Catastrophic Failure Research Articles

A hybrid artificial neural network–genetic algorithm back-analysis technique for local anomaly detection in railway track substructure

The UK’s ageing railway transportation network is increasingly at risk of substructure failure, often caused by malfunctioning buried drainage systems. These drainage issues lead to localised soil weaknesses in the substructure layers, which, if undetected, can result in costly maintenance interventions or, worse, catastrophic system failure. Regular non-destructive test (NDT) assessments are essential for monitoring the condition of the substructure, yet current interpretation techniques for NDT data provide limited insight into the size, location and even the presence of weakened zones. This results in an incomplete understanding of the substructure's condition, impeding effective maintenance planning. A novel hybrid back-analysis technique to detect weakened zones in railway substructures caused by drainage malfunctions is proposed, addressing a critical gap in existing solutions. The method employs an artificial neural network surrogate model, trained on virtual experimental data generated through finite-element simulations, and couples it with a genetic algorithm to optimise the match between modelled and measured deflections. This novel method is computationally efficient, independent of seed modulus values and thoroughly validated for accuracy. It delivers a precise understanding of soil weaknesses in railway substructures, transforming maintenance strategies by improving safety, reducing costs and promoting infrastructure sustainability.

Experimental investigation on the seismic resistance of RC columns after acid rain corrosion

Acid rain can significantly undermine the structural integrity and seismic resilience of concrete structures, posing substantial risks of catastrophic failures and jeopardizing safety. However, studies on the seismic behavior of reinforced concrete (RC) columns affected by acid rain corrosion remain nascent. Therefore, this study explored the impact of acid-rain corrosion extent and axial compression ratio on the seismic behavior of RC columns that experienced flexural failure using an artificial rapid corrosion method and pseudo-static test in sequence. The corrosion-induced damage, weight loss of the reinforcement, failure pattern, hysteretic behavior, load-bearing capacity, deformation capacity, stiffness degradation, and energy dissipation were analyzed. The test observations showed that the acid rain corrosion extent was more pronounced in the column peripheries compared to their central sections. As the number of ARCCs (acid rain corrosion cycles) increased, the damage extent of column specimens was gradually aggravated; the load-bearing, deformation, and energy absorption capacities were significantly reduced. Notably, the column specimen RCZ-4 compared to RCZ-1, with reductions of 14.54% in peak load, 22.58% in plastic rotation, and 28.6% in total cumulative energy dissipation. As the axial compression ratio was increased from 0.3 to 0.5, the column specimens exhibited a 17.12% increase in peak load, alongside a decline in plastic rotation by 25.40% and a reduction in cumulative energy dissipation by 25.85%. Based on the experimental results and the existing theoretical, a calculation formula for the flexural failure skeleton curve characteristic point parameters of RC columns was proposed, considering the impact of acid rain corrosion damage and axial compression ratio. The proposed calculation method could effectively determine the load-bearing and deformation capacity of RC columns under low cyclic loading. The results of this study enable engineers to better understand the seismic behavior of RC columns in an acid rain corrosion environment.

Ultimate Strength Analysis of Aluminium Honeycomb Sandwich Panels Subjected to Uniaxial Compressive Loads and Lateral Pressure

Ultimate strength is critical for hull structures because it determines the maximum load the structure can withstand before catastrophic failure. Aluminium honeycomb sandwich panels provide excellent energy absorption and a high strength-to-weight ratio. However, further investigation of honeycomb sandwich panel structural performance is needed in typical marine conditions. This study focuses on the numerical analysis of honeycomb sandwich panels employing the nonlinear finite element method through the commercial software ANSYS. It investigates their performance under uniaxial compression and varying lateral pressure conditions while considering different cell edge lengths and core height configurations. Several structural configurations are compared to the experimental work published in the literature. Enhanced by experimental accuracy, the present study is a further step in expanding the application of honeycomb sandwich panels for ship hull applications that may lead to light and energy-efficient structures.

