Failure Mechanisms Of Materials Research Articles

A Realistic 3D Grain-Based Modeling Approach for Reproducing the Mechanical and Failure Behavior of Brittle Granites

Exploring cracking behavior from mineral-scale do good help to understand the failure mechanism of rock materials. The present study proposes a realistic three-dimensional grain-based modeling (3D-GBM) method considering the actual distribution, geometry and mesoscopic mechanical properties of different minerals in granite samples. The geometrical characteristic and distribution were captured based on high-precision computed tomography (CT) scanning and polarized microscopy. The mesoscopic mechanical properties were measured using nanoindentation combined with the scanning electron microscope-energy dispersive spectroscopy scanning (SEM-EDS). The results indicate that the established model can realistically reproduce the mechanical and failure behavior of granite subjected to unconfined compression in terms of stress-strain curves, failure mode, crack evolution, and force transmission. Investigating crack propagation at mineral-scale shows that the relative damage degree is greater at weak boundaries (i.e., boundary related to mica) and relatively soft minerals (i.e., mica) than that of strong boundaries (i.e., quartz-quartz and quartz-feldspar) and stiffer minerals (i.e., quartz and feldspar). Grain boundaries and soft mica minerals play an important role in guiding and deflecting the crack propagation path due to the mismatch in elasticity and strength compared with the stiffer and harder minerals (i.e., quartz and feldspar).

Running-In Behavior and Failure Mechanism Between AgCuNi Alloy and Au-Electroplated Layer

To avoid wear and tear of the slip ring due to electrical corrosion, the slip ring needs to undergo the running-in process under atmospheric conditions without current after assembly. To address the urgent demand for long-service capability space conductive slip rings in the aerospace field, the running-in behavior and failure mechanism between the AgCuNi alloy and Au-electroplated layer are investigated using a ball-on-disc tribometer in this paper. The results show that the transfer film composed of Au plays an important role in modifying the friction during the sliding process. With the accumulation of wear debris composed of Ag on the disc, the contact material of the friction pair changed from Au and Au to Au, Ag and Au, so the surface roughness of wear tracks increased. Finally, the transfer film broke, which made the layer fail. This paper reveals the key element failure mechanism that causes transfer film failure in the running-in contact area, which is used to reveal the friction behavior and failure mechanism of slip ring friction pair materials, and provides a basis for the selection of running-in parameters during the running-in process of slip rings before power-on operation.

Finite Element Simulation of Acoustic Emissions from Different Failure Mechanisms in Composite Materials

Damage in composite laminates evolves through complex interactions of different failure modes, influenced by load type, environment, and initial damage, such as from transverse impact. This paper investigates damage growth in cross-ply polymeric matrix laminates under tensile load, focusing on three primary failure modes: transverse matrix cracks, delaminations, and fiber breaks in the primary loadbearing 0-degree laminae. Acoustic emission (AE) techniques can monitor and quantify damage in real time, provided the signals from these failure modes can be distinguished. However, directly observing crack growth and related AE signals is challenging, making numerical simulations a useful alternative. AE signals generated by the three failure modes were simulated using modified step impulses of appropriate durations based on incremental crack growth. Linear elastic finite element analysis (FEA) was applied to model the AE signal propagating as Lamb waves. Experimental attenuation data were used to modify the simulated AE waveforms by designing arbitrary magnitude response filters. The propagating waves can be detected as surface displacements or surface strains depending upon the type of sensor employed. This paper presents the signals corresponding to surface strains measured by surface-bonded piezoelectric sensors. Fiber break events showed higher-order Lamb wave modes with frequencies over 2 MHz, while matrix cracks primarily exhibited the fundamental S0 and A0 modes with frequencies ranging up to 650 kHz, with delaminations having a dominant A0 mode and frequency content less than 250 kHz. The amplitude and frequency content of signals from these failure modes are seen to change significantly with source–sensor distance, hence requiring an array of dense sensors to acquire the signals effectively. Furthermore, the reasonable correlation between the simulated waveforms and experimental acoustic emission signals obtained during quasi-static tensile test highlights the effectiveness of FEA in accurately modeling these failure modes in composite materials.

