Engineering Fracture Mechanics最新文献_第2页

A deformation-diffusion interactive model to study crack-tip behaviour and predict crack growth rate under fatigue and hydrogen-embrittlement conditions 研究疲劳和氢脆条件下裂纹尖端行为和预测裂纹生长率的变形-扩散交互模型

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2024-11-12 DOI: 10.1016/j.engfracmech.2024.110642

Rudolph J. Kashinga , Shenguang Liu , Tianyu Zhang , Xing Zhang , Lu Zhang , Liguo Zhao

Hydrogen is accepted as a cleaner and more sustainable energy source, since it carries abundant energy and does not produce any effluent gas from burning when compared to fossil fuels. However, long-term degradation in mechanical properties, attributed to hydrogen embrittlement, is reported for metallic materials exposed to gaseous hydrogen, leading to accelerated crack growth behaviour under fatigue. In this paper, a visco-plastic deformation-diffusion interactive model is developed to study fatigue crack growth behaviour in a nickel-based superalloy under hydrogen-embrittlement condition. In the model, cyclic deformation is described by visco-plasticity constitutive model, while hydrogen diffusion is simulated by a modified form of Fick’s first law of diffusion which can address hydrogen diffusion driven by the hydrostatic stress gradient. In particular, trapped hydrogen, expressed as dependent on both diffusible hydrogen concentration and inelastic strain, is considered in the modelling of hydrogen diffusion. The model also describes the effects of hydrogen concentration on mechanical deformation by considering its influence on the evolution of isotropic hardening as well as on the strain state. Interaction between cyclic deformation and hydrogen diffusion is therefore studied for a crack tip in a compact tension specimen subjected to fatigue and hydrogen attack, showing a strong dependency on both loading frequency and stress intensity factor range. Subsequently, a two-parameter criterion is proposed for fatigue crack growth prediction, which accounts for the contributions of both cyclic deformation and hydrogen diffusion. The predictions show a good agreement with experimental data in terms of crack growth rate under fatigue and hydrogen-embrittlement conditions.

氢被认为是一种更清洁、更可持续的能源，因为与化石燃料相比，氢蕴含丰富的能量，燃烧时不会产生任何废气。然而，据报道，暴露在气态氢中的金属材料会因氢脆而导致机械性能的长期退化，从而导致疲劳状态下裂纹的加速生长。本文建立了一个粘弹性变形-扩散交互模型，以研究氢脆条件下镍基超级合金的疲劳裂纹增长行为。在该模型中，循环变形由粘弹性构成模型描述，而氢扩散则由修正形式的菲克第一扩散定律模拟，该定律可解决由静水压力梯度驱动的氢扩散问题。特别是，在氢扩散模型中考虑了滞留氢，它取决于可扩散氢浓度和非弹性应变。该模型还通过考虑氢浓度对各向同性硬化演变和应变状态的影响，描述了氢浓度对机械变形的影响。因此，该模型对受到疲劳和氢气侵蚀的紧凑拉伸试样中的裂纹尖端进行了循环变形和氢气扩散之间的相互作用研究，结果表明其与加载频率和应力强度因子范围都有很大关系。随后，针对疲劳裂纹生长预测提出了一个双参数准则，该准则考虑了循环变形和氢扩散的贡献。就疲劳和氢脆条件下的裂纹生长率而言，预测结果与实验数据非常吻合。

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引用次数: 0

Vibration fatigue of film cooling hole structure of Ni-based single crystal turbine blade: Failure behavior and life prediction 镍基单晶涡轮叶片薄膜冷却孔结构的振动疲劳：失效行为和寿命预测

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2024-11-10 DOI: 10.1016/j.engfracmech.2024.110637

