Rupture Behavior Research Articles

EASRAPP: An Open-Source Semiautomatic Python GUI-Based Application for Extraction and Analysis of Surface Ruptures in a Large Earthquake

Abstract Earthquake surface ruptures record the kinematics of the rupture behavior and rheology of the fault zone. General methods of acquiring coseismic surface ruptures, including the field geological survey and the visual interpretation of remote sensing images, are generally time consuming and challenging to obtain detailed features of surface ruptures. Here, we developed an open-source semiautomatic Python graphical user interface-based application named EASRAPP (An Application for Extraction and Analysis of Surface Ruptures). EASRAPP is a graphical Python application that provides an interactive, user-friendly framework for semiautomatically extracting and analyzing earthquake surface ruptures and associated quantitative parameters. It consists of four main modules for obtaining the region of interest for surface ruptures in a remote sensing image, extracting surface ruptures, editing the vector extraction results, and analyzing the width of the surface rupture zone and strikes of all surface ruptures. Moreover, some additional functions are available, including data structure conversion for vector and raster data, vector merging, raster mosaicing, and batch cropping from multiple large images to many small images. EASRAPP is written in Python 3, based on several open-source Python packages such as Tkinter, SciPy, and so forth. Because of its modular design, it is convenient to modify the code and add new functionalities to a collaborative development environment. Furthermore, the output of the editing module may serve as a machine learning or deep learning training dataset, and offer conditions for detailed kinematic analysis and acquiring accurate width of the active fault deformation zone. EASRAPP was tested on a single unmanned aerial vehicle image to demonstrate all modules and tools. In addition, EASRAPP was also applied to other drone and satellite images to extract surface ruptures from recent and historical earthquakes. Our results indicate that: (1) the tool can quickly extract the fine structures of surface fractures, (2) EASRAPP can be used to extract surface ruptures generated by historical events, and (3) it can be applied to high-resolution aerial and satellite images.

Multi-fault rupture behavior of the 1786 M 73/4 Kangding earthquake on the eastern margin of the Tibetan Plateau

The 2022 LudingMs6.8 earthquake has drawn attention to the Xianshuihe fault zone. Historically, there was anM73/4earthquake in this region in 1786. Because the surface rupture of this historic earthquake was not obvious, there is still much debate over the extent of the surface rupture, which is critical for comprehending tectonic activity and assessing seismic risk for the Xianshuihe fault (XSHF). In particular, the seismogenic structure of this earthquake was connected by three active left-lateral strike-slip faults—the Anninghe fault (ANHF), Daliangshan fault (DLSF), and XSHF—where a large earthquake could cause multi-fault rupture.Giventhese criteria, we report the results of a series of trenches excavated in the vicinity of the epicenter at the northern section of the DLSF, the northern section of the ANHF, the Zheduotang section, and the Selaha section of the XSHF. We find that 1) three palaeoseismic events have been revealed on the northern section of the ANHF: BE1, ∼1003 AD; BE2, 1000–1182 AD; and BE3, 1536 AD asM7 earthquakes, and 2) two palaeoseismic events have occurred on the Selaha fault during the last 500 years. The first event corresponds to the AD 1725 KangdingM7 earthquake, and the latest event may be the AD 1786 M73/4earthquake. 3) Three palaeoseismic events occurred on Zheduotang: ZD1, 1215 BC∼315 AD; ZD2, 830 BC∼705 AD; and ZD3, the 1955 AD KangdingM71/2earthquake. 4) The 1786 KangdingM73/4earthquake was probably a multi-fault rupture event, as evidenced by the trenching profile evidence, nearby offset geomorphic features, and historical earthquake data. Not only the Moxi fault, a seismogenic structure, but also the southern end of the Selaha fault to the north and the Shimian fault (DLSF) to the south simultaneously broke during this earthquake.

