Cracks In Materials Research Articles

State-of-the-Art Review of Microcapsule Self-Repairing Concrete: Principles, Applications, Test Methods, Prospects

Cement-based materials are widely used in construction worldwide, but they are vulnerable to environmental stressors and thermal fluctuations, leading to the formation of internal cracks that compromise structural integrity and durability. Traditional repair methods such as surface coatings, grouting, and groove filling are often costly and labor-intensive. In response, self-repairing technologies for cement-based materials have emerged as an innovative and promising solution, offering the potential to significantly extend the lifespan of structures and reduce maintenance costs. A particularly novel approach is the development of microcapsule-based self-repairing concrete. In this system, repair agents are encapsulated within microcapsules and combined with curing agents in the concrete matrix. When cracks form, the microcapsules rupture, releasing the repair agents to autonomously heal the damage. This self-repairing mechanism is characterized by its high efficiency, durability, environmental sustainability, and versatility, making it a promising alternative to traditional repair methods. Recent research has focused on the development of microcapsules with various core materials, such as TDI (toluene diisocyanate), IPDI (isophorone diisocyanate), or epoxy resin, as well as composite shell materials including paraffin wax, PE (polyethylene) wax, nano-SiO2, and nano-CaCO3. A novel advancement in this area involves the enhancement of microcapsules through the incorporation of magnetic nanomaterials into the shell, providing new possibilities for self-repairing systems that address cracks in cement-based materials.

Life Cycle Cost Analysis and Deterioration Patterns of Limestone Paving

Stone is a durable and high-performance paving material in standard and in intensive service regimes. Stone is thus a preferable material for sidewalk and promenade paving under intensive service regimes, such as touristic promenades and historic sites. Recent studies on the weathering and degradation of stones in buildings have revealed differing analytical approaches among geologists, geo-engineers, and civil engineers. The present research aims to develop a structured analytical–empirical methodology for the assessment of stone pedestrian pavements’ life cycle and life cycle costs. This study presents an integrated methodology that combines diagnostic field surveys, core laboratory tests, and the characterization of deterioration patterns. This approach allows for evaluating how faulty construction methods impact the durability and degradation of natural stone pedestrian pavements. It also assesses their effect on the pavement’s life cycle and associated costs. The diagnostic field survey concentrates on specific construction details, including: (a) Cracks in the paving stones. (b) Peeling of stone layers. (c) Subsidence and cracking at the paving edges. (d) Cracking of filler materials in joints between stone slabs. The laboratory tests focus on five core physical properties for the stone deterioration: (1) apparent density, (2) Water absorption, (3) Compressive strength, (4) Flexural strength, and (5) Abrasion resistance. This study proposes linear and exponential patterns for deterioration. A case study carried out on a Capernaum promenade revealed excessive deterioration patterns caused by the poor core properties of the paving stone and defective construction. The consequences of excessive deterioration on life cycle costs result in additional expenses of 73%, indicating a reduction in the life cycle. The novelty of this research lies in developing and delivering an integrated methodology that enables the assessment of how defective construction methods impact the durability, deterioration, life cycle, and life cycle costs of natural stone pedestrian pavements.

A numerical study of Mullins softening effects on mode I crack propagation in viscoelastic solids

This paper presents a finite element analysis of steady-state crack propagation in viscoelastic soft solids exhibiting Mullins softening. A cohesive-zone model is employed to simulate the localized processes at the tip of a Mode I crack in materials governed by viscoelastic behavior and damage-induced Mullins effects. The study numerically evaluates the intrinsic dissipation characteristics of typical rubber-like materials, focusing on the influence of key factors such as Mullins damage, relaxation modulus, and relaxation time. The impact of these factors on material toughening is examined, with particular emphasis on their role in crack propagation. The results reveal that crack propagation velocity is highly sensitive to the interplay between energy dissipation mechanisms. Specifically, Mullins damage parameters are shown to increase fracture toughness by raising the local energy release rate threshold at the crack tip. Additionally, the relaxation modulus enhances viscous dissipation, further elevating this threshold and subsequently reducing crack propagation velocity. Interestingly, an inverse relationship between relaxation time and crack propagation velocity is observed. The study provides a detailed analysis of the dissipation mechanisms at the crack tip, offering valuable insights for improving material toughness.

