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Engineering rock mass often involves bedding planes and U-shaped defects. Under the combined influence of bedding planes and defects, the fracture mode of engineering rock mass is more complicated. To better understand the failure law of U-shaped defects in rock mass with bedding planes and better control or predict the crack propagation morphology, three-point bending tests were conducted on semicircular disk specimens with U-shaped notches under three different notch radii. The load variation law, different stages of the load–displacement curve, and fracture characteristics of specimens under five bedding angles were analyzed. Then, numerical models of semicircular three-point bending tests were established in particle flow code 2D (PFC2D). The influence of notch radius and bedding angle on the failure path of semicircular specimens was simulated and analyzed, and the three failure modes were verified again. In addition, the stress at the notch tip of the model was monitored by the measurement circle in the discrete-element method, and the fracture toughness of the model specimen was calculated, which provides a new calculation idea for fracture toughness. The research results help us more comprehensively understand the mechanical behavior and failure characteristics of layered rock mass with notch under external load. [ABSTRACT FROM AUTHOR]

The purpose of this study is to identify the integrity challenges encountered by buried pipeline steels, specifically to address Circumferential Near-Neutral pH Corrosion Fatigue (C-NNpH-CF). Damage to the pipeline's protective coating and corrosion conditions increase the risk of service failures caused by C-NNpH-CF. (Note that this mechanism has previously been termed near-neutral pH stress corrosion cracking.) Unlike axial cracking, circumferential cracking is primarily influenced by residual stress from pipeline bending, geohazards, and girth welds. External corrosion pits often lead to dormant cracks, with growth ceasing around 1 mm depth due to reduced dissolution rates. Investigating the impact of bending residual stress (an appropriate source of axial residual stress) and cyclic loading (simulated pipeline pressure fluctuation), the study employs the digital image correlation (DIC) method for stress distribution analysis. Factors like applied loading, initial notch depth, and bending conditions influence crack initiation and recovery from the dormancy stage by affecting stress distribution, stress cells, and stress concentration. Cross-sectional and fractographic images reveal time/stress-dependent mechanisms governing crack initiation, including dissolution rate and hydrogen-enhanced corrosion fatigue. The study emphasizes the role of various residual stress types and their interactions with axial cyclic loading in determining the threshold conditions for crack initiation. [ABSTRACT FROM AUTHOR]

The paper presents a fatigue test of AA2519 T62 aluminium alloy in high-cycles region for smooth and notched specimens with stress concentration factors 1.75 and 2.28 for radii r1 = 2 mm and r2 = 1 mm, respectively. A number of cycles with no notch effect was determined for each notched specimens. The estimated values were compared with the distribution estimated on the literature data. Based on this knowledge, an analytical-experimental method was proposed to determine S-N curves for notched elements for aluminium alloys. The verification of the method gives satisfactory results. Additionally, the FITNET method and the Lee and Taylor method were used for comparison. The proposed method got the best results. The FITNET method and Lee and Taylor method obtained overestimated fatigue life and it can be concluded that the analytical method presented methods are suitable for steel materials. The proposed method can be used by engineers. [ABSTRACT FROM AUTHOR]

Hydrogen‐induced cracking (HIC) in high‐strength 45CrNiMoVA steel is investigated using smooth and notched cylindrical specimens by performing uniaxial tensile tests. Specimens with different notch geometries are used to analyze the interacting effects of the stress concentration factor and HIC micromechanism. The results show that hydrogen charging reduces the elongation at fracture and the ultimate tensile strength of smooth tensile specimens. The microscopic fracture mode changes from ductile dimples with some quasicleavage fracture without hydrogen to a mixture of brittle quasicleavage and intergranular cracking with hydrogen. For notched specimens with a lower notch root radius, significant stress concentration occurs at the notch root, which enriches hydrogen in these highly stressed regions. This causes a lower notch tensile strength and greater susceptibility to hydrogen embrittlement. Microfracture observations show that the area fraction of the intergranular cracking surface increases gradually, and the brittle zone moves farther away from the notch root upon decreasing the notch root radius, causing the embrittlement index to remain high. These results will help determine the applicability of existing steel for hydrogen service and also provide guidance for developing new high‐strength martensitic steels that can resist hydrogen embrittlement. [ABSTRACT FROM AUTHOR]

In this paper, a reasonable explanation is given to unify notch effect and geometric size effect into notch geometric feature effect (NGFE), and energy gradient is utilized to depict the influence of the NGFE on the critical distance. The correlation of energy gradient with critical distance and fatigue life is discussed respectively. The weight index of the high energy region is used to quantify the contribution of the high energy region to the fatigue damage. Finally, a model of the reconstructed critical distance theory considering the geometric notch characteristic effect is established. The fatigue test of Q355 (D) alloy steel notched components was carried out, and the evaluation precision of the presented method is compared with Yang’ model and Shen’ model combining with the existing fatigue test data of En8. The results indicate that prediction results of the proposed method are consistent with the test results. [ABSTRACT FROM AUTHOR]

