CN112116128A - Simulation prediction method for structural spalling and multiple spalling under impact load action - Google Patents

Simulation prediction method for structural spalling and multiple spalling under impact load action Download PDF

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CN112116128A
CN112116128A CN202010841404.9A CN202010841404A CN112116128A CN 112116128 A CN112116128 A CN 112116128A CN 202010841404 A CN202010841404 A CN 202010841404A CN 112116128 A CN112116128 A CN 112116128A
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顾鑫
杨思阳
章青
夏晓舟
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Hohai University HHU
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Abstract

The invention discloses a novel method for simulating and predicting structural spalling and multiple spalling under the action of impact load, and belongs to the technical field of simulation of materials and structural damage. Building a structure entity model, endowing material parameters to each region, and using a substance point set to disperse the structure; determining a key association near field range based on the point association near field range, defining a key association non-local deformation gradient tensor, establishing a key association force vector state and a near field dynamics strong form equation, and greatly breaking through the accuracy and stability limitations of the original non-conventional state type near field dynamics; constructing an elastic-plastic damage constitutive updating algorithm; setting initial conditions and boundary conditions, updating the position and speed of a substance point in real time by adopting a Verlet algorithm, describing the damage and cracking of a structure by using a key breaking rule, and analyzing the position, thickness and time of the spallation. The method can stably and accurately predict the structural spalling and multiple spalling problems under the action of the impact load.

Description

Simulation prediction method for structural spalling and multiple spalling under impact load action
Technical Field
The invention belongs to the technical field of simulation of materials and structural damage, and particularly relates to a novel method for simulation prediction of structural deformation spallation and multiple spallation damage under the action of impact load, namely a bond-related unconventional near-field dynamics method.
Background
The spalling and the multiple spalling are typical failure modes of a solid structure under the action of dynamic load, particularly when an obvious impact load source and a free boundary surface exist, incident impact compression waves are easy to be reflected to form tensile waves on the free boundary surface, and the tensile waves and the compression waves jointly act to cause the stress state of the material to exceed the tensile strength, so the spalling and the multiple spalling occur.
At present, publicly published simulation prediction research on the spallation and the multiple spallation is quite deficient, the root of the research is that classical continuous medium mechanics has certain theoretical limit, methods such as molecular dynamics have calculation scale limit, and dynamic load conditions aggravate the complexity of the problem, so that the theoretical method and the numerical calculation tool for simulation prediction of the spallation and the multiple spallation of the macroscopic solid structure are still quite deficient, and the development and analysis reliability of simulation prediction of spallation and multiple spallation damage of the structure are greatly limited.
Solid structure failure simulation is a problem which is long-term concerned by academic and engineering circles, structural spallation and multiple spallation are typical phenomena of solid failure, a conventional modeling analysis method for the discontinuity problems is a traditional continuous medium mechanical theory based on partial differential equations and a finite element method thereof, but the method is lack of length scale parameters for describing fractures, needs to preset crack paths and crack propagation criteria, and therefore the problems of discontinuity singularity, grid dependence, inaccurate fracture description, calculation precision bottleneck and the like are faced; an extended finite element method and various non-grid methods are developed later, but the extended finite element method is difficult to track crack surfaces when complex three-dimensional fracture is processed, and the non-grid method has advantages in structural large deformation simulation analysis, but still has the problems of low calculation precision and calculation efficiency and singularity at discontinuous parts. Non-local near-field dynamics (Peridynamics) adopts a space integral equation to describe the mechanical behavior of a substance, introduces a length scale parameter for describing structural fracture, avoids the singularity of the traditional numerical calculation method in solving the discontinuous problem, and shows the inherent advantages in analyzing fracture damage problems such as crack propagation, spallation and the like.
