Transverse Cracks Research Articles

Corrosion of Yb2SiO5/Yb2Si2O7/Si EBCs against Na2SO4 + 25 wt%NaCl molten salt at 1350 ℃

The reaction behaviors and corrosion mechanisms of tri-layer Yb2SiO5/Yb2Si2O7/Si EBCs were explored in Na2SO4 + 25 wt%NaCl molten salt environment at 1350 °C. Results showed that the molten salt rapidly penetrated the Yb2SiO5 layer and then reacted with the Yb2Si2O7 layer to form SiO2-riched Na-Yb-Si-O glass phase. The reaction product of glass phase diffused to the EBCs surface through the cracks and reacted with Yb2SiO5 to form Yb2Si2O7. The reaction of Yb2Si2O7 caused the development of transverse cracks, which eventually led to the failure of the EBCs. Moreover, the Yb2SiO5 layer exhibited better corrosion resistance than the Yb2Si2O7 layer.

Dynamic analysis of double cracked bi-directional functionally graded nanobeam using the differential quadrature method

This study investigates the free vibration behavior of a double cracked nanobeam composed of bi-directional functionally graded material. The analysis incorporates Eringen’s nonlocal elasticity theory and the Euler–Bernoulli theory. The material properties are considered to vary in both the thickness and length directions. The cracked nanobeam is modeled as a series of interconnected sub-beams, with rotational springs placed at the cracked sections. This modeling approach accounts for the discontinuities in rotational displacement resulting from bending, which is directly related to the bending moment transmitted by the cracked section. The problem is solved using the differential quadrature method, which approximates the derivatives of the field quantities by employing a weighted linear sum of the nodal values. By doing so, the problem is transformed into a linear algebraic system. Various supporting cases are examined, and a parametric study is conducted to analyze the impact of the axial and transverse gradient indices, nonlocal parameter, and crack severity on the obtained results.

Research on crack propagation of CRTS III track slabs under train load

Microcracks may occur in Chinese Railway Track System type III (CRTS III) ballastless track slabs during service, and it is necessary to investigate their potential propagation under train load, which could lead to slab deterioration and affect the durability of the track structure. In this paper, based on the fracture mechanics theory, the stress intensity factors (SIFs) at the tips of transverse crack, longitudinal crack and vertical crack on the CRTS III track slabs under train load are solved by the extended finite element method (XFEM) in Abaqus software. The changes of SIFs at the crack tips during the passage of the train are analyzed, and the effects of the crack length and depth on the SIFs of the three types of cracks are discussed under train load. Crack growth rate is calculated using Paris' semi-empirical law to estimate slab life. The results show that the train load contributes to the propagation of transverse and vertical cracks in the vertical direction and inhibits the longitudinal cracks. When the middle of the sixth vehicle is above the crack, the SIFs at the tips of the crack reach their maximum values. The SIF of vertical cracks exceeds the fracture toughness at a certain depth. The fatigue load cycles calculated by Paris' semi-empirical law suggest that maintenance will not be required due to insufficient propagation under train load during service.

Correlation analysis of highway asphalt pavement distress based on Spearman correlation coefficient

In order to improve the operational life of highway asphalt pavements, reduce urban traffic safety accidents, and improve pavement travelling comfort, this paper analyze the frequency of different highway asphalt pavement distresses and calculates the percentage of each other based on highway asphalt pavement data sets in Shandong. The results showed that the five types of highway asphalt pavement distresses including alligator cracks, longitudinal cracks, transverse cracks, sealed cracks and patches occur with high frequency and account for 96.2% of the total proportion. For revealing the coupling principle between different highway asphalt pavement distress, this paper analyze the correlation between the five types of highway asphalt pavement distresses by Spearman correlation coefficient. The results showed that alligator cracks have a higher positive correlation with transverse cracks and longitudinal cracks and sealed cracks have a negative correlation with transverse cracks. The research findings are helpful to understand the characteristics of pavement distress conditions more clearly and to optimize he level of service of asphalt pavements on urban roads.

