Mechanics of Materials最新文献_第10页

The influences of temperature on the macroscopic elastoplastic behaviors of heterogeneous materials 温度对异质材料宏观弹塑性行为的影响

IF 3.4 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2024-10-16 DOI: 10.1016/j.mechmat.2024.105176

W.Q. Shen

The microstructure of heterogeneous materials affects importantly their macroscopic mechanical behavior. For a thermal-mechanical coupling problem, the temperature also has a significant effect. Firstly, the effect of temperature on the elastic behavior of heterogeneous material has been investigated in the present work with the consideration of its microstructure. Then, an explicit expression of the macroscopic yield criterion has been derived for the plastic behavior of porous material by using the homogenization approach. This yield criterion takes into account explicitly and simultaneously the influence of porosity and the effect of temperature on its overall mechanical behavior. To consider the pressure sensitivity of the matrix, the Drucker–Prager type criterion is adopted at the microscopic scale. After that, the heterogeneous material with a matrix reinforced by rigid inclusions has been studied. The microstructure information, such as the inclusion content, matrix property and the temperature have been considered explicitly in the obtained yield function. The influences of temperature and the confining pressure on the macroscopic material strength are captured by the obtained criterion. Then, the obtained result is applied to describe the temperature-dependent mechanical behaviors of sandstone.

异质材料的微观结构对其宏观机械行为有重要影响。对于热机械耦合问题，温度也有重要影响。在本研究中，首先考虑了温度对异质材料弹性行为的影响。然后，利用均质化方法推导出了多孔材料塑性行为的宏观屈服准则的明确表达式。该屈服准则同时明确考虑了多孔性和温度对其整体机械行为的影响。为了考虑基体的压力敏感性，在微观尺度上采用了 Drucker-Prager 类型准则。随后，研究了由刚性夹杂物增强基体的异质材料。在获得的屈服函数中明确考虑了微观结构信息，如夹杂物含量、基体性质和温度。所获得的准则捕捉到了温度和约束压力对材料宏观强度的影响。然后，将所得结果用于描述砂岩随温度变化的力学行为。

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引用次数: 0

Thermalized and mixed meanfield ADP potentials for magnesium hydrides 镁氢化物的热化和混合均场 ADP 电位

IF 3.4 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2024-10-15 DOI: 10.1016/j.mechmat.2024.105175

M. Molinos , M. Ortiz , M.P. Ariza

We develop meanfield approximation and numerical quadrature schemes for the evaluation of Angular-Dependent interatomic Potentials (ADPs) for magnesium and magnesium hydrides at finite temperature (thermalization) and arbitrary atomic molar fractions (mixing) within a non-equilibrium statistical mechanical framework and derive local equilibrium relations. We numerically verify and experimentally validate the accuracy and fidelity of the resulting thermalized/mixed ADPs (TADPs) by means of selected numerical tests including free entropy, heat capacity, thermal expansion, molar volumes, equation of state and elastic constants. We show that the local equilibrium properties predicted by TADPs agree closely with those computed directly from ADP by means of Molecular Dynamics (MD).

我们开发了均场近似和数值正交方案，用于在非平衡统计力学框架内评估有限温度（热化）和任意原子摩尔分数（混合）下镁和镁氢化物的角相关原子间势（ADPs），并推导出局部平衡关系。我们通过选定的数值测试，包括自由熵、热容量、热膨胀、摩尔体积、状态方程和弹性常数，对所得到的热化/混合 ADP（TADPs）的准确性和保真度进行了数值验证和实验验证。我们的研究表明，TADPs 预测的局部平衡特性与通过分子动力学（MD）直接从 ADP 计算出的特性非常接近。

引用次数: 0

Low-dose neutron irradiation effects on the elastoplastic deformation mechanisms of aluminum-doped gallium nitride under contact loading 低剂量中子辐照对接触加载下掺铝氮化镓弹塑性变形机制的影响

IF 3.4 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2024-10-15 DOI: 10.1016/j.mechmat.2024.105180

