Critical Stress Intensity Factor Research Articles

Multi-Parameter Methodology for Assessing Quality Indicators of Nanomodified Fiber-Reinforced Concrete for Construction Site

Nanomodified fiber-reinforced concrete is a building material for which the required characteristics of fracture toughness are a distinctive feature. Determination of the stress intensity factor of fiber-reinforced concrete makes it possible to correctly assess the resistance of the material during the formation and development of cracks. The proposed multi-parameter methodology for assessing the quality indicators of nanomodified fiber-reinforced concrete makes it possible to evaluate the quality of a fiber-reinforced concrete structure in construction and laboratory conditions. To carry out control at the construction site, modern and long-used methods of non-destructive testing are used: ultrasonic sounding, ultrasonic tomography, elastic rebound, separation with chipping. For laboratory studies, the technique provides for the manufacture of prism samples that can be molded or cut from the body of the structure. This methodology makes it possible to obtain in laboratory conditions such material parameters as tensile strength in bending, tensile strength in splitting, critical stress intensity factor for normal separation, critical stress intensity factor for transverse shear, energy consumption for individual stages of deformation and destruction of the sample, as well as to evaluate the uniformity of distribution fibers. Moreover, it is provided to obtain all the parameters on one sample from the series, which eliminates errors and inaccuracies in the quality indicators of the material associated with different conditions of hardening, molding, inaccuracies in duplicating the composition.

Effect of loading rate on the dislocation emission from crack-tip under hydrogen environment

The interplay between H atoms and crack-tip plasticity is essential to understand hydrogen embrittlement. By formulating a novel closed-form energy-based analytical model, the effect of hydrogen on the emission of dislocations in the vicinity of a crack-tip is investigated. Using fcc Ni as model material, the analytical model predicts that the critical radius of the stably developed dislocation loop decreases with applied Mode-I stress intensity factor (SIF) KI. Combined with the transition state theory, it is found that the most probable Mode-I SIF of Ni-H system increases with the H concentration under lower loading rates, but is not sensitive to the H content under higher loading rates. Further atomistic simulations show that, 1) the critical SIF required for dislocation emission does not vary significantly with the H concentration; 2) the dislocation loop is emitted from the crack-tip along the (111) slip plane at ∼ KIe=0.58∼0.64MPam, which is consistent with the present theoretical prediction ∼ 0.63 MPam. These results thus indicate that the crack-tip plasticity is suppressed by the H insertion (i.e. the Song-Curtin nanohydrides formation mechanism) under lower loading rates, but might not be influenced under higher loading rates.

New experimental investigation of 3D defects propagation in mortar under tension loading

Among the construction materials, the mortar is the weakest component, especially against tensile loading and cracking. We propose in this paper an experimental study of the propagation of 3D internal defects in the mortar for different dosages and their effects on the tensile strength of the mortar. We start by deter- mining the tensile strength of a non-cracked specimen for five different dosages. After that, as our first contribution, we calculate the tensile strength and the critical Stress Intensity Factor SIF for the different dosages. Then, as our second contribution, we investigate the effect of the defects shape on the stability limit. Finally, we consolidate, through a comparative study, the obtained experimental results with the numerical ones.

Fracture toughness of hybrid natural fiber/nanoclay reinforced starch biocomposite material

In this paper, fracture toughness of banana fiber reinforced thermoplastic starch (BF_TPS) material was studied. Fiber weight percent (30, 40, and 50 wt.%) to starch polymer was fabricated using hot press at a pressure of 5 MPa of 160°C for 30 min. Experimental result shows that 40 wt.% BF_TPS biocomposite gave optimum tensile strength. Furthermore, nanoclay with varying weight percentage (1–5 wt.%) of dry cornstarch (CS) powder was added to enhance the property of the optimum 40 wt.% BF_TPS biocomposite, hence, forming hybrid clay/BF_TPS biocomposite. Tensile, impact, and fracture mechanics (Mode I fracture test) through Single End Notched Bending (SENB) Test were studied concurrently. Thermal properties and degradations were equally studied through Dynamic Mechanical Analysis (DMA) and Thermogravimetric Analysis (TGA). Results show that tensile strength and impact resistance increased to the maximum of 65% and 15.6%, respectively, at 3 wt.% clay addition. Critical stress intensity factor ( K IC) was approximately higher by 276% when compared to neat BF_TPS material. Strain energy release rates ( G IC) values were minimal. Delamination and catastrophic failures occurred with less fiber crack propagation along the crack initiation notches. In TGA, less weight reduction was observed at 3 wt.% clay/BF_TPS material, while a positive shift occurred in DMA tan delta (Tan δ) T g by 30°C. The micrography of the clay-enhanced biocomposites resulted in better bonding interaction between the polymer and fiber.