On the Simulation of Artificial Cracks in Brittle Materials Using Julia Set Fractals

On the Simulation of Artificial Cracks in Brittle Materials Using Julia Set Fractals

On cleavage crack morphology in some rock materials of different genesis

Fracture of rocks and biominerals on the microscopic scale under bending was examined. Eggs of some birds were used in the study because an eggshell is biomineral consisted of 90% of calcium carbonate of the biological genesis. Cracking in the model materials was studied in optical microscopes including in situ bending of eggshell samples. It was shown that despite brittle deformation behavior on the macroscopic scale and brittle transgranular fracture as fracture mode, the morphology of cracking of model materials looks like cracks in the neck of aluminum under tension.

Partially insulated cracks in orthotropic materials under steady state thermo-mechanical loadings

An attempt has been made to investigate the cracked composite medium with thermally conducting multiple cracks at its interface of the dissimilar orthotropic media subjected to thermal and mechanical loadings. The present article examines the governing equations, the associated differential constraints and boundary conditions those govern the temperature field and stress field. Fourier integral transforms, together with their corresponding inverses, have been employed to convert the singular integral equations into a set of linear equations by using the concept of orthogonality and completeness. The numerical technique, namely the Schmidt method, which employs a polynomial expansion of the unknown functions, is used to solve algebraic equations to determine the desired temperature and stress fields. The semi-analytical findings of the expressions for heat flux intensity factor (HFIF), stress intensity factor (SIF), and crack displacements have been mentioned in the article. Both mode-I and II types of cracks have been studied to investigate the effect of thermal conductivity. Detailed graphical representations effectively illustrate the numerical results and the interrelations between crack lengths, bonded strip width, and the partial conductivity coefficient of the crack surface. As the thermal conductivity coefficient increases, the temperature difference tends to zero. The results reveal that an increase in thermal conductivity decreases the SIFs.

Cutting behaviors of cortical bone ultrasonic vibration-assisted cutting immersed in physiological saline

In orthopedic surgery, cortical bone cutting usually involves washing and cooling with physiological saline. However, how the saline changes the cutting behaviors of bone ultrasonic vibration cutting remains challenging. Hence, this paper simulates the clinical ultrasonic cutting condition in orthopedics to reveal the cutting behaviors of bone ultrasonic vibration orthogonal cutting immersed in physiological saline. The dynamic equation and motion process curves of ultrasonic cavitation bubbles were established. The results showed that the bone cutting immersed in physiological saline significantly improved the surface quality, reduced surface roughness and mechanical damage, and avoided large brittle cracks propagation. In saline immersed cutting, the physiological saline changes the mechanical behaviors of bone materials, resulting in plastic behaviors for the material removal and crack deflection. This study establishes the influence of physiological saline on the ultrasonic vibration cutting performance, providing guidance for orthopedic bone cutting surgery methods.

Оцінка можливості виявлення тріщин під час контролю ЛЮМ1-ОВ на лопатках турбін після нанесення комплексних жаростійких покриттів

Currently, gas turbine engines (GTD) are being improved and made more powerful by increasing the temperature of the gases in front of the turbine and increasing the air compression ratio in the compressor. In the aviation industry, nickel heat-resistant alloys such as ЖС6У-ВІ, ЖС26-ВІ, ЖС32-ВІ, etc. are used to manufacture GTD blades. Despite their high properties in terms of corrosion resistance and heat resistance, the service life of GTD blades and their protection against oxidation and corrosion damage is ensured by applying coatings using various technologies both to the flowing surface of the blade blades (heat-resistant and heat-protective) and to the inner surfaces of the cooled channels (diffusion coatings). Failure of turbine blades is one of the most severe types of damage to turbine blades, so at different stages of serial production, including after applying heat-resistant coatings, LUM1-OV inspection of blades is performed to detect cracks that can form during processing and lead to their failure during engine operation. The paper evaluates the possibility of detecting cracks on GTD turbine blades with complex heat-resistant coatings GCP+SDP-2. The study was carried out on samples of working blades in the form of an experiment. First, fatigue tests of the samples were carried out on a test bench until cracks appeared. Then, a complex heat-resistant coating of GCP (CrAl gas circulation coating) + SDP-2 (heat-resistant alloy of the Ni-Cr-Al-Y system) was applied to the blade profile in stages according to the serial technology. After each coating was applied, the blades were inspected by the LUM1-OV method to determine the possibility of crack detection. The results showed that immediately after the application of the complex heat-resistant coating, cracks on the blades were not detected, because they spread only in the GCP layer and partially pass into the SDP-2 layer without reaching the surface. The results obtained can be the basis for removing the luminescent inspection operation from the technological process, immediately after applying complex heat-resistant coatings. Since this does not allow detecting cracks in the blade material and can lead to unnecessary costs for additional technological operations.