Parts manufactured by wire arc additive manufacturing (WAAM) are characterized by a peculiar surface morphology, namely, surface waviness, that negatively affects the fatigue performance. To exploit the full potential of WAAM and minimize the need for postproduction work, it is crucial to utilize the components in the as‐built state. This is because conventional machining techniques, typically employed for postprocessing operations, severely curtail the freedom of geometry of the components. This study focuses on an experimental and numerical characterization of the notch effect of the surface waviness for an AISI 308 LSi stainless steel. This is done by quantifying the fatigue notch factor in a probabilistic fashion, considering the results of ad‐hoc designed fatigue tests. A finite element model is developed by considering a 3D scan of the geometry of WAAMed plates, allowing to determine the theoretical stress concentration factor. The fatigue notch factor is also estimated from the numerical model by making use of the gradient correction according to the FKM guidelines. To validate the numerical approach, test data produced for different testing conditions are correlated by using the local stress approach, showing that classical methods are also applicable to additive manufactured parts. [ABSTRACT FROM AUTHOR]

The notch effect significantly influences the fatigue response of components and is particularly relevant for parts produced with additive manufacturing (AM) processes, characterized by complex geometries and possible geometric discontinuities inducing local and critical peak stresses. Moreover, the low surface quality, as well as manufacturing defects and residual stresses, interacts with the local peak stress induced by geometric discontinuities, complicating the assessment of the notch effect for AM parts and requiring extensive experimental fatigue investigations. In the present paper, the notch sensitivity of as‐built AlSi10Mg specimens produced with the laser beam powder bed fusion in the Very High Cycle Fatigue regime is investigated. Ultrasonic fatigue tests up to 109 cycles have been carried out on rectangular bars and rectangular bars with a central through‐thickness hole. The notch effect has been found to significantly affect the fatigue response of the investigated AlSi10Mg specimens, with surface defects having a main role and pointing out the influence of the surface quality on the crack formation. [ABSTRACT FROM AUTHOR]

In fatigue strength assessment, the methods based on ideal elastic stresses according to Basquin and the less established method based on elastic‐plastic stress quantities according to Manson, Coffin and Morrow are applied. The former calculates loads using linear‐elastic stresses, the latter requires elastic‐plastic evaluation parameters, such as stresses and strains. These can be determined by finite element analysis (FEA) with a linear‐elastic constitutive law, and subsequent conversion to elastic‐plastic loads, using the macro support formula by Neuber. In this contribution, an alternative approach to approximate elastic‐plastic parameters proposed by Glinka is compared to the the strain‐life method using Neuber's formula, as well as the stress‐life method of Basquin. Several component tests on 42CrMoS4‐QT specimens are investigated. To determine the input data for the fatigue strength evaluations, the entire test setup is computed by FEA. The nodal displacements from these validated full‐model simulations are used as boundary conditions for a submodel simulation of a notch, whose results serve as input for the fatigue strength assessments. It is shown that all approaches provide a reliable assessment of components. Our key result is that the strain‐life method using the concept by Glinka for notch stress computation, yields improved results in fatigue strength assessments. [ABSTRACT FROM AUTHOR]

Highlights Glass fiber reinforced polymer (GFRP) composite tubes have become increasingly popular in crashworthiness applications. On the other hand, square section GFRP tubes are prone to damage in a catastrophic failure mode in the early stages of the crushing process. At this point, triggering mechanisms have great potential to ensure deformation in progressive mode and improve the compression performance of GFRP tubes. Motivated by these facts, this paper aims to optimize the compression performance of square GFRP tubes by implementing notch‐type triggering mechanisms. The effects of notch width, number and length on the axial compression response of tubes were investigated to determine the optimal trigger configurations that would maximize specific energy absorption (SEA) and minimize peak crushing force (PCF). Experiments were conducted based on Taguchi L9 orthogonal array design, and Taguchi coupled Weighted Aggregated Sum Product Assessment (WASPAS) method was employed for optimizing multiple responses. The optimization results revealed that the proposed trigger mechanisms induced progressive crushing by preventing catastrophic failure, thereby significantly improving the compression performance of GFRP tubes. In particular, the results showed that the PCF of intact GFRP tube decreased by up to 38%, while SEA increased by up to 130% with the help of proposed trigger mechanism. The compression performance of square GFRP tubes improved by notch‐type triggering. The notch width, length and number were chosen as design parameters. Taguchi experimental design was used to find the best configuration of design parameters. The optimum configurations were examined through the entropy‐WASPAS approach. The results revealed that significant improvements can be achieved using trigger mechanism. [ABSTRACT FROM AUTHOR]