Addressing Missing Data in Slope Displacement Monitoring: Comparative Analysis of Advanced Imputation Methods

Slope displacement monitoring is essential for assessing slope stability and preventing catastrophic failures, particularly in geotechnically sensitive areas. However, continuous data collection is often disrupted by environmental factors, sensor malfunctions, and communication issues, leading to missing data that can compromise analysis accuracy and reliability. This study addresses these challenges by evaluating advanced machine learning models—SAITS, ImputeFormer, and BRITS (Bidirectional Recurrent Imputation for Time Series)—for missing data imputation in slope displacement datasets. Sensors installed at two field locations, Yangyang and Omi, provided high-resolution displacement data, with approximately 34,000 data points per sensor. We simulated missing data scenarios at rates of 1%, 3%, 5%, and 10%, reflecting both random and block missing patterns to mimic realistic conditions. The imputation performance of each model was evaluated using Mean Absolute Error, Mean Squared Error, and Root Mean Square Error to assess accuracy and robustness across varying levels of data loss. Results demonstrate that each model has distinct advantages under specific missingness patterns, with the ImputeFormer model showing strong performance in capturing long-term dependencies. These findings underscore the potential of machine learning-based imputation methods to maintain data integrity in slope displacement monitoring, supporting reliable slope stability assessments even in the presence of significant data gaps. This research offers insights into the optimal selection and application of imputation models for enhancing the quality and continuity of geotechnical monitoring data.

Vibration-Based Damage Prediction in Composite Concrete–Steel Structures Using Finite Elements

The prediction of structural damage through vibrational analysis is a critical task in the field of composite structures. Structural defects and damage can negatively influence the load-carrying capacity of the beam. Therefore, detecting structural damage early is essential to preventing catastrophic failures. This study addresses the challenge of predicting damage in composite concrete–steel beams using a vibration-based finite element approach. To tackle this complex task, a finite element model to a quasi-static analysis emulating a four-point pure bending experimental test was performed. Notably, the numerical model equations were carefully modified using the Newton–Raphson method to account for the stiffness degradation resulting from material strains. These modified equations were subsequently employed in a modal analysis to compute modal shapes and natural frequencies corresponding to the stressed state. The difference between initial and damaged modal shape curvatures served as the foundation for predicting a damage index. The approach effectively captured stiffness degradation in the model, leading to observable changes in modal responses, including a reduction in natural frequencies and variations in modal shapes. This enabled the accurate prediction of damage instances during construction, service, or accidental load scenarios, thereby enhancing the structural and operational safety of composite system designs. This research contributes to the advancement of vibration-based methods for damage detection, emphasizing the complexities in characterizing damage in composite structural geometries. Further exploration and refinement of this approach are essential for the precise classification of damage types.

Structural Fatigue Life Monitoring with Piezoelectric-Based Sensors: Fundamentals, Current Advances, and Future Directions.

Structural fatigue can lead to catastrophic failures in various engineering applications and must be properly monitored and effectively managed. This paper provides a state-of-the-art review of recent developments in structural fatigue monitoring using piezoelectric-based sensors. Compared to alternative sensing technologies, piezoelectric sensors offer distinct advantages, including compact size, lightweight design, low cost, flexible formats, and high sensitivity to dynamic loads. The paper reviews the working principles and recent advancements in passive piezoelectric-based sensors, such as acoustic emission wave and strain measurements, and active piezoelectric-based sensors, including ultrasonic wave and dynamic characteristic measurements. These measurements, captured under in-service dynamic strain, can be correlated to the remaining structural fatigue life. Case studies are presented, highlighting applications of fatigue life monitoring in metals, polymeric composites, and reinforced concrete structures. The paper concludes by identifying challenges and opportunities for advancing piezoelectric-based sensors for fatigue life monitoring in engineering structures.