Looking into failure mode identification driven by differential capacity in Ni-rich layered cathodes

Nickel-rich layered cathodes are one of the ideal electrode materials for high-energy lithium-ion batteries, yet suffer from capacity decay and structural degradation during cycling. Although the degradation mechanisms of electrode materials are flourishing, the analysis of performance decay and physicochemical properties dynamic evolution during cycling have not been well developed. Here, we propose a coupling analysis strategy based on differential capacity that distinguishes the failure behavior of electrode materials during cycling by the characteristic evolution of the dQ dV–1 curve recorded cycle-by-cycle. By coupling in-situ electrochemical tests with differential capacity characterization and comparing them with electrochemical characteristics recorded at different aging upper cut-off voltages cycles, the capacity decay mechanism and physicochemical properties evolution of electrode materials can be dynamically analyzed. The potential failure modes include loss of active Li inventory (LALI), loss of active structure integrity (LASI), and various dominant combinations of these factors. In addition, the distinction of aging behavior can also be applied to the failure level classification of spent electrode materials. Our findings demonstrate a general strategy for analyzing the dynamic failure mechanisms of electrode materials, thereby offering valuable insights for subsequent technology route selection in terms of recycling and reuse.

Building Robust Manganese Hexacyanoferrate Cathode for Long-Cycle-Life Sodium-Ion Batteries.

Manganese Hexacyanoferrate (Mn─HCF) is a preferred cathode material for sodium-ion batteries used in large-scale energy storage. However, the inherent vacancies and the presence of H2O within the imperfect crystal structure of Mn─HCF lead to material failure and interface failure when used as a cathode. Addressing the challenge of constructing a stable cathode is an urgent scientific problem that needs to be solved to enhance the performance and lifespan of these batteries. In this review, the crystal structure of Mn─HCF is first introduced, explaining the formation mechanism of vacancies and exploring the various ways in which H2O molecules can be present within the crystal structure. Then comprehensively summarize the mechanisms of material and interfacial failure in Mn─HCF, highlighting the key factors contributing to these issues. Additionally, eight modification strategies designed to address these failure mechanisms are encapsulated, including vacancy regulation, transition metal substitution, high entropy, the pillar effect, interstitial H2O removal, surface coating, surface vacancy repair, and cathode electrolyte interphasereinforcement. This comprehensive review of the current research advances on Mn─HCF aims to provide valuable guidance and direction for addressing the existing challenges in their application within SIBs.

Dynamic response and constitutive model for coal-rock composite material subjected to impact loading

Comprehensive understanding related to the dynamic responses of the composite materials is critical to prevent natural disasters in underground engineering and mining activities. For this reason, experimental studies were undertaken using dynamic impact tests at different strain rates to explore the failure mechanism using split Hopkinson pressure bar (SHPB) system and Digital Image Correlation (DIC) on composite materials; coal-rock (C-R) and rock-coal (R-C). These results suggest a linear correlation between dissipative energy and fractal dimensions. In addition, they suggest cracks that develop predominantly on the coal side have a dominant influence on the failure process that could be attributed to the interface effects. The damage evolution was established assuming elastic conditions using a three-dimensional coupled FDM-DEM numerical simulation system. Anumerical approach is also developed for interpreting failure mechanism of the composite material based on the fabric tensor and strain energy density. Finally, a constitutiverelationshipis established considering strain rate effect and damage evolution using series element studies. There is a good agreement between the experimental and numerical results, providing justification to the proposed constitutive relationship. The numerical approach in this study is promising for assessing the performance of composite materialstaking account of dynamic loading conditions.

Dynamic Behavior and Energy Absorption of Typical Porous Materials under Impacts.

Porous materials are known for their excellent energy absorption capability and, thus, are widely used in anti-impact applications. However, how the pore shape and size impact the failure mechanism and overall behavior of the porous materials under impact loading is still unclear or limitedly touched. Instead of using homogeneous solids for the porous material model, pores with various shapes and sizes were implanted in a solid to establish the porous materials that have true porous structures, which permits exploration of the local failure mechanism. The results revealed that differently shaped holes have two different dominant deformation modes. And due to their different local stress distributions, they enter the plastic phase earlier and, thus, have higher specific energy absorption. Meanwhile, the model changes from hardening to a quasi-zero stiffness model as the hole size increases. The application of this work can be extended into the field of impact resistance.