In this paper, a comparative study of the mode-I fracture behaviors of two types of specimens with a V-notch defect under plane stress conditions was performed using the digital gradient sensing (DGS) method. First, two types of specimens (namely one-piece specimen and bonded specimen) with the same V-notch defect were both made of polymethyl methacrylate (PMMA), and three different V-notch angles' defect were considered for each type of specimen. Then, three-point bending tests were performed on both types of specimens. The angular deflection field of light near the V-notch region was recorded using a CCD during the experiments. Finally, by utilizing the relationship between the stress gradient and angular deflection as established by the elasto-optic effect, in conjunction with the principles of linear elastic fracture mechanics theory, the stress intensity factors (SIFs) of two types of specimens under different stress conditions were calculated using the least square method. According to the experimental results, the influence of V-notch angle on fracture load and fracture toughness of two kinds of specimens was discussed. Meanwhile, the experimental results show the significant differences in the fracture behaviors of the two types of specimens under mode-I loading conditions. [ABSTRACT FROM AUTHOR]

Fracture toughness, which is the resistance of a material to crack propagation, is a critical material property for ensuring the mechanical reliability of damage‐tolerant design. Recently, damage‐tolerant design is introduced to flexible electronics by adopting micro‐cracked ultra‐thin nanocrystalline (NC) gold films as stretchable electrodes in a plane stress state. However, experimental investigation of the plane stress fracture toughness of those films remains challenging due to the intrinsic fragility from their sub‐100 nm thicknesses. Here, a quantitative method for systematically evaluating the plane stress fracture toughness of freestanding ultra‐thin NC gold film on water surface platform is presented. After effectively fabricating single‐edge‐notched‐tension samples with femtosecond laser, mode I stress intensity factors are measured in the plane stress state on water surface. Moreover, investigation regarding the effect of notch length, notch sharpness, and notch tip plasticity validates this method based on linear elastic fracture mechanics theory. As a demonstration, the thickness‐dependent plane stress fracture toughness of ultra‐thin NC gold films is qualitatively unveiled. It is revealed that the thickness confinement effect on grain boundary sliding induces a transition in fracture behavior. This method is expected to further clarify the fracture‐related properties of various ultra‐thin films for next‐generation electronics. [ABSTRACT FROM AUTHOR]

Load‐bearing and fatigue behaviour of butt welds in plates of different thicknesses The cross‐section of long‐span steel structures is usually adapted to the bending moment distribution. For this purpose, a thickness transition is applied in the area of butt‐welded joints in flanges of I‐shaped beam members. The fatigue behaviour of these constructional details is complex and differs from a butt‐welded joint in steel plates of the same thickness. This paper presents the results of 30 notch detail tests and compares the behaviour of butt‐welded joints in plates with a thickness transition with those of the same thickness. The statistical analysis of the experimental studies shows a higher fatigue resistance for butt‐welded joints with a thickness transition compared to butt welds of plates of the same thickness. The classification of the latter constructional detail in detail category 90 acc. to FprEN1993‐1‐9:2024 can be confirmed. The prognosis of the notch detail tests with the Two‐Stage‐Model confirms its applicability for the analytical‐numerical prediction of the service life of complex welded constructional details. In addition, the application of the model proves the influence of the thickness ratio and stress ratio on the service life of butt‐welded joints with thickness transition. [ABSTRACT FROM AUTHOR]

This paper reviews quantitively the multiaxial fatigue assessment of steel and aluminum welded joints, focusing on Eurocodes (ECs) and the recommendations of the International Institute of Welding (IIW). Extensive fatigue data under constant and variable amplitude loading are reanalyzed using stress analysis approaches such as nominal stress, hot spot stress, and effective notch stress. Evaluation of the ECs and IIW criteria reveals an effective assessment of multiaxial fatigue, with a satisfactory level of conservatism. Further research is needed especially for variable amplitude (VA) loading to enhance the precision and reliability of assessments, contributing to improved design practices and structural integrity in welded joint applications. Highlights: The multiaxial fatigue criteria proposed by EC3 and the IIW are reviewedDesign criteria are applied in terms of nominal, hot spot, and effective notch stressBoth constant and variable amplitude load histories are consideredStandard approaches are characterized by a large level of conservatism [ABSTRACT FROM AUTHOR]

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Chongqing University of Technology (Natural Science) is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this work, a new approach is proposed for predicting the life to crack initiation in Short Fiber Reinforced Polymers (SFRPs) under cyclic loadings in the presence of notches, cut‐outs and stress concentrations. A multiscale model is presented, encompassing two length scales for correlating the applied loads to the local stress fields in the matrix. These are used for defining an effective stress for predicting the life to crack initiation, accounting for the simultaneous influence of the notch geometry, the fiber content, orientation and distribution. The criterion was successfully validated on a large set of experimental results. Highlights: A new model is proposed for predicting fatigue crack initiation in notched SFRPsThe model is based on a multiscale procedurePrediction is based on local matrix stresses averaged in a structural volumeThe model accounts for fiber orientation, distribution and notch geometry [ABSTRACT FROM AUTHOR]

