Engineering Fracture Mechanics最新文献_第3页

Dynamic response and constitutive model for coal-rock composite material subjected to impact loading 煤岩复合材料在冲击荷载作用下的动态响应和构成模型

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2024-11-06 DOI: 10.1016/j.engfracmech.2024.110616

Dongliang Ji , Sai K. Vanapalli , Hongbao Zhao , Zurun Yue

Comprehensive understanding related to the dynamic responses of the composite materials is critical to prevent natural disasters in underground engineering and mining activities. For this reason, experimental studies were undertaken using dynamic impact tests at different strain rates to explore the failure mechanism using split Hopkinson pressure bar (SHPB) system and Digital Image Correlation (DIC) on composite materials; coal-rock (C-R) and rock-coal (R-C). These results suggest a linear correlation between dissipative energy and fractal dimensions. In addition, they suggest cracks that develop predominantly on the coal side have a dominant influence on the failure process that could be attributed to the interface effects. The damage evolution was established assuming elastic conditions using a three-dimensional coupled FDM-DEM numerical simulation system. A numerical approach is also developed for interpreting failure mechanism of the composite material based on the fabric tensor and strain energy density. Finally, a constitutive relationship is established considering strain rate effect and damage evolution using series element studies. There is a good agreement between the experimental and numerical results, providing justification to the proposed constitutive relationship. The numerical approach in this study is promising for assessing the performance of composite materials taking account of dynamic loading conditions.

全面了解复合材料的动态响应对于预防地下工程和采矿活动中的自然灾害至关重要。为此，我们利用分体式霍普金森压力棒（SHPB）系统和数字图像关联（DIC）对复合材料（煤-岩（C-R）和岩-煤（R-C））进行了不同应变速率的动态冲击试验，以探索其破坏机制。这些结果表明，耗散能与分形尺寸之间存在线性相关。此外，这些结果表明，主要在煤一侧产生的裂缝对破坏过程有主要影响，这可能归因于界面效应。利用三维耦合 FDM-DEM 数值模拟系统，在假设弹性条件下确定了损伤演变过程。此外，还开发了一种数值方法，用于根据织物张量和应变能密度解释复合材料的破坏机制。最后，考虑到应变率效应和损伤演变，利用系列元素研究建立了构成关系。实验结果与数值结果之间存在良好的一致性，为所提出的构成关系提供了依据。本研究中的数值方法有望在考虑动态加载条件的情况下评估复合材料的性能。

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引用次数: 0

Three-dimensional peridynamic simulation on triaxial compression failure mechanical behavior of cylindrical marble specimen containing pre-existing fissures 对含有已存在裂缝的圆柱形大理石试样的三轴压缩破坏力学行为进行三维围动力学模拟

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2024-11-04 DOI: 10.1016/j.engfracmech.2024.110600

Sheng-Qi Yang , Heng Li , Zhen Yang , Su-Sheng Wang , Bo-Wen Sun , Yun-Jin Hu

A series of triaxial compression experiments and analyses were conducted out by using the three-dimensional bond-based peridynamics (BB-PD) model to investigate the mechanical behavior, deformability, and failure behavior of marble samples under different confining pressures. This study assessed the impact of confining pressure on mechanical performance of the intact marble, calibrated PD model micro-parameters using experimental data, and predicted the fissure behavior of marble specimens with single or parallel fissures. Through detailed analysis of crack evolution, crack pattern, displacement fields, and principal stress fields, the research revealed that the ductility of marble depended on the confining pressure, especially in the presence of fissures. Increasing confining pressure facilitated a transition from splitting failure to conjugate shear failure modes and induced stress concentration at fissure tips, leading to wing cracks and secondary cracks initiation. The presence and number of fissures were found to directly influence the mechanical behavior and failure process complexity of marble. A higher number of fissures reduced brittleness and strength while enhancing ductility and variety of failure modes. Seven distinct failure patterns of marble were identified under triaxial compression, illustrating the combined effect of confining pressure and fissures on marble specimen failure modes. This work can provide a theoretical and numerical basis for fissured rocks fracture in deep engineering.