Review of Drone-Based Technologies for Wind Turbine Blade Inspection

Wind energy is one of the most rapidly growing sectors in renewable energy generation, with wind turbines being central to this expansion. Regular maintenance, particularly the inspection of wind turbine blades, is critical to ensure operational efficiency and prevent catastrophic failures. Conventional methods of blade inspection, including ground-based visual inspections, rope-access inspections, and cranes, are time-consuming, expensive, and often hazardous. In recent years, drone-based technologies have emerged as a promising alternative for wind turbine blade inspection. This paper provides a comprehensive review of current drone-based technologies for wind turbine blade inspection, highlighting their advantages, challenges, and future prospects.

Soft hydrogel-embedded ceramic skeleton mimicking bone structure via sacrificial bond concept.

Bone, consisting of calcium phosphate minerals, rigid collagen fibrils, and acidic proteins, exhibits stiff and tough mechanical properties. On a molecular scale, covalent cross-linking in proteins and ionic interactions within proteins and at the protein-mineral boundary contribute to bone's toughness. In addition, hierarchical structures, like the sponge-like arrangement, are also crucial for the energy dissipation system in bone. Inspired by the multiple sacrificial bonds found in bone, we developed a soft/hard composite made up of two components with contrasting mechanical properties: a porous calcium phosphate skeleton and an acidic polymer hydrogel matrix. The porous ceramic skeleton alone is extremely rigid but brittle. However, the presence of the hydrogel matrix transforms the brittle nature of the porous ceramic skeleton into a soft/hard composite with stretchable and tough characteristics. The composite exhibits significant energy dissipation due to the fracture of the ceramic skeleton under small deformation, while catastrophic failure of the composite is prevented because the hybridized matrix disperses the damage throughout the entire sample. The Ca2+-mediated ionic bonding within the matrix hydrogel and at the boundary between the gel and skeleton effectively transfers the stress, enhancing the composite's toughness. Furthermore, the cyclic deformation generates new bare surfaces on the ceramic skeleton, leading to increased interaction between the matrix and these new surfaces, which enhances the composite's healing capability. This study demonstrates that the concept of multiple sacrificial bonds in bone is a smart strategy for designing polymer-ceramic composites with excellent mechanical properties.

Understanding delamination behavior of air electrode in solid oxide electrolysis cells through in situ monitoring of internal oxygen partial pressure

In this study, we monitored the development of internal pO2 in solid oxide electrolysis cells (SOECs) in situ using an embedded probe and a reference electrode. Three types of air electrode cells were compared: LSM (La0.8Sr0.2MnO3−δ) + YSZ (Y0.08Zr0.92O2−δ), LSCF (La0.6Sr0.4Co0.2Fe0.8O3−δ) + GDC (Gd-doped ceria) and LSM + GdCeScSZ ((Gd2O3)0.005(CeO2)0.005(Sc2O3)0.1(ZrO2)0.89). The rate of pO2 increase with the increase in current density was highest in the LSM + YSZ cell, reaching ∼32201 atm at 0.6 A cm−2, resulting in air electrode delamination and intergranular fractures. This physically developed delamination with high pO2 is akin to catastrophic failure, accelerating degradation. The LSCF + GDC cells exhibited a maximum pO2 of ∼12.25 atm and operated stably without increasing pO2 or delamination. In the LSM + GdCeScSZ cells, internal pO2 was substantially suppressed to ∼10−3 atm, with a degradation rate comparable to that of the LSCF + GDC cell. However, the air electrode delaminated without intergranular fractures. This chemically developed delamination without high internal pO2 does not significantly accelerate degradation. These results indicate that the delamination mechanism may vary even with the same LSM electrode, depending on its ionic conduction characteristics.

Bionic Inner-Tapered Energy Absorption Tube Featuring Progressively Enhanced Fold Deformation Mode.