Crack Detection, Classification, and Segmentation on Road Pavement Material Using Multi-Scale Feature Aggregation and Transformer-Based Attention Mechanisms

This paper introduces a novel approach to pavement material crack detection, classification, and segmentation using advanced deep learning techniques, including multi-scale feature aggregation and transformer-based attention mechanisms. The proposed methodology significantly enhances the model’s ability to handle varying crack sizes, shapes, and complex pavement textures. Trained on a dataset of 10,000 images, the model achieved substantial performance improvements across all tasks after integrating transformer-based attention. Detection precision increased from 88.7% to 94.3%, and IoU improved from 78.8% to 93.2%. In classification, precision rose from 88.3% to 94.8%, and recall improved from 86.8% to 94.2%. For segmentation, the Dice Coefficient increased from 80.3% to 94.7%, and IoU for segmentation advanced from 74.2% to 92.3%. These results underscore the model’s robustness and accuracy in identifying pavement cracks in challenging real-world scenarios. This framework not only advances automated pavement maintenance but also provides a foundation for future research focused on optimizing real-time processing and extending the model’s applicability to more diverse pavement conditions.

Crack monitoring and repair model of SMA composite material based on strain transfer

In the process of using composite materials, crack damage is unavoidable. These cracks may cause a decrease in the structural performance of the material and may even pose a threat to the safety of the entire structure. In this paper, the shape memory alloy (SMA) is embedded into the composite material, and the strain transfer effect of the interface layer is considered. The crack monitoring and repair model of SMA composite material based on strain transfer are established using SMA resistance-sensing characteristics and SMA constitutive model. Based on this monitoring and repair model, the crack monitoring behavior of SMA under different initial states and temperature conditions is discussed, and the crack repair behavior of SMA under specific initial states and temperature conditions is also discussed. The research results show that the change in SMA resistance and the strain of the composite material crack are linearly segmented, and as the temperature increases, the composite material crack is gradually repaired. This study can provide theoretical guidance for the further engineering application of SMA composite material crack monitoring and repair theory.

Generative AI-Driven Data Augmentation for Crack Detection in Physical Structures

The accurate segmentation of cracks in structural materials is crucial for assessing the safety and durability of infrastructure. Although conventional segmentation models based on deep learning techniques have shown impressive detection capabilities in these tasks, their performance can be restricted by small amounts of training data. Data augmentation techniques have been proposed to mitigate the data availability issue; however, these systems often have limitations in texture diversity, scalability over multiple physical structures, and the need for manual annotation. In this paper, a novel generative artificial intelligence (GAI)-driven data augmentation framework is proposed to overcome these limitations by integrating a projected generative adversarial network (ProjectedGAN) and a multi-crack texture transfer generative adversarial network (MCT2GAN). Additionally, a novel metric is proposed to evaluate the quality of the generated data. The proposed method is evaluated using three datasets: the bridge crack library (BCL), DeepCrack, and Volker. From the simulation results, it is confirmed that the segmentation performance can be improved by the proposed method in terms of intersection over union (IoU) and Dice scores across three datasets.

Self-healing of cracks in cement-based materials through bio-mineralization of low air-dependency microorganisms

Microbial self-healing technology for concrete is attracting widespread attention due to its environmentally friendly, non-toxic, and sustainable attributes. Currently, microbial agents utilized in concrete exhibit a high dependence on atmospheric conditions, relying on atmospheric oxygen to activate or capture carbon dioxide from the air for the generation of carbonate ions. This paper introduces an innovative low-dependency microbial restorative aimed at augmenting the self-healing capability of concrete by nearly doubling the available carbonate ions and providing 80 % of them internally, especially targeting deep cracks. A pioneering approach was employed by combining microorganisms that rapidly produce carbon dioxide with those that expedite carbon dioxide hydration. Microbial functional components were meticulously pelletized to create core-shell structure restorative particles, featuring an outer protective layer constructed with low-alkali cement. This study investigates the mechanism through simulation and experimentation, including substrate conversion, carbon dioxide transformation, and the generation and accumulation of carbonate ions and calcium ions. Essentially, this research not only presents a path towards reduced atmospheric dependence but also provides valuable insights for comprehending the mechanism behind microbial self-healing concrete.

