Propellant cohesion zone model parameter calculation method

Abstract

The invention discloses a propellant cohesion zone model parameter calculation method, and belongs to the technical field of experimental mechanics and fracture mechanics calculation, and the method comprises the steps: employing a pre-constructed propellant cohesion zone model main curve to calculate and obtain propellant cohesion zone model parameters; wherein the main curve of the propellant cohesion zone model is constructed according to parameters of the propellant test piece cohesion zone model under each temperature point condition by carrying out a plurality of groups of tests under different temperature point conditions to obtain parameters of the propellant test piece cohesion zone model under each temperature point condition. According to the method, the cohesion zone model parameters of the propellant under any loading time and temperature conditions can be calculated and obtained.

Description

Technical Field

[0001] The invention relates to a method for calculating parameters of a propellant cohesive zone model, and belongs to the technical field 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 study of crack propagation simulation and mechanism.

[0003] At present, the criterion for crack propagation in propellants, the distribution characteristics of cohesive force on the crack surface after crack propagation and its evolution mechanism are still unclear, and the existing cohesive zone model cannot be directly applied to propellants.

[0004] How to get rid of the constraints of the existing cohesive zone model and construct a cohesive zone model suitable for propellants that can dynamically adjust its own parameters as the loading environment and other conditions change is an important prerequisite for conducting propellant crack propagation simulation and mechanism research. Summary of the invention

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

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

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

[0008] The parameters of the propellant cohesive zone model are obtained by calculating the pre-built propellant cohesive zone model master curve;

[0009] Among them, the main curve of the propellant cohesive zone model is constructed by conducting several groups of tests under different temperature points to obtain the propellant specimen cohesive zone model parameters under each temperature point condition, and based on the propellant specimen cohesive zone model parameters under each temperature point condition.

[0010] In combination with the first aspect, further, several groups of tests under different temperature conditions are carried out to obtain the model parameters of the cohesive zone of the propellant specimen under the conditions of each temperature point, including:

[0011] 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;

[0012] 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;

[0013] 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;

[0014] 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.

[0015] In combination with the first aspect, further, stretching the propellant specimen to obtain the crack path distribution on the crack surface of the propellant specimen at each time point includes:

[0016] Stretching the propellant specimen and collecting the surface deformation of the propellant specimen;

[0017] 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.

[0018] In combination with the first aspect, further, 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 includes:

[0019] 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;

[0020] Based on the time point and length of crack propagation, a finite element model of the propellant specimen is constructed.

[0021] In combination with the first aspect, further, performing finite element calculation includes:

[0022] According to the actual loading conditions of the test, finite element calculation is carried out;

[0023] 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.

[0024] In combination with the first aspect, further, the cohesion zone model adopted by the cohesion unit is a two-parameter linear attenuation model.

[0025] In combination with the first aspect, further, 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 inversion to obtain the cohesive zone model parameters of the propellant specimen under the temperature point condition includes:

[0026] 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 condition of the temperature point.

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

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

[0029] 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.

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

[0031] Wherein, the main curve of the propellant cohesive zone model is:

[0032]

[0033] Where Tn(T,δ) represents the main curve of the propellant cohesive zone model, 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.

[0034] In combination 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] In combination with the first aspect, further, the propellant specimen adopts a rectangular propellant specimen containing type I prefabricated cracks.

[0036] In a second aspect, the present invention provides a propellant cohesive zone model parameter calculation device, comprising:

[0037] Calculation module: used to calculate and obtain the parameters of the propellant cohesive zone model using the pre-built propellant cohesive zone model master curve;

[0038] Among them, the main curve of the propellant cohesive zone model is constructed by conducting several groups of tests under different temperature points to obtain the propellant specimen cohesive zone model parameters under each temperature point condition, and based on the propellant specimen cohesive zone model parameters under each temperature point condition.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The method for calculating the model parameters of the propellant cohesive zone provided by the present invention obtains the model parameters of the cohesive zone of the propellant specimen under the conditions of each temperature point by carrying out several groups of tests under different temperature point conditions. According to the model parameters of the cohesive zone of the propellant specimen under the conditions of each temperature point, a master curve of the propellant cohesive zone model is constructed, which can calculate and obtain the model parameters of the cohesive zone of the propellant under any loading time and temperature conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram of a rectangular propellant specimen with type I prefabricated cracks and its displacement loading conditions provided by an embodiment of the present invention;

[0042] Figure 2 is a schematic diagram of the crack propagation on the crack surface of the propellant specimen at various time points provided in the embodiment of the present invention, wherein (a) is t start Crack extension on the crack surface of the propellant specimen at time t between The crack extension on the crack surface of the propellant specimen at time t end Crack propagation on the crack surface of the propellant specimen at the moment;

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

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

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

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

[0047] The technical solution of the present application is further described in detail below in conjunction with specific implementation methods.