A polymer latex modified superfine cement grouting material for cement-stabilized macadam – Experimental and simulation study

Cement-stabilized macadam (CSM) has been prevalently employed in transportation infrastructure owing to its superior bearing capacity and stability. However, with inherent dry shrinkage, temperature shrinkage, and inadequate tensile capacity, cracks will inevitably occur. These cracks can reflect on the asphalt layer and cause diseases such as transverse cracks, dynamic water scouring, voids, etc. A predominant remediation method involves utilizing grouting material for trenchless repair. In this research, a vinyl acetate-ethylene (VAE) latex modified superfine cement (VMSC) for grouting material is proposed to improve the flexibility of the grouting material and enhance crack repair dimensions. The interaction mechanism was investigated through mechanical experiments, microscopic tests, and molecular simulation. The results show that VMSC30 exhibits the highest fluidity. VAE latex addition extends the initial and final setting times of the grouting material, alongside an escalation in yield stress and plastic viscosity. VAE latex reduces the compressive strength of the grouting material, while 10% can increase the flexural strength, and the overall toughness can be improved. Characteristic spectral peaks of VAE latex are identified at 1740 cm−1 and 1240 cm−1, respectively, and it can form a film to cover the surface of cement, inhibit hydration diminish the CH peak value. VAE can form the 2.95 Å ionic bond and the 3.05 Å hydrogen bond on the Ca atom and water molecules, respectively. The peak value of the ionic bond is higher. The ionic bond and hydrogen bond formed by bridging can improve the strength of VAE and cement interfaces.

Enhanced stability of a three-dimensional graphene nanosheets networks modified asphalt mixture

To date, several concepts have been developed to enhance the mechanical and service life of asphalt pavements. Additives such as graphene, carbon nanotubes, carbon fibers and carbon black are used in the hot mix asphalt (HMA) or the asphalt binder (i.e., bitumen) for higher resistance to permanent deformations such as rutting, and transverse thermal cracking due to increased traffic volumes, vehicle mass and axle loads. In this study, graphene nanosheets (GNs) were used as potential modifier of bitumen binder in the HMA. The objective of this work is to investigate the impact of GNs modified bitumen on the Marshall stability and flow of the asphalt mixture using laboratory-compacted samples. The X-ray diffraction (XRD) study revealed a diffraction peak of GNs (002) at 2θ =26.5° along the bitumen’s γ-band and 10-band, which confirm a successful dispersion of GNs into bitumen binder. Furthermore, morphological analysis showed formation of a three dimensional (3d) interconnected networks of GNs between the bitumen micro-structures which could act as bridges for increased flexural strength of the binder. The Marshall stability and flow test results indicate that the mechanical properties of asphalt mixture were influenced by the addition of GNs to the bitumen binder. At 5% by weight of GNs modified bitumen (GNs-B), the compacted hot-mix Asphalt sample showed a higher Marshall stability of 11.7 kN recording 13.6% enhancement in comparison with the asphalt mixture with pure bitumen (P-B). In addition, when GNs-B was used, a lower flow of 1.4 mm was recorded which is desirable to prevent rutting and other forms of failure in asphalt pavements. This study underlines that adding GNs into asphalt binders such as bitumen could play a key role in enhancing the performance of asphalt pavements, which in turn extends their service life and saves maintenance expenses.

Comparison of road damage analysis using PCI method and Bina Marga method and the analysis of road improvement methods using the road pavement design manual (Case study: Citayam – Parung road)

The Citayam - Parung road section is an inter-district and city route between Bogor Regency and Depok City, West Java Province, on this road section there is high mobility. This research aims to determine the type of road damage using the PCI method and Bina Marga method and analyze repairs using the 2017 MDP. Data collection was carried out by direct survey and interviews with related agencies. The results of the research analysis of damage to the Citayam - Parung road are alligator cracking, block cracking, edge cracking, transverse longitudinal cracks, utility patches and excavations, polished aggregate, photoles and weathering and raveling. The PCI method damage analysis has a value of 71.96 with Very Good pavement quality, and the results of the Bina Marga method damage analysis have a priority order of 10 with the priority order of the Routine Maintenance Program. The relationship between the PCI method is directly proportional to the Bina Maarga method, with a PCI value between 71-85 and the priority order for Bina Marga, namely 10, the regression equation obtained is PCI = 207.52 – 13.296*(BM). The results of the repair analysis are a 45 mm thick non-structural overlay with an estimated cost of Rp. 2,404,076,800.00.