Adhesive Strength and Rupture Behaviour of Birch Tars Made with Different Stone Age Methods

Birch tar is the earliest adhesive produced by Neanderthals in the European Palaeolithic. Experimental studies have proposed a number of aceramic (i.e. without the use of ceramics) birch tar–making techniques, but to date, no archaeological evidence for any of these techniques has been brought forward. The likelihood of one of those methods being actually used in the Stone Age may be investigated by evaluating the method’s complexity, efficiency and the performance of the tar obtained. In this study, we experimentally produce birch tar with four common experimental aceramic techniques. These tars are tested for their mechanical properties using lap-shear tests. We found that tar made with the aboveground condensation method is strongest in terms of its adhesive strength. The tar also shows the most consistent behaviour throughout our test series. The weakest adhesive was observed in tar made with an underground (i.e. oxygen-depleted) technique resembling double-pot distillation (raised structure). Two supplementary methods yielded intermediate values: the recently proposed cobble-groove method produces tar with plastic behaviour. Tar made with another underground technique (pit roll) is almost as strong as condensation method tar. This study adds to our understanding of adhesive performance of birch tar made with different aceramic techniques. It also allows understanding the potential use of one method instead of another.

Nonsystematic Rupture Directivity of Geothermal Energy Induced Microseismicity in Helsinki, Finland

AbstractThe rupture behavior of microseismicity in fluid‐injection settings with low fault stresses is generally believed to be controlled by the pore pressure, including a tendency of the larger induced earthquakes to rupture into the perturbed volume toward the injection well, implying a degree of predictability. Here, we examine directivity patterns to identify fault planes and rupture directions of the 21 largest earthquakes (local magnitudes, 1.3–1.9) recorded during the 2018 St1 Deep Heat geothermal project near Helsinki, Finland. We use the Empirical Green's Function technique to retrieve per‐seismic‐station corner frequencies, earthquake durations, and directivity trends. After combining the directivity trends with focal mechanisms calculated using principle component analysis, we resolve rupture planes and rupture directions of 10 events. In contrast to studies of induced events at other sites, we find that one event rupture toward, two rupture away, and the remaining rupture parallel to the well. Furthermore, we find that the events prefer mode II failures rather than mode III. These observations provide new constraints for mechanical models of rupture growth in pore‐pressure dominated settings.

The 1673 Tianzhen Earthquake and Rupture Behavior of the Yanggao‐Tianzhen Fault in the Northern Shanxi Graben, China

AbstractStudying the causative structure, extent, and magnitude of historical earthquakes is essential for regional seismic hazard assessment. There has been some debate in the literature regarding the epicenter, magnitude, and seismogenic source of the 1673 Tianzhen earthquake, one of the few documented strong earthquakes that occurred in northern Shanxi Graben, China. The Yanggao‐Tianzhen Fault (YTF) has long been recognized as a seismogenic fault; however, previous studies have suggested that the fault has not ruptured at the surface for several thousand years. In this work, we investigate fresh surface ruptures along the YTF based on field investigations, unmanned aerial vehicle photogrammetry, and ground‐penetrating radar surveys. Scarp formation at Yanjiabu is bracketed to the last 1.4 ± 0.6 kyr using optically stimulated luminescence dating. More importantly, we found that the Great Wall at Li'erkou (dated from 1546 CE) was likely faulted, which led us to conclude that the YTF is the causative fault of the 1673 event. Based on our measured fault parameters, the magnitude of the 1673 event was re‐estimated to Mw 6.8–7.2, suggesting that previous magnitudes were underestimated. Four trenches were excavated to investigate paleoearthquakes on the fault. Together with previous paleoseismic data, we suggest a bimodal rupture model in which the fault can produce multi‐segment rupturing events with large magnitudes, such as the 1673 event, and smaller partial or single‐segment rupturing events. Our results shed light on the reassessment of seismic hazards in the densely populated Yangao‐Tianzhen Basin and its nearby regions.

Do upper-plate material properties or fault frictional properties play more important roles in tsunami earthquake characteristics?