Tiankun Li , Pengfei Zhao , Fulin Shang

The elastoplastic deformation mechanisms of irradiated aluminum (Al)-doped gallium nitride (GaN) under contact loading are investigated in this work using the nanoindentation simulations, which is of great significance for understanding the mechanical properties of the Al-doped GaN and guiding the design of durable and high-performance GaN-based devices. The mechanical behaviors of the Al-doped GaN with different doping concentrations are analyzed, including the indentation hardness, Young's modulus, elastic recovery rates, phase transformations, and stress distribution. It is found that Al doping increases their hardness, Young's modulus, and elastic recovery rates, and leads to an enlargement of the phase transformation regions, which is dominated by the high coordination number (CN) phase transformations. Furthermore, the effects of low-dose neutron irradiation on their elastoplastic deformation mechanisms are studied by triggering cascade collisions within the structure. When subjected to such irradiation, structural changes occur in the Al-doped GaN, their indentation hardness, Young's modulus, and elastic recovery rates increase remarkably, and its phase transformation mechanism is changed remarkably. The dislocation behaviors of the doped and undoped GaN are different under neutron irradiation. This study is important for capturing the mechanical stability and integrity of Al-doped GaN in an irradiation environment, as well as developing GaN-based devices with superior irradiation resistance.

本研究利用纳米压痕模拟研究了辐照掺铝氮化镓（GaN）在接触载荷作用下的弹塑性变形机制，这对于理解掺铝氮化镓的力学性能以及指导设计耐用的高性能氮化镓基器件具有重要意义。研究分析了不同掺杂浓度的铝掺杂氮化镓的力学行为，包括压痕硬度、杨氏模量、弹性恢复率、相变和应力分布。结果发现，铝掺杂增加了它们的硬度、杨氏模量和弹性恢复率，并导致相变区域的扩大，其中以高配位数（CN）相变为主。此外，通过在结构内部引发级联碰撞，研究了低剂量中子辐照对其弹塑性变形机制的影响。在这种辐照下，掺铝氮化镓的结构发生了变化，其压痕硬度、杨氏模量和弹性恢复率显著增加，相变机制也发生了显著变化。在中子辐照下，掺杂和未掺杂 GaN 的位错行为有所不同。这项研究对于掌握掺铝氮化镓在辐照环境下的力学稳定性和完整性，以及开发具有优异抗辐照性能的氮化镓基器件具有重要意义。

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引用次数: 0

Damage quantification in concrete under uniaxial compression using microcomputed tomography and digital volume correlation with consideration of heterogeneity 利用微计算机断层扫描和数字体积相关技术量化单轴压缩下混凝土的损伤，并考虑异质性

IF 3.4 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2024-10-11 DOI: 10.1016/j.mechmat.2024.105178

Shangyu Yang , Haizhou Liu , Lingtao Mao , Fangao Li , Bingjie Wei , Yang Ju , François Hild

Finite element-based digital volume correlation with mechanical regularization was utilized to measure the deformation fields in a concrete specimen under uniaxial compression based on in-situ (via microcomputed tomography) experiment. Heterogeneous and damage settings were introduced in the mechanical regularization. The mechanical response of the matrix and aggregates was investigated. The three-dimensional morphology of subvoxel microcrack openings was measured, the overall assessment and local depiction of concrete damage were quantified. Subvoxel microcrack openings greater than 0.26 vx were identified. The average maximum principal and average volumetric strains in the matrix were higher than those in the aggregates, and noticeable strain concentrations existed in the interfacial transition zone and pore edges. Microcracks initiated in the macroscopic elastic stage, whereas voxel-level crack openings were observed at 90% of the ultimate load. This study provides experimental support for further revealing the growth process of concrete damage.