Influences of induced heating-healing on fracture properties and life extension of asphalt mixtures: Experimental investigations

In recent years, researchers have concentrated on identifying the effectiveness of induced healing techniques and increasing the healing capacity of asphalt materials. However, the impact of the induced healing method on extending pavement life or the behavior of the pavement in terms of cracking progression has not been evaluated. The main objective of this study is to develop a methodology to evaluate the impact of induced healing on fracture characteristics and life extension of asphalt mixtures. Semi-circular bending (SCB) tests were conducted at both 25 °C and −20 °C. From the SCB test results, fracture-related parameters such as peak load, critical stress intensity factor, strain energy, J-integral, fracture energy, and stiffness were determined. The SCB tests were carried out under cyclic cracking-healing scenarios to assess the effectiveness of the healing process. To quantify the healing efficiency, fracture-related parameters and corresponding healing indices (HI) were measured at each damage cycle. Additionally, service life extensions were calculated based on the analysis of fatigue and thermal cracking resistance. Finally, the HI obtained through other fracture-related parameters were used as a response factor to evaluate the statistical significance of each fracture parameter. The results show that for unaged asphalt mixtures, service life extensions for fatigue and thermal cracking resistance were 3.61 and 3.46 times the initial pavement life, respectively. In contrast, for specimens that experienced 20 years of aging after construction, the corresponding values were 1.50 and 2.23. This suggests that while increasing levels of aging reduce the effectiveness of the induced healing process, the pavement life can still be extended by using the induced healing method. Furthermore, a significant variation was observed in the HI obtained from different fracture-related parameters for asphalt mixtures at different aging levels. This suggests that using the ultimate strength of specimens to determine HI may present conservative results for aged asphalt mixtures since it does not explain the cracking features of the asphalt mixture at intermediate temperatures. The proposed fracture-based method can represent the interactions of cracking and time-dependent behaviors of materials, allowing for the combined effects of the healing process on fatigue and thermal fatigue life extensions to be addressed.

Effect of Coarse Aggregate Grading on Mechanical Parameters and Fracture Toughness of Limestone Concrete

This work presents a discussion of the basic properties of broken mineral limestone aggregates with the specification of the properties affecting the fracture toughness of concretes made with these aggregates. To determine the influence of the grain-size distribution of coarse aggregates for each concrete series, two types of aggregate grain were used, with maximum grain sizes of 8 mm (series of concrete L1) and 16 mm (series of concrete L2). Fracture-toughness tests were carried out using mode I fractures in accordance with the RILEM Draft recommendations, TC-89 FMT. During the experiments the critical stress-intensity factor (KIcS) and crack-tip-opening displacements (CTODc) were determined. The main mechanical parameters, i.e., the compressive strength (fcm) and splitting tensile strength (fctm), were also assessed. Based on the obtained results, it was found that the grain-size distribution of the limestone aggregate influenced the concrete’s mechanical and fracture-mechanics parameters. The obtained results showed that the series-L2 concrete had higher strength and fracture-mechanics parameters, i.e.,: fcm—45.06 MPa, fctm—3.03 MPa, KIcS—1.22 MN/m3/2, and CTODc —12.87 m10−6. However, the concrete with a maximum grain size of 8 mm (series of concrete L1) presented lower values for all the analyzed parameters, i.e.,: fcm—39.17 MPa, fctm—2.57 MPa, KIcS—0.99 MN/m3/2, and CTODc —10.02 m10−6. The main reason for the lower fracture toughness of the concretes with smaller grain sizes was the weakness of the ITZ in this composite compared to the ITZ in the concrete with a maximum grain size of 16 mm. The obtained test results can help designers, concrete producers, and contractors working with concrete structures to ensure the more conscious composition of concrete mixes with limestone aggregates, as well as to produce precise forecasts for the operational properties of concrete composites containing fillers obtained from carbonate rocks.

