Rupture Time Research Articles

The high-temperature creep mechanism of G115 steel joint under the vacuum electron beam welding

The welding joints of G115 steel were obtained from vacuum electron beam welding technology (VEBW), and their creep behavior was tested under the temperature at 630[Formula: see text]C, 650[Formula: see text]C and 670[Formula: see text]C with different stresses. According to the results, at the same temperature, the time of creep rupture decreases significantly with the test stress increasing, while the time of creep rupture declines significantly with the increased temperature at the same stress condition. The critical stress of creep for the welding joints at 630[Formula: see text]C, 650[Formula: see text]C and 670[Formula: see text]C is 115.28 MPa, 104.73 MPa and 96.98 MPa respectively. The stress index of welding joints between different temperature and stress conditions is about six, which indicates that the mechanism of creep deformation is controlled by the dislocation-climbing mechanism.

Simulation of great earthquakes along the Nankai Trough: reproduction of event history, slip areas of the Showa Tonankai and Nankai earthquakes, heterogeneous slip-deficit rates, and long-term slow slip events

Great earthquakes have occurred repeatedly along the Nankai Trough, but only for recent events are details known, such as rupture areas and time lags between paired events. It is meaningful for disaster prevention to consider in advance what kind of phenomena are likely after an earthquake that partially ruptures a seismogenic zone in this region. We constructed three-dimensional simulations to partially reproduce the spatial and temporal distribution of seismic or aseismic slip and the heterogeneous distribution of the slip-deficit rate beneath the seafloor on the plate boundary along the Nankai Trough. We found it necessary to assign spatial heterogeneity to two friction parameters, the effective normal stress and characteristic distance, based on a hierarchical asperity model. Our model produced many event pairs consisting of events east and west of Cape Shiono (Tokai/Tonankai and Nankai events, respectively), nearly all of them either simultaneous or separated by less than 3 years. The rupture areas of these event pairs were rich in variation, and even when the rupture areas were the same, the magnitudes and maximum displacements differed. The Tonankai earthquakes rarely occurred alone. Our model also simulated recurring long-term slow slip events in deeper parts of the seismogenic zone, and these events were caused by stress disturbance and heterogeneous stress distributions associated with non-ruptured portions of the seismogenic zone.Graphical

Abdominal Aortic Aneurysm: A Case Report in Western Maharashtra, India

An arterial aneurysm is defined as a permanent localized dilatation of the vessel at least 150% compared to a relative normal adjacent diameter of that artery. Abdominal aortic aneurysm (AAA) is defined as localized enlargement of the abdominal aorta such that the diameter is greater than 3 cm. AAA is potentially life-threatening finding. AAA may be detected incidentally or at the time of rupture. We reported a case of fusiform type of abdominal aortic aneurysm in a donated cadaver which was found during the routine dissection of a 76-year-old male died of acute myocardial infarction in western Maharashtra. The dimensions were measured by using both manual and verniers caliper method. The dimensions were 7 cm in length, 3.5cm in width, 11 cm in circumference, unruptured and positioned below the renal arteries, just above the aortic bifurcation. Owing to the vital role of aorta in the abdomen, we believe that the knowledge of this vascular pathology will be enlightening the field of medicine.

Effect of heat treatment on microstructure and small punch creep property of selective laser melted Inconel 718 alloy

In present study, the Inconel 718 alloys fabricated by selective laser melting (SLM) were subjected to traditional homogenization plus double aging heat treatment (HT1), and a novel heat treatment (HT2). The effect of heat treatment on the anisotropic microstructure and the small punch creep (SPC) property of Inconel 718 samples was investigated. The experimental results show that the general high-angle grain boundaries with stress concentration, and the equiaxed and columnar grains are observed in the HT1 samples. Compared with the traditional solution treatment at 1065 °C for the HT1 samples, a higher solution performed at 1150 °C can efficiently eliminate the stress concentration and lead to the transformation of columnar grains to equiaxed grains in the HT2 samples by introducing complete recrystallization. The recrystallization is accompanied by the formation of annealing twins with high proportion Σ3n (n = 1, 2, 3) twin boundaries. The larger γ″ phases, less grain boundaries perpendicular to the load direction and smaller Laves phases in the HT1-Z (Z represents parallel to the building direction) sample result in a longer creep life. Microcracks distributed along the general high-angle grain boundaries rather than twin boundaries promote the final intergranular fracture. The anisotropy in creep rupture time of SLMed Inconel 718 alloy can be obviously alleviated by applying higher temperature solution treatment.