根据现场实验（通过微计算机断层扫描），利用基于有限元的数字体积相关和机械正则化来测量单轴压缩下混凝土试样的变形场。机械正则化中引入了异质和损伤设置。研究了基体和集料的力学响应。测量了亚体细胞微裂缝开口的三维形态，量化了混凝土损伤的整体评估和局部描述。确定了大于 0.26 vx 的亚体细胞微裂缝开口。基体中的平均最大主应变和平均体积应变高于集料中的应变，界面过渡区和孔隙边缘存在明显的应变集中。在宏观弹性阶段出现了微裂缝，而在极限载荷的 90% 时观察到了体素级裂缝开口。这项研究为进一步揭示混凝土损伤的生长过程提供了实验支持。

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引用次数: 0

Influence of shot-peening on the self-heating behavior and fatigue properties of 300M steel 喷丸强化对 300M 钢自热行为和疲劳性能的影响

IF 3.4 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2024-10-09 DOI: 10.1016/j.mechmat.2024.105174

Pierrick Lepitre , Louis-Maël Merlet , Cédric Doudard , Matthieu Dhondt , Martin Surand , Sylvain Calloch

Shot peening is an established cold working process used to introduce residual compressive stresses on a surface and is extensively studied using conventional fatigue tests. However, it has not been widely studied using the self-heating method. Specifically, the heterogeneity of the dissipation field has not been estimated, with only an average approach being used. Previous investigations in the case of 300M steel demonstrated that the effect of shot peening on the high cycle fatigue properties can be either beneficial or detrimental. This study proposes to apply the self-heating method on polished 300M and to investigate the effect of mean stress and shot peening on the dissipation behavior. A modified self-heating model is proposed and calibrated for 300M steel. Combined with residual stress profiles, a method to compute and determine the shot peening effect on self-heating behavior through single point surface measurements is proposed. Application on 300M steel shows excellent results, the over-dissipation being mainly due to the sub-surface compressive residual stresses. The self-heating method has proven useful to quickly estimate fatigue properties of polished 300M steel. Based on the understanding of the self-heating curve of shot peened 300M steel, a quantification of shot-peening effect on fatigue limit is discussed.

喷丸强化是一种成熟的冷加工工艺，用于在表面上引入残余压应力，并通过传统的疲劳试验进行广泛研究。然而，使用自加热方法对其进行的研究并不广泛。具体来说，对耗散场的异质性尚未进行估算，仅采用了平均值法。以前对 300M 钢的研究表明，喷丸强化对高循环疲劳性能的影响可能是有利的，也可能是不利的。本研究建议在抛光 300M 钢上应用自加热方法，并研究平均应力和喷丸强化对耗散行为的影响。针对 300M 钢提出并校准了改进的自热模型。结合残余应力曲线，提出了一种通过单点表面测量来计算和确定喷丸强化对自热行为影响的方法。在 300M 钢上的应用显示出了极佳的效果，过度破坏主要是由于表层下的压缩残余应力造成的。事实证明，自加热方法有助于快速估算抛光 300M 钢的疲劳特性。基于对喷丸强化 300M 钢自热曲线的理解，讨论了喷丸强化对疲劳极限影响的量化问题。

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引用次数: 0

Investigation of the strain rate and stretch level dependent behavior of elastomeric nanocomposites in complex uniaxial tests under finite strains 有限应变下复杂单轴试验中弹性纳米复合材料的应变率和拉伸水平相关行为研究

IF 3.4 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2024-10-09 DOI: 10.1016/j.mechmat.2024.105177

Kseniia A. Mokhireva, Alexander L. Svistkov, Vladimir V. Shadrin

The mechanical behavior of elastomeric nanocomposites in experiments with nested stress-strain cycles and in cyclic tests with increasing strain amplitude was considered. In the proposed testing procedures, long time stops at each stage of the change in loading direction were of great importance. This revealed two significant features of the behavior of elastomeric nanocomposites that have received little attention. It was shown that material softening (the Mullins effect) should be considered not only in the elastic part of the Cauchy stress tensor, but also in its dissipative part. The second peculiarity was the difference between the characteristic relaxation time at loading and the characteristic relaxation time at unloading observed in the experiments.

