Macro-micro damage analysis method of warhead charge under hypersonic aerodynamic thermal force coupling

Abstract

This invention relates to a method for macroscopic and microscopic damage analysis of warhead charges under hypersonic aero-thermal coupling, belonging to the field of warhead numerical simulation technology. It solves the problem that existing technologies have failed to achieve coordinated macroscopic and microscopic damage analysis and rapid prediction of warhead charges under hypersonic aero-thermal coupling. The method includes: acquiring aero-thermal coupling load data of the warhead; establishing a macroscopic finite element model of the warhead and embedding cohesive elements; establishing a microscopic geometric model of the charge and embedding cohesive elements; performing thermo-coupling calculations on the macroscopic finite element model based on the aero-thermal coupling load data to obtain the temperature and strain histories; performing microscopic thermo-coupling calculations on the microscopic geometric model of the warhead charge based on the temperature and strain histories to obtain the microscopic damage field, determining and updating the constitutive model in the macroscopic finite element model based on the stiffness reduction factor; repeating the above steps until a preset stopping condition is met. This achieves macroscopic and microscopic damage analysis of the warhead charge.

Description

Technical Field

[0001] This invention relates to the field of numerical simulation technology for warheads, and in particular to a method for macroscopic and microscopic damage analysis of warhead charges under hypersonic aerodynamic-thermal coupling. Background Technology

[0002] When a warhead flies at hypersonic speeds, its surface experiences intense friction and compression with the air. The shell surface is subjected to extremely severe aero-thermal coupling, with heat being conducted to the internal structure, causing non-uniform temperature rise in the internal explosive charge and subsequently inducing significant thermal stress. Damage accumulation under the thermo-thermal coupling effect weakens the overall structural integrity and load-bearing capacity, seriously threatening the warhead's operational effectiveness. Simultaneously, the explosive charge, typically composed of high-energy particles and binders, exhibits multi-scale damage behavior. Under the temperature gradient caused by aerodynamic heating, significant thermal expansion mismatch occurs between components at the microscale, inducing interfacial debonding and localized cracking, which gradually expand and connect under continuous thermo-thermal coupling, eventually evolving into macroscopic damage regions, leading to structural performance degradation. Therefore, it is necessary to conduct research on explosive damage analysis under the aero-thermal coupling effect during hypersonic flight.

[0003] Existing research on the thermal safety of hypersonic warheads during flight mainly focuses on the response characteristics of the macroscopic temperature and thermal stress fields of the warhead under aerodynamic thermal loads. Specifically, three-dimensional numerical simulations of hypersonic warheads are conducted to obtain the temperature distribution field of the warhead under different operating conditions. However, this research mainly focuses on the temperature field response and does not further consider the thermal stress distribution induced by the temperature gradient and its impact on the structural integrity of the warhead. Numerical simulations are conducted for two-dimensional hypersonic warheads to perform coupled analysis of hypersonic aerodynamic heating and structural temperature fields under different operating conditions. The final temperature field distribution is then transferred as a thermal load to the solid domain to calculate the thermal stress and displacement changes of the warhead. This research considers the thermo-mechanical coupling effect at the macroscopic level but does not introduce a damage evolution model or address the mechanical damage behavior at the macroscopic and mesoscopic scales.

[0004] In summary, existing research mainly focuses on the temperature field response of the warhead charge, without considering the systematic correlation analysis of the temperature field, stress field and damage field of the warhead charge under hypersonic flight conditions, without conducting a correlation analysis between the macroscopic thermal response of the charge and the microscopic damage behavior, and without being able to quickly assess the degree of charge damage under multiple operating conditions, resulting in insufficient accuracy and physical reliability of structural integrity assessment. Summary of the Invention

[0005] Based on the above analysis, the embodiments of the present invention aim to provide a method for macroscopic and microscopic damage analysis of warhead charges under hypersonic aerodynamic-thermal coupling, in order to solve the problem that the prior art has not achieved the coordinated analysis and rapid prediction of macroscopic and microscopic damage of warhead charges under hypersonic aerodynamic-thermal coupling.

[0006] This invention provides a method for macroscopic and microscopic damage analysis of warhead charges under hypersonic aerodynamic-thermal coupling, comprising the following steps: S1. Obtain aerodynamic and thermodynamic coupling load data of the warhead under hypersonic flight conditions; establish a macroscopic finite element model of the warhead and embed cohesive elements between the solid elements of the warhead charge; establish a mesoscopic geometric model of the warhead charge and embed cohesive elements inside each material component and at the component interface in the mesoscopic geometric model. S2. Based on the aero-thermal coupling load data, perform thermo-coupling calculations on the macroscopic finite element model of the warhead to obtain the macroscopic temperature field and macroscopic damage field, and then obtain the temperature history and strain history characterizing the damage evolution. S3. Based on the temperature history and strain history, perform micro-thermal coupling calculation on the micro-geometric model of the warhead charge to obtain the micro-damage field, and then determine the stiffness reduction factor of the macro-charge material. Based on the stiffness reduction factor, update the constitutive model of the charge entity element in the macro-finite element model of the warhead. S4. Repeat steps S2 to S3 until the preset stopping condition is met to obtain the final macroscopic temperature field, macroscopic damage field and corresponding microscopic damage evolution results; wherein, the microscopic damage evolution results include the microscopic damage field of the microscopic geometric model and the time history data of the damage factor of each cohesive unit.