Yujie Zhao , Yuyu Song , Weizhu Yang , Yixin Qu , Lei Li , Zhufeng Yue

The vibration fatigue failure behavior and fatigue life of the film cooling hole (FCH) structure of Ni-based single crystal superalloy were investigated at high temperature. The vibration fatigue test of the FCH specimens were carried out based on the paired staircase method. The cracks are mostly initiated in the stress concentration area at the edge of the FCH, and may also be initiated in non-stress concentrated areas with large defects. At high temperature, the crack initiation mechanism of the FCH specimens of Ni-based single crystal superalloy is oxidative cracking nucleation in stress concentration area, and the crack propagation mechanism is the competition mechanism of dislocation slip and dislocation climbing. Based on the Fatigue Indicator Parameter (FIP) of the critical plane method, a vibration fatigue life prediction model for FCH structures considering stress concentration and high temperature oxidation damage is proposed. The life prediction model proposed in this paper is applied to the vibration fatigue life prediction of FCH specimens. The deviation between the predicted results and the experimental results is within 2.5 times at 850℃, and the deviation is within 2 times at 980℃. Besides, the life prediction method proposed is compared with other two FIP life prediction methods, and the high accuracy and effectiveness of the proposed life prediction method are verified.

研究了高温下镍基单晶超合金薄膜冷却孔（FCH）结构的振动疲劳失效行为和疲劳寿命。根据成对阶梯法对 FCH 试样进行了振动疲劳试验。裂纹大多出现在 FCH 边缘的应力集中区域，也可能出现在存在较大缺陷的非应力集中区域。高温下，镍基单晶超合金 FCH 试样的裂纹萌发机制是应力集中区的氧化裂纹成核，裂纹扩展机制是位错滑移和位错爬升的竞争机制。基于临界面法的疲劳指示参数（FIP），提出了一种考虑应力集中和高温氧化损伤的 FCH 结构振动疲劳寿命预测模型。本文提出的寿命预测模型被应用于 FCH 试样的振动疲劳寿命预测。在 850℃时，预测结果与实验结果的偏差在 2.5 倍以内；在 980℃时，偏差在 2 倍以内。此外，还将所提出的寿命预测方法与其他两种 FIP 寿命预测方法进行了比较，验证了所提出的寿命预测方法的高准确性和有效性。

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引用次数: 0

Effect of aged treatment on improving the performance of HVAF WC–Cr3C2–Ni coating on crystallization roller 时效处理对改善结晶辊上 HVAF WC-Cr3C2-Ni 涂层性能的影响

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2024-11-10 DOI: 10.1016/j.engfracmech.2024.110640

Diyao Zhang , Sheng Qu , Zijun Peng , Zhenli Liu , Jingkun Yu , Lei Yuan

The thermal shock resistance and high-temperature performance of WC–Cr₃C₂–Ni coatings on the surface of the crystallization roll after aged treatment were investigated in this study. The aging treatment at 320 ℃ for 2.5 h facilitated the diffusion of Cu element from the C17200 beryllium copper substrate toward the coating side of WC–Cr₃C₂–Ni coating, thereby enhancing the bonding between the coatings and substrates. After the aged treatment, the internal structure of the C17200 substrate changed from a dendritic structure to an equiaxed crystal structure, the hardness increased from 225.71 Hv_0.5 to 406.52 Hv_0.5 (80.4 % increased), and the wear resistance increased.

Although the aging treatment reduced the hardness of the coating slightly (from 1257.58 Hv_0.5 to 1155.16 Hv_0.5, a decrease of 8.1%) and wear resistance (the coefficient of friction, from 0.335 to 0.312, a decrease of 6.9%). However, in the thermal shock test, the thermal shock resistance of the coating after aging treatment was increased from 19 times to 20 times (5.3% increased). However, the thermal shock failure cracks between the coatings and the substrates were transferred from the substrate part to the joint part of the two, which effectively avoided the waste of the crystallization roller substrate in the maintenance process. This research effectively reduces the purchase and maintenance costs of steel mills in actual production and provides theoretical support for cost reduction and efficiency increase in other HVAF (high-velocity air fuel) coating applications.