Mathematical modeling of rectilinear cohesive transverse shear cracks in a fiber-reinforced composite reinforced with unidirectional fibers

Mathematical modeling of rectilinear cohesive transverse shear cracks in a fiber-reinforced composite reinforced with unidirectional fibers

DIC study of strain concentrations and damage within web-flange junctions of pultruded GFRP bridge decking

This paper reports an experimental study into damage progression within the web-flange junctions of locally-loaded pultruded glass-fibre reinforced-polymer bridge decking, owing to amplified normal and shear stresses at misaligned fibre-resin interfaces. To that end 3D digital image correlation (DIC) is used in three roles, namely quantifying high strains along misaligned fibre layers, detecting onset of damage and identifying macroscopic damage via patterns in the unfiltered strain fields. Both DIC and strain gauges alongside analytical strain predictions are used to increase confidence in the test data. The DIC data reveal that the strains along the misaligned fibre-resin interfaces were shear dominated, and that a 0.8 mm increase of wrinkle-amplitude led to a 92 % increase in peak shear strain. Micro-cracking was detected at approximately 50 % of the test load that caused the first delamination. In repeat tests this load dropped by 27 % due to random transverse cracks within the roving core.

Transverse Crack Initiation in Thin-Ply Laminates Subjected to Tensile Loading at Low and Cryogenic Temperatures

Transverse Crack Initiation in Thin-Ply Laminates Subjected to Tensile Loading at Low and Cryogenic Temperatures

On transverse crack effects in beams under free vibration using finite element analysis

The research attempt towards quantifying the free vibration frequencies for cracked uniform isotropic beam through finite element analysis for analyzing the crack effects is discussed in this investigation. The present approach involves dividing the beam into segments at the crack section, which were modelled for simulation for eigen frequencies on ABAQUS platform. The simulation model is developed considering a C3D8R element. The segments are then joined together by considering interaction forces through flexibility matrices. These matrices are resulted from the compliance matrix that is governed using expressions of release rate of strains considering the stress intensity factors as described in fracture mechanics. Within the equal domain of analysis for a comparison, the findings align remarkably well with previous research, affirming the reliability, effectiveness and precision of the proposed simulation model. By examining the results of present numerical simulations, an understanding towards how the crack magnitude in depth and position affects the mode shape and frequencies of the cracked beams is elicited. This study solidifies the application suitability of developed simulation model for effective analysis of beam-like structural components.

ANALYSIS OF NATURAL FREQUENCIES FOR EARLY DAMAGE DETECTION IN CFRP SHAFTS USING RSM-BASED FREQUENCY CONTOUR PLOTS

This study explores early damage detection in carbon fiber-reinforced polymer shafts by analyzing natural frequencies. Modern engineering components often face increased flexibility and high stress levels, leading to cracks in rotating parts, which can result in premature failures. To address this issue, modal analysis, specifically natural frequency analysis, is employed to identify deviations caused by cracks. Cracks alter stiffness and mass distribution, leading to shifts in natural frequencies. The study employs finite element models to simulate various crack locations and depths, normalizing them with respect to shaft diameter and length. A cantilever shaft configuration is utilized with refined mesh structures near the transverse crack. The analysis leverages the frequency contour method with response surface methodology to visualize how crack depth and location influence normalized natural frequencies. Results indicate that crack depth has a significant impact on natural frequencies, while crack location has a subtler effect. Combining depth and location produces the most pronounced frequency variations. The corresponding R² values for the normalized first and third natural frequencies are 95.69% and 96.32%, while for the normalized second natural frequency this value is 75.70%. The study also demonstrates the use of frequency contour curves for accurate crack detection, with the 1st and 3rd natural frequencies being reliable indicators.

