Crack Propagation Research Articles

Rutting and fatigue behavior of neat and nanomodified asphalt mixture with SiO2 and TiO2

Modern asphalt technology has adopted nanomaterials as an alternative option to assert that asphalt pavement can survive harsh climates and repeated heavy axle loading during service life and prolong pavement life. This work aims to elucidate the behavior of the modified asphalt mixture fracture model and assess the fatigue and Rutting performance of Hot Mix Asphalt (HMA) mixes using the outcomes of indirect Tensile Strength (IDT), Semicircular bend (SCB) and rutting resistance; for this, a single PG (64−16) nanomodified asphalt binder with 5 % SiO2 and TiO2 have been investigated through a series of laboratory tests, including: Resilient modulus, Creep compliance, and tensile strength, SCB, and Flow Number (FN) to study their potential role of these nanomaterials to improve the rutting characteristics and fatigue life of wearing asphalt mixture at different temperatures. The outcome of this study revealed the positive role of these materials in enhancing mixture IDT characteristics, fracture energy, and viscoelastic deformation component of crack propagation; on the other hand, at higher temperatures, the modified mixture exhibited a superior performance in reducing the permanent deformation of asphalt mixture with SiO2 followed by TiO2 as compared to neat asphalt mixture.

Evaluation of Fracture Durability and Wear Resistance Properties for Orthopaedic Implant Application

Hydroxyapatite (HA) coated metallic substrates are commonly used for load-bearing orthopedic implants. In the present work Titanium grade 2 and Titanium grade 5 substrates were coated with hydroxyapatite and hydroxyapatite reinforced with 5% (by wt.) multiwalled carbon nanotubes (MCNT) separately using plasma spray coating. The wear behavior of these coated substrates was studied with the simulated body fluid (SBF) having a pH between 7.20 to 7.40. Fracture toughness and wear resistance of HA reinforced with 5 % (by wt.) MCNT composite coating was found to be higher as compared to pure HA coating. This improvement is by virtue of inherent mechanical properties and the crack bridging effect offered by MCNT. The addition of MCNT also helped in restricting crack propagation in the coatings. As evident from SEM images, abrasive and adhesive wear mechanism were observed which reduces greatly with reinforcement of MCNT.

Failure Prediction of an Airfoil-Type Crack in Thermoelectric Coupling Materials

Airfoil-type cracks with curved surfaces and sharp tips are frequently encountered in modern engineering applications and the aerospace industry. However, such cracks significantly threaten structures due to stress concentration and further cause damage. This study investigates the theoretical analysis and failure prediction of airfoil-type cracks within thermoelectric coupling materials under the interaction of remote mechanical loads, heat flux and electric current density. By employing complex variable theory, conformal mapping methods, and the analytic continuation theorem, the full-field stress and stress intensity factors of an airfoil-type crack were determined under three different loading conditions. The results indicate that when the airfoil-shaped crack tip is subjected to horizontal compression, vertical tensile mechanical load, and both heat flux and current density parallel to the crack, the crack tip would reach a dangerous state. Additionally, the full-field stress distribution reveals stress concentration around the crack tip, which explains variations in SIFs under different external forces and shape factors. Four critical situations suppressing crack propagation under mixed loading conditions are proposed. Furthermore, using an acrylic plate and bismuth telluride alloy as examples, the critical values of external loading for the mixed-mode fracture are determined based on the strain energy density criterion. These critical values can be used to predict failure initiation, thus reducing the risk of structural failure due to airfoil cracks within thermoelectric coupling materials.