本研究考察了结晶辊表面经时效处理后的 WC-Cr3C2-Ni 涂层的抗热震性和高温性能。在 320 ℃ 下进行 2.5 h 的老化处理有利于 C17200 铍铜基体中的铜元素向 WC-Cr3C2-Ni 涂层一侧扩散，从而增强涂层与基体之间的结合力。经过时效处理后，C17200 基材的内部结构从树枝状结构转变为等轴晶状结构，硬度从 225.71 Hv0.5 提高到 406.52 Hv0.5（提高了 80.4%），耐磨性也有所提高。虽然老化处理略微降低了涂层的硬度（从 1257.58 Hv0.5 降至 1155.16 Hv0.5，降幅为 8.1%）和耐磨性（摩擦系数从 0.335 降至 0.312，降幅为 6.9%）。但在热冲击试验中，涂层经老化处理后的抗热冲击性能从 19 倍提高到 20 倍（提高了 5.3%）。但涂层与基材之间的热震失效裂纹从基材部分转移到了二者的结合部，有效避免了维修过程中结晶辊基材的浪费。这项研究有效降低了钢厂在实际生产中的采购和维护成本，并为其他 HVAF（高速空气燃料）涂层应用中的降本增效提供了理论支持。

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引用次数: 0

Improved fracture toughness evaluation for fiber-reinforced asphalt concrete through double-parameter theory 通过双参数理论改进纤维增强沥青混凝土的断裂韧性评估

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2024-11-10 DOI: 10.1016/j.engfracmech.2024.110638

Peng Cao , Jialiang Nie , Guoqing Chen , Liang Cao , Li Li , Feiting Shi , Zhifei Tan

Fracture toughness serves as a key parameter in the design and durability assessment of asphalt concrete. Quantifying the fracture toughness for fiber-reinforced asphalt concrete (FRAC), remains challenging due to the incorporation of fibers. This study proposes an improved method for evaluating the fracture toughness of FRAC, based on the double-parameter theory derived from the theoretical concepts of stress intensity factor K and energy release rate (double-K and double-G fracture models). Using Digital Image Correlation (DIC) technology, crack propagation during three-point bending beam tests on FRAC beams was measured, refining the calculation of critical crack length a_c in the double-K fracture parameters. Additionally, a method is introduced to calculate the improved solution of double-G fracture parameters by monitoring crack propagation in real-time to determine the effective crack length a, and simultaneously computing the energy absorbed per unit crack extension, thereby constructing the J-R curve during stable crack growth phases. The fracture toughness of FRAC is evaluated by the improved method obtained double-G fracture parameters were used in Virtual Crack Closure Technique (VCCT) simulations to achieve virtual modeling of FRAC. The results demonstrate that the improved method provides accurate fracture performance indicators for FRAC. Moreover, the study establishes modified calculation formulas for (

G_{IC}^{u}

) and (

K_{IC}^{u}

) at unstable fracture toughness for FRAC at different temperatures, considering various fiber types and contents, thereby enhancing computational efficiency for practical applications. This research contributes to more accurate and effective methods for testing and evaluating the fracture performance of FRAC.

断裂韧性是沥青混凝土设计和耐久性评估的关键参数。由于纤维的加入，量化纤维增强沥青混凝土（FRAC）的断裂韧性仍然具有挑战性。本研究根据应力强度因子 K 和能量释放率（双 K 和双 G 断裂模型）的理论概念衍生出的双参数理论，提出了一种评估 FRAC 断裂韧性的改进方法。利用数字图像相关（DIC）技术，测量了 FRAC 梁在三点弯曲梁试验中的裂纹扩展情况，完善了双 K 断裂参数中临界裂纹长度 ac 的计算。此外，还介绍了一种方法，通过实时监测裂纹扩展来确定有效裂纹长度 a，同时计算单位裂纹扩展所吸收的能量，从而构建稳定裂纹生长阶段的 J-R 曲线，从而计算出双 G 断裂参数的改进方案。在虚拟裂缝闭合技术（VCCT）模拟中使用改进方法获得的双 G 断裂参数评估了 FRAC 的断裂韧性，从而实现了 FRAC 的虚拟建模。结果表明，改进方法可为 FRAC 提供精确的断裂性能指标。此外，考虑到不同的纤维类型和含量，该研究还建立了 FRAC 在不同温度下不稳定断裂韧性下 (GICu) 和 (KICu) 的修正计算公式，从而提高了实际应用的计算效率。这项研究有助于为测试和评估 FRAC 的断裂性能提供更准确、更有效的方法。