[0048] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as limitations on the present application. In the absence of conflict, the embodiments of the present application and the technical features in the embodiments may be combined with each other.

[0049] Embodiment 1:

[0050] This embodiment provides a method for calculating parameters of a propellant cohesive zone model, which uses a pre-constructed master curve of the propellant cohesive zone model to calculate and obtain the parameters of the propellant cohesive zone model.

[0051] In this embodiment, the main curve of the propellant cohesive zone model is constructed by conducting several groups of tests under different temperature points to obtain the model parameters of the propellant specimen cohesive zone under each temperature point, and according to the model parameters of the propellant specimen cohesive zone under each temperature point.

[0052] In this embodiment, several groups of tests under different temperature conditions are carried out to obtain the model parameters of the cohesive zone of the propellant specimen under the conditions of each temperature point, which specifically includes the following steps:

[0053] Step 1: Under a temperature point condition, 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;

[0054] In this embodiment, the propellant specimen is stretched to obtain the crack path distribution on the crack surface of the propellant specimen at each time point, specifically including:

[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, 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;

[0058] In this embodiment, based on the crack path distribution on the crack surface of the propellant specimen at each time point, constructing the finite element model of the propellant specimen 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 point at which crack propagation occurs, and calculate the length of crack propagation;

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

[0061] In this embodiment, performing finite element calculation specifically includes: performing finite element calculation according to 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: 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, inversion is performed to obtain the model parameters of the cohesive zone of the propellant specimen under the temperature point conditions in step 1;

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

[0064] Step 4: Change the temperature point conditions 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 according to 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 model parameters of the cohesive zone of the propellant specimen at each temperature point, the temperature-cohesive strength relationship and the temperature-critical displacement relationship are fitted using the least squares method;

[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 main curve of the propellant cohesive zone model is:

[0069]

[0070] Where Tn(T,δ) represents the main curve of the propellant cohesive zone model, 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 model parameters of the propellant cohesive zone provided in this embodiment obtains the model parameters of the cohesive zone of the propellant specimen under the conditions of each temperature point by carrying out several groups of tests under different temperature point conditions. According to the model parameters of the cohesive zone of the propellant specimen under the conditions of each temperature point, a master curve of the propellant cohesive zone model is constructed, which can calculate and obtain the model parameters of the cohesive zone of the propellant under any loading time and temperature conditions.

[0072] Embodiment 2:

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

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

[0075] In this embodiment, at room temperature 20°C, a rectangular propellant specimen containing type I prefabricated cracks is stretched. The rectangular propellant specimen containing type I prefabricated cracks and its displacement loading are shown in FIG. Figure 1 At the same time, a high-definition camera is used to record the deformation of the propellant specimen surface. The acquisition frequency of the high-definition camera is as high as possible to ensure that the real-time situation of 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. end The crack propagation on the crack surface of the propellant specimen at the moment is as follows Figure 2 As shown. Under the condition of high-definition camera and high-frequency acquisition, a constant-speed tensile test was carried out on a rectangular specimen with a type I prefabricated crack, and the tensile rate was 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, it is necessary to paste a paper ruler on the surface of the propellant specimen, such as Figure 1 As shown. The paper ruler on the surface of the propellant specimen is used to 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, a finite element model of the propellant specimen is constructed, and finite element calculation is carried out. During the finite element calculation process, the corresponding cohesive force unit is inserted 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 point at which crack extension occurs is screened out, and the length of crack extension is calculated. The time points at which crack extension occurs, such as t0, t1, t2, t3, t4, t5, t6, t7, etc., are marked on the complete crack path. Figure 3 As shown, and based on Figure 3 Construct a finite element model of the propellant specimen. Carry out finite element calculations according to the actual loading conditions of the test. During the finite element calculation process, insert cohesive units according to the real-time crack extension conditions. The finite element model of the propellant specimen is as follows: Figure 5 As shown, Figure 5 In the figure, the bold black part represents the cohesive force unit set along the crack propagation path. The cohesive zone model used by the cohesive force unit is a two-parameter linear attenuation model, such as Figure 4 shown.