Unveiling the mechanism secret of abrasion emissions of particulate matter and microplastics

Recent research highlights that non-exhaust emissions from the abrasion of tires and other organic materials have emerged as a substantial source of airborne particulate matter and marine microplastics. Despite their growing impact, the underlying mechanisms driving these abrasion emissions have remained largely unexplored. In this study, we uncover that abrasion emissions from organic materials are fundamentally governed by a fatigue fracture process, wherein particles are progressively detached from the material surface under cyclic abrasion loads. Our findings demonstrate that these emissions increase significantly only when the applied abrasion loads surpass the material’s toughness threshold. We establish a scaling relationship between the concentration of emitted particulate matter and the measurable crack propagation rate of the organic material, offering a robust quantitative method to estimate abrasion emissions. This work not only introduces a novel mechanistic framework for understanding particulate matter pollution from organic material abrasion but also provides a scientific basis for developing strategies to mitigate emissions of airborne particulates and marine microplastics.

Fracture behaviors and crack propagation anisotropy in multi-ions modified bismuth titanate ferroelectrics

Bismuth titanate (BIT) is widely considered a promising lead-free piezoelectric material for advanced high-temperature applications. Despite significant advances in high-performance BIT ferroelectrics, there remains little understanding of mechanical properties including fracture failure and crack propagation behaviors, hindering the optimization of stability and reliability for next-generation high-temperature ferroelectrics. In this work, we investigated mechanical fracture and crack propagation behaviors of a type of high-performance bismuth titanate-based ceramic (Bi3.96Ce0.04Ti3–2xWxNbxO12, BCTWN) with different doping contents and electric poling states. High-resolution transmission electron microscopy (HRTEM) and electron backscatter diffraction (EBSD) results reveal that the BCTWN ceramics possess a single ferroelectric phase and exhibit layered crystal structures characterized by periodic fringe features. In addition, the striped domain structures are observed on the surface of plate-like grains. Mechanical measurements indicate that fracture behaviors of BCTWN ceramics are significantly affected by doping contents. The ceramics with the largest grain size present inferior microstructure with more defects, endowing the lowest bending strength and fracture toughness. For the samples with different poling states, strong anisotropy in crack propagation and fracture toughness is observed, attributed to the different domain switching mechanisms driven by local incompatible stress fields, which is experimentally validated by the intriguing evolutions of striped domain structures around crack tips. This work advances our understanding of the fracture and crack propagation mechanisms of BIT-based ceramics and provides insight into tailoring the mechanical behaviors through doping and poling strategies.

Experimental Study on Damage Constitutive Model of Rock under Thermo-Confining Pressure Coupling

Underground engineering frequently encounters the challenges of high temperatures and high confining pressures. The combined effects of temperature and confining pressure can significantly alter the mechanical properties of rock. Evaluating the impact of these factors on rock is a crucial aspect of engineering. This study investigates the mechanical properties of rocks under various temperature and stress conditions, focusing on the deformation and failure characteristics of four typical rock types: granite, red sandstone, gray sandstone, and shale under temperature-confining pressure coupling. The results indicate that high temperatures cause internal structural damage and crack propagation in rocks, leading to a reduction in compressive strength and elastic modulus. Conversely, high confining pressures can inhibit crack propagation and enhance rock deformation capacity. Additionally, significant differences were observed in the mechanical responses of different rocks; red sandstone and shale predominantly exhibited shear failure under the coupled effects of temperature and confining pressure, whereas granite and gray sandstone exhibited bulging failure. Based on the experimental results, an elastic modulus fitting model considering the temperature-confining pressure coupling effect was proposed, and the parameters of the Drucker–Prager criterion were modified. A constitutive model was constructed to accurately reflect the stress–strain state of rocks under the coupled effects of temperature and confining pressure. The constitutive model results show good agreement with the experimental findings.

Cracking Mechanism and Inhibition Strategies of Polycrystalline NCM Electrode Particles.