利用三维粘结周动力学（BB-PD）模型进行了一系列三轴压缩实验和分析，研究了不同约束压力下大理石样品的力学行为、变形性和破坏行为。该研究评估了约束压力对完整大理石力学性能的影响，利用实验数据校准了 PD 模型的微观参数，并预测了单裂缝或平行裂缝大理石试样的裂缝行为。通过对裂纹演变、裂纹形态、位移场和主应力场的详细分析，研究发现大理石的延展性取决于密闭压力，尤其是在存在裂纹的情况下。增加密闭压力有利于从劈裂破坏模式过渡到共轭剪切破坏模式，并在裂缝尖端引起应力集中，导致翼状裂缝和次生裂缝的产生。研究发现，裂缝的存在和数量会直接影响大理石的力学行为和破坏过程的复杂性。裂隙数量越多，脆性和强度越低，而延展性和破坏模式的多样性则越强。在三轴压缩条件下，大理石出现了七种不同的破坏模式，说明了约束压力和裂隙对大理石试样破坏模式的综合影响。这项研究可为深部工程中的裂隙岩断裂提供理论和数值依据。

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引用次数: 0

Stiffness degradation and mechanical behavior of microfiber-modified high-toughness recycled aggregate concrete under constant load cycling 微纤维改性高韧性再生骨料混凝土在恒定荷载循环下的刚度退化和力学行为

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2024-11-04 DOI: 10.1016/j.engfracmech.2024.110608

Changqing Wang , Jinyan Liu , Bo Lu , Youchao Zhang , Zhiming Ma

The mechanical properties of High-Toughness Recycled Aggregate Concrete (HTRAC) were investigated in this study as an innovative and environmentally friendly construction material, along with its potential applications in structural stability. Small-scale specimens with six levels of micro-steel fiber content were made, and a series of cyclic tests with constant loads were carried out. Using In-Situ 4D CT technology, the damage characteristics of the microstructure of HTRAC and the reinforcing effects of fibers on key mechanical parameters (peak stress, peak strain, ultimate strain, post-peak modulus, and toughness indicators) were analyzed. A comprehensive fiber reinforcing factor calculation model was proposed to assess its contribution to strength, deformability, and toughness, and the correlation between the number of cyclic loadings and stiffness degradation was also quantified. it is confirmed that HTRAC exhibits a significant advantage in toughness compared to traditional recycled aggregate concrete (RAC). The findings of this study provide crucial technical support for the further development and application of HTRAC, indicating its promising prospects in the field of sustainable construction materials.

本研究调查了高韧性再生骨料混凝土（HTRAC）作为一种创新型环保建筑材料的力学性能及其在结构稳定性方面的潜在应用。研究人员制作了六种微钢纤维含量的小尺寸试样，并进行了一系列恒载循环试验。利用原位四维 CT 技术，分析了 HTRAC 微结构的损伤特征以及纤维对关键力学参数（峰值应力、峰值应变、极限应变、峰后模量和韧性指标）的增强效应。提出了一个全面的纤维增强因子计算模型，以评估其对强度、变形性和韧性的贡献，并量化了循环加载次数与刚度退化之间的相关性。研究证实，与传统的再生骨料混凝土（RAC）相比，HTRAC 在韧性方面具有显著优势。这项研究结果为进一步开发和应用 HTRAC 提供了重要的技术支持，表明其在可持续建筑材料领域具有广阔的前景。

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引用次数: 0

Numerical investigation on the influence of cutting parameters on rock breakage using a conical pick 锥形凿岩机切削参数对岩石破碎影响的数值研究

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2024-11-04 DOI: 10.1016/j.engfracmech.2024.110607

Xin Cai , Jifeng Yuan , Zilong Zhou , Sheng Zhang , Shaofeng Wang , Dan Ma , Yinghua Huang