The fracture toughness (mode I) of shotcrete specimens was obtained using edge-notched partial disc (ENPD) specimens. Notched Brazilian discs (NBDs) were also tested to validate the results of the ENPD experiments. Numerical analysis was also conducted on the ENPD results to compare the measured and numerically obtained fracture toughness values. The notch lengths in the ENPD specimens were 15, 30, 45 and 60 mm, while the notch lengths in the NBD specimens were 10, 20, 30, 40, 50 and 60 mm. It was found that the flat joint model accurately predicted the potential crack growth path and crack initiation stress as compared with the experimental results. It was also deduced that the fracture toughness was roughly the same with an increase in the notch length. The tensile strength (σt) and fracture toughness (KIC) of the shotcrete specimens were found to be meaningfully correlated (σt = 7.92KIC). The ENPD tests yielded the lowest fracture toughness values because of the pure tensile stress distribution on the failure surface. It was also found that the derived fracture extension patterns from the laboratory investigations were in acceptable agreement with the outputs of numerical simulations. [ABSTRACT FROM AUTHOR]

Glass fiber-reinforced composite cylinders, capable of withstanding internal pressure generated during service, are increasingly utilized as insulators in high voltage circuit breakers. Different testing procedures have been suggested by various standards to assess the pressure resistance of these components. Due to its simplicity and cost-effectiveness, the split-disk testing method is the most widely used for evaluating the hoop strength of pressure cylinders during the development and verification phases. However, the method presents several aspects, such as those related to the influence of specimen geometry and friction, which require further examination since they may impact the outcome of the experimental tests. The investigation, carried out by a combination of experimental testing and finite element analyses, shows that the friction between the specimen and the semi-disks has a noteworthy effect on the hoop load applied to the specimen. Almost constant load distributions along the hoop direction, representative of the real operating conditions in a pressurized cylinder, can be achieved via proper lubrication of the contact surfaces. Furthermore, FE analyses demonstrate that the notch geometry suggested by specific standards (short notch) is not capable of inducing a uniform strain distribution in the notched region. A different notch geometry (long notch) is proposed in the study to attain a more uniform strain field over the reduced area region. The experimental results indicate that the strength measured on the short notch specimens is higher than that determined on the long notch specimens, thus confirming the significant influence of strain distribution on the strength properties measured with the split-disk method. [ABSTRACT FROM AUTHOR]

In this paper, a novel machine-learning based models are presented to predict the effect of notch depth on elastic new strain-concentration factor of rectangular bars with single edge U-notch under combined loading of static tension and pure bending. Regarding the importance of this study, the database with 162 samples is utilized to develop the new methodology of machine learning based models. The database includes the notch radius, the Poisson's ratio, and the thick ratio that represent the influential inputs. The predicted key feature is the elastic new strain-concentration factor under combined loading of static tension and pure bending. These samples were tested with high precision and the predicted values of SNCF were obtained. For comparison, adaptive neural fuzzy inference system, artificial neural network, fine tree, ensemble boosted tree, and ensemble optimized bagged tree were designed and developed in this study. To evaluate and compare the performance of the models, four statistical indices of MAE, MSE, root mean square error (RMSE)and determination coefficient (R) were utilized. Based on the results, all models can predict the SNCF appropriately. However, the Ensemble optimized Bagged tree model had a better performance than other models and it had a significant priority in term of prediction accuracy. Finally, the results indicated that the elastic SNCF increased with increasing notch depth from 0.2 ≤ ho/Ho ≤ 0.7 and sharply decreases with increasing notch depth for shallow notches (0.8 ≤ ho/Ho ≤ 0.95). [ABSTRACT FROM AUTHOR]

The fatigue crack growth behavior of a submicron-grained WC–Co hardmetal is investigated by artificially introducing small flaws by means of sharp indentation. Similar fatigue testing is also conducted on notched specimens with long through-thickness cracks for comparison purposes. The use of controlled small indentations flaws is shown to be a valid and successful approach for studying and describing crack growth behavior under cyclic loading for the material under consideration. This statement is based on the similitude found in fatigue mechanics and mechanisms between both crack types. Regarding the former, accounting of the indentation-induced residual stresses is key to rationalize the experimental findings. Concerning the latter, inspection of crack-microstructure interaction as well as fracture surfaces permit to discern similar features and scenarios, at both meso- and micrometric length scales. Results from this research yield an immediate practical implication, as indentation techniques may then be proposed as an alternative testing route for investigating fatigue crack growth behavior of hardmetal grades where sharp indentation is capable to induce well-developed radial crack systems. [ABSTRACT FROM AUTHOR]

In fatigue assessments, local strains and stresses can be easily evaluated using accurate finite element analysis in a case of an individual fatigue‐critical notch or structural detail. In practical design and analysis of global models, the consideration of local notch effects using suitable estimation rules in the combination with linear elastic analysis is reasonable. Various notch rules exist but the current knowledge lacks understanding how applicable different notch rules are for estimating notch strains from elastic stresses. This work studies the Neuber′s rules for sharp and mild notches, Glinka′s equivalent strain energy density method, the correction of Neuber′s rule proposed by Sonsino for mild notches, as well as the Seeger‐Beste method. The application of different estimation rules for notch strains, applied to the elastic‐perfectly plastic steel material and to Ramberg‐Osgood material model for the aluminum material, including work hardening effect, was studied in this work by comparing the estimations with the corresponding experimental data and finite element analysis results. The Neuber′s rule for mild notches and Sonsino′s averaging method gave best correlations with the experimental data and numerical (finite element analysis) results and can be thus recommended for such analyses in compatible cases studied in this work. [ABSTRACT FROM AUTHOR]