[0007] Furthermore, acquire aerodynamic and thermodynamic coupling load data of the warhead under hypersonic flight conditions, including: A geometric model of the external fluid domain of the warhead was established and meshed. The calculation conditions for the fluid domain material and flight conditions were set, and numerical calculations of the flow field were carried out. The pressure distribution and heat flux density distribution of the outer wall of the warhead shell were extracted to obtain an aero-thermal coupling load dataset. The aero-thermal coupling load dataset includes the three-dimensional spatial coordinates of the mesh nodes of the outer wall of the warhead shell and their corresponding wall pressure and heat flux density values. The fluid domain material is air, and the calculation conditions include flight speed, flight angle of attack, atmospheric pressure, and atmospheric temperature.

[0008] Furthermore, the embedding of cohesive units between the physical units of the warhead charge includes: A zero-thickness cohesive element is embedded at the common surface of adjacent solid elements within the warhead charge area. The constitutive model of the cohesive element is a traction-separation constitutive model. Its constitutive model parameters include cohesive stiffness, damage initiation strength, and maximum damage displacement, and at least one parameter changes dynamically with the current temperature and strain rate values.

[0009] Furthermore, the relationship between the constitutive parameters and temperature is described by a linear softening function, an exponential decay function, or a piecewise linear function, wherein the cohesive stiffness and damage initiation strength decrease and the maximum damage displacement increases as the temperature increases; the relationship between the constitutive parameters and strain rate is described by a logarithmic function or a power function, wherein the cohesive stiffness and damage initiation strength increase and the maximum damage displacement decreases as the strain rate increases.

[0010] Furthermore, the constitutive model parameters of the cohesive elements are embedded between the solid units of the warhead charge: Cohesive stiffness Represented as: ; In the formula, This represents the initial cohesive stiffness at the reference temperature and reference strain rate. This indicates the cohesive unit at the current temperature. The softening value at that temperature This indicates the cohesive element at the current strain rate. The strain rate intensification value at that time; Damage initiation strength Represented as: ; In the formula, This represents the maximum normal stress at the reference temperature and reference strain rate. Maximum damage displacement Represented as: ; In the formula, This represents the maximum damage displacement at the reference temperature and reference strain rate. This indicates the cohesive unit at the current temperature. Temperature toughness value at that time This indicates the cohesive element at the current strain rate. The strain rate brittleness value at that time.

[0011] Furthermore, the macroscopic temperature field and macroscopic damage field are obtained in the following way: The three-dimensional spatial coordinates of the mesh nodes on the outer wall of the warhead shell and their corresponding wall pressure values ​​in the aero-thermal coupling load dataset are used as the external loads of the structure, and the three-dimensional spatial coordinates of the mesh nodes on the outer wall of the warhead shell and their corresponding wall heat flux density values ​​are used as the thermal boundary conditions. These are mapped to the corresponding nodes on the outer surface of the shell of the macroscopic finite element model through spatial interpolation, and then thermo-mechanical coupling calculations are performed to obtain the macroscopic temperature field and macroscopic damage field.

[0012] Furthermore, the temperature and strain histories characterizing the damage evolution were obtained in the following ways: Extract the temperature values ​​of the solid units on both sides of the cohesive unit with the largest damage factor in the macroscopic damage field, take the average value as the representative temperature at the location of the cohesive unit, record its value at each time point in the thermo-coupling calculation time history, construct a function of temperature change over time as the temperature history. Extract the strain component values ​​of the solid elements on both sides of the cohesive element with the largest damage factor in the macroscopic damage field, take the average value as the representative strain at the location of the cohesive element, record the values ​​at each time point in the thermo-coupling calculation time history, and construct a function of the strain component changing with time as the strain history.

[0013] Furthermore, the constitutive model of the explosive solid element in the macroscopic finite element model of the warhead updated based on the stiffness reduction coefficient includes: The initial elastic matrix of the macroscopic charge solid element is multiplied by the stiffness reduction factor to obtain the updated elastic matrix, which is then used in the next round of macroscopic thermo-coupling calculations. The initial elastic matrix of the macroscopic charge solid element is the linear elastic constitutive matrix of the macroscopic charge material when no damage occurs.

