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Time discontinuous state-based near-field dynamics method for structure impact elastic-plastic fracture analysis

A technology of structural impact and elastoplasticity, applied in the field of computational mechanics, can solve problems such as reducing the difficulty of numerical implementation, reducing numerical accuracy, reducing the complexity of fracture mechanics damage representation, etc., achieving the goal of simple numerical simulation method, reducing complexity and reducing difficulty Effect

Active Publication Date: 2022-03-15
DALIAN UNIV OF TECH
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  • Application Information

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Problems solved by technology

[0009] The technical problem to be solved by the present invention: Based on the idea of ​​time discontinuity and the method of state-based peridynamics, combined with the classical constitutive model, the present invention conducts research on damage and fracture caused by stress waves under structural impact loads, and innovatively proposes a A time-discontinuous state-based peridynamics method (Time-discontinuous state-based peridynamics, referred to as SBPD-TD), the purpose of which is to solve the following problems existing in the prior art: the use of time-discontinuous methods to overcome the traditional time history integration format is difficult to accurately Capture the high gradient characteristics of the stress solution and the shortcomings of false numerical oscillations; use the peridynamic model to overcome the inherent singularity of the fracture behavior that is difficult to describe under the traditional continuum mechanics framework, and reduce the difficulty of numerical implementation; overcome the traditional The finite element method (FEM) has the disadvantage that the numerical accuracy is seriously reduced due to mesh distortion when simulating the elastoplastic fracture and failure of materials with finite deformation; the state-based peridynamics method is used to compensate for the poise caused by the bond-based peridynamics method. The loose ratio is fixed and it is not easy to introduce the shortcomings of the classical constitutive relationship; the Johnson-Cook model is used to calculate the impact response of the material and introduce a variety of simple damage characterizations, which reduces the complexity of traditional fracture mechanics damage characterization

Method used

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  • Time discontinuous state-based near-field dynamics method for structure impact elastic-plastic fracture analysis
  • Time discontinuous state-based near-field dynamics method for structure impact elastic-plastic fracture analysis
  • Time discontinuous state-based near-field dynamics method for structure impact elastic-plastic fracture analysis

Examples

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Effect test

Embodiment 1

[0149] Example 1: Propagation of Stress Waves in Elastoplastic Rods (attached Figure 4~5 )

[0150] This example is a standard numerical example, considering the propagation of stress waves in a one-dimensional structure, the structure size and boundary conditions are as follows Figure 4 shown. The length of the rod is 10m, which is discretized into 5000 material points. The right end of the rod is free, and its left end is subject to impact load,

[0151]

[0152] Using Johnson-Cook constitutive model, Young's modulus E=10000Pa, Poisson's ratio ν=0, mass density ρ=1kg / m 3 . The material constants of the Johnson-Cook model are A=5Pa, B=600Pa, m 1 =0.7, C=0. Figure 5 Illustrated at t a = 0.055s and t b = 0.135s Stress wave distributions obtained using time-discontinuous state-based peridynamics SBPD-TD and peridynamics-coupled central difference method SBPD-CDM, respectively. Since the plastic modulus varies with the stress state, the propagation of the stress wa...

Embodiment 2

[0153] Embodiment 2: the prediction of elastoplastic rod fracture position (attachment Figure 6~7 )

[0154] This embodiment is an example of predicting the fracture position of an elastoplastic rod under impact load. Peridynamics, as a non-local theory, can overcome the singularity problems encountered in traditional continuum mechanics damage research to a certain extent. Therefore, peridynamics has a significant advantage in dealing with fracture problems. In the following, a numerical example is used to illustrate the advantages and necessity of time-discontinuous state-based peridynamics in predicting crack locations. First consider a bar that can be compressed but can only bear a low tensile stress. The dimensions of the model and the boundary conditions are as follows Figure 4 shown. The length of the rod is 10m, which is discretized into 5000 material points. The right end of the rod is free, and the left end is subjected to impact load as shown in formula (44)....

Embodiment 3

[0157] Embodiment 3: the impact fracture problem of two-dimensional elastoplastic plate (attachment Figure 8-10 )

[0158] This example is a verification example of a two-dimensional impact fracture test, which was completed by Zhou et al. Figure 8 For the model size and boundary conditions (the unit of length is mm), the plate is evenly divided into 100×200 material points. Its elastic modulus E=192GPa, Poisson's ratio ν=0.3, mass density ρ=7830kg / m 3 . Using a linear hardening model, the initial yield stress σ y0 =2GPa, plastic modulus E p = 200 GPa. Impact velocity v=25m / s. According to the experimental observation, when the impact velocity is 20m / s Figure 9 It can be seen that the SBPD-TD method effectively suppresses the serious numerical oscillation caused by SBPD-CDM. The final damage morphology of the plate is as follows Figure 10 shown.

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Abstract

The invention belongs to the field of computational mechanics, and provides a time-discontinuous state-based near-field dynamics method for structural impact elastic-plastic fracture analysis, which introduces a time-discontinuous idea into a state-based near-field dynamics theory, and effectively improves the precision of near-field dynamics explicit dynamic analysis and the capability of accurately predicting structural fracture damage. According to the method, false numerical oscillation caused by a traditional time-history integral method can be effectively controlled by adopting a time-discontinuous explicit time-history integral format, and complex mechanical behaviors of the material under the impact load are simply, conveniently and comprehensively described by adopting an unconventional state-based near-field dynamic model; and the impact fracture failure mode of the structure is effectively represented through a plurality of damage fracture criteria. In addition, a material point neighborhood is constructed and a contact neighborhood is updated by adopting a fast neighborhood search algorithm, so that the calculation efficiency is improved. As a new numerical solution format, the method provided by the invention can be realized by simply modifying an original calculation program, and the numerical implementation complexity is reduced.

Description

technical field [0001] The invention belongs to the field of computational mechanics, and in particular relates to a time-discontinuous state-based perifield dynamics method for structure impact elastic-plastic fracture analysis. Background technique [0002] Impact damage problems widely exist in engineering practice, such as landslides caused by earthquakes, the interaction between neutron bombs and targets in the development of military weapons, the drop of electronic products in daily life, and the interaction between icebreakers and ice in polar scientific expeditions. It can be said that there is a high probability of impact load and impact dynamics problems in engineering accidents; and for the research and development of military and civilian products, the research on the dynamic fracture mechanics behavior of materials is even more inevitable. Therefore, the impact fracture mechanical behavior analysis of structures plays an important role in disaster prevention and...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F30/23G06F30/28G06F17/13G06F119/14
CPCG06F30/23G06F17/13G06F30/28G06F2119/14
Inventor 郑勇刚刘振海胡志强张洪武叶宏飞张家永章子健
Owner DALIAN UNIV OF TECH
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