Tsunami earthquakes are a type of shallow subduction zone events that rupture slowly (<1.5 km/s) with exceptionally long duration and depleted high frequency radiation, resulting in a large discrepancy of Mw and Ms magnitudes and abnormally large tsunami along coastal areas. Heterogeneous fault frictional properties at shallow depth have been thought to dominate tsunami earthquake generation. Some recent studies propose heterogeneous upper-plate material properties determine rupture behavior of megathrust earthquakes, including characteristics of tsunami earthquakes. In this study, we use a recently developed 3D dynamic earthquake simulator to explore tsunami earthquake generation and systematically examine roles of upper-plate material properties and fault frictional properties in tsunami earthquake characteristics in a physics-based framework. For heterogeneous fault friction, we consider isolated asperities with strongly velocity-weakening properties embedded in a conditionally stable zone with weakly velocity-weakening properties. For heterogeneous upper-plate properties, we consider a generic depth profile of seismic velocity and rigidity constrained from seismic surveys. We design a set of models to explore their effects on tsunami earthquake generation and characteristics. We find that the conditionally stable zone can significantly slow down rupture speeds of earthquakes that nucleate on asperities to be <1.5 km/s over a large depth range (1–20 km), while heterogeneous upper-plate properties can only reduce rupture speeds to be ∼1.5–2.0 km/s over a narrow depth range (1-3 km). Nevertheless, heterogeneous upper-plate properties promote cascading rupture over multiple isolated asperities on the shallow subduction plane, contributing to large tsunami earthquake generation. We also find that fault frictional properties play much more important roles than upper-plate material properties in long normalized duration, high-frequency depletion and low moment-scaled radiated energy in tsunami earthquakes. In addition, the effective normal stress on the subduction plane, which affects fault frictional strength, also influences the characteristics of tsunami earthquakes, including duration, stress drop and moment-scaled radiated energy.

Coseismic Rupture Behaviors of the January and March 2022 MW &gt; 5.5 Hala Lake Earthquakes, NE Tibet, Constrained by InSAR Observations

On 23 January and 25 March 2022, two MW &gt; 5.5 Hala Lake earthquakes characterized by right-lateral strike-slip faulting occurred around the Elashan Fault in Northeastern Tibet, marking the two largest events since the 1927 MW 6.2 Hala Lake earthquake. Since no surface rupture related to the two earthquakes has been reported, the seismogenic faults and coseismic rupture behaviors of the two events are still unknown. The occurrence of the two events provides a rare opportunity to gain insight into the seismogenic structure and rupture behavior of the less studied region, further helping us accurately evaluate the regional seismic hazard. Here, we first exploit Interferometric synthetic aperture radar (InSAR) data to obtain the coseismic deformation associated with the two earthquakes and then invert for the fault geometry and detailed coseismic slip of the two events. Coseismic modeling reveals that the January and March 2022 earthquakes ruptured two buried west-dipping moderate-angle and high-angle right-lateral strike-slip faults, respectively. Most of the slip of the January event occurred at depths from 1.7–7.6 km, while the majority of the slip associated with the March event occurred at depths from 2.5–10 km, which may have been restricted by the intersections between the January and March Hala Lake seismogenic faults. By a comprehensive analysis of the coseismic inversions, stress changes, and early postseismic signal, we suggest that the significant fault dip difference (~30°), highlighting a fault segmentation, stops the rupture propagation from one fault segment to another and that fluid migration may encourage the restart of the rupture of the later event, which requires further investigation. Moreover, Coulomb stress modeling shows stress loading on the eastern segment of the Daxueshan–Shule Fault and the northern segment of the Elashan fault, which we should pay more attention to.

A statistical mechanics framework for polymer chain scission, based on the concepts of distorted bond potential and asymptotic matching

To design increasingly tough, resilient, and fatigue-resistant elastomers and hydrogels, the relationship between controllable network parameters at the molecular level (bond type, non-uniform chain length, entanglement density, etc.) to macroscopic quantities that govern damage and failure must be established. Many of the most successful constitutive models for elastomers have been rooted in statistical mechanical treatments of polymer chains. Typically, such constitutive models have used variants of the freely jointed chain model with rigid links. However, since the free energy state of a polymer chain is dominated by enthalpic bond distortion effects as the chain approaches its rupture point, bond extensibility ought to be accounted for if the model is intended to capture chain rupture. To that end, a new bond potential is supplemented to the freely jointed chain model (as derived in the uFJC framework of Buche and Silberstein (2021) and Buche et al. (2022)), which we have extended to yield a tractable, closed-form model of single chain behavior that should be amenable to continuum-level constitutive model development. Inspired by the asymptotically matched uFJC model response in both the low/intermediate chain force and high chain force regimes, a simple, quasi-polynomial bond potential energy function is derived. This bond potential exhibits harmonic behavior near the equilibrium state and anharmonic behavior for large bond stretches tending to a characteristic energy plateau (akin to the Lennard-Jones and Morse bond potentials). Using this bond potential, approximate yet highly-accurate analytical functions for bond stretch and chain force dependent upon chain stretch are established. Then, using this polymer chain model, a stochastic thermal fluctuation-driven chain rupture framework is developed. This framework is based upon a force-modified tilted bond potential that accounts for distortional bond potential energy, allowing for the derivation and subsequent calculation of the dissipated chain scission energy. The cases of rate-dependent and rate-independent scission are accounted for throughout the rupture framework. The impact of Kuhn segment number on chain rupture behavior is also investigated. The model is fit to single chain mechanical response data collected from atomic force microscopy tensile tests for validation and to glean deeper insight into the molecular physics taking place. Due to their analytical nature, this polymer chain model and the associated rupture framework can in the future be implemented in finite element models accounting for fracture and fatigue in polydisperse elastomer networks.