Developing a high-energy-density cathode material (LiNi1-x-yCoxMnyO2, NCM) for lithium-ion batteries is crucial to the electric vehicle and energy storage industries. However, the continuous insertion/extraction of Li+ generates diffusion-induced stress, causing NCM particles to crack or even pulverize, leading to battery capacity loss and limiting its wider commercial application. Current experimental studies are primarily postmortem examinations, and it is difficult to capture the particle cracking evolution. Simulation studies frequently ignore or simplify anisotropic volume contraction, demonstrating an insufficient understanding of the cracking mechanism of NCM polycrystalline particles, and cracking prevention strategies still need improvement. Therefore, we develop an anisotropic polycrystalline fracture phase-field model (AP-FPFM) that focuses on the anisotropic volume contraction of primary particles and precisely generates grain boundary distribution, coupling with Li+ diffusion, mechanical stress, and particle cracking. We employ AP-FPFM to demonstrate the behavior and mechanism of NCM polycrystalline particle cracking and illustrate the necessity and importance of anisotropic volume contraction to understand particle cracking. Furthermore, we explore the effects of average primary particle size, secondary particle size, and core-shell structure modulation on crack initiation and propagation and propose strategies to inhibit or migrate NCM polycrystalline particle cracking. This work provides theoretical support for revealing the cracking mechanism of anisotropic polycrystalline NCM particles and supplying optimization strategies to suppress particle cracking and improve the mechanical stability.

Competitive Fracture Mechanism and Microstructure‐Related Life Assessment of GH4169 Superalloy in High and Very High Cycle Fatigue Regimes

ABSTRACTHigh and very high cycle fatigue tests were performed to examine the microstructure and fracture mechanism of GH4169 superalloy in combination with techniques including electron‐backscatter diffraction (EBSD). Fractographic analysis revealed that surface failures are induced by surface flaws, whereas internal failures are caused by pores, facets, and inclusions. The three‐dimensional observation shows that fracture surfaces exhibit an irregular texture due to crystallographic mismatch of grains and plastic deformation at the crack tip. Based on EBSD analysis, Euler angles exhibited a complex geometry of grain orientation at the crack tip area, hindering crack propagation as evidenced by lower values of the Schmid factor and misorientation at the crack tip. Furthermore, the threshold values of small and long cracks decrease, whereas the transformation sizes from small to long crack growth increase from surface to internal failure. Finally, a novel microstructure defect‐based life prediction model is established, and the predicted results demonstrate a close resemblance to experimental outcomes.

Natural Seawater Impact on Crack Propagation and Fatigue Behavior of Welded Nickel Aluminum Bronze

ABSTRACTNickel aluminum bronze (NAB) is a complex alloy used extensively in the marine environment. Fatigue strength of NAB is reduced by welding and prior seawater corrosion. This study investigated the combined effect of corrosion and plasma welding on the fatigue behavior of NAB. Natural seawater corroded samples were used in tension‐tension cyclic loading tests to observe fatigue crack initiation, propagation, and failure. Fatigue cracks initiated from corrosion pits at the weld toe. Stress corrosion and fatigue cracks propagated along the path of β′ and κIII phases. A short crack growth model (SCGM) predicted fatigue strength using experimentally obtained material properties and corrosion pit dimensions. Model predictions were used to develop S‐N curves and were within 30% of experimental results. The SCGM produced accurate and reliable fatigue life results that could be applied by industry to aid in revalidation decision making and inspection scheduling.

Mesoscale Modeling of Microcapsule-Based Self-Healing Cementitious Composites under Dynamic Splitting Tension

Microcapsule-based self-healing cementitious composite (MSCC) offers autonomous damage repair, extending the service life of structures. However, most of the existing studies focus on static behavior and healing effectiveness but rarely explore dynamic responses. This study developed the mesoscale modeling approach to investigate MSCC behavior under dynamic split tensile loading. At the mesoscale, MSCC can be treated as a four-phase composite consisting of coarse aggregates, interfacial transition zones, cement mortar, and microcapsules. Alternatively, it can be simplified as a two-phase composite comprising a homogeneous mortar matrix and microcapsules. Four-phase and two-phase mesoscale MSCC models were developed for 2D simulations, while a two-phase 3D model was also developed for comparison. Mesoscale numerical simulations were conducted based on Split-Hopkinson Pressure Bar Brazilian disk-splitting tests, considering various strain rates. Simulation results of different mesoscale models were compared with experimental results. All of the models accurately predicted the tensile strength of MSCC, with the 2D four-phase model providing the best representation of failure modes and crack propagation. Both experimental and numerical data exhibited obvious strain rate effects, indicating that MSCC’s mechanical properties were sensitive to the loading rate. Dynamic increase factors were obtained, quantifying rate sensitivity. The obtained dynamic mechanical properties of MSCC provide insights for designing MSCC components and structures that can better withstand collisions or explosions.

