Simulation analysis method for implosion of liquid tank
By using acousto-solid-coupled solver and finite element model on the ABAQUS platform, the problems of large amount of calculation and inaccurate damage effects in liquid tank implosion analysis are solved, and more efficient and accurate analysis is achieved.
Patent Information
- Application Number
- CN202411818775.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-11
- Publication Date
- 2025-04-18
AI Technical Summary
The existing flow-solid coupling method has a large amount of calculation and inaccurate damage effect in the liquid tank implosion analysis, which cannot effectively capture the highly nonlinear detonation process, resulting in large losses of overpressure and weak damage.
Based on the pre-processing function of ABAQUS, a finite element model of liquid tank implosion is established, and an acoustic solid coupling solver is used. By setting the explosion source and explosion distance point, the loading surface is set on the acoustic domain side of the acoustic solid coupling surface using a diffusing algorithm. The ratio of the fluid grid size to the solid grid size is between 0.5 and 1.5, and the fluid grid size is less than 1/10 of the shock wave wavelength.
This significantly reduces the calculation amount, improves the analysis efficiency, and ensures the analysis accuracy of the liquid tank implosion, especially when the shock wave is repeatedly reflected.
Smart Images
Figure CN119849236A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of explosion damage simulation, and in particular to a simulation analysis method for liquid tank implosion. Background Art
[0002] Liquid tanks such as water tanks and oil tanks are important facilities in large industrial areas and have certain damage value. In particular, when gasoline vapor and air are mixed to a certain concentration in oil tanks, chemical explosions will occur when encountering ignition sources, causing serious damage to the oil tanks and the surrounding environment. Fluid-structure coupling is a traditional liquid tank implosion analysis method, such as the ALE fluid-structure coupling algorithm of LS-DYNA and the CEL fluid-structure coupling algorithm of ABAQUS, but they all have the following shortcomings:
[0003] The entire explosion damage process needs to be calculated, including explosive detonation, blast wave propagation, shock wave propagation, and structural damage, which requires a lot of calculations.
[0004] All simulation technologies based on finite discretization of physical space will be unable to capture the highly nonlinear detonation process due to the large grid size when it comes to explosion problems, which often leads to significant overpressure losses and weak damage. In theory, the grid size can be constrained to ≤1mm to ensure overpressure accuracy, but the corresponding amount of calculation is unaffordable. Summary of the invention
[0005] The invention provides a simulation analysis method for liquid tank implosion, which is used to solve the problems of large amount of calculation and inaccurate damage effect when analyzing liquid tank implosion using the existing fluid-solid coupling method.
[0006] The present invention provides a simulation analysis method for liquid tank implosion, comprising:
[0007] Based on the pre-processing function of ABAQUS, a finite element model of a liquid tank implosion is established, including a liquid tank, a liquid and a ground. The liquid tank and the ground are solids, the liquid is a fluid, the solid is simulated using nonlinear solid mechanics, the liquid tank is simulated using a bilinear constitutive model, the fluid is simulated using a linear acoustic model, the liquid tank and the liquid are set to bidirectionally transmit velocity and pressure, the ground is set as a rigid body, the liquid tank and the ground are set as universal contact, the ratio of the fluid grid size to the solid grid size is between 0.5 and 1.5, and the fluid grid size is less than 1 / 10 of the shock wave wavelength;
[0008] The explosion source and explosion distance point are set based on the pre-processing function of ABAQUS, and the loading surface is set on the acoustic domain side of the acoustic-solid coupling surface by using the scattered wave algorithm. The overpressure peak of the explosion distance point is calculated based on the empirical formula of liquid implosion. The acoustic-solid coupling surface is the part of the contact surface between the liquid tank and the liquid used for calculation;
[0009] The calculation is performed based on the acoustic-solid coupling solver of ABAQUS, and the overpressure peak value of the target point is obtained according to the post-processing function of ABAQUS. The target point is a point near the liquid tank that is closest to the explosion source.