However, there are some points to be developed and perfected by the three types of mainstream models (bond-type, conventional-type, and unconventional-type near-field dynamics) of the existing near-field dynamics and the gridless particle method thereof. The key type and conventional state near field dynamics are not enough in description of complex mechanical behaviors such as plasticity and strain rate effects, the relation with the traditional stress-strain tensor is not tight enough, and the unconventional state near field dynamics can effectively overcome the limitation, but developed unconventional state near field dynamics models show numerical instability phenomena of displacement oscillation during static and dynamic deformation calculation (Gu X, Madenci E, Zhang Q.Recisit of non-ideal state-based characteristics. engineering performance mechanics.2018; 190:31-52.), and the models need to be further perfected and the calculation efficiency is improved.
Furthermore, in Gu X, Zhang Q, Madenci E, Xia X.positional housings of numerical pathologies in non-organized state-based peridynamics and a bond-organized high-level-organized model. computer Methods in Applied Mechanics and engineering.2019; 357, 112592, deeply analyzing the reasons of numerical instability of the unconventional near field dynamics method, firstly providing the unconventional near field dynamics method associated with the key, providing a corresponding static numerical implementation method and carrying out static deformation reference example analysis; however, the application of the method in structural dynamic deformation, especially damage cracking, is not developed, and the model algorithm needs to be further improved. Therefore, it is necessary to develop a key-associated abnormal near-field dynamics model and a numerical algorithm, apply the key-associated abnormal near-field dynamics model and the numerical algorithm to the solid structure spallation and multiple spallation damage analysis, and provide theoretical modeling and numerical implementation details so as to fully exert the advantages of the near-field dynamics in analyzing the discontinuous problems and effectively guide engineering practice.
In summary, the problems of the prior art are as follows:
(1) when the traditional numerical methods such as a continuous medium mechanics theory, a finite element and the like are used for processing the discontinuity problems of spallation and multi-spallation damage, the problems of discontinuity singularity, grid dependency, inaccurate fracture description and bottleneck of calculation precision are faced.
(2) The existing bond type and conventional state type near field dynamics are not enough in description of complex mechanical behaviors such as plasticity and strain rate effect and are not closely related to the traditional stress-strain tensor.
(3) The existing unconventional state near-field dynamics model shows the numerical instability phenomenon of displacement oscillation during static and dynamic deformation calculation, the existing key-associated unconventional state near-field dynamics method can effectively solve the problems, but the method is still in the research and perfection stage, the details of theoretical modeling and numerical implementation of the general three-dimensional dynamic deformation problem are lacked, and the application and analysis of the example are also insufficient.
The difficulty in solving the technical problems is as follows: aiming at the problem of spallation and multiple spallation caused by general three-dimensional structure dynamic deformation under the action of impact dynamic load, a key-associated unconventional state type near field dynamics theoretical model and algorithm formula need to be constructed, and a perfect numerical solving system is provided, wherein the perfect numerical solving system comprises a calculation method of deformation gradient, strain, stress, force vector state and the like, a boundary condition applying method, a time stepping algorithm, a broken key damage method, a false motion deformation inhibiting method and the like.
The significance of solving the technical problems is as follows: the method for developing the unconventional state type near field dynamics associated with the key can perfect a near field dynamics model and a numerical value solving system, enhance the relation between the near field dynamics and the classical continuous medium mechanics, effectively eliminate the instability problem of numerical value oscillation of the original unconventional state type near field dynamics, effectively improve the calculation precision and stability of power deformation and damage problems, lay a theoretical foundation for deeply developing calculation simulation and damage prediction evaluation of solid structure spallation and multiple spallation damage under the action of impact load, simultaneously have wide applicability, and can meet the design calculation requirements of complex models under various complex impact load conditions.
Disclosure of Invention
The invention aims to solve the problems of bottleneck faced by the discontinuous problem of the traditional continuous medium mechanical treatment, imperfect existing near-field dynamics theoretical model and numerical solving system, and deficient simulation prediction and analysis means of solid structure impact spallation and multiple spallation damage. The invention provides a key-associated unconventional state near field dynamics modeling and solving method for simulation and prediction of structural spallation and multiple spallation under the action of an impact load, which gives full play to the advantages of the accurate stability and fracture damage analysis of the key-associated unconventional state near field dynamics and provides a scientific method for the accurate simulation of the problems of the impact spallation and the multiple spallation.