Micro-scale fracture toughness of textured alumina ceramics

Enhanced fracture resistance of textured alumina is ascribed to crack deflection along grain boundaries. In this work, we quantify and compare the micro-scale fracture toughness of textured alumina grains and grain boundaries by micro-bending tests. Notched micro-cantilevers were milled from single alumina textured grains (perpendicular to the [0001] direction) and across several textured grains (along the [0001] direction), using a focused ion beam technique. Bending tests were performed with a nanoindenter. A shape function for notched pentagonal-shaped cantilevers was developed using finite element analysis. The critical stress intensity factor at the notch tip was determined based on the measured fracture loads. The micro-scale fracture toughness of the textured alumina grain boundaries (2.3 ± 0.2 MPa m1/2) was about 30% lower than that of the grains (3.3 ± 0.2 MPa m1/2). These findings at the micro-scale are paramount for understanding the macroscopic fracture behaviour of textured alumina ceramics.

Plastic deformation response during crack propagation in Mg bicrystals with twin boundaries

The present study is committed to exploring the intergranular crack performance of magnesium (Mg) bicrystals with typical twin boundaries (TBs) by molecular dynamics simulations coupled with finite element method. Atomic modeling is conducted to determine the traction–separation (T–S) law in a cohesive zone. Importantly, the T–S curves together with microstructure evolutions are employed to investigate the plastic response during crack propagating. Afterwards, the obtained T–S parameters are embedded into cohesive elements along grain boundaries of polycrystalline structure, which is efficiently characterized by the Voronoi tessellation. As consequence, the simulation of intergranular fracture in Mg bicrystal is successfully realized by finite element analysis with failure criteria. Eventually, the critical stress intensity factors of compact tension specimens with various TBs are predicted availably. The results demonstrate that the crack propagation is strongly sensitive to twin boundary and resultant plastic deformation behavior at the crack tip. Moreover, it is found that microcracks are produced when TBs interact with dislocations. A comparison between simulated results and published experimental data is provided to highlight the reliability of the multiscale method for studying the cracking performance.

Regarding the possibility of using the SEVNB method to determine the fracture resistance of glass

Background. Today, methods have been developed that take into account the of the feature initiation and development of cracks in the material during fracture, and the corresponding calculation equations have been proposed. However, the problem of reliably determining the fracture resistance of glass is relevant and requires attention when creating responsible elements of constructions. Objective. Solving the problem of the possibility of determining the fracture resistance of glass of different chemical composition by the SEVNB method, checking the reliability of the obtained results by comparing them with data from literary sources. Methods. The SEVNB method consisted in testing of the standard sample with an applied stress concentrator in the form of a V-notch under three or four-point bending. Results. The values of the critical stress intensity factor of the studied glasses were determined within 0.5...1.0 MPa·m1/2. The subject of research was silicate float glass for technical purposes (soda-lime glass), quartz (fused silica glass) and optical (heavy flint SF5) glass. Conclusions. The obtained values of the fracture resistance of the glasses were conformed with the known literary data of its determination according to the IF method common in practice. It has been shown that the SEVNB method can be used to determine the fracture resistance of glasses provided that all the testing requirements specified in BS EN ISO 23146:2016 are met. The research method allows obtaining results with tolerable accuracy and can be considered open and relatively simple for its using in scientific research and production spheres.

CaSiO3-HAp Metal-Reinforced Biocomposite Ceramics for Bone Tissue Engineering.

Reconstructive and regenerative bone surgery is based on the use of high-tech biocompatible implants needed to restore the functions of the musculoskeletal system of patients. Ti6Al4V is one of the most widely used titanium alloys for a variety of applications where low density and excellent corrosion resistance are required, including biomechanical applications (implants and prostheses). Calcium silicate or wollastonite (CaSiO3) and calcium hydroxyapatite (HAp) is a bioceramic material used in biomedicine due to its bioactive properties, which can potentially be used for bone repair. In this regard, the research investigates the possibility of using spark plasma sintering technology to obtain new CaSiO3-HAp biocomposite ceramics reinforced with a Ti6Al4V titanium alloy matrix obtained by additive manufacturing. The phase and elemental compositions, structure, and morphology of the initial CaSiO3-HAp powder and its ceramic metal biocomposite were studied by X-ray fluorescence, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Brunauer-Emmett-Teller analysis methods. The spark plasma sintering technology was shown to be efficient for the consolidation of CaSiO3-HAp powder in volume with a Ti6Al4V reinforcing matrix to obtain a ceramic metal biocomposite of an integral form. Vickers microhardness values were determined for the alloy and bioceramics (~500 and 560 HV, respectively), as well as for their interface area (~640 HV). An assessment of the critical stress intensity factor KIc (crack resistance) was performed. The research result is new and represents a prospect for the creation of high-tech implant products for regenerative bone surgery.