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引用次数: 0

Mechanical properties and constitutive model of deep marble under alternating creep-fatigue action 蠕变-疲劳交变作用下深层大理石的力学性能和构成模型

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2024-11-08 DOI: 10.1016/j.engfracmech.2024.110611

Yaoliang Zhu , Yanyan Cai , Qinzheng Huang , Chonghong Ren , Yonggang Zhang , Jin Yu

Given the time dependence and susceptibility to disturbance of deep rocks, this paper analyzes mechanical properties, acoustic emission (AE) signals, and pore radius distribution characteristics of deep marble under alternating creep-fatigue (ACF) action at different confining pressures by experiment and theoretical analysis. The results show that: (1) the alternation of creep and fatigue accelerates the rock damage, and the number of alternations increases with the increasing confining pressure. (2) Strain increments exhibit a pattern of first decreasing and then increasing, and they undergo a transformation from “V”-type to “U”-type with the increase of confining pressure. (3) The AE ringing count is mainly generated in the fatigue segment. The radius of large pores inside the rock is constrained by the confining pressure. (4) The ACF constitutive model is established, where model parameters show a nonlinear decreasing trend of the power exponential function with the strain increment.

鉴于深部岩石的时间依赖性和易受扰动性，本文通过实验和理论分析，分析了不同约束压力下交变蠕变疲劳（ACF）作用下深部大理岩的力学性能、声发射（AE）信号和孔隙半径分布特征。结果表明(1) 蠕变和疲劳交替作用加速了岩石的破坏，且交替次数随约束压力的增加而增加。(2）应变增量呈现先减小后增大的规律，且随着约束压力的增大，应变增量由 "V "型转变为 "U "型。(3) AE 振纹主要产生于疲劳段。岩石内部大孔隙的半径受到约束压力的限制。(4) 建立了 ACF 构成模型，模型参数随应变增量呈非线性幂指数函数递减趋势。

引用次数: 0

Specimen reconstitution method for the assessment of fracture properties of reactor pressure vessel steels 评估反应堆压力容器钢断裂特性的试样重组方法

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2024-11-07 DOI: 10.1016/j.engfracmech.2024.110610

Shuang Qi , Yinghui An , Wenjing Ding , Ping Huang , Minyu Fan , Kuiyuan Fang , Chen Bao , Kexin Cai

Routine testing of the fracture properties of irradiated surveillance specimens is a critical method for evaluating irradiation embrittlement in reactor pressure vessel (RPV) steels. Given the limited space in irradiation surveillance tubes, specimen reconstitution technology is expected to provide a viable solution to the shortage of irradiated specimens. This study investigates the specimen reconstitution method for 16MND5 steel 0.5 T CT specimens used in the RPV. By studying the local mechanical properties of the residual specimen and performing finite element analysis of the crack tip plastic zone, the appropriate size for specimen reconstitution is determined. The electron beam welding method is used to join the residual specimen and the base material, and the J-integral formula for the reconstituted specimen is determined based on the finite element analysis, taking into account the influence of the weld seam and the degradation of the mechanical properties of the residual specimen. The feasibility of the specimen reconstitution method is validated through fracture tests on base material specimens and reconstituted specimens at different temperature.