To comprehensively understand the effects of roadheader cutting parameters on rock breakage, this paper conducts a numerical investigation of rock vertical indentation tests using a conical pick, utilizing the discrete element method (DEM). Three crucial cutting parameters, including cone angle, attack angle, and cutting depth, are analyzed as independent variables to elucidate their impact on rock breakage characteristics, such as peak cutting force and specific energy. The research results indicate that the ultimate failure of rock is primarily caused by the accumulation of microcracks from each local fracture, predominantly governed by tensile failure. As the cone angle increases, both the peak cutting force and specific energy exhibit a monotonic upward trend, while the maximum stress at the tip of the conical pick shows a fluctuating pattern. To achieve a balance between cost effectiveness and efficient rock breakage, an optimal cone angle range of 55° to 100° is recommended. The peak cutting force and specific energy decease exponentially as the attack angle increases, with an optimal range of 70° to 90°. Under continuous cutting conditions with a fixed total length of 60 mm, the average peak cutting force increases with cutting depth, while the average specific energy initially decreases and then increases, identifying an optimal cutting depth of 20 mm. These findings have significant engineering implications for optimizing the cutting parameters of roadheader to enhance the efficiency of mechanized excavation.

为全面了解掘进机切削参数对岩石破碎的影响，本文利用离散元法（DEM）对使用锥形镐进行的岩石垂直压痕试验进行了数值研究。将锥角、攻角和切削深度等三个关键切削参数作为自变量进行分析，以阐明它们对岩石破碎特性（如峰值切削力和比能量）的影响。研究结果表明，岩石的最终破坏主要是由每个局部断裂产生的微裂缝累积造成的，主要受拉伸破坏的支配。随着锥角的增大，峰值切削力和比能量都呈现出单调上升的趋势，而锥形截齿顶端的最大应力则呈现出波动模式。为了在成本效益和高效破岩之间取得平衡，建议最佳锥角范围为 55° 至 100°。随着攻击角的增大，峰值切削力和比能量呈指数下降，最佳范围为 70° 至 90°。在总长度固定为 60 毫米的连续切削条件下，平均峰值切削力随切削深度的增加而增加，而平均比能量则先减后增，确定最佳切削深度为 20 毫米。这些发现对优化掘进机的切割参数以提高机械化挖掘效率具有重要的工程意义。

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引用次数: 0

Experimental research on hydraulic fracture evolution characteristics of multi-well pad fracturing in a tight conglomerate reservoir 致密砾岩储层多井垫压裂水力压裂演化特征试验研究

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2024-11-04 DOI: 10.1016/j.engfracmech.2024.110609

Bo Zhang , Tiankui Guo , Ming Chen , Linrui Xue , Yuanhang Zhang , Zunpeng Hu , Zhanqing Qu

Natural gas is considered a cleaner and more efficient energy pillar than oil and coal, so it has become one of the focuses of global energy exploitation. The tight conglomerate gas reservoir has a broad development prospect. However, the previous fracturing experiments focus on single horizontal well fracturing research, and it is difficult to realize the economies of scale development. Therefore, the true triaxial fracturing experiment of three horizontal wells was carried out with the large-size specimen (400 mm × 400 mm × 400 mm) to study the hydraulic fracture (HF) propagation mechanism and the effects of geostress, fracturing sequence, vertical well spacing and fracture initiation position on the HF evolution characteristics during the multi-well pad fracturing in the conglomerate reservoir. The results show that under the stress shadow, the later fracturing HF tends to avoid the stress shadow zone of the preceding HF, and the breakdown pressure gradually increases. A higher horizontal stress difference helps the HF tend to cross the gravel and increases the proportion of tensile events to 73.2 %, but intermediate HF height propagation is inhibited, and the upward propagation distance has a decline of about 31.8 %. The preferential fracturing of the intermediate fracturing well can enable the intermediate HF to extend fully, and the upward propagation distance has an increment of approximately 140.3 %, which improves the reservoir reconstruction effect between the bilateral HFs. Meanwhile, it can intensify the induced stress interference between the HFs and increase the proportion of shear failure to 43.6 %. A shorter vertical well spacing seriously inhibits the upward propagation of intermediate HF height by around 57.9 % and increases the proportion of shear failure to 38.5 % under the induced stress interference. The preferential fracturing in the intermediate fracturing well can enhance the gas productivity, but it is necessary to control the pumping rate or pumping schedule to reduce the frac hit risk. This study can provide theoretical guidance and suggestions for multi-well pad fracturing in field fracturing.

