical properties of viscoelastic materials bring many difficulties to the research on crack propagation simulation and mechanism.

[0003] Currently, the criterion for crack propagation of propellants, the distribution characteristics and evolution mechanism of cohesive forces on the crack surface after crack propagation are not clear, and the existing cohesive zone models cannot be directly applied to propellants.

[0004] How to get rid of the constraints of the existing cohesive zone models and construct a cohesive zone model applicable to propellants that can dynamically adjust its own parameters according to conditions such as the loading environment is an important prerequisite for carrying out research on crack propagation simulation and mechanism of propellants. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for calculating parameters of a cohesive zone model of a propellant, which can calculate and obtain the parameters of the cohesive zone model of the propellant under any loading time and temperature conditions.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a method for calculating parameters of a cohesive zone model of a propellant, including:

[0008] Calculating and obtaining the parameters of the cohesive zone model of the propellant by using a pre-constructed master curve of the cohesive zone model of the propellant;

[0009] Wherein, the master curve of the cohesive zone model of the propellant is constructed according to the parameters of the cohesive zone model of the propellant specimens under each temperature point condition obtained by conducting several groups of tests under different temperature point conditions.

[0010] Combined with the first aspect, further, conducting several groups of tests under different temperature point conditions, and obtaining the parameters of the cohesive zone model of the propellant specimens under each temperature point condition includes:

[0011] Under a temperature point condition, stretching the propellant specimen to obtain the actual force-displacement response of the propellant specimen and the crack path distribution on the crack surface of the propellant specimen at each time point;

[0012] Based on the crack path distribution on the crack surface of the propellant specimen at each time point, constructing a finite element model of the propellant specimen, conducting finite element calculations, and obtaining the force-displacement simulation response of the propellant specimen;

[0013] Aiming to make the force-displacement simulation response of the propellant specimen consistent with the actual force-displacement response of the propellant specimen, the cohesive zone model parameters of the propellant specimen under the condition of this temperature point are inversely obtained;

[0014] Change the conditions of different temperature points, repeat the above steps, and obtain the cohesive zone model parameters of the propellant specimen under the conditions of each temperature point.

[0015] Combined with the first aspect, further, stretch the propellant specimen to obtain the crack path distribution on the crack surface of the propellant specimen at each time point, including:

[0016] Stretch the propellant specimen and collect the surface deformation of the propellant specimen;

[0017] Based on the surface deformation of the propellant specimen, draw the crack path distribution on the crack surface of the propellant specimen at each time point.

[0018] Combined with the first aspect, further, based on the crack path distribution on the crack surface of the propellant specimen at each time point, construct a finite element model of the propellant specimen, including:

[0019] Based on the crack path distribution on the crack surface of the propellant specimen at each time point, screen out the time points when crack propagation occurs, and calculate the length of crack propagation;

[0020] Based on the time points when crack propagation occurs and the length of crack propagation, construct a finite element model of the propellant specimen.

[0021] Combined with the first aspect, further, perform finite element calculations, including:

[0022] According to the actual loading situation of the test, perform finite element calculations;

[0023] During the finite element calculation process, insert cohesive force units according to the crack path distribution on the crack surface of the propellant specimen at each time point.

[0024] Combined with the first aspect, further, the cohesive zone model adopted by the cohesive force unit is a two-parameter linear attenuation model.

[0025] Combined with the first aspect, further, aiming to make the force-displacement simulation response of the propellant specimen consistent with the actual force-displacement response of the propellant specimen, the cohesive zone model parameters of the propellant specimen under the condition of this temperature point are inversely obtained, including:

[0026] Aiming to make the force-displacement simulation response of the propellant specimen consistent with the actual force-displacement response of the propellant specimen, use the genetic algorithm to inversely obtain the cohesive zone model parameters of the propellant specimen under the condition of this temperature point;

[0027] During the inversion process, the selection of time points is consistent with the crack occurrence time on the crack surface of the propellant specimen.

[0028] Combined with the first aspect, further, constructing the master curve of the propellant cohesive zone model according to the cohesive zone model parameters of the propellant specimen under each temperature point condition includes:

[0029] According to the cohesive zone model parameters of the propellant specimen under each temperature point condition, use the least squares method to fit the temperature - cohesive strength relationship and the temperature - critical displacement relationship;

[0030] Based on the temperature - cohesive strength relationship and the temperature - critical displacement relationship, construct the master curve of the propellant cohesive zone model;

[0031] Among them, the master curve of the propellant cohesive zone model is:

[0032]

[0033] Among them, Tn(T,δ) represents the master curve of the propellant cohesive zone model, Tn max (T) represents the cohesive strength related to temperature T, δ(T) represents the critical displacement related to temperature T, and δn represents the separation displacement.