In order to realize the purpose of the invention, the technical scheme adopted by the invention is as follows: a simulation and prediction method for structural spalling and multiple spalling under the action of impact load comprises the following steps:
establishing a structural entity model, determining each material area and endowing corresponding material attributes;
generating a uniform and orthogonal discrete material point set, wherein the size of the material points meets the calculation precision requirement;
generating a near field range associated with the point and a near field range associated with the key according to the size of the substance point and the characteristic scale of the loaded material structure;
fourthly, constructing a key correlation non-local deformation gradient tensor and a key correlation force vector state based on the key correlation near field range, and constructing a new integral type strong form near field dynamics motion equation;
step five, updating the strain rate tensor, the stress tensor, the force vector state and the resultant force borne by the material point in real time according to a constitutive model updating algorithm in a strain rate-stress increment form, and giving a stress deformation calculation method of the whole configuration;
step six, initially assigning values to deformation gradient, strain, stress, force vector state, resultant force and damage variable, setting initial conditions, and applying physical force, stress and displacement boundary conditions;
step seven, performing explicit dynamics calculation, and updating the position, the speed and the acceleration of the material point in real time; describing damage cracking by adopting a critical elongation bond breaking criterion; and outputting displacement results and damage results at different moments, recording the position and time of damage close to a critical value, calculating the time and position of multiple times of occurrence of the spalling and the thickness of each time of spalling, and carrying out spalling and multiple spalling analysis of the solid structure under the action of the impact load.
Further, in the second step, the method for generating the set of discrete material particles is as follows:
the method comprises the steps of carrying out uniform orthogonal grid-free particle division on the whole structure solid model, wherein N material points are in total, the two-dimensional model adopts square material points, the three-dimensional model adopts cubic material points, the size d of each material point is L/400-L/50, and L is the maximum side length of the solid model.
Further, in the third step, according to the size d of the matter point and the characteristic dimension of the loaded material structure, determining that the radius of the near field range is mxd, where m is the ratio of the near field range to the size of the matter point, and usually the value of m is 3; determining the near field range H associated with the point according to the initial position coordinates and the near field range radius of the material pointxAnd Hx′Expressed as:
Hx＝H(x,)＝{x′∈R:{||x′-x||≤}},
Hx′＝H(x′,)＝{x″∈R:{||x″-x′||≤}}
wherein, x, x' is the coordinates of the material points in the initial configuration;
furthermore, the object points x and x' at the two ends of the bond are considered to have the same importance, and the near field range radius is selected as a key parameter to define HxAnd Hx′Is the near field range H of the key associationξNamely, the following steps are provided:
Hξ＝Hx∩Hx′；
where ξ ═ x' -x is the initial relative position vector between the particles, and also represents the bond between the two particles.
Further, in the fourth step, a new key correlation non-local deformation gradient tensor F is defined based on the key correlation near-field rangebPoint-associated non-local deformation gradient tensor
Figure BDA0002641567240000041
Respectively as follows:
Figure BDA0002641567240000042
Figure BDA0002641567240000043
wherein, omega is an influence function,Yfor deformation of vector states, dVx′Integration of volume for material point x', KbA shape tensor that is a key association and has:
Figure BDA0002641567240000044
further, in the fourth step, based on the near field range of key correlation, a new key correlation force vector t is deduced and established by adopting an energy equivalent methodbOr force vector stateT b[x,t]Expressed as:
Figure BDA0002641567240000045
wherein t is a time variable, PbThe first Piola-Kirchoff stress tensor for bond association, square bracket<·>Representing the force vector state to act on a certain key to obtain a force vector;
further, a new integrated strong form near field dynamics equation of motion is constructed as follows:
Figure BDA0002641567240000046
where ρ is0Is the material mass density, u is the acceleration of the material point, and b is the vector of the physical density applied to the material point.