3D mesoscale model of steel fiber reinforced concrete based on equivalent failure of steel fibers

Steel fiber reinforced concrete (SFRC) is widely used in civil engineering. Investigating the mechanical properties and failure mechanisms of SFRC materials using mesoscopic models holds significant theoretical and practical importance. The bond-slip interaction between steel fibers and the cementitious matrix is crucial, yet current computational capabilities struggle to simulate the interactions among the numerous components within concrete containing a large number of steel fibers. This paper establishes an equivalent failure model to replace the bond-slip interaction. Based on this model, a multiphase mesoscopic model (including aggregates, the interfacial transition zone (ITZ), mortar, and steel fibers) is developed to predict the mechanical properties and failure modes of SFRC. The accuracy and validity of the model are verified by comparing the simulation results with the experimental results from four-point bending tests on SFRC beams, focusing on load-displacement curves, failure modes, and crack propagation. The results indicate that under load, the ITZ at the sharp edges of large aggregates in the SFRC beam is the first to be damaged, forming microcracks. Subsequently, these cracks bypass the large particles and propagate towards weaker regions with fewer steel fibers, forming macrocracks. At this stage, the steel fibers take over the load from the cementitious matrix and limit crack propagation. The simulated crack propagation trend and crack width during the loading process of the SFRC multiphase mesoscale model match well with the experimental observations. A higher fiber content can mitigate stress concentration within SFRC beams and enhance the fiber bridging effect, significantly improving the flexural load-bearing capacity and toughness of the beams. A smaller steel fiber inclination angle can effectively inhibit the propagation of vertical cracks, thereby increasing the load-bearing capacity and toughness of SFRC beams and extending the service life of the structure.

Study of corrosion and failure mechanism of the galvanized steel pipes of meteorological tower serviced in the South China Sea

Corrosion issues of steel in the natural tropical marine atmospheric environment widely exist, and they can easily cause the failure of engineering equipment. However, the related studies are poor. Therefore, a deep analysis of the corrosion behavior and failure mechanism of steel materials in natural environments is urgent and important. In this work, the corrosion and failure mechanisms of galvanized steel pipes of a meteorological tower in the South China Sea were deeply studied. Results demonstrated that galvanized steel pipes at a low height happen a serious uniform and localized corrosion, while the bottom surface of each pipe facing the ground is severely corroded. The damage to the galvanized layer and the subsequent steel corrosion in high temperature and humidity conditions are mainly caused by bacteria and Cl−. Some bacteria with high corrosivity, such as Desulfovibrionales, Seminibacterium, Acinetobacter, Ralstonia, Proteobacteria Streptococcus, and Lactobacillus, are found beneath the rust layer, and they can significantly accelerate steel corrosion. The maximum localized corrosion rate is 0.20 mm/y.

Investigation of the failure mechanisms of photocurable resins under explosive shock loads

Resin components produced by photocuring technology and 3D printing are commonly utilized as seals across various media owing to their flexible molding, precise structure, and excellent watertightness. Under certain specific conditions, it is necessary to detach the photocurable resin seals from the main body using explosive cord blasting. However, the mechanical performance of photocurable resins under explosive shock loads remains underexplored. This study aimed to explore the mechanisms underlying the destruction of photocurable resins by explosive cords in different environments. We conducted explosive shock experiments on photocurable resin specimens both in air and underwater and employed explicit dynamics software to simulate the damage process of the resin material. The experiments showed that a 10 mm thick specimen in air reached a critical fracture state under the equivalent explosive shock of the explosive cord, leading to adjustments in the constitutive parameters of the photocurable resin model in the simulations. In addition, the JH-2 strength and failure model was applied in AUTODYN explicit dynamics software to characterize the mechanical properties of the resin materials. The fluid–structure interaction method was utilized for modeling and simulating the shock process on photocurable specimens in air and water, clarifying the role of groove shape in the fracture state of the specimens and the failure mechanisms of the photocurable resin materials under explosive shock.

Textile-reinforced composite structural-health monitoring systems

In recent decades, composites have been widely employed in various sectors to reduce the weight of structural materials whilst enhancing their mechanical qualities. This issue of Textile Progress provides a detailed overview of composite material types, failure mechanisms, and damage-detection techniques applicable to composite structures. Due to their heterogeneity, composite materials are susceptible to several complicated forms of damage. Thus, for early damage identification of composites, structural health monitoring (SHM) may assist in efficient maintenance-scheduling, reducing wasteful inspections, and avoiding catastrophic occurrences and tragic outcomes. SHM is more sophisticated than most non-destructive testing approaches in that it involves establishing systems capable of continually gathering, analyzing, and interpreting data from structures to evaluate their health and lifespan. Several SHM approaches for composite structural-damage diagnosis are available; however, none are adequate for all situations. The number of techniques accessible now is too large to discuss in a single study so methods that may be used as a foundation for further research are the main focus of the current review.

A mini review on coated pipes: Materials, manufacturing and anti-corrosion protection

Pipelines are ubiquitous engineering structures used to transport fluid substances. To increase the durability and lifespan of pipes, engineers often coat chemically inactive materials onto the inner and/or outer surfaces of pipes, resulting in coated pipes. This article offers a review of research on coated pipes with a focus on their material selections, manufacturing methods, failure mechanisms and protection approaches. The information provided in this review article will be of great value to researchers and engineers dedicated to the design and manufacturing of coated pipes and their applications.