Study on Stress Intensity Factor of the Pit-Crack Model for Portal Crane Girders

In shipbuilding gantry cranes in long-term service in the coastal humid salt-spray environment, the main beam is affected in many places by corrosion fatigue-formed corrosion pits, affecting the structural strength of the main beam. This paper focuses on the impact of corrosion-generated pits under the conditions of crack nucleation. Corrosion fatigue crack nucleation is a local damage evolution process and the stress intensity factor criterion is one of the critical conditions to discern whether a crack sprouts at the corrosion pit. This paper establishes a corrosion pit-crack model based on the overall finite element model of the portal crane, and uses ANSYS software to simulate the stress intensity factor under complex boundary conditions. The results show that the different sizes and depth-to-diameter ratio of the pits greatly affect the value of the stress intensity factor and the stress concentration phenomenon may be the main factor causing the emergence of cracks; the change in the size of the pits on the stress intensity factor is not obvious, but with the increase in the depth-to-diameter ratio of the pits, the stress intensity factor of the pit-crack model is significantly increased. According to the hypothesis of semi-ellipsoidal pitting, the relationship between the stress intensity factor and the stress concentration factor at the pit is proposed, and its calculation results are within 5% error compared with the finite element method, and it is found that the effect of the etch pit on the stress intensity factor is positively correlated with the stress concentration factor; with the increase in the etch pit depth–diameter ratio, the crack budding location changes with the change in the stress concentration location, and the crack is more likely to be generated from the shoulder of the etch pit when the depth–diameter ratio of etch pit exceeds 1.

The applicability and the low limit of the classical fracture theory at nanoscale: The fracture of graphene

Miniaturization of mechanical structures offers excellent performances of the device while has brought problems of fracture at nanoscale. However, whether the classical fracture theory is applicable at such a small scale and what is its low limit are still challenging problems. In this paper, by conducting atomistic simulation of graphene and compared with the reported in-situ experiments, the applicable range of distance from crack tip for crack-tip stress distribution models and the low limit of crack length for fracture criterion are investigated. It is found that all crack-tip stress models are invalid within fracture process zone whose dimension is 2.5 Å away from crack tip. The energy-based fracture criteria are not applicable when the crack length is less than 8 nm due to the nonlinear stress–strain relationship, while the modified Griffith criterion can be applied to low limit of crack length 5 Å. For the stress-based fracture criterion, the stress intensity factor criterion fails when the crack length is less than 8 nm due to the decreasing size of critical K-dominant zone ΛK, while the theory of critical distances and quantized fracture mechanics can accurately predict the critical fracture stress regardless of the crack length, which can be unified by a non-local stress criterion. This work will provide a mechanical basis for the reliable application of the microelectronic devices at nanoscale.

Fracture properties of self-compacting mortar in terms of contents and high temperatures

In this research, the effects of five parameters, namely, water/cementitious materials ratio, limestone powder, high temperatures, polypropylene and steel microfibres, on the fracture energy (GF) and critical stress intensity factor (KIC) of notched self-compacting mortar beams were investigated. Four levels were assumed, using the Taguchi method, with an L16 orthogonal array for each parameter, and 32 mix designs were considered instead of 512. The prepared specimens were placed in a furnace and exposed to three temperature levels of 200, 400 and 600°C at a heating rate of 2°C/min. Mortar specimens were kept at each target temperature for 6 h. As a result, the fracture properties of the specimens initially improved but then decreased after exposure to temperatures above 400°C. At 200°C, the density of self-compacting mortar increased and reached a maximum value; this, in turn, increased the fracture energy and critical stress intensity factor of the specimens at this temperature, compared with those at an ambient temperature. Above this temperature, up to 600°C, increasing the temperature had destructive effects on the fracture properties. Furthermore, the reliability of the results are discussed and confirmed by using analysis of variance.