Further, according to the relation Pb＝det(Fb)σb(Fb)-TObtaining a first Piola-Kirchoff stress tensor P for bond associationbWherein σ is the rotated Cauchy stress tensor; according to the relation σ ═ R τ RTObtaining σ from the unrotated Cauchy stress tensor τ, where R is the rotationA tensor; the rotation-free Cauchy stress tensor tau is obtained by a strain rate-stress increment form constitutive updating algorithm, specifically, a speed gradient tensor L is obtained according to a deformation gradient tensor F, and then a deformation rate tensor D, a rotation rate tensor W and a rotation-free deformation rate tensor D are obtained; starting from the deformation rate tensor d, updating the constitutive of the incremental form to obtain the rotation-free Cauchy stress tensor tau.
Further, giving initial moment displacement and speed, applying time-related physical strength, stress and displacement boundary conditions, and realizing time-stepping iterative loop calculation through a differential algorithm in an explicit Verlet speed format to obtain speed and displacement at t + delta t time, namely:
Figure BDA0002641567240000047
Figure BDA0002641567240000051
Figure BDA0002641567240000052
wherein t is the current deformation moment, delta t is the time step length, and n is the calculation step number;
Figure BDA0002641567240000053
velocity of the object point at times t + Δ t and t, u(n+1),u(n)The displacement of the mass point at time t + Δ t and t, respectively.
Compared with the prior art, the technical scheme of the invention has the following beneficial technical effects:
(1) the invention gives an explicit dynamics non-grid particle method of unconventional near field dynamics associated with a key for the first time, expands and perfects a near field dynamics model and a numerical solving system, and lays a foundation for engineering application of the near field dynamics.
(2) The invention provides the near field range of key association, the non-local deformation gradient of key association, the force vector state of key association and a new strong form near field dynamics motion equation, completely realizes the modeling analysis of key hierarchy, breaks through the problems of the theoretical model and numerical calculation of the original unconventional state type near field dynamics, and effectively improves the calculation precision and stability of the structural dynamics deformation and damage problems.
(3) The invention adopts the virtual bond breaking rule among the non-grid particles, can naturally describe the whole process from structural damage accumulation, crack propagation to fracture, has complete and reliable method and excellent effect on the analysis of the problems of impact spallation and multiple spallation.
(4) The method can efficiently, accurately and stably solve the problems of static and dynamic deformation, elastic wave propagation and cracking damage of the structure, has high calculation precision and stability and wide applicability, and meets the design requirements of complex structures under various complex impact conditions.
Drawings
FIG. 1 is a flow chart of a method of an embodiment of the present invention;
FIG. 2 is a schematic diagram of an embodiment of the present invention;
FIG. 3(a) is a schematic diagram of a point-correlated near field range provided by an embodiment of the present invention;
FIG. 3(b) is a schematic diagram of a key association near field range provided by an embodiment of the present invention;
FIG. 4 is a schematic diagram of a solid model containing geometry and impact loading information according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a shock waveform applied to a dummification front end provided by an embodiment of the present invention;
6(a) -6 (e) are schematic diagrams of the damage distribution in the damage cracking process according to the calculation results provided by the embodiment of the invention;
fig. 7(a) -7 (e) are schematic diagrams of axial displacement distribution in the damage cracking process according to the calculation results provided by the embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
As shown in fig. 1, a modeling and solving process of the bond-related unconventional near-field dynamics method for simulation and prediction of structural spallation and multiple spallation under the action of an impact load provided by the embodiment of the invention is shown in fig. 2, and the method has high reliability when being used for structural impact spallation and multiple spallation analysis. In the embodiment, the dynamic deformation and the multiple-layer fracture damage of the concrete three-dimensional square rod with the size of 1000mm multiplied by 100mm under the action of the triangular pulse load are taken as examples, and the near-field dynamics modeling and analysis are carried out by using the method disclosed by the invention; young modulus is 34GPa, Poisson ratio is 0.1454, and mass density is 2400kg/m3With an energy release rate of GF175MN/m, giving JH-2 constitutive model parameters; one end of the rod piece is acted by the uniform triangular unloading carrier wave, the amplitude of the rod piece is 90kN, the acting time is 360 mu s, and other surfaces of the rod piece are free and unconstrained. The specific implementation comprises the following steps:
s101: and establishing a structural entity model, determining each material area and endowing corresponding material attributes. In this embodiment, a physical model is established, the outer dimension of the model is 1000mm × 100mm × 100mm, the same material parameters are given to the material, and the physical model is shown in fig. 4.