Flexural cracking behavior of steel-NC-UHPC composite beam under negative bending moment

Steel-concrete structures are widely applied in bridge engineering due to their superior mechanical performance and cost-effectiveness. However, normal concrete (NC) decks often suffer cracking problems, adversely affecting their serviceability. Ultra-high performance concrete (UHPC) can be used to partially replace the top of NC decks to enhance their post-cracking behavior because UHPC shows high tensile strength, strain-hardening characteristics in tension, and strong bond strength with NC. To this end, this paper focused on the flexural behavior of steel-NC-UHPC composite beams regarding their failure mode, stiffness, strain development, cracking behavior, crack width, etc. Test results indicated that the test specimens mainly exhibited two types of failure modes: shear failure of the NC layer and local buckling of the compressive flange at the steel girder, which were mainly determined by the reinforcement ratio. Flexural stiffness was controlled by the steel girder, and the reinforcement ratio had a notable effect on the reinforcement strain and crack propagation. Additionally, cracks can be categorized into three types: through cracks, connecting cracks, and separate cracks. These cracks in the UHPC layer and NC layer would affect each other, especially those near the roughening interface. The sectional nonlinear analysis was employed to calculate the strain of reinforcement and the steel girder accurately. Finally, the prediction methods of crack width for the NC layer and UHPC layer were discussed. Formulas in NF P18–710 were verified to be feasible for the prediction of UHPC crack width. The UHPC influence factor was introduced to modify the calculation results of the NC crack width by the Chinese NC code.

Performance of Recycled Opaque PET Modified by Reactive Extrusion

A comparative study of the structural integrity of an opaque recycled poly(ethylene terephthalate) (rPET-O) has been carried out with two types of modified rPET-O by applying reactive extrusion techniques, namely (a) using a multi-epoxide reactive agent (REx-rPET-O) and (b) a 90/10 (wt/wt) rPET-O/polycarbonate (PC) blend. The chemical modifications introduced during reactive extrusion were confirmed using differential scanning calorimetry (DSC) and rheological dynamic analysis (RDA). For the quantification of the fracture parameters, an instrumented pendulum impact testing machine was used using specimens in SENB configuration. The structural modifications generated during reactive extrusion promote an increase of between 16 (REx-rPET-O) and 20% (rPET-O/PC) in the stress-intensity factor (KQ) compared to unmodified rPET-O. The most significant differences between both modifications are registered in the “specific work of fracture” (wf) (alternative parameter to the standardized impact strength), where an increase of 61% is reached for the case of rPET-O/PC and only 11% for REx-rPET-O. This trend can be attributed to the type of reactive modification that is generated, namely chain branching (REx-rPET-O) vs. the generation of a random copolymer “in situ” (rPET-O/PC). This copolymer decreases the crystallization capacity and degree of crystalline perfection of rPET-O, promoting an increase in the critical hydrostatic stress conditions for the generation of crazing and crack propagation.