Highly Toughened Nanostructured Self-Assembled Epoxy-Based Material—Correlation Study between Nanostructured Morphology and Fracture Toughness—Impact Characteristics

We present an efficient and effective method for preparing a novel self-assembled nanostructured material with high toughness and impact strength from a blend of di-glycidyl ether of bisphenol-A (DGEBA) and epoxidized poly(styrene-block-butadiene-block-styrene) (eSBS55) tri-block copolymer. The field emission scanning electron microscopy and transmission electron microscope results show the nanostructured morphological characteristics of the blends. This study achieved the highest fracture toughness, with a fracture toughness in the form of critical stress intensity factors (KIC) value of 2.54 MPa m1/2, in epoxy/block copolymer blends compared to previous works in the field. The impact strength also increased by 116% compared to neat epoxy. This is a major advancement in epoxy toughening due to the use of a single secondary phase. The resulting highly tough and impact-resistant material is a promising candidate for coating applications in industries such as flooring, building, aerospace, and automobiles.

Understanding the helicoidal damage behavior of bio-inspired laminates by conducting multiscale concurrent simulation and experimental analysis

Bio-inspired helicoidal structures exhibit excellent fracture toughness. A multiscale concurrent simulation of the damage propagation process is critical for understanding the fracture behavior of such structures with pre-existing cracks. However, such an analysis is extremely challenging owing to computational complexity. In this study, the in-plane critical stress intensity factor and energy release rate of six different helicoidal carbon-fiber-reinforced plastic structures are measured experimentally by conducting a single-edge-notch bending test. The damage distribution of the different structures is examined by performing computed tomography scanning. Several multiscale concurrent analyses are conducted by using the self-consistent clustering analysis method to study the specific damage propagation process and evaluate the fracture toughness contribution of different layers. The results indicate that the pitch angle significantly impacts the fracture toughness, whereas the stacking mode changes the crack propagation orientation. When the pitch angle is appropriately adjusted, the fiber damage length is enhanced, resulting in a significant increase in the fracture toughness. The interaction between fiber damage, matrix damage, and hybrid damage during the failure process is interpreted using the dissipated energy ratios of the fiber damage layer, transition layer, and matrix damage layer.

A localized stress field approach for calculating the critical stress intensity factor for an isotropic solid at atomistic scale

Crack growth initiation in brittle materials is generally studied using the stress intensity factor (SIF) since linear elasticity is assumed to be valid in the crack-tip region. The critical SIF is the SIF just before the onset of crack growth. In atomistic simulations, the “local” critical SIF is usually found indirectly by relating it to the “global” energetically calculated critical energy release rate. Since the crack growth happens at the crack tip, a method for calculating critical SIF (at a state just before crack growth initiation) directly by near-tip stress field has been implemented. The implementation of this methodology for amorphous isotropic solids is not trivial due to the random arrangement of atoms. Further, the presence of two types of elements in amorphous solids (silica is considered here) complicates the process since the volume occupied by each atom will be different (making the use of virial stress extremely complicated). In the present work, it has first been shown that the amorphous solid is indeed linear elastic isotropic by conducting various tests for finding elastic constants and showing that only two of them are independent. Then, a near-tip stress field is calculated by averaging the analytically calculated stress. The near-tip stresses in amorphous silica, validates the presence of linear elasticity beyond a small region from the crack tip. Even with the truly amorphous nature of silica, the minimum reported R2 for the inverse square-root fit (K-dominance) is around 80% at the critical state just before the onset of crack growth. The value of critical SIF calculated directly from the near-tip stresses in the present work comes out to be very close to those predicted by other indirect methods (experiments and atomistic simulations). The proposed method in the present work has a general applicability to measure the critical SIF directly using the near-tip stress field for any amorphous isotropic solid at the atomistic scale irrespective of the number of type of constituent elements.

A study on XFEM simulation of tensile, fracture toughness, and fatigue crack growth behavior of Al 2024 alloy through fatigue crack growth rate models using genetic algorithm

AbstractThis study aims to numerically validate and simulate the fatigue crack growth rate (FCGR), tensile, and fracture toughness properties of T3 and T351 tempered aerospace grade Al 2024 alloy. The extended finite element method (XFEM) coupled with a genetic algorithm (GA) was used to predict FCGR behavior in the framework of an in‐house developed MATLAB code. The numerical simulation was performed using three different FCGR models, i.e., Paris, Forman, and Nasgro. The FCGR prediction ability of simulation models was improved and compared further using GA. The Nasgro model with genetically optimized parameters shows the highest FCGR prediction accuracy compared to other FCGR models. The critical stress intensity factor and von Mises stress distribution under static loading were also predicted for C(T) specimen. A similar XFEM approach was used for analyzing the tensile behavior using a center cracked specimen at the gage section of a dog bone‐shaped specimen.