[0014] Furthermore, the stiffness reduction factor of the macroscopic charge material Represented as: ; In the formula, This represents the total volume of the mesoscopic geometric model. This represents the total number of cohesive elements in the mesoscopic geometric model. Representing the mesoscopic geometric model Damage factor of each cohesive unit Representing the mesoscopic geometric model The virtual volume of each cohesive unit Representing the mesoscopic geometric model The weighting coefficient of each cohesive unit.

[0015] Furthermore, steps S1 to S4 are repeated under different flight angles of attack to obtain the macroscopic damage field corresponding to each angle of attack. The spatial location of the damage peak region and the peak value of the damage variable are extracted under each angle of attack, and a mapping relationship between the flight angle of attack and the characteristic parameters of the damage peak is established. For the target angle of attack that has not been analyzed, the mapping relationship is used to predict the spatial location of the damage peak region and the peak value of the damage variable under that target angle of attack. Among them, the spatial location of the damage peak region is the coordinate of the maximum value of the damage factor, and the peak value of the damage variable is the damage factor value of the damage peak region.

[0016] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: This invention provides a method for macroscopic and microscopic damage analysis of warhead charges under hypersonic aero-thermal coupling. By constructing a collaborative computational framework of fluid and solid domains, aerodynamic pressure and aero-thermal load are simultaneously used as inputs, and an internal cohesive constitutive model is introduced to realize the systematic correlation analysis of the temperature field, stress field, and damage field of the warhead charge under hypersonic flight conditions. Considering the dynamic changes of stiffness, strength, and damage evolution parameters of the internal cohesive elements with the current temperature and strain rate, it can realistically reflect the mechanical behavior of the charge under aerodynamic heating and high-speed flight environments, significantly improving the physical realism of damage prediction. The temperature and strain histories of key macroscopic damage regions are transferred to the microscopic model, and the stiffness reduction coefficient obtained from the microscopic calculation is fed back to update the constitutive model of the macroscopic solid elements. This overcomes the problem of insufficient stiffness degradation estimation caused by neglecting microscopic damage feedback in traditional one-way transfer methods, greatly improving the accuracy of charge structural integrity assessment. Furthermore, a method for predicting the peak damage region of the charge based on the flight angle of attack is proposed, enabling rapid prediction of the charge damage state under uncalculated conditions, significantly improving the efficiency of multi-condition assessment.

[0017] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0018] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0019] Figure 1 A flowchart illustrating the method for macroscopic and microscopic damage analysis of warhead charge under hypersonic aerodynamic-thermal coupling provided in an embodiment of the present invention; Figure 2 A schematic diagram of the external fluid domain of the warhead provided in an embodiment of the present invention; Figure 3 This is a schematic diagram illustrating the embedding of cohesive units between the physical units of the warhead charge, as provided in an embodiment of the present invention. Figure 4 This is a schematic diagram of the micro-geometric model of the propellant charge provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the embedding of cohesive elements in the micro-geometric model provided in an embodiment of the present invention. Detailed Implementation

[0020] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0021] A specific embodiment of the present invention discloses a method for macroscopic and microscopic damage analysis of warhead charges under hypersonic aerodynamic-thermal coupling, such as... Figure 1 As shown, it includes the following steps: S1. Obtain aerodynamic and thermodynamic coupling load data of the warhead under hypersonic flight conditions; establish a macroscopic finite element model of the warhead and embed cohesive elements between the solid elements of the warhead charge; establish a microscopic geometric model of the warhead charge and embed cohesive elements inside each material component and at the component interface in the microscopic geometric model.

[0022] During implementation, in step S1, aerodynamic and thermodynamic coupling load data of the warhead under hypersonic flight conditions are acquired, including: A geometric model of the external fluid domain of the warhead is established and meshed. The calculation conditions for fluid domain materials and flight conditions are set, and numerical calculations of the flow field are carried out. The pressure distribution and heat flux density distribution of the outer wall of the warhead shell are extracted to obtain an aero-thermal coupling load dataset. The aero-thermal coupling load dataset includes the three-dimensional spatial coordinates of the mesh nodes of the outer wall of the warhead shell and their corresponding wall pressure values ​​and wall heat flux density values.

[0023] Specifically, a geometric model of the fluid domain surrounding the warhead is constructed using SpaceClaim. For example, the fluid domain is set as a cylindrical region, such as... Figure 2 As shown.

[0024] Specifically, the geometric model of the fluid domain is divided into hexahedral structured meshes, and a boundary layer mesh is generated at the shell wall. At the same time, based on the flow characteristics, the local mesh is refined in the regions with significant flow gradients at the head and tail of the warhead to ensure the accuracy of the flow field calculation.

[0025] More specifically, Hypermesh is used for mesh generation.