Application of Surface Ultrasonic Waves for Detection of Contact Fatigue Cracks in the Rail Surface

The integrity and durability of rails plays a key role in train safety. However, the interaction of the rail head surface with the wheels of the rolling stock leads to high damage to these areas. The surface of the rail head is subject to the greatest damage, in which fatigue cracks develop on the surface with subsequent development. Timely detection of fatigue cracks in the rolling surface is possible using the ultrasonic technique using surface waves. To do this, the work investigated the sensitivity of a surface ultrasonic wave to obstacles in the surface of rails in the form of extended grooves, notches of finite length and known depth, as well as real cracks. The studies were carried out using the pulse-echo method at frequencies of 1.25, 1.8, 2.5, 4 MHz. Research has shown that surface waves are sensitive to surface fatigue cracks. The amplitude of the reflected pulses depends on the wavelength and the depth of crack propagation. The influence of the distance to fatigue cracks and the orientation angle of the transducer relative to the rail axis on the sensitivity of the surface wave to these defects was also studied. The results obtained allow us to conclude that the use of surface ultrasonic waves makes it possible to detect fatigue cracks in the crack surface. Thus, the use of the pulse-echo technique and surface wave converters makes it possible to detect contact fatigue cracks in the rail head, which can be used to eliminate them in a timely manner. The determination of their depth by amplitude is influenced by many factors, which are difficult to take into account in real conditions.

Research Progress on Electrical Properties of Self-sensing Concrete

In order to effectively avoid the different degrees of impact and damage to the existing buildings and structures, it is particularly important to strengthen the health detection of such structures and facilities, which is also an important research field in the development of green building discipline. Smart concrete is both structural and functional, and has the potential of self-monitoring of concrete structures. This paper reviews the basic concepts of self-sensing concrete, including the research progress of self-sensing concrete materials, and summarizes the classification of different conductive phase materials and their conductive properties. Secondly, the basic mechanical properties and electrical properties of self-sensing concrete are discussed. The factors affecting the perceptual performance of self-sensing concrete considered by different scholars are summarized. It is concluded that few scholars have studied the mechano-electric interaction evaluation mechanism that takes the electrical parameters into account the stress, strain, crack or damage of concrete, and evaluates mechanical properties and crack propagation length through the change of electrical signals. Finally, the importance of self-sensing performance of intelligent concrete is emphasized, and the prospect of future research is put forward.

Method of understanding for investigation of crack propagation trajectory and fracture aspects in dental cracks on view of fracture mechanics theories.

Current research introduces understanding of dental-cracks mechanistic with fundamental fracture behavior in natural-teeth and orthodontics including mode I crack under both tension and compression, mode II crack under both clockwise-shear and anticlockwise-shear and mixed-mode cracks under both compression-shear and tension-shear. It depends on experimental models of transparent-Plexiglas including pre-cracks of different orientations angle (b) based on fundamental theoretical fracture analysis with comparison. Problem-concept, cracking aspects of fracture-initiation, propagation-direction, fracture-increment length, critical external-load and fracture path are predicted experimentally and theoretically using directional fracture approach and directional strain-energy density theory. Tests are carried out for (36) samples for compression and tension in LEFM. Friction-resistance between crack-surfaces is considered with derivation of equations and charts. Negative stress-intensity factor (-KI) is developed for solving complicated problems of cracks under occlusal compression loads. The occlusal loads are compression and shear producing lateral tensile mixed mode cracks. The critical propagation angle (qc), critical propagation load (sc) and critical propagation envelope of stress intensity factors (KI-KII) are developed with respect to crack orientation angle (b) with comparisons. They are necessary to predict the fracture propagation early before teeth-failure. It helps for prevention and control of dental-cracks, correct-restoration, prosthodontics, orthodontics, and development of new dental-materials and technologies.

Phase field numerical strategies for positive volumetric strain energy fractures

AbstractA reasonable crack driving force is the key to preventing compression cracks and eliminating unrealistic crack propagation in phase field fracture analysis. Thus, examining the roles of volumetric strain energy (VSE) and deviatoric strain energy (DSE) in influencing crack propagation is necessary. This paper presents a comprehensive analysis of the following four different approaches to energy decomposition‐driven crack propagation: the positive volumetric strain energy method (VSEM), deviatoric strain energy method (DSEM), volumetric‐deviatoric strain energy method (VDSEM), and no decomposition method (NM). All of the strain energy is involved in the development of the crack propagation. The following four examples are investigated: two benchmark single‐side notched examples, a complex crack containing a hole example, and a crack coalescence in an asymmetric double notch example. The VSEM's numerical findings align with literature and experimental observations, confirming that positive VSE rather than DSE promotes crack propagation.