This paper focuses on the behavior of highly-filled elastomeric materials based on different matrices (styrene-butadiene rubber (SBR) and nitrile-butadiene rubber (NBR)) and with different concentrations of carbon black (CB) or a combination of two fillers (CB and purified multi-walled carbon nanotubes (MWCNTs)).

A mathematical model of the viscoelastic behavior of elastomeric nanocomposites under finite strains is proposed. It takes into account the peculiarities of the behavior of highly filled elastomers observed in the experiments. The specificity of the model consists in a new variant of the form of the free energy potential. It is shown that the new model satisfies the thermodynamic inequality, which is a consequence of the first law of thermodynamics and the second law in the form of the Clausius-Duhem inequality. A good agreement between theoretical calculations and experimental data was obtained.

在嵌套应力-应变循环试验和应变振幅不断增大的循环试验中，考虑了弹性纳米复合材料的机械行为。在拟议的测试程序中，加载方向变化的每个阶段都需要长时间停止，这一点非常重要。这揭示了弹性纳米复合材料行为的两个重要特征，而这两个特征很少受到关注。研究表明，材料软化（穆林斯效应）不仅应在考奇应力张量的弹性部分中考虑，还应在其耗散部分中考虑。第二个特点是在实验中观察到加载时的特征松弛时间与卸载时的特征松弛时间之间存在差异。本文重点研究了基于不同基质（丁苯橡胶（SBR）和丁腈橡胶（NBR））、不同浓度的炭黑（CB）或两种填料组合（CB 和纯化多壁碳纳米管（MWCNTs））的高填充弹性材料的行为。该模型考虑到了实验中观察到的高填充弹性体行为的特殊性。该模型的特殊性在于自由能势形式的新变体。研究表明，新模型满足热力学不等式，这是热力学第一定律和克劳修斯-杜恒不等式形式的第二定律的结果。理论计算与实验数据之间取得了良好的一致性。

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引用次数: 0

A cooperative relaxation model with two physical parameters for investigating the temperature and cure dependence of relaxation mechanisms in resins 具有两个物理参数的协同松弛模型，用于研究树脂中松弛机制的温度和固化依赖性

IF 3.4 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2024-10-05 DOI: 10.1016/j.mechmat.2024.105172

Xiaotian Mao, Fulin Shang

Modeling the relaxation properties of resin matrix during cure plays an important role in predicting process-induced residual stresses and final distortions of resin-based composites. This paper develops a physical characterization model, which explains the temperature and cure-degree dependence of relaxation behaviors in terms of the size of cooperatively rearranging region, and special emphasis is placed on investigating the general physical mechanism of cure degree affecting the relaxation properties. In this model, the relaxation time is governed by a modified Adam-Gibbs equation, which is extended here to include the cure dependence. In addition, the relaxation modulus is modeled in a chemo-rheologically simple manner (CSM) based on the free volume theory. Material characterization is carried out using experimental data of two typical resins. It is shown that two cure-dependent model parameters, i.e., the smallest size of the cooperatively rearranging region and the glass transition temperature, are sufficient in accounting for the effect of cure on the relaxation modulus, and could provide a physical explanation of the influence of cure on relaxation behaviors. Furthermore, the proposed model is numerically realized by incorporating ABAQUS with UMAT subroutine, and its validity in predicting the residual stresses and final distortion of composites is also numerically verified by comparing with the results available in literature.