[0026] Specifically, the fluid domain material is air, and the calculation conditions include flight speed, angle of attack, atmospheric pressure, and atmospheric temperature. The angle of attack refers to the angle between the warhead's longitudinal axis and its relative airflow velocity direction.

[0027] More specifically, the numerical calculation of the flow field was performed using the computational fluid dynamics software Fluent. In Fluent, the outer wall of the warhead casing was set as a non-slip wall, the thermal boundary condition was set as an isothermal wall, and the initial temperature was the same as the initial temperature of the subsequent solid domain.

[0028] During implementation, in step S1, a macroscopic finite element model of the warhead is established in the following manner: A solid domain geometric model of the warhead is established and meshed. The solid domain includes the shell and the explosive charge. The solid domain material and boundary conditions are set to complete the construction of the macroscopic finite element model of the warhead. The shell and the explosive charge are in surface-to-surface contact.

[0029] Specifically, SpaceClaim is used to construct the geometric model of the solid domain of the warhead.

[0030] Specifically, the mesh of the macroscopic finite element model adopts hexahedral structured elements, and the node distribution on the outer wall of the shell matches the node distribution on the corresponding wall in the fluid domain mesh to ensure the spatial mapping accuracy of the aero-thermal coupling load data.

[0031] More specifically, Hypermesh is used to mesh the solid domain.

[0032] In specific implementation, such as Figure 3 As shown, in step S1, embedding cohesive units between the solid units of the warhead charge includes: A zero-thickness cohesive element is embedded at the common surface of adjacent solid elements within the warhead charge area. The constitutive model of the cohesive element is a traction-separation constitutive model. Its constitutive model parameters include cohesive stiffness, damage initiation strength, and maximum damage displacement, and at least one parameter changes dynamically with the current temperature and strain rate values.

[0033] Specifically, the relationship between constitutive parameters and temperature is described by a linear softening function, an exponential decay function, or a piecewise linear function. Among these, as the temperature increases, the cohesive stiffness and damage initiation strength decrease, while the maximum damage displacement increases. The relationship between constitutive parameters and strain rate is described by a logarithmic function or a power function. Among these, as the strain rate increases, the cohesive stiffness and damage initiation strength increase, while the maximum damage displacement decreases.

[0034] More specifically, the traction-separation constitutive model includes an elastic stage, a damage evolution stage, and a complete failure stage. This constitutive model describes the mechanical response of zero-thickness cohesive units embedded between the charge solid units, characterizing the damage initiation, damage propagation, and final failure process of the charge under load. The elastic stage refers to the stress stage before damage occurs in the cohesive units, at which point they remain intact. The damage stage refers to the stage after the cohesive units reach the damage initiation condition, at which point microcracks, debonding, or cracking begin to occur, and the load-bearing capacity gradually decreases. The complete failure stage indicates that the cohesive units have completely failed and no longer transmit any traction force. Specifically, During the elastic phase, the cohesive units have not yet been damaged, and the traction force... With damage displacement Satisfies a linear relationship: ; In the formula, T For traction force, For cohesive stiffness, δ This represents the damage displacement.

[0035] Once the cohesive unit satisfies the damage initiation condition, it enters the damage evolution stage, and its traction force expression is: ; in, ; In the formula, is the damage factor of the cohesive element, with a value range of [0,1], where 0 represents no damage and 1 represents complete failure; The damage initiation displacement represents the damage displacement corresponding to the point when the cohesive unit begins to enter the damage evolution stage. The maximum damage displacement represents the damage displacement corresponding to the complete failure of the cohesive element.

[0036] When the damage displacement reaches δ max At this point, the cohesive unit reaches the stage of complete failure: ; The damage initiation condition of the cohesive element is determined using the maximum nominal stress criterion, which is used to determine whether the cohesive element has transitioned from the elastic stage to the damage evolution stage. The maximum nominal stress criterion is expressed as: ; In the formula, This is the current normal stress value. This is the maximum normal stress, i.e., the damage initiation strength. The shear stress is in the first direction. The maximum value of the shear stress in the first direction. For the second direction shear stress, The maximum value of the second direction shear stress; when the maximum value of the above normalized stress ratio is less than 1, the cohesive unit is in the elastic stage; when it is equal to 1, damage is determined to have started.

[0037] Specifically, the damage initiation displacement can be determined based on the strength parameters corresponding to the damage initiation criterion and the initial stiffness of the cohesive element.

[0038] More specifically, the cohesive stiffness of the constitutive model parameters of the cohesive elements embedded between the solid units of the warhead charge. Represented as: ; In the formula, This represents the initial cohesive stiffness at the reference temperature and reference strain rate. This indicates the cohesive unit at the current temperature. The softening value at that temperature This indicates the cohesive element at the current strain rate. The strain rate strengthening value at that time.