天然气被认为是比石油和煤炭更清洁、更高效的能源支柱，因此已成为全球能源开发的重点之一。致密砾岩气藏具有广阔的开发前景。然而，以往的压裂实验主要集中在单水平井压裂研究上，难以实现规模化开发。因此，采用大尺寸试样（400 mm × 400 mm × 400 mm）进行了三口水平井的真实三轴压裂实验，研究砾岩气藏多井垫压裂过程中水力裂缝（HF）的传播机理以及地应力、压裂顺序、垂直井距和裂缝起始位置对HF演化特征的影响。结果表明，在应力阴影作用下，后压裂高频倾向于避开前压裂高频的应力阴影区，击穿压力逐渐增大。较高的水平应力差有助于高频倾向于穿过砾石，并将拉伸事件的比例提高到 73.2%，但中间高频高度传播受到抑制，向上传播距离下降了约 31.8%。中间压裂井的优先压裂可使中间高频充分扩展，向上传播距离增加了约 140.3%，提高了双边高频之间的储层重构效果。同时，它还能加强高频之间的诱导应力干扰，使剪切破坏的比例增加到 43.6%。较短的垂直井距严重抑制了中间高频高度的向上传播，抑制率约为 57.9%，并使诱导应力干扰下的剪切破坏比例增加到 38.5%。在中间压裂井优先压裂可以提高气产，但必须控制抽速或抽速计划，以降低压裂命中风险。本研究可为油田压裂中的多井垫压裂提供理论指导和建议。

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引用次数: 0

Promoted cutting and energy transition efficiency by an asymmetric cutter 通过非对称切割机提高切割和能源转换效率

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2024-11-03 DOI: 10.1016/j.engfracmech.2024.110599

Jie Liu , Boyang Hu , Zhaofeng Liu , Junlin Li , Yexing Chen , Wei Chen , Taoying Liu

Laboratory and numerical tests were performed to understand the rock breakage mechanism of a CCS (constant cross section) cutter and an asymmetric cutter. The laboratory and numerical tests consistently show that the asymmetric cutter frequently generates larger breakage areas and consumes less indentation energy than the CCS cutter, but there is a defect spacing of 70 mm. Thus, the asymmetric cutter frequently has a higher cutting efficiency than the CCS cutter. In addition, the numerical tests reveal that the CCS cutter first generates a plastic zone and subsequently forms cracks to connect with the defect tips. In this process, a large proportion of the energy is wasted in the particle friction in the plastic zone. However, the asymmetric cutter tends to form much smaller plastic zones, which makes it difficult to generate particle friction. Only a small amount of friction energy is consumed in the later crack propagation process. Thus, the asymmetric cutter has a higher energy transition efficiency than the CCS cutter.

为了解 CCS（恒定截面）铣挖机和非对称铣挖机的破岩机理，进行了实验室和数值测试。实验室和数值试验一致表明，与 CCS 切割器相比，非对称切割器经常产生更大的破碎区域，消耗更少的压痕能量，但缺陷间距为 70 毫米。因此，不对称铣刀的切割效率往往高于 CCS 铣刀。此外，数值测试表明，CCS 切割器首先产生塑性区，然后形成裂纹与缺陷尖端连接。在此过程中，很大一部分能量浪费在塑性区的颗粒摩擦上。然而，非对称切割机往往会形成小得多的塑性区，从而难以产生颗粒摩擦。在后来的裂纹扩展过程中，只有少量的摩擦能被消耗掉。因此，非对称切割机的能量转换效率高于 CCS 切割机。

引用次数: 0

A cohesive fracture-enhanced phase-field approach for modeling the damage behavior of steel fiber-reinforced concrete 钢纤维增强混凝土损伤行为建模的内聚断裂增强相场方法

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2024-11-02 DOI: 10.1016/j.engfracmech.2024.110603