Experimentally‐based in‐plane drift limits for the upper threshold of masonry light damage

AbstractDrift limits are useful thresholds; during design or retrofitting analyses, engineers can compare the expected behaviour of a structure to drift limits that predict when the structure will reach a certain condition. This helps ensure that structures satisfy specified performance goals when exposed to certain hazards. Masonry walls are susceptible to damage from lateral in‐plane actions such as wind or earthquake loading; ensuring that in‐plane drift remains sufficiently small will help limit this damage. Drift limits based on crack‐based damage are scarce, however, with DS1 limits being extrapolated from higher damage grades based on structural strength capacity or ductility. In this work, crack‐based damage is evaluated on a multitude of full‐scale experimental walls surveyed with digital image correlation. This method observes the initiation and propagation of cracking. Cyclically incremental in‐plane tests provide a range of drift‐damage relationships. These are explored with machine learning to determine influential predictors and ultimately establish drift limits for light damage. Two types of brick masonry are explored: fired‐clay and calcium‐silicate. For the latter, light damage begins at an in‐plane drift of 0.5 mm/m and can extend to 4.8 mm/m (or 0.48%) for the former before the masonry surpasses light damage and reaches structural damage grades. In comparison to drift limits set by other authors and (international) guidelines to characterise light damage, significant damage, or the ultimate capacity of masonry walls, the resulting drift limits for light damage from this work are set directly on the basis of experiments and are in good agreement with other authors. Most importantly, all the consulted values for ultimate capacity are much larger than the upper threshold for light damage determined herein, with limits for significant damage in the same order of magnitude. This result verifies the accuracy of the experimental crack‐based characterisation used to establish the drift thresholds.

Investigating Hot corrosion, CMAS, and Thermal Shock Behaviour of Double-layer YSZ/La2Ce2O7 + YSZ Thermal Barrier Coatings

AbstractIn this work, new double-layer YSZ/La2Ce2O7 (LC) + YSZ coatings were developed using air plasma spraying (APS). The surface of the prepared coatings was relatively smooth and consisted of melted and partially melted areas. Their resistance to hot corrosion, CaO-MgO-Al2O3-SiO2 (CMAS), and thermal shock were examined. YSZ was added to the upper layer to enhance the lanthanum cerate (La2Ce2O7, LC) properties. During the hot corrosion tests, the corrosion salt reacted with the upper layer, and the CeO2 phase and new corrosion products were identified. The main phase was LaVO4, and the secondary phases were CeVO4 and YVO4. SEM confirmed the formation of new, cuboidal-shaped corrosion products. The infiltration of CMAS led to the formation of additional new products: Ca4MgxAl4Si(6-x-γ)O14 and Ca2.8(LaxCe1-x).6(SiO4)O6-4x. SEM revealed CMAS infiltration through the upper layer in the form of islands. Following the thermal shock resistance tests, the upper layer gradually peeled off, and the coating survived 67 cycles. Possible failure mechanisms were identified, and failure was attributed to the spallation of the upper layer from the surface layer by layer. After all tests, the top layer showed partial spalling and delamination. This was mainly caused by the reaction of corrosive salt or CMAS with the top layer, which changed its composition, leading to the formation and propagation of cracks and, ultimately, the separation of part of the upper layer. Peeling of the upper layer through mainly horizontal cracks was observed after hot corrosion, CMAS and thermal shocks. The NiCrAlY bond coat and YSZ interlayer remained undamaged.