对辐照监测试样的断裂特性进行常规测试，是评估反应堆压力容器（RPV）钢辐照脆性的重要方法。鉴于辐照监测管空间有限，试样重组技术有望为辐照试样短缺问题提供可行的解决方案。本研究调查了用于 RPV 的 16MND5 钢 0.5 T CT 试样的试样重组方法。通过研究残余试样的局部机械性能和对裂纹尖端塑性区进行有限元分析，确定了试样重组的适当尺寸。采用电子束焊接方法连接残余试样和母材，并在有限元分析的基础上确定重组试样的 J 积分公式，同时考虑到焊缝的影响和残余试样机械性能的退化。通过在不同温度下对母材试样和重组试样进行断裂测试，验证了试样重组方法的可行性。

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引用次数: 0

Peridynamics-coupled finite element method implication in concrete material crack prediction 周边动力学耦合有限元法在混凝土材料裂缝预测中的意义

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2024-11-07 DOI: 10.1016/j.engfracmech.2024.110615

Gaopeng Liang , Tanghong Liu , Zhengwei Chen , Yutao Xia

This study presents a multi-bond element stiffness matrix to couple peridynamics with the finite element method, where mass points are denoted as elements with the degree of freedom to have a certain number of mass points. The proposed peridynamics-coupled finite element method (PDFEM) based on multi-bond element is demonstrated to be effective in the crack and fracture prediction of concrete materials. In addition, experimental test results and the compression and bidirectional load numerical simulations’ results are compared, and good agreement is observed. In the single compression simulation of concrete specimen, fracture crack occurs along with the compression load direction. In bidirectional load simulations of concrete specimen, different settings of load lead to changeable fracture cracks. Furthermore, the comparison with finite element method (FEM) also shows good agreement. The crack, mass point fracture percentage, and stress state of the concrete specimen are investigated under different load conditions and simulation times, and the results demonstrate a promising prospect of the proposed PDFEM in the field of fracture prediction of concrete materials.

本研究提出了将周动力学与有限元方法耦合的多结合单元刚度矩阵，其中质量点表示为具有一定数量质量点自由度的单元。所提出的基于多结合单元的周动力学耦合有限元法（PDFEM）在混凝土材料的裂缝和断裂预测中证明是有效的。此外，实验测试结果与压缩和双向载荷数值模拟结果进行了比较，发现两者具有良好的一致性。在混凝土试样的单向压缩模拟中，断裂裂缝沿压缩荷载方向出现。在混凝土试样的双向荷载模拟中，不同的荷载设置会导致断裂裂缝的变化。此外，与有限元法（FEM）的比较也显示出良好的一致性。研究了不同荷载条件和模拟时间下混凝土试样的裂缝、质量点断裂百分比和应力状态，结果表明所提出的 PDFEM 在混凝土材料断裂预测领域具有广阔的前景。

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引用次数: 0

Fracture and fractal characteristics of high-temperature granite under confined space water jet impact 密闭空间水射流冲击下高温花岗岩的断裂和分形特征

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2024-11-07 DOI: 10.1016/j.engfracmech.2024.110606

Jianming Shangguan , Zhaolong Ge , Qinglin Deng , Zhe Zhou , Zhi Yao , Yuhuai Cui

In the application of jet assisted deep drilling technology, the fracture mode and rock fragment characteristics of high-temperature rock in the confined space of jet drilling are not yet clear. We analyzed the fragmentation and debris distribution of high-temperature granite under confined space jet action using 3D reconstruction technology and statistical fractal theory to examine their fragmentation patterns and fractal characteristics. The results show that high-temperature rocks exhibit obvious thermal fracturing characteristics under the impact of confined water jet, and as the rock temperature increases, vertical compression shear cracks connect with radial tensile cracks. The maximum damage area is located near the bottom of the confined hole, and the distribution of cracks is more complex. As the degree of jet confinement decreases, the rock cracking form changes from radial tensile cracking to vertical compression shear cracking. As the rock temperature increases and the confined space size decreases, the total mass and large debris mass percentages of rock debris increase. The particle size distribution of rock debris follows an Rosin-Rammler (R-R) distribution and has obvious fractal characteristics. The fracture and fragmentation of high-temperature rocks under confined water jet impact are mainly caused by the combination of jet impact stress waves and thermal stress. The temperature difference of rocks affects the heat transfer between jet and rock, and the confined space size directly affects the heat transfer efficiency between jet and rock, which is manifested in different numbers of fracture cracks, internal damage area, and rock debris size distribution. These findings can provide a theoretical and parameter optimization basis for jet-assisted deep reservoir drilling applications.