ISO 23228:2011 proposed a testing method in which the plastic material, experimental resins or compounds for pipes and fittings, can be exposed to stress conditions that mimic internally pressurised end‐capped pipes. The stress conditions are mimicked by the use of a plaque specimen having a grooved reduced section called plane–strain grooved tensile (PSGT) specimens producing a biaxial state of stress under uniaxial loading. In this study, PSGT specimens were cut out from high‐density polyethylene (HDPE) pipes. Two shape ratios, ratio between the width and the groove thickness, were used. Both the axial and transverse displacements and strain fields were followed by a digital image correlation (DIC) camera during tensile and creep loading, both at room and high temperature; furthermore, DIC images were used to estimate the notch opening displacement. The increasing effect of the temperature in both the axial and transverse displacement and strain was highlighted. No significant effect of the width was noticed. The results have evidenced that, as the plane–strain condition in the width is assured during the tests, PSGT specimens can be used to mimic internally pressurised pipes under monotonic increasing or constant‐in‐time loading at both room and high temperature, but it must be better to use specimens with a higher shape ratio, that is, higher width. The results contribute to the 9th Sustainable Development Goal: Industry, Innovation and Infrastructure by promoting a sustainable industrialisation and fostering innovation. [ABSTRACT FROM AUTHOR]

A novel quadruple band-notched spatial diversity/MIMO antenna for super wideband (SWB) application is investigated. The proposed antenna comprises two identical tapered semicircular radiators with two microstrip feedlines and a common slotted ground plane (CSGP), contributing a wide impedance bandwidth from 1.88–30 GHz. Further, a wiggly-line-decoupling-structure (WLDS) is introduced among the radiating ports to maximize the average isolation, more than 24 dB. The first band-notched functionality at 2.4 GHz is produced by etching a meandering slot on the CSGP, while the remaining three notch bands at 3.5, 5.5, and 7.5 GHz are obtained by implanting open-ended-semicircular (OES), complementary-split-ringresonator (CSRR), and elliptical-split-ring-resonator (ESRR) slots in each radiating patch. The designed and fabricated results for the two and four elements are analyzed, which exhibit wideband characteristics, stable radiation pattern, higher efficiency (above 85%), and reasonably high peak gain within the working frequency, excluding the quadruple notched bands. Moreover, other essential parameters such as ECC, DG, CCL, and TARC have also been analyzed, showing the antenna’s usefulness for radar imaging, cognitive radio, military, and long-range RF applications. [ABSTRACT FROM AUTHOR]

In this paper, the notch effect in weldments has been investigated, and the optimal configuration of different types of welded joints has been analysed using the implicit gradient approach. By considering this implicit gradient method, it is possible to calculate the effective stress related to fatigue damage, with the effective stress being a continuous scalar function of the real stress tensor components, even in the presence of sharp edges. Hence, the search for the optimal configuration that maximises fatigue life can be tackled as the condition of minimum effective stress obtained by changing the weld shape and geometrical parameters. Both load-carrying cruciform joints and spot welds made of steel have been considered. The structural details have been studied by modelling actual shapes without any geometric simplification. Moreover, the same numerical procedure has been considered independently of the size, shape or load condition without imposing restrictive rules on the FE mesh. [ABSTRACT FROM AUTHOR]

High thermal conductivity and low coefficient of thermal expansion make P92 a candidate material for Ultra Super Critical (USC) power plant piping. Microstructural features viz., high dislocation density, lath martensitic microstructure, and fine precipitates of M23C6 and MX (X= C, N) contribute towards the high rupture strength. However, most components are typically subjected to multiaxial stress conditions; either metallurgical (weldments) or mechanical (change in the dimension). The present work involves stress rupture testing of circumferential 60° V- notch specimens in the 300 – 375 MPa range at 650°C. A notch strengthening effect was observed; with rupture times ranging from 200 – 1300 h. Scanning electron microscopy (SEM) fractography revealed a mixed mode of fracture with brittle fracture observed at the notch root, while ductile fracture was seen at the centre of the specimen. [ABSTRACT FROM AUTHOR]

The article deals with the determination of the influence of the relative width of an approach channel with a rectangular cross-section on the discharge of clean water flowing over thin-plated weirs with a triangular notch and zero height of the weir above the bottom of the approach channel. To evaluate the influence, the Kindsvater-Shen equation was modified by introducing the basic effective discharge coefficient and the coefficient of the relative width of the approach channel. The coefficient of the relative width of the approach channel was determined based on the evaluation of data from three extensive experimental research investigations. It is valid for the entire possible range of relative widths of the approach channel and for the range of notch angles from 5.25° to 91.17°. The relative error of discharge determination is approximately up to ±2% over the entire range of discharges used in the conducted experimental research. The evaluation made it possible to determine the boundary distinguishing the partially contracted weirs from the fully contracted weirs in terms of impact on discharge. [ABSTRACT FROM AUTHOR]