Summary of Rock Damage Mechanics Classification

As an important means to study the mechanical properties and failure mechanism of rock materials and engineering mechanics, damage mechanics is often used to assist in the analysis of the failure process and mechanism of rock, metal, and other materials in the current research. In the use of damage mechanics to study the properties of rock materials and explore the deformation and failure law of rock, important research results have been achieved. The research methods of damage mechanics can be roughly divided into three types: statistical damage model, mesoscopic damage model, and continuous damage model. Based on the existing literature in hand, according to the division of damage mechanics research methods in the academic community, this paper collates and considers that the existing damage model construction can be summarized from the mechanical point of view. The pure theory is derived or fitted from the mathematical point of view. One of them is derived from the mechanism point of view, and the other is derived from the phenomenon point of view. The stress, strain, acoustic emission, and other data are analyzed and reconstructed, and both have advantages and disadvantages.

Experimental study on the effects of temperature on mechanical properties of 3D printed continuous carbon fiber reinforced polymer (C[sbnd]CFRP) composites

Design for safety of 3D printed continuous carbon fiber reinforced polymer (CCFRP) composites remains challenging for accommodating harsh service environments with a wide range of temperatures. To investigate thermal effects on mechanical properties and failure mechanism of CCFRP materials, this study carried out a series of experimental tests on the laminates with layups of [0]n, [90]n and [0/90]n for tension, as well as [±45]n for in-plane shearing. The application of classical laminate theory and rule of mixtures to the 3D printed CCFRP composites under varying temperatures is then evaluated. The results indicate that the transverse elastic modulus/strength and in-plane shear modulus/strength increase at a low temperature, but all the mechanical properties decrease at a high temperature. Notably, an unexpected decrease in strength of [0/90]n laminates is observed when the temperature drops from −10 °C to −40 °C. Significant strain concentrations are visualized during tensile experiments at high temperature through the digital image correlation (DIC) technique. With increasing temperature, the [0]n laminates undergo a transition from an explosive to a jagged failure mode, while the [90]n laminates shift from brittle to ductile failure. The alteration is attributed to decrease in the mechanical properties of both the matrix and the matrix fiber interface, as revealed by scanning electron microscopy (SEM) analysis. It is found that although the classical laminate theory exhibits an acceptable prediction accuracy for the 3D printed CCFRP composites under varying temperature conditions, the rule of mixtures is not applicable. For this reason, the new formulations for the rule of mixtures are then proposed to enable accurate predictions for 3D printed CCFRP composites under different temperatures. This study is anticipated to provide insightful understanding on mechanical properties and failure mechanisms for 3D printed CCFRP composites at different temperatures.

Limit states of thin-walled composite structures with closed sections under axial compression

The subjects of the study were thin-walled composite columns with closed cross sections manufactured using the autoclave technique. The composite profiles were characterized by the fact that they had a constant height and arrangement of laminate layers, however, varied cross-sectional shapes. The study was conducted using several interdisciplinary experimental research methods and advanced numerical simulations. In the course of the research, both forms of structural stability loss were registered, and damage to composite structures was assessed. In the course of the research, the influence of the shape of the cross-section on the stability and load-carrying capacity of the structure was evaluated. A measurable effect of the conducted research was the determination of the structure's post-buckling equilibrium paths, which made it possible to determine the structure's behavior in the full range of loading. In addition, the author's numerical models developed enabled validation of parallel experimental studies. The developed numerical models were based on a failure criterion known as progressive failure analysis - which allowed a thorough assessment of the failure mechanism of the composite material.

Enhancing wear resistance, mechanical properties of composite materials through sisal and glass fiber reinforcement with epoxy resin and graphite filler

This study investigates the mechanical and wears properties of sisal and glass fiber-reinforced epoxy composites with graphite as filler material. We assessed the mechanical properties of the hand-layup-fabricated composite materials, including hardness, tensile strength, flexural strength, and impact strength, by ASTM standards. We also performed wear evaluations using a pin-on-disc apparatus. The results showed that the weight fractions of sisal fiber, glass fiber, graphite, and epoxy resin significantly affected the mechanical properties of the composites. In contrast to composites reinforced with individual fibers, hybrid composites exhibited enhanced mechanical properties. The optimized compositions showed improvements in tensile, flexural, impact, and hardness properties. The wear analysis revealed that a variety of factors, including the weight percentage of reinforcement, sliding velocity, load, and sliding distance, had an impact on the composites' wear resistance. The SEM images provided significant insights into the composite material's micro structural characteristics and failure mechanisms. In general, this research showcases the potential of graphite filler-reinforced sisal and glass fiber epoxy composites for use in applications that demand exceptional abrasion resistance and mechanical strength. Further refinement of the composition and processing methodologies could lead to the development of composites tailored to specific application demands.