[0034] Combined with the first aspect, further, different temperature point conditions include: 20°C temperature point condition, 70°C temperature point condition, 50°C temperature point condition, 0°C temperature point condition, -20°C temperature point condition, -40°C temperature point condition.

[0035] Combined with the first aspect, further, the propellant specimen uses a rectangular propellant specimen with a type I prefabricated crack.

[0036] In the second aspect, the present invention provides a device for calculating the parameters of the propellant cohesive zone model, including:

[0037] A calculation module: used to calculate and obtain the parameters of the propellant cohesive zone model by using the pre - constructed master curve of the propellant cohesive zone model;

[0038] Among them, the master curve of the propellant cohesive zone model is constructed by conducting a number of tests under different temperature point conditions, obtaining the cohesive zone model parameters of the propellant specimen under each temperature point condition, and according to the cohesive zone model parameters of the propellant specimen under each temperature point condition.

[0039] Compared with the prior art, the beneficial effects of the present invention are:

[0040] The method for calculating the parameters of the cohesive zone model of the propellant provided by the present invention obtains the parameters of the cohesive zone model of the propellant specimen under the conditions of each temperature point through a number of tests carried out under the conditions of different temperature points. According to the parameters of the cohesive zone model of the propellant specimen under the conditions of each temperature point, the master curve of the cohesive zone model of the propellant constructed can calculate and obtain the parameters of the cohesive zone model of the propellant under any loading time and temperature conditions. Description of the Drawings

[0041] Figure 1 It is a schematic diagram of a rectangular propellant specimen with a type-I prefabricated crack and its displacement loading situation provided by an embodiment of the present invention;

[0042] Figure 2 It is a schematic diagram of the crack propagation situation on the crack surface of the propellant specimen at each time point provided by an embodiment of the present invention. Among them, (a) is the crack propagation situation on the crack surface of the propellant specimen at time t start moment, (b) is the crack propagation situation on the crack surface of the propellant specimen at time t between moment, and (c) is the crack propagation situation on the crack surface of the propellant specimen at time t end moment;

[0043] Figure 3 It is a schematic diagram of the time points at which crack propagation occurs on the crack surface of the propellant specimen provided by an embodiment of the present invention;

[0044] Figure 4 It is a schematic diagram of a two-parameter linear attenuation cohesive zone model provided by an embodiment of the present invention;

[0045] Figure 5 It is a finite element model of the propellant specimen provided by an embodiment of the present invention;

[0046] Figure 6 It is a schematic diagram of the force-displacement response curve of the propellant specimen provided by an embodiment of the present invention. Detailed Embodiments

[0047] The technical solutions of the present application will be further described in detail below in conjunction with the specific embodiments.

[0048] The embodiments of the present application are described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present application and should not be construed as a limitation to the present application. Without conflict, the embodiments of the present application and the technical features in the embodiments can be combined with each other.

[0049] Embodiment 1:

[0050] This embodiment provides a method for calculating the parameters of the propellant cohesive zone model, and calculates the parameters of the propellant cohesive zone model by using the pre-constructed master curve of the propellant cohesive zone model.

[0051] In this embodiment, the master curve of the propellant cohesive zone model is constructed based on the parameters of the propellant specimen cohesive zone model under the conditions of each temperature point, where the parameters of the propellant specimen cohesive zone model under the conditions of each temperature point are obtained by conducting several groups of tests under different temperature point conditions.

[0052] In this embodiment, conducting several groups of tests under different temperature point conditions and obtaining the parameters of the propellant specimen cohesive zone model under the conditions of each temperature point specifically include the following steps:

[0053] Step 1: Under the condition of a temperature point, stretch the propellant specimen to obtain the actual force-displacement response of the propellant specimen and the crack path distribution on the crack surface of the propellant specimen at each time point.

[0054] In this embodiment, stretching the propellant specimen and obtaining the crack path distribution on the crack surface of the propellant specimen at each time point specifically include:

[0055] Step ①: Stretch the propellant specimen and collect the surface deformation of the propellant specimen.