In order to strengthen the sealing at the small clearance of the stator-based dual air-cooled external rotor permanent magnet synchronous motor and ensuring the heat dissipation of the clearance, the numerical simulations of the flow field and heat transfer characteristics of the small clearance of the motor with different labyrinth sealing structures under different working conditions were carried out by using computational fluid dynamics, taking into account the rotational factor. The influences of different labyrinth sealing structures at the upper and lower clearance on the overall sealing performance of the motor and the heat dissipation of the stator sidewalls were explored by analyzing the pressure and velocity at the clearance. The sealing performance and heat dissipation were evaluated using leakage and Nusselt number as evaluation factors. The results show that when the axial fan operates with suction, it is more conducive to improving the sealing performance of the motor and ensuring the heat dissipation at the clearance. Adding labyrinth seals at the upper and lower stator clearances can effectively improve the sealing performance of the motor in the dual air-cooled system,and the greater the total pressure drop of the sealing structure at the upper and lower clearances,the smaller the leakage. The average Nussell number of the stator sidewall at the clearance will decrease due to the addition of the labyrinth seal. When the incoming temperature is lower than the wall temperature,the extent of decrease of average Nussell number will increase with the increase of the flow-blocking effect of the sealing structure,and when the incoming temperature is higher than the wall temperature,the extent of decrease of average Nussell number will increase with the decrease of the flow-blocking effect and the notch vortex strength.Compared to the unsealed structure,the stator side double groove structure effectively ensures the heat dissipation of the clearances while improving the overall sealing performance of the motor.The research results provide a reference for the design of the sealing and heat dissipation structure at the internal clearances of the external rotor permanent magnet synchronous motor. [ABSTRACT FROM AUTHOR]

Stroke, resulting in hypoxia and glucose deprivation, is a leading cause of death and disability worldwide. Presently, there are no treatments that reduce neuronal damage and preserve function aside from tissue plasminogen activator administration and rehabilitation therapy. Interestingly, Drosophila melanogaster, the common fruit fly, demonstrates robust hypoxic tolerance, characterized by minimal effects on survival and motor function following systemic hypoxia. Due to its organized brain, conserved neurotransmitter systems, and genetic similarity to humans and other mammals, uncovering the mechanisms of Drosophila's tolerance could be a promising approach for the development of new therapeutics. Interestingly, a key facet of hypoxic tolerance in Drosophila is organism-wide metabolic suppression, a response involving multiple genes and pathways. Specifically, studies have demonstrated that pathways associated with oxidative stress, insulin, hypoxia-inducible factors, NFκB, Wnt, Hippo, and Notch, all potentially contribute to Drosophila hypoxic tolerance. While manipulating the oxidative stress response and insulin signaling pathway has similar outcomes in Drosophila hypoxia and the mammalian middle cerebral artery occlusion (MCAO) model of ischemia, effects of Notch pathway manipulation differ between Drosophila and mammals. Additional research is warranted to further explore how other pathways implicated in hypoxic tolerance in Drosophila, such as NFκB, and Hippo, may be utilized to benefit mammalian response to ischemia. Together, these studies demonstrate that exploration of the hypoxic response in Drosophila may lead to new avenues of research for stroke treatment in humans. [ABSTRACT FROM AUTHOR]

In this study, the mechanical performances of glass fiber-reinforced notched and pin-connected composite plates were investigated experimentally and numerically. For this purpose, composite plates with a circular hole, semicircular double-edge notched, U-edge notched, and single and double pin joints were prepared from [ 0 ° ] 8 layer glass fiber composites. Tensile tests were carried out on the obtained specimens. The effect of notch type, number of pins, and position of pins on plate damage load and type was investigated for linear and non-linear material behavior. Progressive failure analysis was performed using the Hashin damage criteria. Subprogram codes were written in the Ansys program using the finite element method. According to the obtained data, it was determined that the type of notch and the number of pins have a significant effect on the damage loads of the plates and the behavior of the material is important in terms of convergence to the experimental results in numerical solutions. In single-pin composites, the type of damage changed from net-tension to shear out as the pin approached the free edge of the plate. It was observed that the distance between the pins did not have any effect on the damage type of the composites in the double-pin joint structure. Compared to single-pin joint composites, double-pin joint composites were found to carry a maximum of 34% more damage load. The convergence rate of experimental and numerical data was obtained as a minimum of 92.1% for nonlinear material behavior and a minimum of 73.4% for linear material behavior [ABSTRACT FROM AUTHOR]