在射流辅助深孔钻进技术的应用中，高温岩石在射流钻进受限空间内的断裂模式和岩石碎屑特征尚不明确。我们利用三维重建技术和统计分形理论分析了高温花岗岩在密闭空间射流作用下的碎裂和碎屑分布，研究了其碎裂模式和分形特征。结果表明，高温岩石在约束水射流的冲击下表现出明显的热断裂特征，随着岩石温度的升高，垂直压缩剪切裂缝与径向拉伸裂缝相连。最大破坏区域位于约束孔底部附近，裂缝分布较为复杂。随着喷射密闭程度的降低，岩石开裂形式由径向拉伸裂缝转变为垂直压缩剪切裂缝。随着岩石温度的升高和封闭空间尺寸的减小，岩石碎屑的总质量和大块碎屑的质量百分比都会增加。岩石碎屑的粒度分布遵循罗辛-拉姆勒（R-R）分布，具有明显的分形特征。高温岩石在约束水射流冲击下的断裂和破碎主要是由水射流冲击应力波和热应力共同作用造成的。岩石的温差影响射流与岩石之间的传热，密闭空间大小直接影响射流与岩石之间的传热效率，表现为不同的断裂裂纹数量、内部损伤面积和岩石碎屑大小分布。这些发现可为射流辅助深层储层钻井应用提供理论和参数优化依据。

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引用次数: 0

Micromechanics and microstructure based machine learning approach: Unveiling the role of porosity and hydrated phases on the tensile behaviour of cement pastes 基于微观力学和微观结构的机器学习方法：揭示孔隙率和水化相对水泥浆拉伸行为的作用

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2024-11-06 DOI: 10.1016/j.engfracmech.2024.110613

Jinane Murr , Syed Yasir Alam , Frédéric Grondin

The fracture process and the mechanical performance of the cement paste rely significantly on its tensile behaviour. Machine learning methods have been recently developed to predict this behaviour based on numerous experimental measurements. Due to multi-phase heterogeneous nature of cement paste microstructure, evaluation of the role of each chemical phase on the cracking of cement paste is necessary to develop optimized binder systems. Numerous experimental tests would be necessary to determine the best cement pastes in a considered environment. Therefore, in this study, a hybrid approach based on an ensemble machine learning model and a microstructure informed micromechanical model is proposed for predicting the tensile behaviour of hydrated cement pastes. The model can be used as a quick prediction tool for tensile strength of a given microstructure or for deep analysis on the optimization of binder system. A Deep Neural Networks (DNN) model was developed by training and validating a large dataset detailing the chemical phase composition, phase volume fractions and the tensile strength of the cement pastes. This dataset covers an extensive range of Portland cements, hydration ages and water-to-cement ratios. It was developed by simulating cement thermodynamics and tensile behaviour using a damage micromechanical model; which is otherwise almost impossible to obtain through experimental means. Additionally, two generative algorithms, tabular generative adversial networks (TGAN) and conditional generative adversial networks (CTGAN), were employed for dataset augmentation as a sampling method for the sensitivity analysis. This machine learning study provides an in-depth investigation to identify the role of volume fraction of solid phases (C-S-H, ettringite, portlandite and hydrogarnet) and micro porosity (dry and filled) in affecting the tensile behaviour of hydrated cement paste. Optimization assessment of the microstructure was then performed using micromechanical analysis and damage propagation in hydrated cement paste phases and porous network.