Physical Discharge of Spent Lithium-Ion Batteries Induced Copper Dissolution and Deposition.

Complete discharge of spent lithium-ion batteries (LIBs) is a crucial step in LIB recycling, with the physical discharge method being particularly noted for its high discharge efficiency and environmental friendliness. However, previous studies and standards have focused on the performances of the discharge methods, neglecting the battery materials changes caused by discharge. Here we demonstrate that although prolonged discharge of spent batteries keeps the voltage around 0 V, an obvious current flow can be still observed, resulting from the dissolution and subsequent deposition of the copper foil. The deposited copper, primarily in the forms of Cu, Cu2O, and CuO, shows a gradient distribution on the surface of the anode and cathode active materials. This copper deposition significantly compromises the electrochemical performance of the discharged battery, with evident deterioration observed in the first charge-discharge capacity, cycling performance, and coulombic efficiency when compared to the original battery. This study provides guidance for the discharge methods and offers new insights into the materials failure mechanisms during discharge of spent batteries.

Piecewise Linear Strength Models for Analyzing Multiple Failure Mechanisms in Rocks Materials.

Rock materials failures are accompanied by the co-existence of various failure mechanisms, including rock fracturing, shearing, and compaction yield. These mechanisms manifest macroscopically as multiple failure modes and nonlinear strength characteristics related to stress levels. Considering the limitations of current rock mechanics strength theories, which are primarily derived from single failure mechanisms, this study evaluates the applicability of alternative strength theories. Based on the extensional-strain criterion and the PMC (Paul-Mohr-Coulomb) model, a piecewise linear strength model was proposed that is suitable for analyzing multiple failure mechanisms in rocks, revealing the intrinsic mechanisms of multi-mechanism rock material failure. A multiple failure mechanism strength model in the form of inequalities was proposed, using the generalized shear stress, mean stress, and stress Lode angle as parameters. Strength tests conducted on sandstone and granite rock material samples under different stress conditions revealed distinct piecewise linear strength characteristics for both rock types, validating the rationality and applicability of the multiple failure mechanism model. The findings construct a multi-mechanism failure model for rocks, providing enhanced predictive capabilities and aiding in the prevention of rock structural failures.

A multi‐phase mechanical model of biochar–cement composites at the mesoscale

AbstractThis study presents a five‐phase mesoscale modeling framework specifically developed to investigate crack propagation and mechanical properties of biochar–cement composites. The multi‐phase model includes porous biochar particles with precise geometric construction, sand aggregates, cement matrix, and interfacial transition zone adjunct to both the biochar particles and sand aggregates. The 3D porous biochar library was first proposed and established in this study, which could provide an external interface for describing different pore shapes, wall thicknesses, and pore areas. All the simulation results were experimentally validated using a digital image correlation. Through precise geometric modeling, the unique failure modes and timing of biochar particles within the mortar were identified. This is analogous to the “strong column–weak beam” concept, accounting for the enhanced ductility observed in the biochar–cement composites under compression test. This work can advance the geometric modeling of porous aggregates broadly and elucidate their mesoscopic failure mechanisms in cementitious materials, thus providing new insights for developing high‐ductility and lightweight cement composites.

Experimental Characterization of Anisotropic Mechanical Behaviour and Failure Mechanisms of Hardened Printed Concrete.

Extrusion-based printing of cementitious materials represents an innovative technology in civil engineering. The additive manufacturing process significantly influences the material properties in the hardened state, leading to anisotropic behaviour in terms of stiffness and strength compared to conventionally cast concrete. This experimental study aims to deepen the understanding of the mechanical behaviour of hardened printed concrete. Beam-like specimens with varying printing patterns, loading orientations and lengths are investigated within three-point bending tests (3PBT) and uniaxial compression tests (UCT). Homogenized material parameters such as Young's modulus, compressive and flexural tensile strength and density are statistically evaluated using optically measured displacement and strain fields on the specimen surface. The qualitative and quantitative results demonstrate a strong dependency of material properties and failure mechanisms on the printing pattern. The interfilamental and interlayer areas with weak adhesion are identified as the main reason for anisotropy.