Determination of multiaxial stress rupture criteria for creeping materials: A critical analysis of different approaches

• Factors affecting different methods for the determination of MSRC are analyzed. • Principles in the determination of MSRC are recommended. • The factor, α , is strongly dependent on the operative creep failure mechanism. • A relation exists between multiaxial factor, α , and damage tolerance parameter, λ . Materials in engineering applications are rarely uniaxially-loaded. In reality, failures under multiaxial loading has been widely observed in engineering structures. The life prediction of a component under multiaxial stresses has long been a challenging issue, particularly for high temperature applications. To distinguish the mode of failure ranging from a maximum principal stress intergranular damage to von Mises effective stress rupture mode a multiaxial stress rupture criterion (MSRC) was originally proposed by Sdobyrev and then Hayhurst and Leckie (SHL MSRC). A multiaxial-factor, α , was developed as a result which was intended to be a material constant and differentiates the bias of the MSRC between maximum principal stress and effective stress. The success of the SHL MSRC relies on accurately calibrating the value of α to quantify the multiaxial response of the material/geometry combination. To find a more suitable approach for determining MSRC, the applicability of different methods are evaluated. Given that the resulting analysis of the various approaches can be affected by the creep failure mechanism, principles in the determination of MSRC with and without using continuum damage mechanics approaches are recommended. The viability of uniaxial material parameters in correlating with α through the analysis of available data in literature is also presented. It is found that the increase of the uniaxial creep damage tolerance parameter λ is accompanied by the decrease of the α –value, which implies that the creep ductility plays an important role in affecting the multiaxial rupture behavior of materials.

Microstructure evolution and its effect on the stress rupture behavior of 9%Cr-CrMoV dissimilar welded joint

Taking the economic factor into account, 9 %Cr martensite heat-resistant steel is chosen to be joined with CrMoV steel by welding technique to utilize their potential at different temperatures. In the present study, the dependence of rupture time on the applied stress was determined and in accordance with the equation of lg(tr) = 7.224–0.014σ. All the stress rupture specimens were ruptured in the base metal of CrMoV steel (CrMoV-BM), indicating the high welding quality and the slight effect carbon migration on the stress rupture properties. The microstructure characterization revealed that the M23C6, M7C3 and MX type carbides were identified in the CrMoV-BM in the original state. These carbides were the typical precipitates existed in the heat resistant steel. Partially coarsened carbides and Mo-rich M6C phase were detected during the stress rupture test. The micro-voids tended to be initiated in the regions near these partially coarsened carbides and Mo-rich M6C ones along the grain boundaries. Subsequently, the macro-cracks formed via the micro-void convergence and eventually caused the fracture of the ruptured specimens.

Late-Quaternary paleoearthquakes along the Liulengshan Fault on the northern Shanxi Rift system