[0010] The above scheme is based on the acoustic-solid coupling solver of ABAQUS, which expands the analysis method widely used in underwater explosions to the simulation analysis of liquid tank implosion that needs to consider repeated reflection of shock waves. While focusing on the damage to the liquid tank without paying attention to the explosion products and the movement of the fluid medium, it not only ensures the accuracy of the analysis, but also greatly reduces the amount of calculation and significantly improves the analysis efficiency.
[0011] Optionally, the unit type of the fluid is AC3D8R.
[0012] Optionally, the unit type of the solid is C3D8R.
[0013] Optionally, simulating the solid using nonlinear solid mechanics includes simulating the solid using solid mechanics governing equations derived from the minimum potential energy principle.
[0014] Optionally, simulating the fluid using a linear acoustic model includes simulating the fluid using the following linearized acoustic control equations:
[0015]
[0016] Where c is the wave speed, is the Hamiltonian operator, and p is the fluid overpressure.
[0017] Optionally, the liquid tank and the liquid are configured to bidirectionally transmit speed and pressure, including setting a Tie constraint on the contact surface between the liquid tank and the liquid.
[0018] Optionally, the fluid is meshed using hexahedrons.
[0019] Optionally, the solid is meshed using hexahedrons or tetrahedrons.
[0020] Optionally, the liquid is water.
[0021] Optionally, the liquid implosion empirical formula is an underwater explosion empirical formula, which is as follows:
[0022]
[0023] Where p is the peak overpressure at the explosion distance, k and α are explosive constants, and m e is the explosive equivalent, and R is the distance between the explosion point and the explosion source. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0025] Figure 1 A schematic flow chart of a simulation analysis method for a liquid tank implosion provided by an embodiment of the present invention;
[0026] Figure 2 A schematic diagram of a fluid unit type configuration provided by an embodiment of the present invention;
[0027] Figure 3 A schematic diagram of a solid unit type configuration provided by an embodiment of the present invention;
[0028] Figure 4 A schematic diagram of Tie constraint settings provided in an embodiment of the present invention;
[0029] Figure 5 A schematic diagram of a calculation model of a liquid tank implosion provided by an embodiment of the present invention;
[0030] Figure 6 A schematic diagram of the bulk modulus and density settings of water provided in an embodiment of the present invention;
[0031] Figure 7 A schematic diagram of underwater explosion parameter settings provided by an embodiment of the present invention;
[0032] Figure 8 A schematic diagram of the overpressure peak setting of the explosion distance point provided by an embodiment of the present invention;
[0033] Fig. 9 A schematic diagram of a scatter wave algorithm configuration provided by an embodiment of the present invention;
[0034] Fig.10 A schematic diagram of the analysis step configuration provided by an embodiment of the present invention;
[0035] Fig.11 A schematic diagram of a water tank damage scene provided by an embodiment of the present invention;
[0036] Fig.12 A schematic diagram of an overpressure curve of a target point provided by an embodiment of the present invention;
[0037] Fig.13 A schematic diagram of an overpressure curve of a target point under the fluid-solid coupling algorithm provided in an embodiment of the present invention. DETAILED DESCRIPTION
[0038] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0039] Figure 1 The process of a simulation analysis method for liquid tank implosion provided by an embodiment of the present invention is shown in detail, including:
[0040] S101. Based on the pre-processing function of ABAQUS, a finite element model of the liquid tank implosion is established, including the liquid tank, liquid and ground.
[0041] Specifically, the liquid tank and the ground are solids, the liquid is a fluid, the solid is simulated using nonlinear solid mechanics, the liquid tank is simulated using a bilinear constitutive model, the fluid is simulated using a linear acoustic model, the liquid tank and the liquid are set to transfer velocity and pressure bidirectionally, the ground is set as a rigid body, and the liquid tank and the ground are set to universal contact.