[0039] Cohesive unit at the current temperature Temperature softening value It can be represented in linear form: ; In the formula, Indicates the temperature softening coefficient. Indicates the reference temperature; where, the reference temperature Room temperature.

[0040] Temperature softening value of cohesive element at current temperature t It can also be expressed in exponential form: ; In the formula, This represents the exponential decay coefficient.

[0041] Cohesive element at current strain rate strain rate strengthening value at time This can be expressed in logarithmic form: ; In the formula, Represents the strain rate sensitivity coefficient. This represents the reference strain rate; where the reference strain rate is taken as the static strain rate, for example, 0.001s. -1 .

[0042] Cohesive element at current strain rate strain rate strengthening value at time It can also be expressed in the form of a power function: ; In the formula, This represents the strain rate sensitivity power coefficient.

[0043] More specifically, the damage initiation strength is the constitutive model parameter of the cohesive element embedded between the solid units of the warhead charge. Represented as: ; In the formula, This represents the maximum normal stress at the reference temperature and reference strain rate.

[0044] More specifically, the maximum damage displacement of the constitutive model parameters of the cohesive elements embedded between the solid units of the warhead charge. Represented as: ; In the formula, This represents the maximum damage displacement at the reference temperature and reference strain rate. This indicates the cohesive unit at the current temperature. Temperature toughness value at that time This indicates the cohesive element at the current strain rate. The strain rate brittleness value at that time.

[0045] Cohesive unit at the current temperature Temperature toughness value Expressed in linear form: ; In the formula, This represents the temperature toughness coefficient.

[0046] Cohesive element at current strain rate Strain rate brittleness value Represented in logarithmic form: ; In the formula, This represents the strain rate brittleness coefficient.

[0047] More specifically, the constitutive model of the cohesive element of the warhead charge is implemented through the user material subroutine (UMAT or VUMAT) of the finite element software. This subroutine reads the temperature and strain rate values ​​at the current integration point in each increment step, updates the constitutive parameters of the cohesive element in real time, and calculates the traction force and damage factor.

[0048] More specifically, the temperature-dependent and strain-rate-dependent parameters of the constitutive model of the cohesive unit of the warhead charge are obtained by combining the finite element inversion method with mechanical experiments of the charge material at different temperatures and loading rates (such as double cantilever beam experiments, three-point bending experiments or Hopkinson bar experiments).

[0049] During implementation, in step S1, establishing the mesoscopic geometric model of the warhead charge includes: Based on the microscopic morphological features of the warhead charge, a three-dimensional microscopic geometric model is generated using the Voronoi algorithm.

[0050] Specifically, the mesoscopic geometric model includes at least two different material component regions. Preferably, in this embodiment, the mesoscopic geometric model has a side length of 1 mm and a thickness of 8 micrometers, including a high-energy particle region and a binder region. An interface between the particle region and the binder region is formed between the particle phase and the binder phase. Figure 4 As shown.

[0051] Specifically, the mesh of the micro-geometry model uses triangular prism elements, and local mesh refinement is performed near the interface between the granular phase and the binder phase to accurately capture the initiation and propagation of interface damage.

[0052] In practical implementation, cohesive elements are embedded within each material component and at the component interfaces of the microscopic geometric model, including: Zero-thickness cohesive elements are embedded between solid units within the granular phase, between solid units within the binder phase, and at the interface between the granular and binder phases in the mesoscopic geometric model. These cohesive elements at different locations have different constitutive model parameters, such as... Figure 5 As shown.

[0053] It should be noted that the cohesive elements in the mesoscopic geometric model and the cohesive elements in the macroscopic finite element model use the same constitutive model, but their respective constitutive model parameters are independently calibrated based on the material experimental data of their respective components. No cohesive elements are inserted at the interface between the warhead charge and the casing.

[0054] S2. Based on the aerodynamic-thermal coupling load data, perform thermodynamic coupling calculations on the macroscopic finite element model of the warhead to obtain the macroscopic temperature field and macroscopic damage field, and then obtain the temperature history and strain history characterizing the damage evolution.

[0055] During implementation, in step S2, the macroscopic temperature field and macroscopic damage field are obtained in the following manner: The three-dimensional spatial coordinates of the mesh nodes on the outer wall of the warhead shell and their corresponding wall pressure values ​​in the aero-thermal coupling load dataset are used as the external loads of the structure, and the three-dimensional spatial coordinates of the mesh nodes on the outer wall of the warhead shell and their corresponding wall heat flux density values ​​are used as the thermal boundary conditions. These are mapped to the corresponding nodes on the outer surface of the shell of the macroscopic finite element model through spatial interpolation, and then thermo-mechanical coupling calculations are performed to obtain the macroscopic temperature field and macroscopic damage field.