Expression of TNF-α and IL-1β in Peripheral Blood of Patients with T2DM Retinopathy.

Aims The expression and clinical significance of tumor necrosis factor-α (INF-α) and interleukin 1-β (IL-1β) in retinal cells of patients with type 2 diabetes (T2DM) retinopathy were detected by flow cytometry. Materials and Methods Fifty patients with T2DM who attended our ophthalmology clinic between May 2021 and May 2022 were selected as the observation group. Another 50 healthy individuals who were examined at our hospital during the same period were selected as the comparison group. Tear film rupture time (BUT), fluorescein staining (FL), basal tear secretion (Schirmer I) test, and conjunctival impression cytology (CIC) were detected in both groups, and the expression of TNF-α and IL-1β in retinal cells was observed by immunohistochemical staining. Results The levels of IL13 and TNF-α in the two groups were not exactly the same. The serum levels of IL13 and TNF-α in the observation group were significantly higher than those in the control group, and there was a statistically significant difference (P < 0.05). TNF-α and IL-1B expressions in the observation group were positively correlated with the fluorescence staining, and the expression of TNF-α and IL-1β in the observation group was significantly negatively correlated with the BUT test and Schirmer I test. Conclusion Serums TNF-α and IL-1β are significantly elevated in patients with T2DM retinopathy and gradually increase with disease progression. Combined detection of serums TNF-α and IL-1β can help determine the severity of the disease and assess the prognosis.

Dual thermodynamics approach to the temperature dependence of viscoplastic creep durability in graphene-based nanocomposites

The ambient temperature at which creep deformation takes place is known to exert significant influence on the creep durability of graphene-based nanocomposites, but at present no theory could illustrate the underlying microstructural evolution to predict such a phenomenon. In this paper, a novel dual thermodynamics approach in conjunction with a time-temperature superposition principle (TTSP) is established to address this issue. First, temperature-dependent secant moduli are exclusively adopted as the unique homogenization variables shifted through TTSP, and then the time- and temperature-dependent effective stresses inside the matrix are calculated via the principle of equivalent work rate combined with the field-fluctuation method. Next, the dual irreversible thermodynamic processes, including the stress-induced creep damage inside the matrix and the temperature-dependent degradation at the interphase, are introduced through two independent sets of evolution equations. The predicted creep rupture strain and rupture time are calibrated with experiments over a wide range of temperature. It is demonstrated that the creep rupture strain increases with the rise of ambient temperature, while the creep rupture time decreases with it. The onset of creep-damage process also commences earlier at higher temperature. This research can provide a design guidance to assess the damage process and failure of low-dimensional nanocomposites at elevated temperature environment.

A pro-inflammatory and fibrous cap thinning transcriptome profile accompanies carotid plaque rupture leading to stroke

Atherosclerotic plaque rupture is the etiology of ischemic stroke and myocardial infarction. The molecular mechanisms responsible for rupture remain unclear, in part, due to the lack of data from plaques at the time of rupture. Ribosome-depleted total RNA was sequenced from carotid plaques obtained from patients undergoing carotid endarterectomy with high-grade stenosis and either (1) a carotid-related ischemic cerebrovascular event within the previous 5 days ('recently ruptured,' n = 6) or (2) an absence of a cerebrovascular event ('asymptomatic,' n = 5). Principal component analysis confirmed plaque rupture was responsible for the greatest percentage of the variability between samples (23.2%), and recently ruptured plaques were enriched for transcripts associated with inflammation and extracellular matrix degradation. Hierarchical clustering achieved differentiation of the asymptomatic from the recently ruptured plaques. This analysis also found co-expression of transcripts for immunoglobulins and B lymphocyte function, matrix metalloproteinases, and interferon response genes. Examination of the differentially expressed genes supported the importance of inflammation and inhibition of proliferation and migration coupled with an increase in apoptosis. Thus, the transcriptome of recently ruptured plaques is enriched with transcripts associated with inflammation and fibrous cap thinning and support further examination of the role of B lymphocytes and interferons in atherosclerotic plaque rupture.