[0042] It should be noted that nonlinear solid mechanics is used to describe forces and motions, and bilinear constitutive models are used to describe material properties.
[0043] The liquid tank is set to be in universal contact with the ground to take into account the phenomenon of the liquid tank taking off after implosion.
[0044] In one example, the unit type of the fluid is AC3D8R, and its settings are as follows Figure 2 shown.
[0045] In one example, the solid element type is C3D8R, and its settings are as follows Figure 3 shown.
[0046] In one example, the nonlinear solid mechanics simulation of the solid includes simulating the solid using a solid mechanics control equation derived from the minimum potential energy principle, which can describe motion processes such as material nonlinearity, contact nonlinearity and large deformation, and truly reflect the failure form of the structure.
[0047] In one example, simulating the fluid using a linear acoustic model includes simulating the fluid using the following linearized acoustic governing equations:
[0048]
[0049] Where c is the wave speed, is the Hamiltonian operator, and p is the fluid overpressure.
[0050] When simulating a fluid using a linear acoustics model, the fluid is the acoustic domain.
[0051] The liquid tank and the liquid are arranged to transmit velocity and pressure in a bidirectional manner so as to realize repeated reflection of the shock wave.
[0052] In one example, the liquid tank and the liquid are configured to bidirectionally transmit velocity and pressure, including setting a Tie constraint on a contact surface between the liquid tank and the liquid.
[0053] The Tie constraint is set to achieve acoustic-solid coupling. Figure 4 After setting the Tie constraint, the fluid and the solid achieve coupling effects by bidirectionally transmitting velocity and pressure at the contact nodes (points on the contact surface). The coupling effects include repeated reflections of shock waves.
[0054] Compared with the traditional fluid-solid coupling algorithm, the acoustic-solid coupling algorithm adopts the empirical formula of liquid implosion, which no longer requires the charge grid to be divided separately, but only the fluid grid and the solid grid to be divided.
[0055] Specifically, the ratio of the fluid grid size to the solid grid size is between 0.5 and 1.5, which can ensure the transmission of velocity and pressure on the contact surface.
[0056] Specifically, the fluid grid size is smaller than 1 / 10 of the shock wave wavelength, so that both the fluid grid size and the solid grid size are at the centimeter level, and thus the amount of calculation is significantly smaller than the fluid-solid interaction method.
[0057] In one example, the fluid is meshed using hexahedrons.
[0058] In one example, the solid is meshed using hexahedrons or tetrahedrons.
[0059] S102. The explosion source and explosion distance point are set based on the pre-processing function of ABAQUS, and the loading surface is set on the acoustic domain side of the acoustic-solid coupling surface using the scattered wave algorithm.
[0060] Figure 5 An example model of liquid tank implosion is shown. According to the symmetry of the working condition, 1 / 4 modeling is adopted, where RP1 is the explosion source and RP2 is the explosion distance point.
[0061] Specifically, the overpressure peak value at the explosion point is calculated based on the empirical formula of liquid implosion.
[0062] The liquid may be water, oil or the like. In one example, the liquid is water.
[0063] The bulk modulus of water is 2.2e9Pa and the density is 1000kg / m^3. Figure 6 When the explosion is set in water, the wave speed is 1500m / s, the density is 1000kg / m^3, and the attenuation coefficient is 0.13. The underwater explosion parameter settings are as follows Figure 7 shown.
[0064] When the liquid is water, the empirical formula for liquid implosion is the empirical formula for underwater explosion, which is as follows:
[0065]
[0066] Among them, p is the peak overpressure at the explosion distance, k and α are explosive constants, and m e is the explosive equivalent, and R is the distance between the explosion point and the explosion source.
[0067] In one example, the explosive is TNT, k=52.27 MPa, α=1.13, m e =0.216kg, R=600mm, calculated p=52.27MPa.