[0056] Step ②: Based on the surface deformation of the propellant specimen, draw the crack path distribution on the crack surface of the propellant specimen at each time point.

[0057] Step 2: Based on the crack path distribution on the crack surface of the propellant specimen at each time point, construct a finite element model of the propellant specimen, conduct finite element calculations, and obtain the force-displacement simulation response of the propellant specimen.

[0058] In this embodiment, constructing a finite element model of the propellant specimen based on the crack path distribution on the crack surface of the propellant specimen at each time point specifically includes:

[0059] Step (1): Based on the crack path distribution on the crack surface of the propellant specimen at each time point, screen out the time points when crack propagation occurs and calculate the length of crack propagation.

[0060] Step (2): Based on the time points when crack propagation occurs and the length of crack propagation, construct a finite element model of the propellant specimen.

[0061] In this embodiment, the finite element calculation specifically includes: performing finite element calculations according to the actual loading conditions of the test; during the finite element calculation process, inserting cohesive force units according to the crack path distribution on the crack surface of the propellant specimen at each time point.

[0062] Step 3: Aiming to make the force-displacement simulation response of the propellant specimen consistent with the actual force-displacement response of the propellant specimen, inversely obtain the cohesive zone model parameters of the propellant specimen under the temperature point conditions in Step 1;

[0063] In this embodiment, during the inversion process, the selection of the time point is consistent with the crack occurrence time on the crack surface of the propellant specimen.

[0064] Step 4: Replace the conditions of different temperature points, and repeat Steps 1 to 3 to obtain the cohesive zone model parameters of the propellant specimen under the conditions of each temperature point.

[0065] In this embodiment, constructing the master curve of the propellant cohesive zone model based on the cohesive zone model parameters of the propellant specimen under the conditions of each temperature point specifically includes the following steps:

[0066] Step i: According to the cohesive zone model parameters of the propellant specimen under the conditions of each temperature point, use the least squares method to fit the temperature-cohesive strength relationship and the temperature-critical displacement relationship;

[0067] Step ii: Based on the temperature-cohesive strength relationship and the temperature-critical displacement relationship, construct the master curve of the propellant cohesive zone model.

[0068] In this embodiment, the master curve of the propellant cohesive zone model is:

[0069]

[0070] Among them, Tn(T,δ) represents the master curve of the propellant cohesive zone model, and Tn max (T) represents the cohesive strength related to the temperature T, δ(T) represents the critical displacement related to the temperature T, and δn represents the separation displacement.

[0071] The method for calculating the cohesive zone model parameters of the propellant provided in this embodiment, by conducting several groups of tests under the conditions of different temperature points, obtaining the cohesive zone model parameters of the propellant specimen under the conditions of each temperature point, and constructing the master curve of the propellant cohesive zone model based on the cohesive zone model parameters of the propellant specimen under the conditions of each temperature point, can calculate and obtain the cohesive zone model parameters of the propellant under any loading time and temperature conditions.

[0072] Example 2:

[0073] This embodiment provides a method for calculating the cohesive zone model parameters of a propellant, which specifically includes the following steps:

[0074] Step 1): Tensile a rectangular propellant specimen with a type-I prefabricated crack to obtain the actual force-displacement response of the propellant specimen, and use a high-definition camera to photograph and record the surface deformation of the propellant specimen;

[0075] In this embodiment, at room temperature of 20 °C, a rectangular propellant specimen with a type-I prefabricated crack is stretched. The rectangular propellant specimen with a type-I prefabricated crack and its displacement loading conditions are as shown in Figure 1 shown. At the same time, a high-definition camera is used to photograph and record the surface deformation of the propellant specimen. The acquisition frequency of the high-definition camera should be as high as possible to ensure that the real-time crack propagation on the crack surface of the propellant specimen can be obtained. The high-definition camera transmits the collected image data back to the computer terminal. The crack propagation on the crack surface of the propellant specimen at times t0, t, and t end recorded by the high-definition camera is as shown in Figure 2 shown. Under the condition of high-frequency acquisition by the high-definition camera, a constant-speed tensile test of a rectangular specimen with a type-I prefabricated crack is carried out, and the tensile rate is 50 mm / min.