S102: generating a uniform and orthogonal discrete material point set, wherein the size of the material points meets the calculation precision requirement; the method comprises the following specific steps: the whole structure solid model is divided into uniformly orthogonal grid-free particles, and the total number of the particles is N, wherein a two-dimensional model adopts square particles, a three-dimensional model adopts cubic particles, the size d of the particles is L/100 which is 0.01m, L is the maximum side length of the solid model, and the embodiment disperses the particles to obtain N which is 12221 particles.
S103: generating a near field range associated with the point and a near field range associated with the key according to the size of the substance point and the characteristic scale of the loaded material structure; specifically, according to the size d of a matter point and the characteristic scale of a loaded material structure, the radius of a near field range is determined to be 3 d; determining the near field range H associated with the point according to the initial position coordinates and the near field range radius of the material pointxAnd Hx′Expressed as:
Hx＝H(x,)＝{x′∈R:{||x′-x||≤}},
Hx′＝H(x′,)＝{x″∈R:{||x″-x′||≤}}
wherein, x, x' is the coordinates of the material points in the initial configuration;
furthermore, the key parameters are the near field radius, defined as H in FIG. 3, considering that the object points x and x' at the two ends of the bond have the same importancexAnd Hx′Is the near field range H of the key associationξNamely, the following steps are provided:
Hξ＝Hx∩Hx′；
where ξ ═ x' -x is the initial relative position vector between the particles, and also represents the bond between the two particles.
S104: introducing a near field range of key association to construct a non-local deformation gradient tensor of key association and a force vector state of key association, and constructing a new integral type strong form near field dynamics motion equation; updating a strain rate tensor, a stress tensor, a force vector state and resultant force borne by a material point in real time according to a constitutive model updating algorithm in a strain rate-stress increment form, and giving a stress deformation calculation method of the whole configuration;
defining a new key-associated non-local deformation gradient tensor F based on the key-associated near-field rangebPoint-associated non-local deformation gradient tensor
Figure BDA0002641567240000061
Respectively as follows:
Figure BDA0002641567240000062
Figure BDA0002641567240000071
wherein, omega is an influence function,Yfor deformation of vector states, dVx′Integration of volume for material point x', KbA shape tensor that is a key association and has:
Figure BDA0002641567240000072
based on the key correlation near field range, a new key correlation force vector t is deduced and established by adopting an energy equivalent methodbOr force vector stateT b[x,t]Expressed as:
Figure BDA0002641567240000073
wherein t is a time variable, PbThe first Piola-Kirchoff stress tensor for bond association, square bracket<·>Representing the force vector state to act on a certain key to obtain a force vector;
further, a new integrated strong form near field dynamics equation of motion is constructed as follows:
Figure BDA0002641567240000074
where ρ is0Is the material mass density, u is the acceleration of the material point, and b is the vector of the physical density applied to the material point.