水泥浆的断裂过程和机械性能在很大程度上取决于其拉伸性能。最近开发的机器学习方法可根据大量实验测量结果预测这种行为。由于水泥浆微观结构的多相异构性质，有必要评估各化学相对水泥浆开裂的作用，以开发优化的粘结剂系统。要在考虑的环境中确定最佳水泥浆，必须进行大量实验测试。因此，本研究提出了一种基于集合机器学习模型和微结构微观力学模型的混合方法，用于预测水化水泥浆的拉伸行为。该模型可用作给定微结构拉伸强度的快速预测工具，也可用于粘结剂系统优化的深入分析。深度神经网络（DNN）模型是通过训练和验证一个大型数据集而开发的，该数据集详细记录了水泥浆的化学相组成、相体积分数和抗拉强度。该数据集涵盖了广泛的波特兰水泥、水化龄期和水灰比。它是通过使用损坏微观机械模型模拟水泥热力学和拉伸行为而开发的，否则几乎不可能通过实验手段获得这些数据。此外，还采用了两种生成算法--表格生成式逆向网络（TGAN）和条件生成式逆向网络（CTGAN）--来扩充数据集，作为敏感性分析的采样方法。这项机器学习研究提供了一项深入调查，以确定固相（C-S-H、埃特林岩、硅酸盐岩和水镁石）的体积分数和微孔率（干燥和填充）在影响水化水泥浆拉伸行为中的作用。然后，利用微机械分析和水合水泥浆相与多孔网络中的损伤扩展，对微结构进行了优化评估。

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引用次数: 0

Multi-stage evolution characteristics and particle size effect of sandstone granules subjected to cyclic loads 砂岩颗粒在循环载荷作用下的多级演化特性和粒度效应

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2024-11-06 DOI: 10.1016/j.engfracmech.2024.110614

Tengfei Ma, Quanle Zou, Jialong Chen, Fanjie Kong, Qican Ran, Pingting Wang

Broken granules of different sizes and poor bearing capacities produced by repeated mining of coal seams contribute to natural disasters, such as rock strata movement. In this study, mechanical tests were performed on broken sandstone granules to explore their compaction and recrushing characteristics under repeated mining. The change characteristics of the relevant mechanical parameters of sandstone granules with different particle sizes and changes in energy density were examined, and compaction and recrushing mechanisms of sandstone granules under cyclic loading were identified. The results show that an increase in the initial particle size of sandstone granules has a significant effect on the increase in the strain under load. The cumulative dissipation energy corresponding to final crushing was greater for granules with larger initial sizes. The particle size of sandstone was found to be proportional to the fractal dimension after compaction and crushing. The probability of granular particles with larger initial particle sizes being broken into smaller particles is greater, resulting in the porosity attenuating most rapidly during the stress loading process of granular particles under repeated mining. Therefore, the degree of sample breakage was relatively severe. Particles were rearranged after compaction and crushing. Repeated mining results in dynamic evolution of the pore compaction, deformation, and fractur of the rock mass, as well as stable recombination. The study results provide important theoretical support for understanding of the movement mechanism of rock strata in the goaf under repeated mining.

反复开采煤层所产生的大小不一的破碎颗粒和较差的承载能力会导致岩层移动等自然灾害。本研究对破碎的砂岩颗粒进行了力学试验，以探讨其在重复开采下的压实和再破碎特性。研究了不同粒度砂岩颗粒相关力学参数的变化特征以及能量密度的变化，并确定了循环加载下砂岩颗粒的压实和再破碎机理。结果表明，砂岩颗粒初始粒径的增加对负载下应变的增加有显著影响。初始粒度越大的砂岩颗粒，最终破碎时的累积耗散能量越大。研究发现，砂岩的粒度与压实和破碎后的分形尺寸成正比。初始粒度较大的颗粒被破碎成较小颗粒的概率较大，导致颗粒在反复开采的应力加载过程中孔隙度衰减最快。因此，样品破碎程度相对严重。颗粒在压实和破碎后重新排列。重复开采导致岩体孔隙压实、变形和断裂的动态演化，以及稳定的重组。研究结果为理解重复采矿条件下羊群岩层的运动机理提供了重要的理论支持。

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引用次数: 0