树脂基复合材料在固化过程中的松弛特性建模对于预测工艺引起的残余应力和最终变形具有重要作用。本文建立了一个物理表征模型，从协同重排区域的大小来解释松弛行为与温度和固化度的关系，并特别强调研究固化度影响松弛特性的一般物理机制。在该模型中，弛豫时间由修正的 Adam-Gibbs 方程控制，在此对该方程进行了扩展，以包括固化依赖性。此外，还根据自由体积理论，以化学流变学简单方式（CSM）建立了松弛模量模型。利用两种典型树脂的实验数据进行了材料表征。结果表明，两个与固化有关的模型参数，即协同重排区的最小尺寸和玻璃化转变温度，足以解释固化对弛豫模量的影响，并能为固化对弛豫行为的影响提供物理解释。此外，通过将 ABAQUS 与 UMAT 子程序相结合，对所提出的模型进行了数值计算，并通过与文献中的结果进行比较，对其在预测复合材料残余应力和最终变形方面的有效性进行了数值验证。

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引用次数: 0

Thermal and thermo-mechanical post-buckling analysis of GNP-reinforced composite laminated plates GNP 增强复合层压板的热和热机械屈曲后分析

IF 3.4 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2024-10-04 DOI: 10.1016/j.mechmat.2024.105171

Vuong Nguyen Van Do , Thang N. Dao , Chin-Hyung Lee

This research utilizes isogeometric analysis (IGA) method to analyze buckling and post-buckling responses of composite laminated plates embedded with graphene nanoplatelets (GNPs) subjected to three-dimensional (3D) conduction of heat or combined 3D heat conduction and mechanical edge compression. A formulation to determine temperature profile produced by 3D conduction of heat in the GNP-reinforced laminate is established, and a new function with smooth transition form of GNP volume fraction across the thickness is presented for dictating the volume fraction of layer. Shear deformable quasi-3D theory with the von Kármán type nonlinearity which takes initial geometric deformation and thermal effect into consideration is employed to construct the nonlinear equilibrium states. Four types of GNP arrangements encompassing uniform, O, X and V shapes are considered. The IGA approach presented, through the benchmark test, is evidenced to estimate the thermal buckling temperature accurately and to successfully trace the thermal post-buckling path. Additional parametric study is carried out to scrutinize the thermal and the thermo-mechanical post-buckling features of the GNP-reinforced composite laminated plates, and the new findings are sure to be served as the benchmark solutions.

本研究采用等几何分析（IGA）方法分析了嵌入石墨烯纳米片（GNP）的复合层压板在三维（3D）热传导或三维热传导与机械边缘压缩联合作用下的屈曲和屈曲后响应。建立了一种公式来确定三维热传导在 GNP 增强层压板中产生的温度曲线，并提出了一种具有平滑过渡形式的 GNP 体积分数跨厚度的新函数，用于确定层的体积分数。采用考虑了初始几何变形和热效应的 von Kármán 型非线性剪切变形准三维理论来构建非线性平衡态。考虑了四种类型的 GNP 排列，包括均匀、O、X 和 V 形。通过基准测试，证明所提出的 IGA 方法能够准确估计热屈曲温度，并成功追踪热屈曲后的路径。此外，还进行了其他参数研究，以仔细观察 GNP 增强复合层压板的热屈曲和热机械屈曲后特征，这些新发现必将成为基准解决方案。

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引用次数: 0

The role of secondary voids in the mechanism of ductile fracture at a crack tip 二次空隙在裂纹尖端韧性断裂机制中的作用

IF 3.4 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2024-10-01 DOI: 10.1016/j.mechmat.2024.105170

A.K. Dwivedi , I.A. Khan , J. Chattopadhyay

The mechanics and mechanisms of ductile fracture, ahead of a blunting crack tip, have been studied extensively. Several computational studies analyzing the effect of initial void volume fraction, void shape, void spatial distribution and the mode of loading (

K_{I}, K_{I I}

etc.) on crack-void interaction and its consequence on the mechanism of fracture have been reported. The influence of small size secondary voids on the failure of ligament between the large primary voids and, hence, on fracture toughness has been analyzed using the Gurson-type homogenized models of ductile fracture. In the present work, the two populations of voids ahead of a crack tip are modeled discretely. A plane strain, central line cracked boundary layer model under small-scale yielding is considered. The role of initial shape and spatial distribution of secondary voids, matrix strain hardening and mode of imposed loading in the mechanism of ductile crack growth initiation and advance is analyzed in detail. For completeness sake, numerical calculations are also performed using a homogenized representation of the secondary voids. The results so obtained are then compared with the predictions based on discrete modeling of the secondary voids. Our numerical studies revealed that plastic flow localization resulting from a small initial volume fraction of favorably distributed secondary voids may alter the path of crack growth initiation and advance, thus, influencing the ductile fracture toughness.