[0076] Step 2): Based on the surface deformation of the propellant specimen, draw the crack path distribution on the crack surface of the propellant specimen at each time point;

[0077] In this embodiment, in order to accurately draw the crack path distribution on the crack surface of the propellant specimen at each time point, a paper scale needs to be pasted on the surface of the propellant specimen, as shown in Figure 1 shown. Using the paper scale on the surface of the propellant specimen, accurately draw the crack path distribution on the crack surface of the propellant specimen at each time point.

[0078] Step 3): Based on the crack path distribution on the crack surface of the propellant specimen at each time point, construct a finite element model of the propellant specimen, carry out finite element calculation, and during the finite element calculation process, insert corresponding cohesive elements according to the crack path distribution on the crack surface of the propellant specimen at each time point to obtain the force-displacement simulation response of the propellant specimen;

[0079] In this embodiment, based on the crack path distribution on the crack surface of the propellant specimen at each time point, the time points at which crack propagation occurs are screened out, and the crack propagation length is calculated. Mark the time points t0, t1, t2, t3, t4, t5, t6, t7, etc. at which crack propagation occurs on the complete crack path, as shown in Figure 3 shown, and based on Figure 3 construct a finite element model of the propellant specimen. Carry out finite element calculation according to the actual loading conditions of the test. During the finite element calculation process, insert cohesive elements according to the real-time crack propagation situation. The finite element model of the propellant specimen is as shown in Figure 5 shown, Figure 5 in which the black bold part represents the cohesive elements set along the crack propagation path. The cohesive zone model adopted by the cohesive elements is a two-parameter linear attenuation model, as shown in Figure 4 shown.

[0080] Step 4): Taking the consistency between the force-displacement simulation response of the propellant specimen and the actual force-displacement response of the propellant specimen as the optimization goal, inversely obtain the cohesive zone model parameters of the propellant specimen.

[0081] In this embodiment, taking the consistency between the force-displacement simulation response of the propellant specimen and the actual force-displacement response of the propellant specimen as the optimization goal, using the genetic algorithm, inversely obtain the cohesive zone model parameters of the propellant specimen. During the inversion process, the selection of time points is consistent with the crack occurrence time on the crack surface of the propellant specimen. The force-displacement response curve of the propellant specimen is as Figure 6 shown.

[0082] Step 5): Conduct tests under different temperature conditions, and sequentially execute steps 1) to 4) to obtain the cohesive zone model parameters of the propellant specimen under each temperature condition, and construct the master curve of the propellant cohesive zone model.

[0083] In this embodiment, conduct tests under the temperature conditions of 70°C, 50°C, 0°C, -20°C, and -40°C, sequentially execute steps 1) to 4), obtain the cohesive zone model parameters of the propellant specimen under the temperature conditions of 70°C, 50°C, 0°C, -20°C, and -40°C, and use the least squares method to fit the temperature-cohesive strength relationship and the temperature-critical displacement relationship to construct the master curve of the propellant cohesive zone model.

[0084] Step 6): Use the master curve of the propellant cohesive zone model to calculate and obtain the cohesive zone model parameters of the propellant under any loading time and temperature conditions.

[0085] Using the master curve of the propellant cohesive zone model provided in this embodiment, the cohesive zone model parameters of the propellant under any loading time and temperature conditions can be calculated and obtained.

[0086] Example 3:

[0087] This embodiment provides a device for calculating the cohesive zone model parameters of a propellant, including:

[0088] A calculation module: used to calculate and obtain the cohesive zone model parameters of the propellant by using the pre-constructed master curve of the propellant cohesive zone model.

[0089] In this embodiment, the master curve of the propellant cohesive zone model is constructed based on the cohesive zone model parameters of the propellant specimen obtained under each temperature condition by conducting a number of tests under different temperature conditions.

[0090] The device for calculating the cohesive zone model parameters of the propellant provided in this embodiment further includes:

[0091] A collection module: used to collect the surface deformation conditions of the propellant specimen.

[0092] In this embodiment, the acquisition module uses a high-definition camera to acquire the surface deformation of the propellant specimen and transmits it back to the computer terminal.

[0093] The propellant cohesive zone model parameter calculation device provided by the embodiment of the present application can execute the propellant cohesive zone model parameter calculation method provided by any embodiment of the present application, and has the corresponding functional modules and beneficial effects for executing the method.

[0094] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can 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.