Hoang-Quan Nguyen , Gia-Khuyen Le , Ba-Anh Le , Bao-Viet Tran

This study introduces a novel computational framework based on the phase-field fracture/damage model (PFM), providing rapid and accurate predictions of the damage behavior of Steel Fiber Reinforced Concrete (SFRC) material. The framework integrates the interfacial cohesive fracture model with the PFM to depict the interaction between the cementitious matrix and fibers, marking the first demonstration that this model adequately captures both local fracture phenomena between fibers and concrete (such as fiber bridging and interfacial debonding) and mesoscopic stress–strain behavior. Additionally, an enhanced geometric approximation is established based on the spatial distribution density function of fibers and particles, allowing for the transformation of the three-dimensions (3-D) fiber-reinforced material structure into an equivalent two-dimensions (2-D) material. This approach enables the reduction of computational time, a significant limitation of the phase-field method, thereby allowing an in-house code to perform various computations with complex material structures such as SFRC. The effectiveness of the approach is demonstrated through four examples involving variations in the microgeometry and material properties of SFRC structures, ranging from the simplest configurations to real experimental material structures. Extensive Monte Carlo simulations of the model are also employed to provide results closer to reality, which are then compared with recent experimental data and numerical models, demonstrating the efficacy of the proposed computational model.

本研究介绍了一种基于相场断裂/损伤模型（PFM）的新型计算框架，可快速准确地预测钢纤维增强混凝土（SFRC）材料的损伤行为。该框架将界面粘聚断裂模型与相场断裂/损伤模型整合在一起，以描述水泥基质与纤维之间的相互作用，首次证明该模型能充分捕捉纤维与混凝土之间的局部断裂现象（如纤维桥接和界面脱粘等）以及介观应力应变行为。此外，还根据纤维和颗粒的空间分布密度函数建立了增强的几何近似，从而可以将三维（3-D）纤维增强材料结构转化为等效的二维（2-D）材料。这种方法可以减少相场方法的一个重要限制因素--计算时间，从而使内部代码能够对 SFRC 等复杂材料结构进行各种计算。通过四个涉及 SFRC 结构微观几何和材料属性变化的示例（从最简单的配置到实际实验材料结构），证明了该方法的有效性。此外，还对模型进行了广泛的蒙特卡罗模拟，以提供更接近实际的结果，然后将这些结果与最新的实验数据和数值模型进行比较，从而证明所提出的计算模型的有效性。

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引用次数: 0

Combining artificial intelligence with different plasticity induced crack closure criteria to determine opening and closing loads on a three-dimensional centre cracked specimen 将人工智能与不同的塑性诱导裂纹闭合标准相结合，确定三维中心开裂试样的开裂和闭合载荷

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2024-11-02 DOI: 10.1016/j.engfracmech.2024.110604

R. Baptista , V. Infante

Fracture due to fatigue crack growth remains a significant failure mode in both brittle and ductile materials. When dealing with crack tip plasticity induced phenomena, characterized by high strain and stress field gradients, only highly refined meshes around the crack tip can produce accurate results. Therefore, optimized mesh parameters must be used, in order to achieve high quality models with low computational costs. In this study, artificial intelligence models and a numerical three-dimensional model for a middle tension specimen were combined to enhance crack closure and opening loads assessment. The numerical accuracy was analysed based on the estimated stress and strain fields, plastic zone shape and size and crack closure and opening load values. Two artificial neural networks were trained using four different crack lengths, mesh sizes and simulated plastic wakes. The networks were capable of stress and strain field predictions and crack opening and closure load determination. It was verified that the crack stress criterion is strongly correlated with the principal strain field and the displacement field around the crack tip, providing a viable way to analyse plasticity induced crack closure.