Predictors of Oculomotor Nerve Palsy with Posterior Communicating Aneurysm Clipping in a Surgically Treated Series of 585 Patients: A Single-Center Study

Oculomotor nerve palsy (OMNP) is a known risk in surgical management of intracranial aneurysms. The aim of this study was to determine the risk factors for surgery-induced OMNP. This retrospective study examined 585 patients with posterior communicating artery aneurysms treated surgically between January 2000 and July 2019. The patients were categorized into 2 groups according to whether they experienced OMNP. Multiple factors, including sex, age, history of subarachnoid hemorrhage, Hunt and Hess grade, Fisher grade, preoperative time, sizes, sides, number, orientation, intraoperative rupture, and morphology, were analyzed to identify factors associated with surgery-induced OMNP. The overall OMNP rate was 4.4%. In univariate analysis, large size (P < 0.001), posterior infratentorial projection (P= 0.003), number of subarachnoid hemorrhages (P= 0.005), and late preoperative time (P < 0.001) were associated with increased risk of OMNP. Overall, multivariate logistic regression analysis showed that size (10.1-25 mm: odds ratio [OR] 30.083, P= 0.001, 95% confidence interval [CI], 3.703-244.419; >25 mm: OR 62.179, P= 0.012, 95% CI, 2.402-1609.418), intraoperative rupture (OR 3.018, P= 0.035, 95% CI, 1.083-8.412), and preoperative time (>14 days: OR 10.985, P < 0.001, 95% CI, 3.840-31.428) were independent risk factors of surgery-induced OMNP. This study showed that size, intraoperative rupture, and preoperative time were independent predictors of surgery-induced OMNP. Use of advanced technologies during the operation can assist in avoiding this complication.

Accelerated qualification of creep-resistant materials using a datum temperature method (DTM) to calibration

In this study, the datum temperature method (DTM) is applied to the Wilshire-Cano-Stewart (WCS) model to predict rupture time, minimum-creep-strain-rate, and creep deformation. The datum temperature method (DTM) is an alternative calibration approach that can be applied to existing models to improve accuracy and extrapolation reliability. The availability of creep data is limited due to the time and costs associated with testing. Often data is not available at desired operating conditions or creep life. Although accelerated testing methods have been developed, there is still a need to extrapolate creep data to conditions of interest. Conventional time-temperature-parametric (TTP) models have been used but the need for a decision which TTP model to use for specific materials, the point of convergence, and the inflection points limit their applicability. As an alternative, the DTM is proposed, where all data is transferred to a datum temperature for ease of calibration. In this study, the DTM is combined with the novel continuum damage mechanics based WCS model. To accomplish this, a single heat of alloy P91 from the National Institute of Material Science (NIMS) is considered and the WCS model is calibrated by DTM, and post-audit validated using the remaining heats of materials and an additional creep deformation dataset from Kimura. This calibration approach allows the model to predict rupture, minimum-creep-strain-rate, and creep deformation from a single datum temperature and single heat. It is found that DTM can significantly reduce the time for materials qualification and effort needed for model calibration.

Risk factors of maternal intrapartum fever and the effect of fever duration on neonatal morbidity in different temperature.

To investigate the clinical risk factors of intrapartum fever and explore the relationship between fever duration and neonatal morbidity of different fever peak. A case-control study was conducted, and 714 pregnant women were divided into fever and nonfever group. Multivariable logistic regression model was estimated to evaluate the risk factors for maternal intrapartum fever. Receiver operating characteristic curve was adopted to explore the relationship between fever duration and fetal distress of different fever peak to find the cut-off point, then the neonatal outcomes of women with fever ≥38°C in two groups of different fever duration were compared. Epidural analgesia (odds ratio [OR]: 6.89, p < 0.001), longer time of membrane rupture (OR: 1.06, p < 0.001) and longer time of first stage of labor (OR: 1.04, p=0.03) were considered as independent risk factors for maternal fever. For women with temperature <38°C, fever duration was not associated with fetal distress, whereas the women with temperature ≥38°C, fever duration longer than 93.5min was a good predictor of fetal distress (Area under curve (AUC)=0.82, p < 0.05). Further analysis showed that infants of women with fever peak ≥38°C and fever duration longer than 90 min had a higher rate of 1min Apgar score <7 (15.5% vs. 2.2%, p=0.03), assisted ventilation (29.6% vs. 11.1%, p=0.02), and admission to neonatal ward (87.3% vs. 60.0%, p=0.001). Epidural analgesia, longer time of membrane rupture, and longer time of first stage of labor were considered as independent risk factors for maternal intrapartum fever. For women with fever ≥38°C, controlling fever time less than 90 min might be helpful to reduce neonatal morbidity.