[0056] Specifically, the thermo-mechanical coupling calculation employs a temperature-displacement coupling analysis step to simultaneously solve for the temperature field, displacement field, and stress field.

[0057] Specifically, the damage factor of each element is calculated by using the cohesive elements embedded in the macroscopic finite element model to obtain the macroscopic damage field.

[0058] During implementation, in step S2, the temperature and strain histories characterizing damage evolution are obtained in the following manner: Extract the temperature values ​​of the solid units on both sides of the cohesive unit with the largest damage factor in the macroscopic damage field, take the average value as the representative temperature at the location of the cohesive unit, record its value at each time point in the thermo-coupling calculation time history, construct a function of temperature change over time as the temperature history. Extract the strain component values ​​of the solid elements on both sides of the cohesive element with the largest damage factor in the macroscopic damage field, take the average value as the representative strain at the location of the cohesive element, record the values ​​at each time point in the thermo-coupling calculation time history, and construct a function of the strain component changing with time as the strain history.

[0059] Specifically, if multiple cohesive units are ranked as the largest, then one can be chosen, or the average history of the corresponding positions of these units can be taken.

[0060] Specifically, the strain components include axial and radial components, which are used for the subsequent transformation of displacement boundary conditions in the microscopic geometric model.

[0061] Specifically, the temperature and strain histories are stored in the form of discrete time point data tables, and continuous functions are constructed through spline interpolation or linear interpolation for loading by the mesoscopic geometric model.

[0062] S3. Based on the temperature history and strain history, perform micro-thermo-coupling calculations on the micro-geometric model of the warhead charge to obtain the micro-damage field, and then determine the stiffness reduction factor of the macro-charge material. Based on the stiffness reduction factor, update the constitutive model of the charge solid element in the macro-finite element model of the warhead.

[0063] In implementation, in step S3, a mesoscopic thermo-mechanical coupling calculation is performed on the mesoscopic geometric model of the warhead charge based on the temperature and strain histories, including: The temperature history is used as a predefined temperature field and uniformly applied to all nodes of the micro-geometric model. Each strain component in the strain history function is multiplied by the corresponding directional characteristic length of the outer boundary of the micro-geometric model to convert it into a time-varying displacement load, which is then applied to the outer boundary of the micro-geometric model. Micro-thermo-mechanical coupling calculation is then performed to obtain the micro-damage field, which is the spatial distribution of the damage factor of each cohesive element in the micro-geometric model.

[0064] Specifically, the displacement load is applied in the following manner: On a set of relative boundaries of a microscopic geometric model, one side is fixed and the other side is displaced; or periodic boundary conditions are used, and all strain components are applied simultaneously.

[0065] In implementation, the stiffness reduction factor of the macroscopic charge material Represented as: ; In the formula, This represents the total volume of the mesoscopic geometric model. This represents the total number of cohesive elements in the mesoscopic geometric model. Representing the mesoscopic geometric model Damage factor of each cohesive unit Representing the mesoscopic geometric model The virtual volume of each cohesive unit Representing the mesoscopic geometric model The weighting coefficients of each cohesive element. The virtual volume of a cohesive element is the average of the volumes of the solid elements on either side of the cohesive element.

[0066] Specifically, weighting coefficients The weighting coefficients at the interface between the particle phase and the binder phase are set according to the location of the cohesive unit. The weighting coefficients at the interface between the particle phase and the binder phase are greater than those at the interior of the binder, and the weighting coefficients at the interior of the binder are greater than those at the particle phase. This is to reflect the different contributions of damage at different locations to the macroscopic stiffness degradation.

[0067] During implementation, the constitutive model of the explosive solid element in the macroscopic finite element model of the warhead is updated based on this stiffness reduction factor, including: The initial elastic matrix of the macroscopic charge solid element is multiplied by the stiffness reduction factor to obtain the updated elastic matrix, which is then used in the next round of macroscopic thermo-coupling calculations. The initial elastic matrix of the macroscopic charge solid element is the linear elastic constitutive matrix of the macroscopic charge material when no damage occurs.

[0068] S4. Repeat steps S2 to S3 until the preset stopping condition is met to obtain the final macroscopic temperature field, macroscopic damage field and corresponding microscopic damage evolution results.

[0069] Specifically, the mesoscopic damage evolution results include the mesoscopic damage field of the mesoscopic geometric model and the time-varying history data of the damage factor of each cohesive unit. It can be understood that the mesoscopic damage field in the mesoscopic damage evolution results is used to identify the final location and severity of the damage; the time-varying history data of the damage factor of each cohesive unit in the mesoscopic damage evolution results is used to analyze the onset time, propagation path, and evolutionary patterns of the damage.

[0070] Specifically, the stopping condition is that the relative error between the macroscopic damage field of the current round and the previous round is less than a preset threshold, or the number of iterations reaches the preset maximum number of iterations. The relative error is the root mean square relative error of the damage factor of each cohesive unit.