According to the relation Pb＝det(Fb)σb(Fb)-TObtaining a first Piola-Kirchoff stress tensor P for bond associationbWherein σ is the rotated Cauchy stress tensor; according to the relation σ ═ R τ RTObtaining sigma from the unrotated Cauchy stress tensor tau, wherein R is a rotation tensor; the rotation-free Cauchy stress tensor tau is obtained by a strain rate-stress increment form constitutive updating algorithm, specifically, a speed gradient tensor L is obtained according to a deformation gradient tensor F, and then a deformation rate tensor D, a rotation rate tensor W and a rotation-free deformation rate tensor D are obtained; starting from the deformation rate tensor d, updating the constitutive of the incremental form to obtain the rotation-free Cauchy stress tensor tau. In the embodiment, the concrete JH-2 constitutive model is selected, and the influence machine of the strength, strain rate, pressure and damage state of the material on the structural mechanical response can be fully reflectedAnd (5) preparing.
S105: initially assigning values to deformation gradient, strain, stress, force vector state, resultant force and damage variable, setting initial conditions, giving initial moment displacement and speed, and applying time-dependent physical force, stress and displacement boundary conditions;
in this embodiment, the initial conditions are set as follows: initial displacement u of all nodes is 0 and initial velocity
Figure BDA0002641567240000075
With a uniform physical force varying with time, a triangular unloading shock wave with an amplitude of 90kN and an action time of 360 mus was applied to one end of the rod, as shown in fig. 5.
S106: performing explicit dynamics calculation, and updating the position, the speed and the acceleration of the material point in real time through iterative loop calculation; specifically, for the dynamic deformation and cracking damage problem of this embodiment, time stepping is implemented by using a differential algorithm in an explicit Verlet speed format, and the speed and displacement of t + Δ t time are obtained, that is:
Figure BDA0002641567240000076
Figure BDA0002641567240000081
wherein t is the current deformation moment, Δ t is the time step,
Figure BDA0002641567240000082
velocity of the object point at times t + Δ t and t, u(n+1),u(n)Respectively displacement of the material point at t + delta t and t moment;
Figure BDA0002641567240000083
s107: after an explicit dynamics calculation result is obtained, a critical elongation broken key criterion is adopted to describe damage cracking, displacement results and damage results at different moments are output, as shown in fig. 6 and 7, the position and time of damage close to a critical value of 0.5 are recorded, the time and position of multiple times of occurrence of spalling and the thickness of each time of spalling are calculated, and the calculated stability and precision are high, so that spalling and multiple spalling analysis of a solid structure under the action of impact load is carried out.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims (7)

1. A simulation prediction method for structural spalling and multiple spalling under the action of impact load is characterized by comprising the following steps: the method comprises the following steps:
establishing a structural entity model, determining each material area and endowing corresponding material attributes;
generating a uniform and orthogonal discrete material point set, wherein the size of the material points meets the calculation precision requirement;
generating a near field range associated with the point and a near field range associated with the key according to the size of the substance point and the characteristic scale of the loaded material structure;
fourthly, constructing a key correlation non-local deformation gradient tensor and a key correlation force vector state based on the key correlation near field range, and constructing a new integral type strong form near field dynamics motion equation;
step five, updating the strain rate tensor, the stress tensor, the force vector state and the resultant force borne by the material point in real time according to a constitutive model updating algorithm in a strain rate-stress increment form;
step six, initially assigning values to deformation gradient, strain, stress, force vector state, resultant force and damage variable, setting initial conditions, and applying physical force, stress and displacement boundary conditions;
step seven, performing explicit dynamics calculation, and updating the position, the speed and the acceleration of the material point in real time; describing damage cracking by adopting a critical elongation bond breaking criterion; and outputting displacement results and damage results at different moments, recording the position and time of damage close to a critical value, calculating the time and position of multiple times of occurrence of the spalling and the thickness of each time of spalling, and carrying out spalling and multiple spalling analysis of the solid structure under the action of the impact load.