[0095] The present application is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram can be implemented by computer program instructions, and the combination of the processes and / or blocks in the flowchart and / or block diagram can also be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for realizing the specified functions in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0096] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and the instruction device realizes the specified functions in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0097] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for realizing the specified functions in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0098] The above are only the preferred embodiments of the present application. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present application, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present application.

Claims

1. A method for calculating parameters of a propellant cohesive zone model, characterized in that: include: The parameters of the propellant cohesive zone model are obtained by calculating the pre-built propellant cohesive zone model master curve; The master curve of the propellant cohesive zone model is constructed by carrying out several groups of tests under different temperature points to obtain the model parameters of the propellant specimen cohesive zone under each temperature point, and the construction method includes: Under the condition of one temperature point, the propellant specimen is stretched to obtain the actual force-displacement response of the propellant specimen and the crack path distribution on the crack surface of the propellant specimen at each time point; Based on the crack path distribution on the crack surface of the propellant specimen at each time point, a finite element model of the propellant specimen is constructed, and finite element calculation is performed to obtain the force-displacement simulation response of the propellant specimen; With the goal of making the force-displacement simulation response of the propellant specimen consistent with the actual force-displacement response of the propellant specimen, the model parameters of the cohesive zone of the propellant specimen under the condition of the temperature point are obtained by inversion; Change the temperature point conditions and repeat the above steps to obtain the cohesive zone model parameters of the propellant specimen under the conditions of each temperature point; According to the model parameters of the cohesive zone of the propellant specimen under the conditions of each temperature point, the relationship between temperature-cohesive strength and temperature-critical displacement is fitted by the least square method. Based on the temperature-cohesive strength relationship and the temperature-critical displacement relationship, the master curve of the propellant cohesive zone model is constructed; Wherein, the main curve of the propellant cohesive zone model is: ； in, represents the main curve of the propellant cohesive zone model, Indication and temperature The related cohesive strength, Indication and temperature The associated critical displacement, Indicates separation displacement.

2. The method for calculating the parameters of the propellant cohesive zone model according to claim 1, characterized in that: The propellant specimen is stretched to obtain the crack path distribution on the crack surface of the propellant specimen at each time point, including: Stretching the propellant specimen and collecting the surface deformation of the propellant specimen; Based on the surface deformation of the propellant specimen, the crack path distribution on the crack surface of the propellant specimen at each time point is drawn.

3. The method for calculating the parameters of the propellant cohesive zone model according to claim 1, characterized in that: Based on the crack path distribution on the crack surface of the propellant specimen at each time point, the finite element model of the propellant specimen is constructed including: Based on the crack path distribution on the crack surface of the propellant specimen at each time point, the time point when crack propagation occurs is screened out, and the length of crack propagation is calculated; Based on the time point and length of crack propagation, a finite element model of the propellant specimen is constructed.

4. The method for calculating the parameters of the propellant cohesive zone model according to claim 1, characterized in that: Finite element calculations include: According to the actual loading conditions of the test, finite element calculation is carried out; During the finite element calculation process, cohesive force units are inserted according to the crack path distribution on the crack surface of the propellant specimen at each time point.

5. The method for calculating the parameters of the propellant cohesive zone model according to claim 4, characterized in that: The cohesive zone model adopted by the cohesive force unit is a two-parameter linear attenuation model.

6. The method for calculating the parameters of the propellant cohesive zone model according to claim 1, characterized in that: With the goal of making the force-displacement simulation response of the propellant specimen consistent with the actual force-displacement response of the propellant specimen, the model parameters of the cohesive zone of the propellant specimen under the temperature point condition are obtained by inversion, including: With the goal of making the force-displacement simulation response of the propellant specimen consistent with the actual force-displacement response of the propellant specimen, the genetic algorithm is used to inversely obtain the model parameters of the cohesive zone of the propellant specimen under the temperature point condition. During the inversion process, the time point selected is consistent with the moment of crack occurrence on the crack surface of the propellant specimen.

7. The method for calculating the parameters of the propellant cohesive zone model according to claim 1, characterized in that: Different temperature point conditions include: 20°C temperature point condition, 70°C temperature point condition, 50°C temperature point condition, 0°C temperature point condition, -20°C temperature point condition, and -40°C temperature point condition.

8. The method for calculating the parameters of the propellant cohesive zone model according to claim 1, characterized in that: The propellant specimen is a rectangular propellant specimen containing type I prefabricated cracks.

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