[0071] Specifically, the threshold value ranges from 0.01 to 0.05, which can ensure the accuracy of macroscopic damage field calculation while avoiding the waste of computing resources caused by excessive iteration and meeting the efficiency requirements of engineering analysis; the maximum number of iterations ranges from 5 to 10, which makes the damage field tend to be stable and prevents infinite loops under extreme working conditions.

[0072] Preferably, steps S1 to S4 are repeated under different flight angles of attack to obtain the macroscopic damage field corresponding to each angle of attack, extract the spatial location of the damage peak region and the peak value of the damage variable under each angle of attack, and establish a mapping relationship between the flight angle of attack and the characteristic parameters of the damage peak. For the target angle of attack that has not been analyzed, the mapping relationship is used to predict the spatial location of the damage peak region and the peak value of the damage variable under the target angle of attack. Wherein, the spatial location of the damage peak region is the coordinate of the maximum value of the damage factor, and the peak value of the damage variable is the damage factor value of the damage peak region.

[0073] Specifically, the mapping relationship can be obtained using interpolation fitting, multinomial regression, response surface fitting, radial basis function interpolation, or Gaussian process regression methods.

[0074] Understandably, based on the bidirectional coupling calculation results of multi-angle-of-attack conditions, a mapping relationship between the flight angle of attack and the damage peak characteristics can be established, enabling rapid prediction of the charge damage state under uncalculated conditions and significantly improving the efficiency of multi-condition assessment.

[0075] Compared with existing technologies, this embodiment provides a method for macroscopic and microscopic damage analysis of warhead charges under hypersonic aero-thermal coupling. By constructing a collaborative computational framework of fluid and solid domains, it simultaneously uses aerodynamic pressure and aero-thermal load as inputs and introduces an internal cohesive constitutive model to achieve systematic correlation analysis of the temperature field, stress field, and damage field of warhead charges under hypersonic flight conditions. Considering the dynamic changes of stiffness, strength, and damage evolution parameters of the internal cohesive elements with the current temperature and strain rate, it can realistically reflect the mechanical behavior of the charge under aerodynamic heating and high-speed flight environments, significantly improving the physical realism of damage prediction. The temperature and strain histories of key macroscopic damage regions are transferred to the microscopic model, and the stiffness reduction coefficient obtained from the microscopic calculation is fed back to update the constitutive model of the macroscopic solid elements. This overcomes the problem of insufficient stiffness degradation estimation caused by neglecting microscopic damage feedback in traditional one-way transfer methods, greatly improving the accuracy of charge structural integrity assessment. Furthermore, a method for predicting the peak damage region of the charge based on the flight angle of attack is proposed, enabling rapid prediction of the charge damage state under uncalculated conditions, significantly improving the efficiency of multi-condition assessment.

[0076] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware, and the program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0077] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for macroscopic and microscopic damage analysis of warhead charge under hypersonic aero-thermal coupling, characterized in that, Includes the following steps: S1. Obtain aerodynamic and thermodynamic coupling load data of the warhead under hypersonic flight conditions; establish a macroscopic finite element model of the warhead and embed cohesive elements between the solid elements of the warhead charge; establish a mesoscopic geometric model of the warhead charge and embed cohesive elements inside each material component and at the component interface in the mesoscopic geometric model. S2. Based on the aero-thermal coupling load data, perform thermo-coupling calculations on the macroscopic finite element model of the warhead to obtain the macroscopic temperature field and macroscopic damage field, and then obtain the temperature history and strain history characterizing the damage evolution. S3. Based on the temperature history and strain history, perform micro-thermal coupling calculation on the micro-geometric model of the warhead charge to obtain the micro-damage field, and then determine the stiffness reduction factor of the macro-charge material. Based on the stiffness reduction factor, update the constitutive model of the charge entity element in the macro-finite element model of the warhead. S4. Repeat steps S2 to S3 until the preset stopping condition is met to obtain the final macroscopic temperature field, macroscopic damage field and corresponding microscopic damage evolution results; wherein, the microscopic damage evolution results include the microscopic damage field of the microscopic geometric model and the time history data of the damage factor of each cohesive unit.

2. The method of claim 1, wherein, Acquire aerodynamic and thermodynamic coupling load data of the warhead under hypersonic flight conditions, including: A geometric model of the external fluid domain of the warhead was established and meshed. The calculation conditions for the fluid domain material and flight conditions were set, and numerical calculations of the flow field were carried out. The pressure distribution and heat flux density distribution of the outer wall of the warhead shell were extracted to obtain an aero-thermal coupling load dataset. The aero-thermal coupling load dataset includes the three-dimensional spatial coordinates of the mesh nodes of the outer wall of the warhead shell and their corresponding wall pressure and heat flux density values. The fluid domain material is air, and the calculation conditions include flight speed, flight angle of attack, atmospheric pressure, and atmospheric temperature.