The Classification of Asphalt Pavement Crack Images Based on Beamlet Transform

Pavement cracking is a common road infrastructure issue which significantly affects road performance, safety and longevity. This article employed a Beamlet Transform algorithm to detect and classify different types of flexible asphalt concrete pavement cracks. Additionally, a dedicated crack segmentation network was employed for precise segmentation of pavement crack. This approach incorporates advancements that has improve precision in crack classification and segmentation. Based on the results of the beamlet transform, significant improvements in the gray scale representation of crack, enhanced crack detection, reduced noise in crack images and a more precise measurement of cracks length were achieved. Computations were performed to determine the length of linear cracks and the area of block cracks. A total of 1000 pavement images were used for training and testing the accuracy of asphalt pavement crack detection and classification models. The research results showed that block cracking, alligator cracking, transverse cracking, and longitudinal cracking can all be recognized with a remarkable accuracy. Alligator cracks and block cracks achieved detection rates more than 90%, while detection rates for the longitudinal and transverse cracks reached more than 95% accuracy.

Adaptive maintenance strategies to mitigate climate change impacts on asphalt pavements

This study aims to explore the potential of optimization-based maintenance strategies in adapting asphalt pavements to future climate change. Based on a highway network in Jiangsu, China, the impacts of climate change, characterized by global warming and intensified precipitation, on pavement life cycle cost (LCC) and performance were quantitively assessed, and the benefits of maintenance optimization in mitigating climate change impacts were examined. The findings indicate that climate change may increase pavement rutting depth and reduce pavement roughness and skid resistance, while its effect on transverse cracking varies over time. Adjusting the maintenance schedules, but still following the threshold-based approach, would increase the LCC by about 15.5 %∼19.1 %. The optimization-based maintenance decision-making model significantly mitigates climate change impacts, ultimately even saving 0.6 % of LCCs compared to the baseline. The outcomes will provide a quantitative understanding of the climate change impacts on asphalt pavements, as well as adaptive maintenance strategies to improve pavement resilience.

Structure and Deformation Behavior of Polyphenylene Sulfide-Based Laminates Reinforced with Carbon Fiber Tapes Activated by Cold Atmospheric Plasma.

Low-temperature plasma treatment with atmospheric discharge with runaway electrons (DRE) was shown to be an efficient way to activate carbon fiber's (CF) surface and subsequently increase its interlayer shear strength (ILSS) values. It was demonstrated that an acceptable ILSS level was achieved after a DRE plasma treatment duration of 15 min. The treatment of CFs resulted in their surface roughness being increased and their functional groups grafting. The XPS data showed a change in the chemical composition and the formation of reactive oxygen-containing groups. SEM examinations of the PPS/CF laminates clearly demonstrated a difference in adhesive interaction at the PPS/CF interface. After the DRE plasma treatment, CFs were better wetted with the polymer, and the samples cohesively fractured predominantly through the matrix, but not along the PPS/CF interface, as was observed for the sample reinforced with the untreated CFs. The computer simulation results showed that raising the adhesive strength enhanced the ILSS values, but reduced resistance to transverse cracking under the loading pin. In general, higher flexural strength of the PPS/CF laminates was achieved with a greater interlayer adhesion level, which was consistent with the obtained experimental data.

Stress Intensity Factor equations for incipient transverse external annular eccentric cracks contained in a shaft under bending

One of the most common failures in rotating machines is the apparition and propagation of fatigue cracks in one of its main elements: the shafts. These cracks can cause catastrophic failures and lead to costly maintenance or repair processes. Most of the studies in relation to cracks contained in shafts have focused on straight or elliptical transverse cracks. However, although it is less common, the shaft breaks also occur with cracks whose fronts are approximately circumferential, that are more difficult to analyze. These cracks are transverse with circular shape that extend over a complete circumference and that have a certain eccentricity. This work presents the equations that provide the value of the Stress Intensity Factor (SIF) of an incipient crack with circumferential shape contained in a shaft subjected to bending, along the front, as a function of the characteristics of the crack, size and eccentricity. For this, an exhaustive numerical study has been carried out, using the Finite Element Method (FEM), to determine the SIF value along the circumferential front for different sizes and eccentricities of the annular crack.