In the present investigation, the scattering nature of SH-waves in the irregular free surface of a linear orthotropic viscoelastic layer lying over orthotropic viscoelastic half-space has been considered. Different types of surface irregularity viz. parabolic type, rectangular type, and triangular notch type have been taken into account in the aforesaid structure. The closed-form expressions of dispersion as well as damping relations have been deduced analytically. The expressions for the induced reflected displacement due to scattering phenomena of SH-waves have also been deduced for all aforesaid cases of surface irregularity. The effects of the anisotropy parameter of the upper layer on the phase velocity and the attenuation coefficient of scattered SH-waves have also been examined. The effects of vertical irregularity parameter and anisotropy parameter on the induced reflected displacement component have also been examined. Further, a comparative observation has also been outlined and discussed. [ABSTRACT FROM AUTHOR]

The notch effects on the mechanical behavior of Liquid Silicon Infiltration (LSI) based continuous carbon fiber reinforced silicon carbide (C/C-SiC) was studied. The in-plane (IP) and out-of-plane (OP) flexural properties of notched and unnotched samples with fiber orientations (0°, 45° and 60°) were determined through 3-point-bending (3PB) and single notched beam (SENB) tests. Despite the significant difference in bending modulus, the strength depends only slightly on the fiber orientation and loading direction, which could be explained through the uneven distribution of SiC-matrix within the block-like structure of C/C-SiC. This unique micro-structure also leads to a relatively constant value of notch sensitivity in the IP direction, and the sensitivity to the notch is relatively low for all tested C/C-SiC specimen configurations. Furthermore, due to the large differences of fracture mechanism, the work of fracture (WOF) in the IP direction is significantly smaller than in the OP direction for all fiber orientations. [ABSTRACT FROM AUTHOR]

This paper proposes an improved matching pursuit (MP) method with a multicomponent interference dictionary (MCID) based on a pipeline guided wave reflection model. The proposed method separates the overlapped time domain reflections from the notch edges and extracts parameters such as amplitude, time of flight (TOF), and phase to identify the number and axial dimensions of notches in pipes. Firstly, the performance of the method in identifying parameters of overlapped components affected by noise and reverberation under different signal-to-noise ratios (SNRs) and frequencies is analyzed using four error metrics. Secondly, finite-element (FE) models of pipes with a single notch and double notches are established, and the accuracy of the reflection model is validated by comparing the predicted amplitudes, TOF, and phase of reflections with the FE results. Finally, experimental validation is conducted on aluminum pipes with multiple notches. The consistency between the experimental results, theoretical results, and FE results in wave packet parameters confirmed the accuracy of the proposed reflection models. The method accurately captures the parameters of the reflections from each notch edge in the experimental pipes, enabling the identification of the number and axial dimensions of the notches. The method holds the potential for identifying a greater number of notches in pipelines and characterizing their axial dimensions. This can provide a reliable reference for developing maintenance plans based on pipeline operational conditions, thereby preventing major safety incidents. [ABSTRACT FROM AUTHOR]

The work is focused on experimental research of deformation characteristics on three grades of hot-dip galvanized steels for the automotive industry. Deformation maps were obtained using the DIC (Digital Image Correlation) method. The map documents the development of longitudinal and transverse deformations under tensile stress. In addition to uniaxial tension, the investigated specimens were subjected to eccentric tension. The stable crack growth (SCG) was evaluated using a non-contact measurement technique on CT (compact tension) specimens. The deformation of steels, which affects the resistance to stable crack growth (confirmed by the Design of Experiments—DOE method), was manifested in the first stages of eccentric loading of specimens. The notch root radius varies considerably due to the blunting of the starting fatigue crack. The resistance to stable crack growth, which represents a safety reserve during a vehicle crash, was obtained. [ABSTRACT FROM AUTHOR]

Misalignment has a significant impact on the fatigue performance of circumferential weld joints in pipelines, which can significantly reduce the fatigue life. Misalignment generates a structural stress concentration on the pipeline, which proportionally reduces its fatigue strength. Moreover, due to the misalignment, the reinforcement of the root and the transition angle of the pipeline inwall are significantly reduced, increasing its notch stress concentration factor and further reducing its fatigue performance. This work investigates the effect of misalignment on stress concentration in the circumferential welds of pipelines, and it is used to predict the fatigue life. The structural stress method is proposed in the present work, and finite element analysis technology with Abaqus is used to calculate the structural stress concentration factor kj at the root-pass toe of misaligned circumferential weld joints, and a formula for the relationship between the structural stress concentration factor kj and the misalignment is established. The total stress concentration factor k of weld joints with different misalignments under several welding processes are calculated, and are compared with the structural stress concentration factor kj. The fatigue test data of weld joints with different misalignments are studied, and it is shown that the fatigue performance could be predicted by the fitting result. [ABSTRACT FROM AUTHOR]