3. The method of claim 1, wherein, The embedding of cohesive units between the physical units of the warhead charge includes: A zero-thickness cohesive element is embedded at the common surface of adjacent solid elements within the warhead charge area. The constitutive model of the cohesive element is a traction-separation constitutive model. Its constitutive model parameters include cohesive stiffness, damage initiation strength, and maximum damage displacement, and at least one parameter changes dynamically with the current temperature and strain rate values.

4. The method of claim 3, wherein, The relationship between the constitutive parameters and temperature is described by a linear softening function, an exponential decay function, or a piecewise linear function. Among these, as the temperature increases, the cohesive stiffness and damage initiation strength decrease, while the maximum damage displacement increases. The relationship between the constitutive parameters and strain rate is described by a logarithmic function or a power function. Among these, as the strain rate increases, the cohesive stiffness and damage initiation strength increase, while the maximum damage displacement decreases.

5. The method of claim 4, wherein, The constitutive model parameters of the solid units of the warhead charge embedded in the cohesive elements are as follows: cohesion stiffness is expressed as: ； In the formula, This represents the initial cohesive stiffness at the reference temperature and reference strain rate. This indicates the cohesive unit at the current temperature. The softening value at that temperature This indicates the cohesive element at the current strain rate. The strain rate intensification value at that time; damage initiation strength is expressed as: ； In the formula, denotes the maximum normal stress at the reference temperature, the reference strain rate; Maximum damage displacement is represented as: ； In the formula, This represents the maximum damage displacement at the reference temperature and reference strain rate. This indicates the cohesive unit at the current temperature. Temperature toughness value at that time This indicates the cohesive element at the current strain rate. The strain rate brittleness value at that time.

6. The method of claim 2, wherein, The macroscopic temperature field and macroscopic damage field are obtained in the following way: The three-dimensional spatial coordinates of the mesh nodes on the outer wall of the warhead shell and their corresponding wall pressure values ​​in the aero-thermal coupling load dataset are used as the external loads of the structure, and the three-dimensional spatial coordinates of the mesh nodes on the outer wall of the warhead shell and their corresponding wall heat flux density values ​​are used as the thermal boundary conditions. These are mapped to the corresponding nodes on the outer surface of the shell of the macroscopic finite element model through spatial interpolation, and then thermo-mechanical coupling calculations are performed to obtain the macroscopic temperature field and macroscopic damage field.

7. The method of claim 1, wherein, The temperature and strain histories characterizing damage evolution were obtained in the following ways: Extract the temperature values ​​of the solid units on both sides of the cohesive unit with the largest damage factor in the macroscopic damage field, take the average value as the representative temperature at the location of the cohesive unit, record its value at each time point in the thermo-coupling calculation time history, construct a function of temperature change over time as the temperature history. Extract the strain component values ​​of the solid elements on both sides of the cohesive element with the largest damage factor in the macroscopic damage field, take the average value as the representative strain at the location of the cohesive element, record the values ​​at each time point in the thermo-coupling calculation time history, and construct a function of the strain component changing with time as the strain history.

8. The method of claim 1, wherein, The constitutive model of the charge solid element in the macroscopic finite element model of the warhead updated based on the stiffness reduction coefficient includes: The initial elastic matrix of the macroscopic charge solid element is multiplied by the stiffness reduction factor to obtain the updated elastic matrix, which is then used in the next round of macroscopic thermo-coupling calculations. The initial elastic matrix of the macroscopic charge solid element is the linear elastic constitutive matrix of the macroscopic charge material when no damage occurs.

9. The method of claim 1 or 8, wherein, The rigidity reduction coefficient of the macroscopic charge material is represented as: ； In the formula, This represents the total volume of the mesoscopic geometric model. This represents the total number of cohesive elements in the mesoscopic geometric model. Representing the mesoscopic geometric model Damage factor of each cohesive unit Representing the mesoscopic geometric model The virtual volume of each cohesive unit Representing the mesoscopic geometric model The weighting coefficient of each cohesive unit.

10. The method of claim 2, wherein, Repeat steps S1 to S4 under different flight angle of attack conditions to obtain the macroscopic damage field corresponding to each angle of attack. Extract the spatial location of the damage peak region and the peak value of the damage variable under each angle of attack, and establish the mapping relationship between the flight angle of attack and the characteristic parameters of the damage peak. For the target angle of attack that has not been analyzed, use the mapping relationship to predict the spatial location of the damage peak region and the peak value of the damage variable under the target angle of attack. Among them, the spatial location of the damage peak region is the coordinate of the maximum value of the damage factor, and the peak value of the damage variable is the damage factor value of the damage peak region.

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