Late Holocene rupture history of the Ash Hill fault, Eastern California Shear Zone, and the potential for seismogenic strain transfer between nearby faults

AbstractUnderstanding how fault systems interact and transfer strain over seismogenic timescales (seconds to ka) requires temporal records of past ruptures along adjacent and intersecting fault networks. Here we document the record of Late Holocene ruptures as recorded in the geomorphology of alluvial deposits along the Ash Hill fault, in the Eastern California Shear Zone (ECSZ). We leverage a multi‐faceted approach to evaluate the relative timing of Ash Hill fault ruptures to those of nearby faults in the ECSZ. We determine the number and timing of Late Holocene earthquakes on the Ash Hill fault using high‐resolution tectono‐geomorphic mapping, a locally calibrated alluvial fan stratigraphy, feldspar luminescence dating, and fault offset analysis from field observations, LiDAR, and drone‐based digital surface elevation models. We find evidence for three surface‐rupturing earthquakes that have occurred since ~4 ka, each with ~1.0 ± 0.2 m of oblique slip per event (Mw ~ 6.9–7.0), and we constrain the timing of these earthquakes by dating deposits that bracket each event. The timing of these three ruptures is similar to the paleoseismic record along the adjacent range‐bounding fault in southern Panamint Valley. Specifically, the two adjacent faults exhibit similar numbers of earthquakes during the Late Holocene, with similar recurrence intervals and rupture timing. These data suggest that it is possible that these two faults have ruptured in the same or closely temporally related events throughout the Late Holocene. Similar spatio‐temporal clustered earthquakes have been recognized in both historic and paleoseismic records in the region, and such behaviour may be common in complexly interlinked fault networks, like those that exist in the ECSZ.

Small ruptured intracranial aneurysms are overrepresented at the anterior and posterior communicating artery: Results of a multiple regression analysis.

Background: Anterior communicating artery (AcomA) represents the most common location for ruptured intracranial aneurysms (rIAs). Approximately 50% of all rIAs are smaller than 7 mm, but factors that lead to rupture are multifactorial. The study investigates whether AcomA location represents an independent risk factor for small size at time of rupture (<7 mm) in a cohort of aneurysmal subarachnoid hemorrhage (aSAH) when controlling for known risk factors.Methods: The aSAH cohort was retrospectively searched from our institution charts. The cohort was dichotomized into small aneurysms (<7 mm) or large aneurysms (≥7 mm). Risk factors for rupture were identified according to the unruptured intracranial aneurysm treatment score (UIATS). These were sex, age, location, smoking, hypertension, alcohol abuse, aneurysm morphology, multiplicity, previous SAH, and family history. With size as independent variable, a multiple regression analysis was performed including UIATS risk factors.Results: One-hundred and seventy-six patients were included in the study. About 49.4% of the aneurysms were <7 mm. Multiple regression analysis demonstrated that aneurysms located at AcomA and posterior communicating artery (PcomA) was significantly more frequent smaller than 7 mm, compared to middle cerebral artery (P = 0.006), internal carotid artery (other than PcomA) (P = 0.013), and posterior circulation (P = 0.017), when controlling for risk factors.Conclusion: Ruptured AcomA and PcomA aneurysms are more frequent smaller than 7 mm compared to other locations. Patients with unruptured UIA at either AcomA or PcomA may be at increased risk of rupture even if the size of the aneurysm is small. Further studies are needed to confirm this finding.