The Liulengshan Fault (LLSF), which lies on the northeastern edge of the Ordos Plateau, is a controlling boundary fault in the northern part of the Shanxi Rift system (SRS). The displaced landforms show that the fault has undergone strong and frequent late-Quaternary seismic activities. In 1989 and 1991, two moderate–strong earthquake swarms (Ms=6.1 and Ms=5.8) successively occurred in the LLSF, and GPS velocity shows that the areas are extending at around 1–2 mm/a. However, there is no surface-rupturing earthquake reported on the LLSF in historical records. Thus, the study of paleoseismic history and rupture behavior of paleoearthquakes in late-Quaternary on the LLSF is of fundamental importance for understanding the future seismic risk of this fault. To solve these problems, we conducted paleoseismological trench excavations at two sites on the LLSF to establish its paleoearthquake history. On the basis of the field geological survey and interpretation of high-precision topographic data, we carried out large-scale fault mapping and excavated two trenches in Xujiabao and Luofengwa across the LLSF. Then, four events in the Xujiabao trench and three events in the Luofengwa trench are identified. Finally, combined with radiocarbon dating (C14), optically stimulated luminescence (OSL) and OxCal modeling, we constrained the ages of these events. Together with the previous results of paleoseismology inYin et al. (1997), we consider that different segments of the LLSF may rupture together at the same time. Therefore, a total of six paleoearthquake events since late-Quaternary have been finally confirmed at 44,151–30881a, 40,163-28045a, 28,233-19215a, 16,742-12915a, 12,788-8252a, and 8203–2300a BP. According to the empirical relationships between moment magnitude and rupture length, the best estimated magnitude is inferred to be in the range between Mw 6.9 and Mw 7.7. Considering the strong late-Quaternary activity and a long earthquake elapsed time, we propose that the LLSF might have a high seismic hazard potential in the near future.

Pulse-like ruptures, seismic swarms, and tremorgenic slow-slip events with thermally activated friction

The evolution of frictional resistance on a fault affects the characteristics of seismic ruptures. A wide range of rupture styles, from slow-slip events to fast earthquakes, can be explained under the isothermal rate- and state-dependent friction framework. However, laboratory experiments indicate that friction also depends on temperature, with a largely unknown impact on rupture patterns. Here, we explore how thermally activated friction affects rupture behavior in quasi-dynamic models of seismic cycles with a single velocity-weakening, temperature-strengthening asperity, whereby frictional healing occurs behind the rupture front due to shear heating. A transition from crack-like to pulse-like rupture propagation with self-healing fronts occurs as the temperature strengthening effect increases, spontaneously inducing steady, decaying, or growing pulses. With increasing activation energy, the cycle turns into earthquake swarms and tremorgenic slow-slip events, both characterized by strong interactions between slow and fast ruptures. The temperature sensitivity of friction may contribute to the natural complexity of the seismic phenomenon, potentially explaining a much wider spectrum of rupture behaviors and recurrence patterns.

Effect of thermal damage on the pore–fracture system during coal spontaneous combustion

Understanding the variation law of pore–fracture system during coal spontaneous combustion (CSC) plays a crucial role in understanding the mechanism of CSC and its prevention as well as control. In this study, three different ranks of coal samples were heat-treated (25–500 °C). Through nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) and uniaxial compression (UC) tests, the changes in the pore-fracture system of different types of coal during CSC were comprehensively summarized. Based on the experimental results, the thermal rupture behavior of coal was simulated using PFC2D software. The results show that During CSC, the pore development of low-rank coal was obvious, the pore development of middle-rank coal was mainly concentrated in the high-temperature stage (T >300 °C), and the pore structure of high-rank coal was more stable. Meanwhile, the heterogeneity of the pore–fracture system of middle- and low-rank coals decreased, and the adsorption and seepage capacities increased. The heterogeneity of the pore–fracture system of high-rank coal was slightly influenced by temperature. The compressive strength of coal decreases with increasing temperature during CSC. The numerical simulation results were similar to the experimental results, i.e., the microcracks in the coal samples increased with temperature during heating; the effect of cracking caused by the high temperature will change the way the sample breaks, and the samples changed from ductile to brittle. The results of this study can serve as a reference for coal-fire control.

Co‐ and Post‐Seismic Mechanisms of the 2020 Mw 6.3 Yutian Earthquake and Local Stress Evolution