Slender tubes are in high demand owing to their lightweight and outstanding energy absorption. However, conventional slender tubes are prone to catastrophic failures such as Euler's buckling under axial load. Interestingly, growing bamboos overcome this similar dilemma via a unique tapered intine in the internodes, which endows them with excellent energy absorption. Inspired by this finding, a bionic inner-tapered tube (BITT) was designed to enhance the energy absorption of slender tubes under axial load. The special energy absorption (SEA) was evaluated via a quasi-static axial compression test. Then, theoretical calculation and finite element analysis were carried out to analyze the energy absorption mechanisms. The results reveal that the tapered inner wall induces a progressively enhanced fold deformation mode for BITT, which not only prevents buckling failure and decreases initial peak crushing load but also improves the energy absorption efficiency by increasing plastic deformation. The influences of taper and length-diameter ratio on the axial energy absorption of BITT are explored. Finally, the bionic square array (BSA) and bionic hexagon array (BHA) are fabricated by taking BITT as the basic structural unit, which significantly improves the main energy absorption performance indicators under axial load.

Parametric Design and Mechanical Characterization of a Selective Laser Sintering Additively Manufactured Biomimetic Ribbed Dome Inspired by the Chorion of Lepidopteran Eggs.

The current research aims to analyze the shape and structural features of the eggs of the lepidoptera species Melitaea sp. (Lepidoptera, Nympalidae) and develop design solutions through the implementation of a novel strategy of biomimetic design. Scanning electron microscopy (SEM) analysis of the chorion reveals a medial zone that forms an arachnoid grid resembling a ribbed dome with convex longitudinal ribs and concave transverse ring members. A parametric design algorithm was created with the aid of computer-aided design (CAD) software Rhinoceros 3D and Grasshopper3D in order to abstract and emulate the biological model. A series of physical models were manufactured with variations in geometric parameters like the number of ribs and rings, their thickness, and curvature. Selective laser sintering (SLS) technology and Polyamide12 (nylon) material were utilized for the prototyping process. Quasi-static compression testing was carried out in conjunction with finite element analysis (FEA) to investigate the deformation patterns and stress dispersion of the models. The biomimetic ribbed dome appears to significantly dampen the snap-through behavior that is observed in typical solid and lattice domes, decreasing dynamic stresses developed during the response and preventing catastrophic failure of the structure. Increasing the curvature of the ring segments further reduces the snap-through phenomenon and improves the overall strength. However, excessive curvature has a negative effect on the maximum sustained load. Increasing the number and thickness of the transverse rings and the number of the longitudinal ribs also increases the strength of the dome. However, excessive increase in the rib radius leads to more acute snap-through behavior and an earlier failure. The above results were validated using respective finite element analyses.

Storm Daniel fueled by anomalously high sea surface temperatures in the Mediterranean

In September 2023, Cyclone Daniel formed in the Mediterranean, severely affecting Greece and Libya, and becoming the deadliest storm in Mediterranean history. The Mediterranean’s unusually high sea surface temperatures (SST) likely contributed to the cyclone’s intensity and extreme rainfall. Greece saw over 700 mm of rain in 18 h, while Libya experienced daily records exceeding 400 mm, leading to catastrophic infrastructure failures. Our hypothesis is that high SSTs provided additional energy and moisture fueling Daniel’s intensification. Using the Weather Research and Forecasting model, we conducted numerical experiments to quantify the role of high SSTs during the event. Comparing actual conditions with a counterfactual scenario, we found that the long-term global warming signal in SSTs significantly increased the storm’s intensity and precipitation. This study underscores the need to understand rising SSTs contribution to predicting and mitigate future tropical-like cyclones as global temperatures increase.

Detection of Stress Corrosion Cracking in SS304 under Calcium Silicate Thermal Insulation Using Acoustic Emission Technique

Despite its remarkable structural strength, austenitic stainless steels such as SS304 are susceptible to stress corrosion cracking (SCC) under thermal insulation due to the synergism of cyclic loading and chloride-containing environments. This study aims to detect SCC for insulated SS304 samples using the acoustic emission technique (AET) as monitoring tool to characterize the various stages of SCC damage mechanism. As-received (AR) and sensitized (SEN) SS304 samples were prepared as per ASTM G30 and experimented with soluble chloride drip test under calcium silicate thermal insulation following ASTM C692. Both AR and SEN samples revealed SCC behavior correlated with measured acoustic signals. AR samples exhibited a single crack with low energetic signals, whereas SEN showed multiple cracks with higher energetic signal events. The difference can be attributed to microstructure change by heat sensitization and the enhancement of the corrosion environment under calcium silicate insulation when wetted by salt solution. The acoustic emission (AE) parameters were characterized and correlated with different stages of SCC phenomena, showing that AET is useful for predicting SCC to avoid catastrophic failures in industries.