Evaluation of the strain energy during the interaction between micro-crack and semi-infinite crack in a brittle material

The main goal of this research is to evaluate the strain energy in a brittle material during the interaction of the semi-infinite crack with a neighboring micro-crack. The problem is formulated by considering a cracked thin plate having a micro-crack that rotates around itself and around the semi-infinite crack whose the cracked plate is subjected to a uniform load under mode I. During the interaction between the semi-infinite crack and micro-crack, the strain energy and stress field can be generated at the crack tip of semi-infinite crack. The theoretical analysis of this interaction is treated mathematically by the complex potentials functions. It is shown that the positioning of the micro-crack relative to the semi-infinite crack leads to amplification, reduction and absorption of the strain energy at the crack-tip. The theoretical results agree with those found numerically.

Investigation of the failure mechanisms of Zr alloy with Cr2AlC coatings using in-situ bending tests: Experiments and simulations

The failure mechanisms of Cr2AlC-coated zirconium samples under different mechanical loading conditions have been investigated by combining in-situ bending tests and finite element simulations. The results of interrupted in-situ bending tests reveal that new critical cracks are mainly initiated in the Cr2AlC coating layer, followed by subsequent propagation into the Zr substrate with increasing plastic deformation. The formation of new critical cracks in Cr2AlC material is described using the maximum principal stress criterion. A stress state-dependent damage mechanics model combined with an advanced plasticity model is used to capture the ductile fracture behavior of the Zr substrate. Finite element simulations have been performed to identify the failure properties of coating and substrate materials, leading to the accurate reproduction of experimental fracture behavior.

Experimental Study on Three‐Dimensional Internal Crack Propagation in Brittle Materials With Combined Defects

ABSTRACTThis study investigates the fracture behavior of brittle solids with combined defects by prefabricating internal cracks in glass materials using three‐dimensional internal laser‐engraved crack (3D‐ILC) technology. The results of physical and numerical experiments indicate that under biaxial compression, cracks first appear on the surface of the cavity, followed by the propagation of the prefabricated cracks. During propagation, these two cracks attract each other, ultimately leading to crack coalescence. As the geometric distribution of the combined defects changes, the propagation direction of the prefabricated cracks deflects to varying degrees as is to be expected. The failure process of the specimens with combined defects was a mixed‐mode I–II–III fracture. This research provides experimental and theoretical references for the study of crack propagation in rock materials containing combined defects.

Effect of random variation in input parameter on cracked orthotropic plate using extended isogeometric analysis (XIGA) under thermomechanical loading

Abstract This research introduces the Stochastic Extended Isogeometric Analysis (XIGA) method to investigate fracture behavior of isotropic and orthotropic materials under mechanical, thermal, and thermomechanical loads. Employing knot spans from Isogeometric Analysis (IGA) for domain discretization, the study utilizes identical basis functions for geometry construction and solution discretization. Utilizing Extended Finite Element Method (XFEM) enrichment functions, accurate crack face displacement discontinuity and tip singularity within the stress field are characterized. Additionally, employing a second-order perturbation technique within XIGA framework, the research derives mean and coefficient of variance values for mixed-mode Stress Intensity Factors (SIF). Stochastic variations in material elastic properties, crack length, and crack angle are considered in this computation. Credibility and robustness of the study are confirmed through comparative analyses against available literatures and Monte Carlo Simulations (MCS). The observed exceptional agreement validates the precision and reliability of the proposed stochastic XIGA method for fracture analysis in orthotropic material systems under thermomechanical loading conditions.