Impact of rotating magnetic field on the microstructure, thermal properties, and creep behavior during the solidification of Sn–2.0Ag–0.5Cu solder alloy

Recently, the application of the magnetic field during the solidification process of alloys has become of great interest, owing to its ability to enhance microstructures. Hence, the present work aims to study the impact of a rotating magnetic field on the microstructure, thermal, and creep properties of the Sn–2.0Ag–0.5Cu (SAC205) alloy during solidification. Results demonstrated that applying a rotary magnetic field homogenized the distribution of intermetallic compounds and improved the microstructure. Additionally, the magnetic field diminished undercooling from 22.5 oC to 11.4 oC, indicating that the magnetic field is very useful in enhancing the microstructure and the alloy’s reliability. The pasty range values for SAC205 and SAC205-B were 7.2 oC and 8.6 oC lower than 11.0 oC for lead-tin, leading to a reduction of the alloy porosity. The SAC205-B alloy exhibited the longest creep rupture time of 158.5% compared to the SAC205. The n values of SAC205-B were higher than those of SAC205. Consequently, the SAC205-B alloy displayed the highest creep resistance and lowest creep rate (28.53%) compared to the SAC205. The Q values were 51.2 and 67.5 kJ/mol for SAC205 and SAC205-B, respectively, controlled by pipe diffusion. This research will provide practical advice for the manufacture of the solder alloy.

Extension of Aseismic Slip Propagation Theory to Slow Earthquake Migration

AbstractNatural faults host various types of migrating slow earthquake phenomena, with migration speeds much lower than seismic wave speeds and different moment‐duration scaling from regular earthquakes. To advance the obtained quantitative understanding of the migration process and long duration of slow earthquakes, I study a chain reaction model in a population of brittle asperities based on a rate‐ and state‐dependent friction on a 3‐D subduction plate boundary. Simulation results show that the migration speed is quantitatively related to frictional properties by an analytical relation derived here. By assuming that local pore water in front of the migration drives rapid tremor reversal and is so local as to hold a constant stress drop, the application of the analytical solution to observational results suggests that (a) the temporal changes of observed migration speeds for the rapid tremor reversal could be explained by about 70% reduction of the effective normal stress; (b) effective normal stress for the deeper extension of seismogenic segment in the western part of Shikoku is about 1.5 times greater than that in the central part. Applying rupture time delay between slow earthquake asperities for the duration longer than regular earthquake, I also conclude that (c) the characteristic slip distance of rate‐and‐state friction for low‐frequency earthquakes is roughly between 30 µm and 30 mm; (d) the stress and strength drops of very low‐frequency earthquakes is much smaller than 1 MPa.

Effect of Wall Thickness and Surface Conditions on Creep Behavior of a Single-Crystal Ni-Based Superalloy

The influence of wall thickness and specimen surface on the creep behavior of the single-crystal nickel-based superalloy MAR M247LC is studied. Specimens with wall thicknesses of 0.4, 0.8, 1 and 2 mm, with and without casting surface, are compared to specimens of the same wall thickness prepared from bulk material. Creep behavior turned out to be independent from surface conditions even for the thinnest specimens. The thickness debit effect is not pronounced for short creep rupture times (≤100 h at 980 °C), whereas it is significant for creep rupture times longer than ~200 h at 980 °C. The thickness debit effect is time-dependent and caused by oxidation and diffusion-controlled mechanisms.

Potential triggering factors associated with aneurysmal subarachnoid hemorrhage: A large single-center retrospective study.

Controlling blood pressure levels is critical to preventing intracranial aneurysm rupture, and a summary review of induced rupture events allows better health education for patients. We retrospectively reviewed all medical records of consecutive patients with aneurysmal subarachnoid hemorrhage (aSAH) admitted to Beijing Tiantan Hospital from 2015 to 2020. We collected patients’ demographic information, aneurysm morphology, blood pressure level on admission, time to onset, and events at the time of aneurysm rupture to analyze the factors precipitating aneurysmal rupture. A total of 764 patients were enrolled for analysis, including 461 (60.3%) female patients and 303 (39.7%) male patients. The mean age of onset in this cohort was 55, and 465 (60.9%) patients had hypertension history. Autumn (245/764 [32.1%]) was the most frequent season for aneurysm rupture, and 07:00–12:59 (277/764 [36.3%]) was the most frequent time frame for aneurysm rupture. The five most prevalent events when aneurysm rupture happened were: (1) daily behaviors that may induce hypertension (181/764 [23.7%]), especially defecation or micturition (116/181 [64.1%]); (2) sporting (162/764 [21.2%]), especially high‐intensity sports (108/162 [66.7%]); (3) mood and mental factors (112/764 [14.7%]), especially arguing or quarreling (61/112 [54.5%]); (4) sudden postural changes (93/764 [12.2%]), especially getting up (69/93 [74.2%]); and (5) sleeping (72/764 [9.4%]). Patients should avoid behaviors that may cause fluctuations in blood pressure, including keeping warm during seasonal alternation, keeping their urine and defecation unobstructed, avoiding high intensity physical exercise, maintaining a happy mood, avoiding sudden postural changes, and should not bathe with too cold or too hot water.