Experimental investigation of the effects of different reinforcement configurations on the shear strength of reinforced concrete block masonry

Reinforced concrete block masonry walls exhibit complex behaviour under lateral loading due to their composite nature and the interaction between their constituents, including units, mortar, grout, and reinforcement. The shear strength of reinforced masonry walls depends on various factors, including the properties of each constituent material, wall geometry, boundary conditions, and the presence of reinforcement with different configurations. International masonry design standards vary significantly in how they address the parameters influencing the shear capacity of reinforced masonry shear walls. Consequently, the predicted capacities show varying levels of conservatism when compared to experimental values. Given that masonry materials and construction practices are similar in the countries being compared, these discrepancies suggest differing interpretations of the significance of each parameter and possibly different philosophies regarding the balance between conservatism and accuracy in shear design. Therefore, this study investigated the influence of different reinforcement schemes on the shear strength of reinforced concrete block masonry (RM) assemblages with running bond. Forty-one concrete block masonry assemblages were tested under diagonal tension following the ASTM E519 to examine the effect of various parameters, namely, the presence of vertical or horizontal reinforcement, the vertical and horizontal reinforcement ratios, and the spacing and combination of vertical and horizontal reinforcement within the masonry assemblages. The behaviour of the masonry assemblages was evaluated based on the maximum shear stress and the corresponding shear strain, shear modulus, toughness, and pseudo-ductility. Furthermore, the effect of the studied parameters on the stress-strain curves, failure mechanisms, and crack propagation was assessed. The obtained maximum shear stresses of the tested concrete block masonry assemblages were compared with the nominal shear capacity calculated using codified equations of different design standards. The RM assemblages showed an enhancement in the shear behaviour, ductility, and distribution of cracks, especially when combining horizontal and vertical reinforcement. The results showed that adding vertical reinforcement improved the shear capacity of reinforced masonry assemblages by 21%, with an increase in the peak shear strain by 52%. Moreover, combining the vertical and horizontal reinforcement in the reinforced concrete block masonry assemblages increases the shear capacity by 15% with an enhancement in the maximum shear strain by 23%. The CSA S304–14, TMS 402/602–22, and NZS 4230 showed an underestimation of the actual shear capacity of masonry assemblages constructed in running bond and with vertical reinforcement by 177%, 138%, and 79%, respectively. Additionally, the results revealed the need for a re-evaluation of the above mentioned code equations that estimate the shear capacity for different configurations of concrete block masonry assemblages. The analyses aimed to provide insights into the effectiveness of different reinforcement configurations in enhancing the shear resistance of RM walls. The findings of this research contribute to the development of optimized design guidelines for reinforced masonry structures, thereby enhancing their overall seismic performance and safety.

Analysis of microstructure of prefabricated fractured granite under thermal effects based on CT technology

In this study, Computed Tomography (CT) technology was employed to visually analyze the influence of thermal effects on the microstructure of prefabricated fractured granite. The porosity and heterogeneity of the samples were calculated using three-dimensional reconstruction techniques, and two parameters, crack length and orientation, were introduced to quantitatively evaluate the impact of prefabricated fractures on subsequent crack propagation. The results indicated that at 400 °C–500 °C, numerous microcracks were generated within the samples, but they did not interconnect. Above 600 °C, microcracks gradually propagated, forming well-connected crack networks. Due to the uneven thermal stress distribution caused by the prefabricated fractures, samples subjected to temperatures above 600 °C exhibited higher heterogeneity in the vertical direction. While in other directions, the samples gradually tended to homogenize as the temperature rose. Below 500 °C, crack length was significantly affected by the prefabricated fractures, although this influence diminished with increasing distance from the fractures. When the temperature was below 400 °C, microcracks mainly propagated along the direction of the prefabricated fractures. However, when the temperature exceeded 500 °C, microcracks began to initiate and propagate in the opposite direction of the prefabricated fractures, and anti-wing cracks started to emerge.