Analysis of compact tension specimens with deflected cracks for orthotropic materials

Anisotropic materials, such as alloy, wood and fiber-reinforced composites, are widely used in load-bearing components. Accurately obtaining its fracture performance is crucial for safety assessment. However, existing testing methods based on compact tension (CT) specimen have not taken into account material anisotropic characteristics and crack deflection. In this work, the systematic finite element analysis (FEA) was conducted for CT specimens with deflected cracks made of orthotropic materials. A wide range of geometric (crack deflection angle, β, and ratio of crack length to width, ap/W) and orthotropic material (λ and ρ) parameters were discussed. Complete solutions of the stress intensity factor (KI and KII) and load-line compliance (C) were determined for the first time. The results showed that the geometric dimensions and material parameters have a significant coupling influence on the fracture parameters. The influence of the λ is generally greater than that of the ρ. Changes of material parameters can make fracture parameters’ dependence on β vary. The variation of β and ap/W could enlarge or minish even dismiss the impact of λ and ρ. In addition, to further verify the importance of the obtained fracture parameters, the CT fracture tests of carbon fiber-reinforced epoxy resin under various orientations were conducted. The solutions will promote the optimization of the fracture toughness testing standards for CT specimens made of anisotropy materials.

Visualization of stepwise electrode decomposition in a nail penetrated commercial lithium-ion cell using low-temperature synchrotron X-ray computed tomography

The transition towards zero carbon emissions in power generation hinges on the integration of efficient electrical energy storage systems, with lithium-ion batteries (LIBs) positioned as a pivotal technology. While generally safe, deviations in their operational guidelines due to manufacturing defects or misuse can lead to critical safety concerns, notably thermal runaway (TR) events. Internal short circuits (ISCs) are primary initiators of TR within LIBs. For abuse testing, ISCs are often triggered by nail penetration. This study explores the morphological changes and mechanisms underlying ISC-induced TR in LIBs using operando synchrotron X-ray computed tomography (SXCT) at subzero temperatures. A novel cryogenic setup was developed to control a stepwise temperature increase in the damaged sample while monitoring electrochemical characteristics and simultaneously enabling acquisition of high-resolution SXCT images. The findings reveal that conducting nail penetration at minus 80 °C prevents immediate TR, enabling detailed analysis of subsequent structural and electrochemical behavior during controlled thawing. Thus, the initiation of TR processes at localized ISC sites has been observed, evidenced by voltage fluctuations and morphological changes, such as cathode material cracking and decomposition. These results underscore the importance of temperature control in mitigating TR risks and provide critical insights into the internal dynamics of LIBs under abusive conditions. The developed cryogenic SXCT methodology offers a powerful tool for non-destructive, high-resolution investigation of battery failure mechanisms, contributing to the enhancement of LIB safety.

A full-depth self-healing strategy for cracks in cement-based materials under marine environment

The depth of crack self-healing is crucial in advancing self-healing technology in cement-based materials. An additional challenge arises in marine environments with the infiltration of corrosion ions into the cracks. A self-healing approach revolving around microbial mineralization and layered double metal hydroxides (LDHs) is proposed to address these dual challenges. The findings demonstrate a significant enhancement in the healing properties of the mortar when mixed with the healing agent, particularly in terms of ultrasonic speed and resistance to cross-cracking, which are indicative of internal self-healing effects. The depth of crack self-healing was greatly improved, with a wide distribution of healing products observed on the crack surface. This healing effect is attributed to the in-situ formation of LDHs within the cracks. LDHs immobilizes a substantial amount of hydroxide ions, chloride ions, sulfate ions, and water molecules, resulting in improved volume expansion performance and effective sealing of the cracks. Moreover, the physical and chemical conditions within the crack solution were optimized, enhancing the activity of microorganisms and thereby improving the healing rate of the crack opening area. This multi-modal synergy-based self-healing strategy holds promise as a potential solution for achieving efficient crack self-healing.

Cracking in semiconductor devices–effect of plasticity under triaxial constraint

A semiconductor device integrates dissimilar materials of small sizes and complex geometries. During fabrication, the materials are deposited at various temperatures. Both deposition and change in temperature cause stresses in the materials. Under the stresses, ductile materials may deform plastically, and brittle materials may crack. Here we focus on how plastic deformation in the ductile materials affects cracking in nearby brittle materials. We study a model structure in which a metal line is encased by a silicon substrate and a brittle oxide layer. In the triaxially constrained metal, the stresses readily exceed the yield strength of the metal. Such high stresses in the metal elevate the stresses in the oxide. The degree of triaxial constraint varies with the aspect ratio of the metal. We compute the stress in the oxide, as well as the energy release rate of an edge crack and a long channel crack. We discuss strategies to avert cracking in the oxide.