Saturation effect of creep-fatigue cyclic-life for Nickel-based superalloy DZ445 under long-term tensile dwell periods at 900 °C

This investigation determined the creep-fatigue cyclic-life (Nf) saturation effect for the DZ445 superalloy with 16–128 min dwell time at 900 °C and total strain range of 1.6%. When the dwell time exceeds 8 min, the mechanical response including maximum stress response, hysteresis loop, plastic strain range, and stress relaxation amount at characteristic cycle are also saturated with dwell time gradually. The Nf saturation effect is also reflected in the creep- and ductile-dominated fracture modes. This critical phenomenon is closely related to the dynamic equilibrium reached between the superdislocations of a/2[101] in γˊ precipitation and the formation of the dislocation networks. While the rupture time is increased continuously with dwell time, which could be better used as an evaluation index when the cyclic life is saturated. The Nf saturation effect can not only reduce the cost of tests with long-dwell time, but also provide the guidance for creep-fatigue safety design.

Effect of W Content in a CrMoV Forging Steel on Creep Property Under Multiaxial Stress and Rupture Time Prediction Methods

Effect of W Content in a CrMoV Forging Steel on Creep Property Under Multiaxial Stress and Rupture Time Prediction Methods

Creep rupture behavior of 2.25Cr1Mo0.25V steel and weld for hydrogenation reactors under different stress levels

Abstract In the present research work, the 2.25Cr1Mo0.25V steel plates with a thickness of 112 mm were welded using the multi-pass submerged automatic arc welding process. The creep specimens were prepared from the base metal (BM) and weld metal (WM) in the welded joint after heat treatment process. The uniaxial creep tests were performed to investigate the creep deformation and rupture behaviors at 550°C under different applied stress levels. The microstructure and fracture surface morphology of crept BM and WM samples were also characterized using the scanning electron microscope with energy-dispersive X-ray spectroscopy. The results showed that typical three-stage creep deformation curves are observed in both BM and WM specimens, and the BM exhibits a faster deformation rate than the WM. Both the creep rupture time and uniaxial creep ductility are found to be increased with a decrease in applied stress. Furthermore, the relationship between the minimum creep rate and time to rupture of both BM and WM samples was obtained, and it can be described using a unified Monkman–Grant equation. In addition, it is found that the creep fractures of the BM and WM are a transgranular ductile failure. The creep damages of both materials are mainly associated with the microstructural degradations, that is, the initiation and coalescence of creep cavities at second phase particles such as carbide and inclusion particles along the loading direction.

Liquid film rupture beyond the thin-film equation: A multi-component lattice Boltzmann study

Under the condition of partial surface wettability, thin liquid films can be destabilized by small perturbations and rupture into droplets. As successfully predicted by the thin film equation (TFE), the rupture dynamics are dictated by the liquid–solid interaction. The theory describes the latter using the disjoining pressure or, equivalently, the contact angle. The introduction of a secondary fluid can lead to a richer phenomenology, thanks to the presence of different fluid/surface interaction energies but has so far not been investigated. In this work, we study the rupture of liquid films with different heights immersed in a secondary fluid using a multi-component lattice Boltzmann (LB) approach. We investigate a wide range of surface interaction energies, equilibrium contact angles, and film thicknesses. We found that the rupture time can differ by about one order of magnitude for identical equilibrium contact angles but different surface free energies. Interestingly, the TFE describes the observed breakup dynamics qualitatively well, up to equilibrium contact angles as large as 130°. A small film thickness is a much stricter requirement for the validity of the TFE, and agreement with LB results is found only for ratios ε=h/L of the film height h and lateral system size L, such as ε≲×10−3.