AbstractThe Mw 6.3 Yutian earthquake, occurred in northwestern Tibet on 25 June 2020, is one of the major events sequentially occurring in the region following the 2008 Mw 7.2, 2012 Mw 6.2, and 2014 Mw 6.9 earthquakes, and is of great significance for studying the tectonic activity and assessing future seismic hazards in the region. In this study, we used Sentinel‐1 Synthetic Aperture Radar images to retrieve co‐ and post‐seismic deformation and to investigate the coseismic rupture behavior of the fault and the mechanisms of postseismic deformation. Based on the slip models of recent four nearby major earthquakes, we explored the local stress evolution, triggering mechanism of the 2020 event and future regional seismic hazards. Postseismic modeling reveals that afterslip on fault patches surrounding the ruptured co‐seismic patches is the main mechanism responsible for the near‐field deformation, with the poroelastic rebound relaxation only accounts for maximumly 25% of the ground displacement and limited impact on the overall deformation pattern. The Coulomb failure stress changes (ΔCFS) suggest that the 2020 Yutian earthquake was inhibited by the 2008 Mw 7.2 earthquake but facilitated by the 2012 Mw 6.2 and 2014 Mw 6.9 earthquakes, resulting in an overall ΔCFS with a large lateral gradient on the 2020 fault. Stress concentrations on nearby major faults indicate increasing chances of seismic hazards in the eastern section of the Altyn Tagh fault at 82.8°E, the western section of the Guozha Co fault at 81.5°E and the entire section of the Ashikule fault.

Fracture Analysis of Sheet Aluminum Alloy AA2024-T3 Through a Complex-Loading Cross-Die Test

Lightweight materials such as aluminum alloys are, nowadays, well recognized as one of the most popular choices in the aerospace industry owing to their fantastic strength-to-weight ratio. Their fabricability is, nevertheless, doubtful down to their low elongation, especially in the present day where geometrical complexity is hugely demanded. Truly understanding fracture behaviors of such sheet metal would benefit all involved parties. To achieve that challenging goal, proper fracture-analysis models and implementation methods are definitely crucial. This work proposes the recent Lou–Huh fracture criterion to describe the rupture behavior of sheet aluminum alloy AA2024-T3. To build such a damage mechanics model, a string of Nakajima stretching and notched tensile tests must be performed to acquire critical strain data, precisely measured using the 2D-DIC principle. The data are used to calibrate the model. A fracture locus (FL), defining an extensive AA2024-T3 fracture threshold, is then established out of the fine-tuned model. The FL is directly coupled into an ABAQUS/Explicit FE process simulation model via the Fortran-based subroutine VUMAT. This leading-edge implementation can supposedly emulate realistic damage evolution by monitoring and actively removing the elements whose degree of injury has reached a certain limit. At the end, the complete integrative FE model is empirically validated through an industrial X-shaped specimen, deformed under nonlinear strain paths. Fracture locations, shapes and development on the FE-simulated specimen are observed and contrasted with those on the experimental one. It is obviously shown that the results from both approaches agree remarkably well in all aspects. When compared with the famous fracture forming limit curve (FFLC), the Lou–Huh FL combined with the element-removal VUMAT implementation clearly outperforms. In summary, the proposed model and the implementation procedure are practically outstanding fracture evaluators of AA2024-T3, wonderfully predicting and vividly laying bare crack appearance and growth.

Experimental and modeling investigation on the gas generation dynamics of lithium-ion batteries during thermal runaway

The gas generation and rupture are the special features of the thermal runaway (TR) of lithium-ion batteries (LIBs). The LIB’s gas generation dynamics during TR are investigated using the extended-volume accelerating rate calorimeter and a gas-tight canister. The pressure within canister is measured, and the internal gas could be regarded as a lumped system before TR thanks to the adiabatic condition. The pressure increase is about 100 kPa at the safety valve opening, and the corresponding gas release is approximately 10 mmol. For 100% SOC cells, the peak pressure recorded before the canister pressure relief is 2.566 MPa. The gas generation rate is approximately proportional to the temperature increase rate, which facilitates the simulation on the gas generation because temperature is easier to measure. The gas generation process can be divided into different stages, and the multi-stage kinetics parameters (Frequency factor and activation energy) of the gas generation process are calculated, which predict the evolution of internal pressure and rupture behavior of LIB under external heating condition. • Gas generation dynamics of Li-ion battery during thermal runaway is investigated. • Relationship between gas and heat producing rates is revealed. • Multi-stage kinetics parameters help predict the pressure and venting.

Enhancement of Resistive Switching Performance in Hafnium Oxide (HfO2) Devices via Sol-Gel Method Stacking Tri-Layer HfO2/Al-ZnO/HfO2 Structures.