Computer-Integrated Surface Image Processing of Hydrogen-Saturated Steel Wear Products

This paper briefly describes the conceptual direction of the application of computer vision (CV) methods that involve controlling the morphology of hydrogenated wear particles (WPs). During long-term operation, in the surface and subsurface layers of the materials of parts in the tribo-joint, changes in the micromechanisms of fracture occur, which change the morphology of WPs. It has been shown that the developed computer program (CP) can be used to monitor the fractography of the surface of wear particles, and, accordingly, it is possible to control changes in the surface morphology. Therefore, it is possible to predict the operational stability and durability of the tribo-joint. A conceptual scheme for determining the performance of a tribotechnical assembly depending on the determined parameters of WPs is presented. The modes marked on it, including normal operation, transient, run-in, and catastrophic failure, can be evaluated by robotics approaches.

Achieving Robust α-Alumina Nanofibers by Ligand Confinement Coupled with Local Disorder Tuning.

As high-performance thermal protection and structure enhancement materials, oxide ceramic fibers have become indispensable in numerous areas, ranging from deep-sea exploration to supersonic aircraft. However, under extreme energy input, abnormal grain growth and inevitable vermiculate structure would break the fiber integrity, causing catastrophic structure failure. Nowadays, the design of nanoceramics brings potential answers for strengthening of mechanical properties, but with the diameter downsized to the nanoscale, the increasing structural susceptibility of ceramic fiber to phase transformation and grain growth becomes a huge barrier. Here, we propose a strong carboxylic ligand confinement strategy by the combination of formic and acetic acids to control the inorganic colloid growth for fabricating robust α-alumina nanofibers. The rapid hydrolysis and coordination of the carboxylate groups with aluminum together with subsequent concentration synergistically promote the formation of small and compact precursor colloids, laying a solid foundation for suppressing abnormal grain growth and achieving refined alumina grain structure. The local disorder induced by silica and boron oxide surrounding α-alumina grains imparts excellent mechanical properties and flexibility with no fractures observed even after 500 buckling cycles and a wide range of temperatures from -196 to 1100 °C, providing an enlightening paradigm for ceramic fiber strengthening.

Management of extra palatal canal in a maxillary molar: A case report

The occurrence of anatomical complexities during Root Canal Treatment often poses a great challenge in terms of management. Such variations, if not treated meticulously could lead to catastrophic failure of the adopted treatment approach. A thorough pre-operative evaluation has been attributed to the prevention of ‘missed’ canals. The persistence of microbiota within these ‘missed’ canals could be a causative factor for post treatment disease. The maxillary molar typically presents with 4 canals: Two mesiobuccal (MB and MB2), one distobuccal (DB) and one palatal (P). The following case report describes an endodontic intervention for a maxillary molar with the presence of an ‘extra’ palatal canal.

Introducing a new method for assessing short railway bridge conditions using vehicle onboard systems

Railway bridges are critical in the transportation network and vital to the profitability of the industry. Maintaining the bridge condition to safety standards is a priority for all railroad owners. However, the accumulation of damage that is not visible during regular inspections may cause catastrophic failures. The recent railroad bridge collapse over the Yellowstone River caused a train carrying toxic materials to fall into the river. The question arises “Could we predict and prevent this bridge collapse?”. The railroad bridge’s dynamic response under the train traversed can enable the assessment of structural conditions and may reveal structural issues that are not visible during the visual inspection itself. The onboard vehicle-based system is a novel concept that allows an autonomous evaluation of the existing railway bridge structures and substructures. An onboard system provides observations for multiple bridges, as opposed to a structural health monitoring system that is capable of monitoring only a single bridge. In 2016 the potential use of existing onboard systems to detect weak bridge stringers and changes in pier elevations was proved by a set of tests performed in the Transportation Technology Center (TTC) in Colorado, USA under controlled conditions. Recently, the research expanded to evaluate bridges in service. Several short, open-deck, railway bridges on the Polish Railway were examined using track geometry cars. The data were analyzed to compare and observe the changes in bridge response. This paper provides a summary of the findings of the analyzed data and future steps for research implementation.