[0080] Step 4): Taking the force-displacement simulation response of the propellant specimen and the actual force-displacement response of the propellant specimen as the optimization goal, inversion is performed to obtain the model parameters of the cohesive zone of the propellant specimen;

[0081] In this embodiment, the force-displacement response of the propellant specimen is consistent with the actual force-displacement response of the propellant specimen as the optimization goal, and the genetic algorithm is used to invert the model parameters of the cohesive zone of the propellant specimen. In the inversion process, the time point is selected to be consistent with the time when the crack occurs on the crack surface of the propellant specimen. The force-displacement response curve of the propellant specimen is shown in Figure 6 shown.

[0082] Step 5): Conduct tests under different temperature conditions, perform steps 1) to 4) in sequence, obtain the model parameters of the cohesive zone of the propellant specimen under the conditions of each temperature point, and construct the master curve of the propellant cohesive zone model;

[0083] In this embodiment, tests are carried out at temperature points of 70°C, 50°C, 0°C, -20°C, and -40°C, and steps 1) to 4) are performed in sequence to obtain the cohesive zone model parameters of the propellant specimen at temperature points of 70°C, 50°C, 0°C, -20°C, and -40°C. The temperature-cohesive strength relationship and the temperature-critical displacement relationship are fitted using the least squares method to construct the master curve of the propellant cohesive zone model.

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

[0085] By 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.

[0086] Embodiment 3:

[0087] This embodiment provides a propellant cohesive zone model parameter calculation device, comprising:

[0088] Calculation module: used to calculate and obtain the parameters of the propellant cohesive zone model using the pre-built propellant cohesive zone model master curve.

[0089] In this embodiment, the main curve of the propellant cohesive zone model is constructed by conducting several groups of tests under different temperature points to obtain the model parameters of the propellant specimen cohesive zone under each temperature point, and according to the model parameters of the propellant specimen cohesive zone under each temperature point.

[0090] The propellant cohesive zone model parameter calculation device provided in this embodiment also includes:

[0091] Collection module: used to collect the surface deformation of the propellant specimen.

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

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

[0094] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0095] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes 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 generate 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.

[0096] 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.

[0097] 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 in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0098] The above are only preferred implementations of the present application. 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 application. These improvements and modifications should also be regarded as the scope of protection 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; Among them, the main curve of the propellant cohesive zone model is constructed by conducting several groups of tests under different temperature points to obtain the propellant specimen cohesive zone model parameters under each temperature point condition, and based on the propellant specimen cohesive zone model parameters under each temperature point condition.

2. The method for calculating the parameters of the propellant cohesive zone model according to claim 1, characterized in that: Conduct several groups of tests at different temperature points to obtain the model parameters of the cohesive zone of the propellant specimen under various temperature points, including: 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 conditions at different points and repeat the above steps to obtain the model parameters of the cohesive zone of the propellant specimen under the conditions of each temperature point.

3. The method for calculating the parameters of the propellant cohesive zone model according to claim 2, 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.

4. The method for calculating the parameters of the propellant cohesive zone model according to claim 2, 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.

5. The method for calculating the parameters of the propellant cohesive zone model according to claim 2, 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.

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

7. The method for calculating the parameters of the propellant cohesive zone model according to claim 2, 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 condition of the temperature point. During the inversion process, the time point selected is consistent with the moment of crack occurrence on the crack surface of the propellant specimen.

8. The method for calculating the parameters of the propellant cohesive zone model according to claim 1, characterized in that: The master curve of the propellant cohesive zone model is constructed according to the model parameters of the propellant specimen cohesive zone under the conditions of each temperature point, including: 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: Where Tn(T,δ) represents the main curve of the propellant cohesive zone model, 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.

9. 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.

10. 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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