Resistive random-access memory (RRAM) is a promising candidate for next-generation non-volatile memory. However, due to the random formation and rupture of conductive filaments, RRMS still has disadvantages, such as small storage windows and poor stability. Therefore, the performance of RRAM can be improved by optimizing the formation and rupture of conductive filaments. In this study, a hafnium oxide-/aluminum-doped zinc oxide/hafnium oxide (HfO2/Al-ZnO/HfO2) tri-layer structure device was prepared using the sol-gel method. The oxygen-rich vacancy Al-ZnO layer was inserted into the HfO2 layers. The device had excellent RS properties, such as an excellent switch ratio of 104, retention of 104 s, and multi-level storage capability of six resistance states (one low-resistance state and five high-resistance states) and four resistance states (three low-resistance states and one high-resistance state) which were obtained by controlling stop voltage and compliance current, respectively. Mechanism analysis revealed that the device is dominated by ohmic conduction and space-charge-limited current (SCLC). We believe that the oxygen-rich vacancy concentration of the Al-ZnO insertion layer can improve the formation and rupture behaviors of conductive filaments, thereby enhancing the resistive switching (RS) performance of the device.

Maximum prime vertical strain criterion to predict rupture of core-shell microspheres

Characterization of the rupture behavior is of great significance to evaluate the service life for microcapsules. Due to the small dimension, complex core-shell structure and curved surface of microcapsules, it is challenging to quantitatively determine the rupture position and rupture strength. In the present work, a microsphere-compression model for characterizing the rupture behavior of microcapsules was established. Through the quantitative investigation of the compression rupture behaviors of microcapsules from the extended finite element models, the cracks were found to initiate at the same parallel circle (latitude) of microcapsule where the curvature change of the deformed shell (i.e., prime vertical strain) is the largest. With the increase of compression displacement, microcapsules show three crack propagation modes. Based on such findings, a maximum prime vertical strain criterion, i.e., cracks initiate when the maximum prime vertical strain exceeds a critical value, for estimating the rupture initiation of microcapsules under compression was proposed. The proposed criterion was validated by both numerical simulations and experiments. It demonstrates that the critical prime vertical strain of rupture is independent of the microcapsule dimensions and is an intrinsic parameter to judge the rupture of microcapsules. The critical prime vertical strain of rupture for n-hexadecane@PMMA microcapsules is 0.023±0.003. The proposed model avoids complicated stress analysis and provides an intrinsic criterion.

The effect of microstructural changes on the rupture behavior of gas turbine damping bolt superalloy (Nimonic 90) after long service time

The present study investigated the microstructure of superalloy gas turbine damping bolt. These damping bolts were selected from new and service-exposed ones made of nickel-based Nimonic 90, which had been served for a long time. The microstructure of new sample had an austenitic matrix with many twins. These twins were located in the intergranular and intragranular regions of the primary carbides. Fine gamma-prime precipitates also could be found in the field. However, due to the high amount of service time, the arranged structure turned into a complex one in which the Sigma and Mayo phases with the Widmanstätten pattern appeared near the grain boundaries. Therefore, secondary continuous carbides formed near the grain boundary, and γ′ precipitates grew, which increased the hardness of the samples by about 30 Vickers. The mentioned microstructural changes reduced the creep rupture to 140 MPa at 870 °C in 11 h, while the sample had a creep life of about 21 h. This indicates that the resulting microstructural changes reduced brittleness and creep life. The soft intergranular failure mechanism in the new damping bolt became an intergranular mechanism. Moreover, the effects of intragranular failure were also abundant.

Experimental Study of Sidewall Rupture of Cylindrical Lithium-Ion Batteries under Radial Nail Penetration

To understand the relationship of the sidewall rupture at different states of charge (SOCs) of cylindrical cells with high specific energy, this work presents the results of radial nail penetration tests of 21700-format cylindrical cells at different SOCs. The thermal runaway and sidewall rupture behaviours were characterised by key performance indicators such as temperature, mass, fire behaviour, and voltage change. In addition, released gases from a subset of tests were measured using the Fourier transform infrared spectroscopy. The change in the internal structure of another subset of cells after the test was observed by X-ray computed tomography. The results show that the sidewall rupture still exists for tests at low SOC (< 30% SOC), but the outcome of thermal runaway and sidewall rupture is milder than those at high SOC (≥ 50% SOC). The average mass loss of cells increases with the increment of SOC. The cell casing thickness is reduced by 12.7% ± 0.3% of the fresh cell, which in combination with the reduction in the strength of the casing material at high temperatures could contribute to sidewall rupture.