疲劳裂纹增长导致的断裂仍然是脆性和韧性材料的重要失效模式。在处理以高应变和应力场梯度为特征的裂纹尖端塑性诱导现象时，只有裂纹尖端周围高度精细的网格才能产生精确的结果。因此，必须使用优化的网格参数，才能以较低的计算成本获得高质量的模型。在本研究中，人工智能模型与中间拉伸试样的三维数值模型相结合，增强了裂纹闭合和张开载荷的评估。根据估算的应力场和应变场、塑性区形状和大小以及裂缝闭合和打开载荷值，对数值精度进行了分析。使用四种不同的裂纹长度、网格尺寸和模拟塑性波浪训练了两个人工神经网络。这些网络能够预测应力场和应变场，并确定裂缝开裂和闭合荷载。经验证，裂纹应力标准与裂纹尖端周围的主应变场和位移场密切相关，为分析塑性诱导的裂纹闭合提供了一种可行的方法。

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引用次数: 0

Crack growth stabilization in the eccentric three-point end-notched flexure test of solid wood using side-grooved samples 在实木偏心三点端面缺口弯曲试验中使用侧凹样品稳定裂纹生长

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2024-11-01 DOI: 10.1016/j.engfracmech.2024.110605

Hiroshi Yoshihara, Makoto Maruta

A three-point eccentric end-notched flexure (3EENF) test was conducted on Sitka spruce to characterize the Mode II resistance curve (R-curve). To extend the range for stabilized crack growth, grooves were cut along both side surfaces of the sample to reduce the region around the neutral axis. The R-curve was determined by varying the initial crack lengths, and fracture toughness values were measured at both the onset and during growth. Additionally, the effect of side grooves on stabilizing crack growth in the 3EENF test was investigated by comparing numerical simulation results with those from four-point end-notched flexure (4ENF) tests. The grooves effectively stabilized crack growth, and the stabilization range was equivalent to that of the 4ENF test when the initial crack length was appropriately determined. The grooved sample exhibited behavior indicative of a longer crack than the actual length.

对锡特卡云杉进行了三点偏心端部缺口弯曲（3EENF）试验，以确定模式 II 阻力曲线（R 曲线）的特征。为了扩大稳定裂纹生长的范围，沿着样品的两侧表面切割了凹槽，以缩小中性轴附近的区域。通过改变初始裂纹长度来确定 R 曲线，并在裂纹开始和生长过程中测量断裂韧性值。此外，通过比较数值模拟结果和四点末端缺口挠曲（4ENF）试验结果，研究了侧槽对稳定 3EENF 试验中裂纹生长的影响。凹槽有效地稳定了裂纹的生长，在适当确定初始裂纹长度的情况下，稳定范围与 4ENF 试验相当。开槽样品表现出的裂纹比实际长度更长。

引用次数: 0

Fracture toughness evaluation of slip-cast fused silica via the single edge V-notched beam method 通过单边 V 型缺口梁法评估滑铸熔融石英的断裂韧性

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2024-11-01 DOI: 10.1016/j.engfracmech.2024.110612

A.R. Shahani, S.M.H. Tavakoli, M. Khosravi

Slip-Cast Fused Silica (SCFS) is a highly resistant ceramic to environmental factors, including heat. Its unique properties, such as high resistance to thermal shocks have led to its wide application as an electromagnetic window material. The main purpose of the present research is to determine the fracture toughness of SCFS. To achieve this, the ASTM C1421 standard, which provides methods for determining fracture toughness of advanced ceramics, was initially followed. After a careful examination of the requirements of each method, the precracked beam method was ultimately chosen for determining the fracture toughness. However, due to the porous nature of the material, creating a precrack proved to be challenging and unfeasible through trial and error. Therefore, the method of single edge V-notched beam (SEVNB) was utilized, known for its applicability to porous materials. The characteristics of this method and the fracture toughness results determined using it are detailed in this research.

滑铸熔融石英（SCFS）是一种对包括热量在内的环境因素具有高度耐受性的陶瓷。其独特的性能（如高抗热震性）使其作为电磁窗材料得到了广泛应用。本研究的主要目的是测定 SCFS 的断裂韧性。为此，我们首先遵循了 ASTM C1421 标准，该标准规定了先进陶瓷断裂韧性的测定方法。在仔细研究了每种方法的要求后，最终选择了预裂梁法来测定断裂韧性。然而，由于材料的多孔性，通过试验和错误来创建预裂缝被证明是具有挑战性的，也是不可行的。因此，我们采用了以适用于多孔材料而著称的单边 V 型缺口梁（SEVNB）方法。本研究详细介绍了这种方法的特点以及用其测定的断裂韧性结果。

引用次数: 0