Performance of Fiberglass Posts Versus Fiber- Reinforced Resin Composites in Endodontically Treated Anterior Teeth Without Ferrule: A Systematic Review.

To perform a systematic review of in vitro studies examining endodontically treated anterior teeth restored with fiberglass posts versus composite posts reinforced with: polyethylene fibers (Ribbond), fiber-reinforced resin (everStick) and composite resin (everX). The search was performed using PubMed, Scopus, Web of Science and LILACS. The studies were selected by two independent reviewers. To assess the risk of bias of each study, the QUIN tool was used. We analyzed the data using a narrative synthesis. Five articles were retained for final analysis. The risk of bias was moderate to high. Most studies reported non-catastrophic failures. With 72 non-catastrophic failures for the glass fiber group and 60 for the fiber-reinforced resins. Catastrophic failures were more prevalent in fiber-reinforced composite, especially in the Ribbond-treated group. Within the limitations of this study, the use of fiberreinforced composites as custom intracanal posts is still questionable, with controversial results. It is not possible to establish the superiority of one approach over the other in endodontically treated anterior teeth without ferrule. It was not possible to identify a superior performance among the approaches analyzed for the restoration of endodontically treated anterior teeth without ferrule.

Strategies and Methods for the Fault-Tolerant Function Development of Multi-Domain Systems

The main focus of this paper is the exploration of fault accommodation possibilities in the context of the function development of multi-domain systems. Faults inevitably occur in complex technical systems and may lead, if no accommodation entities or processes are present, to catastrophic failure. Several entities and processes exist and are applied, but mainly on the concrete levels of product representation. Faults very often concern more than one physical domain and accommodation possibilities are present in many physical or even non-physical domains. This paper explores this specific challenge, investigates causes for the emergence of faults, and proposes an initial collection of countermeasures. These countermeasures are explained on the basis of concrete product development examples. The research is based on reflective participation, observation of best practices, and triangulation. The paper is concluded with an in-depth exploration of possible application areas and directions for further research.

A Critical and Comparative Study of Layered Cylindrical Hollow Roller Bearing Using Numerical and Experimental Analyses for the Assessment of Static Load Carrying Capacity

Abstract The fatigue life of rolling bearings is a critical factor in their selection and application, driving ongoing research aimed at enhancing their performance. Among the solutions explored, the introduction of hollow rollers has been noted for their lighter weight and reduced stress. However, experimental results have shown that hollow rollers can suffer catastrophic failures under low static loading conditions. Recent studies have demonstrated that layered cylindrical hollow rollers (LCHRs) outperform both conventional solid and hollow cylindrical rollers under similar loading conditions. This warrants further investigation into the potential benefits of LCHR. This study aims to estimate the static load carrying capacity of LCHR bearing in comparison to hollow cylindrical roller bearings having different hollowness percentage. Corrected experimental results from individual roller-on-plate tests showed excellent agreement (within 5%) with numerical analyses, validating the numerical approach. Key parameters such as von Mises stress, contact pressure, bending stress, and contact width were obtained through numerical analysis. Additionally, a static load test rig was designed and developed to estimate the static load carrying capacity of the bearings under examination. The results of full bearing sample tests for various roller types corroborated the individual roller-on-plate test findings. The observed superior static load carrying capacity and promising semi-contact width of LCHR indicate their potential for extended fatigue life compared to solid and hollow rollers.