Nanomodified Basalt Fiber Cement Composite with Bottom Ash

Directed control of the process of structure formation of a cement composite from modern positions must be carried out taking into account the synergistic effect of its components. In particular, the cement composite, when applied with pozzolanic additives and fiber reinforcement, is transformed into a more complex material with excellent performance. The aim of the article is to study the combined action of nanomodified basalt fiber (NBF) and bottom ash (BA) as structural elements of concrete. To achieve this aim, a number of tasks were performed, including the development of nanomodified-basalt-fiber–bottom-ash–cement concretes, as well as the study of their fresh, physical and mechanical properties (flowability, average density, compressive and flexural strength, elastic modulus and crack resistance) and durability characteristics (water, frost and abrasion resistance). A series of nanomodified basalt-fiber-reinforced concretes (from 0 to 7 wt.% NBF) were developed, in which the economical Portland cement CEM I 32.5 N was replaced by up to 45 wt.% mechanically activated bottom ash residue (400 m2/kg). An economical superplasticizer with a high water-reducing capacity (35%) made it possible to achieve uniform flowability of the mixes (slump 20–22 cm and slump flow 45–52 cm). The combined effect of BA and NBF provides control over the structure formation of cement materials, which ensures the redistribution of internal stresses from shrinkage deformations throughout the entire volume of the composite; under loading, the process of crack formation slows down, the stress concentration near structural defects decreases, and stresses are redistributed in the microstructure of the cement composite between its components. Perfect values of mechanical properties (compressive strength up to 59.2 MPa, flexural strength up to 17.8 MPa, elastic modulus up to 52.6 GPa, critical stress intensity factor 0.507 MPa m0.5) are explained by the complex action of the ash residue and nanomodified basalt fibers. A mix with 30 wt.% BA and 5 wt.% NBF is characterized by water resistance grade W18, frost resistance class F400 and abrasion resistance 0.59 g/cm2, which confirms the high wear resistance of the developed materials.

Аналитическая модель квазихрупкого разрушения пластины с трещиной

The paper considers a rectangular plate with the edge crack of mode I of normal separation from the elastoplastic material with the ultimate strain. This class of materials includes, for example, the low-alloy steels used in structures operating at temperatures below the cold brittleness threshold. The strength of the plate was studied within the framework of the Neuber --- Novozhilov approach. The crack propagation criterion was formulated using the modified Leonov --- Panasyuk --- Dugdale model using an additional parameter, i.e., the plasticity zone diameter (pre-fracture zone width). Under conditions of small-scale yielding in the presence of the stress field singular feature in the vicinity of the crack tip, the two-parameter (dual) criterion for quasi-brittle fracture was formulated for mode I cracks in the elastoplastic material. The fracture dual criterion included deformation criterion at the crack tip, as well as the force criterion at the fictitious crack tip. The lengths of the original and fictitious cracks were differing by the length of the pre-fracture zone. Diagrams of the plate quasi-brittle fracture under conditions of plane deformation and plane stress were constructed. The parameters included in the proposed quasi-brittle fracture model were analyzed. It was proposed to select model parameters according to the approximation (σ--ε)-diagram of uniaxial tension and the KIc critical stress intensity factor

Nanoscale crack propagation in clay with water adsorption through reactive MD modeling

AbstractThe atomic‐scale cracking mechanism in clay is vital in discovering the cracking mechanism of clay at the continuum scale in that clay is a nanomaterial. In this article, we investigate mechanisms of modes I and II crack propagations in pyrophyllite and Ca‐montmorillonite with water adsorption through reactive molecular dynamics (MD) with a bond‐order force field. Clay water adsorption is considered by adding water molecules to the clay surface. During the equilibration stage, water adsorption could cause bending deformation of the predefined edge crack region. The relatively small orientating angle of water molecules indicates the formation of hydrogen bonds in the crack propagation process. The peak number density of adsorbed water decreases with the increasing strains. The atomistic structure evolution of the crack tip under loading is analyzed to interpret the nanoscale crack propagation mechanism. The numerical results show that the crack tip first gets blunted with a significant increase in the radius of the curvature of the crack tip and a slight change in crack length. The crack tip blunting is studied by tracking the crack tip opening distance and O–Si–O angle in the tetrahedral Si–O cell in modes I and II cracks. We compare bond‐breaking behaviors between Al–O and Si–O. It is found that Si–O bond breaking is primarily responsible for crack propagation. The critical stress intensity factor and critical energy release rate are determined from MD simulation results.