[0068] Set it according to the calculated overpressure peak value of the explosion distance point, such as Figure 8 shown.
[0069] There are two algorithms for acoustic-solid coupling: total wave and scattered wave. The total wave algorithm requires that the explosion source is outside the acoustic domain, while the scattered wave algorithm requires that the explosion source is within the acoustic domain. For the problem of liquid tank explosion, the scattered wave algorithm should be used. Fig. 9 A schematic diagram of the scattered wave algorithm setting is shown. In the Model setting, the wave formulation is set to Scattered wave, that is, the scattered wave algorithm.
[0070] Specifically, the acoustic-solid coupling surface is the portion of the contact surface between the liquid tank and the liquid that is used for calculation.
[0071] S103, performing calculation based on the acoustic-solid coupling solver of ABAQUS, and obtaining the overpressure peak value of the target point according to the post-processing function of ABAQUS.
[0072] The acoustic-solid coupling solver of ABAQUS applies explosion loads through the explosion distance point and the loading surface, and inputs the overpressure peak value (i.e., explosion pressure) of the explosion distance point calculated by the empirical formula of liquid implosion into the explosion distance point, which can ensure that the pressure on the structure meets the expectations of the empirical formula of liquid implosion. Compared with the traditional fluid-solid coupling explosion calculation, the ABAQUS acoustic-solid coupling algorithm does not need to use a high-density fluid grid to ensure the accuracy of overpressure, nor does it need to calculate the process of explosive detonation, detonation wave propagation, and shock wave propagation, which greatly reduces the amount of calculation.
[0073] Specifically, the target point is the point near the liquid tank that is closest to the explosion source. Selecting the target point near the liquid tank can indicate the accuracy of the overpressure to which the liquid tank is subjected. Considering that the liquid tank is cylindrical, there may be many target points, and only one point can be selected.
[0074] It should be noted that when setting the burst distance point, it is recommended to select the point closest to the target point. The closer the distance, the better the effect.
[0075] The acoustic-solid coupling solver of ABAQUS is integrated in Explicit. The analysis step settings before calculation are as follows: Fig.10 shown.
[0076] Submit calculation files, water tank damage scene as follows Fig.11 As shown. Fig.11 It can be seen that the water tank has obvious tears.
[0077] According to the post-processing function of ABAQUS, the overpressure curve of the target point is obtained as follows Fig.12 As shown. Fig.12 It can be seen that when the shock wave reaches the target point for the first time, the overpressure peak is about 63MPa, which is very close to the 64MPa calculated by the empirical formula for underwater explosion.
[0078] It should be noted that, although the embodiment of the present invention is implemented by ABAQUS, other software having an underwater explosion calculation module and corresponding algorithms can also implement the embodiment of the present invention.
[0079] Compared with the calculation of the same working condition using the fluid-structure interaction method, the overpressure curve of the target point is as follows: Fig.13 As shown in the figure, when the shock wave reaches the target point for the first time, the overpressure peak is about 42MPa, which is significantly lower than the empirical formula value. This is because the spatial distribution of the shock wave is similar to a pulse function and is highly nonlinear. All algorithms that solve the control equation approximate solution through discrete physical fields will introduce errors due to the scale of discrete units. According to experience, when the unit size is greater than 1mm, the described detonation wave begins to be distorted. Both the ALE fluid-solid coupling algorithm of LS-DYNA and the CEL algorithm of ABAQUS have overpressure distortion, while the acoustic-solid coupling algorithm of ABAQUS has an explosion distance point, which can ensure the accuracy of the overpressure near the explosion distance point, thereby ensuring the authenticity of the damage effect. Moreover, since the fluid grid size in the ABAQUS acoustic-solid coupling algorithm is less than 1 / 10 of the shock wave wavelength, the grid size is at the centimeter level, so the amount of calculation is significantly less than the fluid-solid coupling method.