Cryogenic damage mechanisms of CFRP laminates based on in-situ X-ray computed tomography characterization

Carbon fiber reinforced polymer (CFRP) composites possess excellent properties suitable for use in spacecraft liquid fuel tanks. However, the cryogenic reliability of composites remains challenging owing to the variation in mechanical responses under cryogenic environments. So far, most previous studies have focused on the cryogenic properties of composites, and little has been devoted to the cryogenic damage behaviors of laminates. Herein, the cryogenic damage evolution of CFRP laminates was investigated by micro-computed tomography (μCT) characterization and micromechanical analysis for the first time. To this end, in-situ μCT tensile tests for quasi-isotropic CFRP laminates were conducted at temperatures of 293 K, 193 K, and 93 K, and the observed cryogenic damage characteristics were analyzed. A micromechanical computational model was then developed, and the temperature-dependent constitutive model of epoxy resin was utilized to investigate the cryogenic damage evolution process of laminates. The effects of matrix property variation and thermal stresses on the cryogenic damage of laminates were examined, and the cryogenic fracture toughness for transverse cracking was deduced. The characterization results revealed a significantly increased damage volume fraction of laminates from 0.65% to 1.56% at cryogenic temperatures, mainly originating from the increased delamination (from 0.08% to 0.54%) and 90° ply transverse cracks (from 0.48% to 0.87%). The numerical analyses indicated the cryogenic brittle transition of the matrix as the primary factor responsible for the delamination, while the transverse cracks were influenced by matrix properties and thermal stresses. This study provides critical insight into the cryogenic damage behavior of CFRP laminates, essential for cryogenic applications of composites.

Electrochemical shock and transverse cracking in solid electrolytes

Ceramic solid electrolytes are crucial for electrochemical devices, including emerging solid-state batteries. However, they are susceptible to degradation and failure under harsh conditions, leading to dendrite growth, cracking and short circuits. While longitudinal lithium dendrites have been identified as a primary degradation mechanism, recent experiments have revealed transverse reduction fronts and bowl-shaped cracks that differ significantly from the longitudinal picture. We propose an electrochemical shock model to explain these transverse degradation modes in solid electrolytes (SE) and mixed ionic-electronic conductors (MIEC), where SE is taken to be the very weakly electronic leaking limit of MIEC. The model describes a transverse layer with an abrupt oxygen potential jump over a short distance, caused by the electronic transport bottleneck on the Brouwer diagram. Using Li7La3Zr2O12 as an example, we demonstrate that even minor nonuniform lithium distribution associated with an electrochemical shock can induce stress concentrations, resulting in electrolyte cracking and bowl-shaped cracks. The electrochemical shock model highlights the significance of finite electronic conductivity in the degradation of SE and MIEC, providing insights for the design of durable solid electrolytes.

Estimating local pavement performance and remaining service interval using neural networks-based models and automation tool

This study introduces an integrated approach to enhance county pavement management, emphasising operational efficiency in determining the Remaining Service Interval (RSI) for rigid and flexible pavements. It establishes a robust methodology for systematically processing raw county road data through dynamic segmentation and summarisation to create a structured pavement database. It also incorporates innovative approaches and input configurations in employing Artificial Neural Networks (ANNs) to predict current and future county pavement performance indicators, including International Roughness Index (IRI), rutting, transverse, and longitudinal cracks, even with limited data. Evaluation of the ANN models on independent county road databases exhibited high prediction accuracies (0.86 < R 2 < 0.99), varying with specific performance indicators. The study results in an automation tool for expediting road performance estimation over multiple years. This tool seamlessly integrates the ANN models, empowering county engineers to make data-driven decisions and optimise resource allocation for effective pavement management, achieving significant cost savings.

Inclined crack identification in bidirectional FG beams on an elastic foundation using the h-version of the finite element method

This article examines the impact of inclined transverse cracking on the natural frequency of Euler-Bernoulli-model imperfect FG beams on an elastic foundation, taking into account the pinned-pinned and clamped-clamped boundary conditions. The equations are diffused using the classic finite element method (h-version). Material properties are considered to vary in both directions of the beam; width and thickness, using the power-law formula. The approximate porosity model is adopted with a uniform distribution. Cracked element stiffness is determined by reducing the cross-section of a bi-directional FG beam. The numerical results are compared with those of previous convergence studies for dimensionless fundamental frequencies. Case studies were carried out to evaluate the effect of the porosity values, the crack depth, the crack location, slope angle, and the Winkler-elastic foundation parameters on the first three natural frequencies of a beam with different support conditions and material gradient. In addition, the results demonstrated that the two-way distribution function plays an important role in the convergence of frequencies.