人们对钝化裂纹尖端前的韧性断裂的力学和机理进行了广泛的研究。一些计算研究分析了初始空隙体积分数、空隙形状、空隙空间分布和加载模式（KI、KII 等）对裂纹-空隙相互作用的影响及其对断裂机制的影响。利用古尔松类型的韧性断裂均质化模型，分析了小尺寸次生空隙对大尺寸原生空隙之间韧带断裂的影响，以及对断裂韧性的影响。在本研究中，裂纹尖端前的两个空隙群被离散地建模。考虑了小尺度屈服下的平面应变、中心线裂纹边界层模型。详细分析了次生空隙的初始形状和空间分布、基体应变硬化和外加载荷模式在韧性裂纹生长和扩展机制中的作用。为完整起见，还使用二次空隙的均质化表示进行了数值计算。然后将计算结果与基于二次空隙离散建模的预测结果进行比较。我们的数值研究表明，由于有利分布的次生空隙的初始体积分数较小而导致的塑性流动局部化可能会改变裂纹生长的起始和推进路径，从而影响韧性断裂韧性。

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引用次数: 0

Failure analysis of unidirectional fiber reinforced plastics based on computational micromechanics and PUCK failure theory 基于计算微机械学和 PUCK 失效理论的单向纤维增强塑料失效分析

IF 3.4 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2024-09-27 DOI: 10.1016/j.mechmat.2024.105169

Xiaofei Pang , Yonglyu He , Xun Chen , Shufeng Zhang

Achievement of accurate and reliable failure criterion is fundamentally important for designing composite structures. This study comprehensively evaluated the failure of unidirectional fiber-reinforced plastics (FRP) from the perspectives of failure theory and computational micromechanics. Further, PUCK failure criterion was analyzed in detail to identify the specific effects of the interfacial reinforcement coefficient on the failure mechanism. The representative volume element model of FRP with randomly distributed fibers was established. The comparative analysis of the results between current failure theory and experiment, indicates that the load bearing capacity of FRP under bi-axial compressive stress and shear stress is understated by the PUCK failure criterion. Microscopic finite element analysis was adopted to investigate the failure envelope of FRP, considering interface reinforcement coefficient. The results reveal that the strength of FRP under the combination of moderate transverse compressive stress and in-plane shear stress is significantly affected by the interface reinforcement coefficient. The accuracy of PUCK failure criterion heavily depends on the value of the interface reinforcement coefficient and if the criterion does not consider the coefficient, it can cause notable error on strength prediction. Consequently, determination of interface reinforcement coefficient would be helpful to achieve more accurate failure criterion for FRP.

准确可靠的失效准则对于设计复合材料结构至关重要。本研究从失效理论和计算微观力学的角度全面评估了单向纤维增强塑料（FRP）的失效。此外，还详细分析了 PUCK 失效准则，以确定界面增强系数对失效机理的具体影响。建立了具有代表性的随机分布纤维 FRP 体积元素模型。对现有破坏理论和实验结果的对比分析表明，PUCK 破坏准则低估了玻璃钢在双轴压应力和剪应力下的承载能力。考虑到界面加固系数，采用微观有限元分析来研究玻璃钢的破坏包络。结果表明，在中等横向压应力和平面剪应力组合下，玻璃钢的强度受界面加固系数的影响很大。PUCK 失效判据的准确性在很大程度上取决于界面加固系数的值，如果判据不考虑该系数，则会对强度预测造成明显误差。因此，确定界面加固系数将有助于获得更准确的玻璃钢破坏准则。

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引用次数: 0