2. The simulation prediction method for structural spallation and multiple spallation under the action of impact load as recited in claim 1, wherein the simulation prediction method comprises the following steps: in the second step, the method for generating the set of discrete particles is as follows:
the method comprises the steps of carrying out uniform orthogonal grid-free particle division on the whole structure solid model, wherein N material points are in total, the two-dimensional model adopts square material points, the three-dimensional model adopts cubic material points, the size d of each material point is L/400-L/50, and L is the maximum side length of the solid model.
3. The simulation prediction method for structural spallation and multiple spallation under the action of impact load as claimed in claim 1 or 2, wherein: in the third step, according to the size d of the matter point and the characteristic scale of the loaded material structure, determining that the radius of the near field range is m × d, wherein m is the ratio of the near field range to the size of the matter point; determining the near field range H associated with the point according to the initial position coordinates and the near field range radius of the material pointxAnd Hx′Expressed as:
Hx＝H(x,)＝{x′∈R:{||x′-x||≤}},
Hx′＝H(x′,)＝{x″∈R:{||x″-x′||≤}}
wherein, x, x' is the coordinates of the material points in the initial configuration;
definition HxAnd Hx′Is the near field range H of the key associationξNamely, the following steps are provided:
Hξ＝Hx∩Hx′；
where ξ ═ x' -x is the initial relative position vector between the particles, and also represents the bond between the two particles.
4. A structure for use under impact load as claimed in claim 3The simulation and prediction method for the spalling and the multiple spalling is characterized in that: in the fourth step, a new key association non-local deformation gradient tensor F is defined based on the key association near-field rangebPoint-associated non-local deformation gradient tensor
Figure FDA0002641567230000021
Respectively as follows:
Figure FDA0002641567230000022
Figure FDA0002641567230000023
wherein, omega is an influence function,Yfor deformation of vector states, dVx′Integration of volume for material point x', KbA shape tensor that is a key association and has:
Figure FDA0002641567230000024
5. the simulation prediction method for structural spallation and multiple spallation under the action of impact load as recited in claim 4, wherein the simulation prediction method comprises the following steps: in the fourth step, based on the near field range of key correlation, a new key correlation force vector t is deduced and established by adopting an energy equivalent methodbOr force vector stateT b[x,t]Expressed as:
Figure FDA0002641567230000025
wherein t is a time variable, PbThe first Piola-Kirchoff stress tensor for bond association, square bracket<·>Representing the force vector state to act on a certain key to obtain a force vector;
further, a new integrated strong form near field dynamics equation of motion is constructed as follows:
Figure FDA0002641567230000026
where ρ is0Is the mass density of the material and is,
Figure FDA0002641567230000027
is the acceleration of the material point, and b is the physical strength density vector of the material point.
6. The simulation prediction method for structural spallation and multiple spallation under the action of impact load as recited in claim 5, wherein the simulation prediction method comprises the following steps: according to the relation Pb＝det(Fb)σb(Fb)-TObtaining a first Piola-Kirchoff stress tensor P for bond associationbWherein σ is the rotated Cauchy stress tensor; according to the relation σ ═ R τ RTObtaining sigma from the unrotated Cauchy stress tensor tau, wherein R is a rotation tensor; the rotation-free Cauchy stress tensor tau is obtained by a strain rate-stress increment form constitutive updating algorithm.
7. The simulation prediction method for structural spalling and multiple spalling under the action of the impact load as recited in claim 6, wherein: giving initial moment displacement and speed, applying time-related physical strength and stress and displacement boundary conditions, and realizing time-stepping iterative loop calculation through a differential algorithm in an explicit Verlet speed format to obtain speed and displacement at t + delta t time, namely:
Figure FDA0002641567230000031
Figure FDA0002641567230000032
Figure FDA0002641567230000033
wherein t is the current deformation time, Δ t is the time step, subscripts n and n +1 respectively correspond to time t and t + Δ t, and n is the number of calculation steps;
Figure FDA0002641567230000034
velocity of the object point at times t + Δ t and t, u(n+1),u(n)The displacement of the mass point at time t + Δ t and t, respectively.
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