[0080] Comparing the application of the acoustic-solid coupling method and the fluid-solid coupling method in the simulation of liquid tank implosion, the number of fluid-solid coupling nodes is 3.77 million, the calculation time is about 300 core hours, and the number of acoustic-solid coupling nodes is 750,000, the calculation time is about 16 core hours. The acoustic-solid coupling method has the advantages of simple modeling and efficient calculation. This is because the acoustic control equation is much simpler than the fluid mechanics control equation, and the acoustic-solid coupling applies the explosion load through the method of explosion distance point and loading surface, and no longer needs to calculate the process of explosive detonation, detonation wave propagation, and shock wave propagation, which greatly reduces the amount of calculation; secondly, the explosion distance point can ensure the accuracy of the overpressure near the damage target, so that the unit size can be appropriately enlarged to reduce the calculation scale.
[0081] In summary, the above scheme, based on the acoustic-solid coupling solver of ABAQUS, expands the analysis method widely used in underwater explosions to the simulation analysis of liquid tank implosion that needs to consider repeated reflection of shock waves. While focusing on the damage to the liquid tank without caring about the movement of explosion products and fluid media, it not only ensures the accuracy of the analysis, but also greatly reduces the amount of calculation and significantly improves the analysis efficiency.
[0082] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.
[0083] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.
Claims
1. A simulation analysis method for liquid tank implosion, characterized in that: include: Based on the pre-processing function of ABAQUS, a finite element model of a liquid tank implosion is established, including a liquid tank, a liquid and a ground. The liquid tank and the ground are solids, the liquid is a fluid, the solid is simulated using nonlinear solid mechanics, the liquid tank is simulated using a bilinear constitutive model, the fluid is simulated using a linear acoustic model, the liquid tank and the liquid are set to bidirectionally transmit velocity and pressure, the ground is set as a rigid body, the liquid tank and the ground are set as universal contact, the ratio of the fluid grid size to the solid grid size is between 0.5 and 1.5, and the fluid grid size is less than 1 / 10 of the shock wave wavelength; The explosion source and explosion distance point are set based on the pre-processing function of ABAQUS, and the loading surface is set on the acoustic domain side of the acoustic-solid coupling surface by using the scattered wave algorithm. The overpressure peak of the explosion distance point is calculated based on the empirical formula of liquid implosion. The acoustic-solid coupling surface is the part of the contact surface between the liquid tank and the liquid used for calculation; The calculation is performed based on the acoustic-solid coupling solver of ABAQUS, and the overpressure peak value of the target point is obtained according to the post-processing function of ABAQUS. The target point is a point near the liquid tank that is closest to the explosion source.
2. The method according to claim 1, characterized in that: The unit type of the fluid is AC3D8R.
3. The method according to claim 1, characterized in that: The unit type of the solid is C3D8R.
4. The method according to claim 1, characterized in that: The solid is simulated using nonlinear solid mechanics including simulating the solid using solid mechanics governing equations derived from the minimum potential energy principle.
5. The method according to claim 1, characterized in that: The fluid is simulated using a linear acoustic model including simulating the fluid using the following linearized acoustic governing equations: Where c is the wave speed, is the Hamiltonian operator, and p is the fluid overpressure.
6. The method according to claim 1, characterized in that: The liquid tank and the liquid are configured to bidirectionally transmit speed and pressure, including setting a Tie constraint on the contact surface between the liquid tank and the liquid.
7. The method according to claim 1, characterized in that: The fluid is meshed using hexahedrons.
8. The method according to claim 1, characterized in that: The solid is meshed using hexahedrons or tetrahedrons.
9. The method according to claim 1, characterized in that: The liquid is water.
10. The method according to claim 9, characterized in that: The liquid implosion empirical formula is an underwater explosion empirical formula, and the formula is as follows: Where p is the peak overpressure at the explosion distance, k and α are explosive constants, and m e is the explosive equivalent, and R is the distance between the explosion point and the explosion source.