The use of microwave energy to recycle high-quality coarse aggregates from waste concrete or assist hard rock breakage in underground building engineering is promising. Controlling or promoting the damage of coarse aggregates, i.e., hard rocks, under microwave irradiation is a crucial issue faced by these techniques. Understanding the damage mechanisms of hard rocks exposed to microwaves is thus urgent. Fracture toughness is a significant mechanical parameter of rocks that reflects their ability to resist crack propagation and damage evolution. In this study, the fracture toughness degradation of microwave-heated granite was investigated by combining experimental investigations and numerical simulations. A three-point-bending (TPB) experiment was conducted on granite specimens after microwave irradiation. A coupled electromagnetic–thermal–mechanical model considering the actual mineral texture of the granite specimen was established. The evolution of the temperature gradient and stress field near the initial notch tip were investigated. The results suggest that the microwave-induced maximum temperature gradient and stress in granite are at the plagioclase–quartz (Pl–Qtz) interfaces or inside the Pl near the boundary. The region of cracking initiation was defined as the damage zone, which could be obtained by comparing the microwave-induced thermal stress with the critical value. The fracture toughness degradation, which corresponds to the evolution of the damage zones, can be divided into two stages. A relatively rapid decrease in fracture toughness in the first stage is primarily caused by the spread of the scattered damage zones along the Pl–Qtz interfaces; subsequently, a gentler fracture toughness degradation results mainly from the extension of the previous damage zones. [ABSTRACT FROM AUTHOR]

The vibration and noise of a low-speed high-torque permanent magnet motor with a dovetail magnetic isolation device (DMID) structure is analyzed. The motor structure and the main structural parameters of the DMID are introduced, and the radial electromagnetic force wave of the motor is investigated. The notch width, radius, and position of the inner circle of the DMID are selected as design variables, and the constraint conditions are given. The influence of a single parameter on the radial electromagnetic force wave is discussed. The multi-objective optimization of the particle swarm optimization (PSO) algorithm is used to obtain the Pareto relatively optimal solution set that simultaneously satisfies the requirements of low noise, ample output torque, and small torque ripple, and the optimal design scheme is selected. Besides, the harmonic amplitudes of the radial electromagnetic force, motor vibration acceleration, electromagnetic noise, losses, and efficiency are compared and analyzed before and after optimization. Finally, the electromagnetic vibration experiment of a permanent magnet synchronous motor is carried out, and the data shows the feasibility of the above analysis. The results show that the optimal design scheme of the structure parameters of DMID can increase the average output torque, reduce the torque ripple, and effectively reduce the electromagnetic vibration and noise of the motor. [ABSTRACT FROM AUTHOR]

Detecting gear rim fatigue cracks using vibration signal analysis is often a challenging task, which typically requires a series of signal processing steps to detect and enhance fault features. This task becomes even harder in helicopter planetary gearboxes due to the complex interactions between different gear sets and the presence of vibration from sources other than the planetary gear set. In this paper, we propose an effectual processing algorithm to isolate and enhance rim crack features and to trend crack growth in planet gears. The algorithm is based on using cepstrum editing (or liftering) of the hunting-tooth synchronous averaged signals (angular domain) to extract harmonics and sidebands of the planet gears and low-pass filtering and minimum entropy deconvolution (MED) to enhance extracted fault features. The algorithm has been successfully applied to a vibration dataset collected from a planet gear rim crack propagation test undertaken in the Helicopter Transmission Test Facility (HTTF) at DSTG Melbourne. In this test, a seeded notch generated by an electric discharge machine (EDM) was used to initiate a fatigue crack that propagated through the gear rim body over 94 load cycles. The proposed algorithm demonstrated a successful isolation of incipient fault features and provided a reliable trending capability to monitor crack progression. Results of a comparative analysis showed that the proposed algorithm outperformed the traditional signal processing approach. [ABSTRACT FROM AUTHOR]

The impact protection applications of polycarbonate (PC) products are gradually increasing. Due to the high sensitivity of PC to notches, research on notch impacts has become very important. In this paper, the impact performance of PC with two different molecular weights under different notch states was investigated. Three notch size factors, namely notch tip radius, notch angle, and notch center depth, were selected to design orthogonal experiments and research impact toughness. Subsequently, a single-factor study was conducted on the impact radius at the tip of the notch, which was the most important factor affecting the impact performance. Research shows that the brittle–ductile-transition tip radius of high-molecular-weight PC is 0.15 mm, and it has a higher impact toughness than low-molecular-weight PC during the brittle fracture process. The brittle–ductile-transition tip radius of lower molecular weight is 0.25 mm, while low-molecular-weight PC has a higher impact toughness during the ductile fracture process. The brittle and ductile fracture mechanisms of PC with different molecular weights were analyzed by observing the stress changes and cross-sectional morphology. [ABSTRACT FROM AUTHOR]

The scaling of the strength of composite parts with part size is referred to as the size effect. In the presence of notches, stress concentration affects a portion of material that increases with the notch size. Furthermore, in woven composites, the notch and tow size can be comparable, thus demanding a mesoscale approach to properly capture the stress intensification. In this paper, a probabilistic mesoscale method to model the size effect in notched woven composites is presented. First, the stress distribution is estimated with a finite element model, calibrated on experimental Digital Image Correlation data. The FE model simulates the mesoscale heterogeneity of the woven reinforced material and replicates the local stress intensification at the tow level. Then, a three-parameter Weibull-based statistical model is introduced to model the probability of failure from the calculated stress distribution and the volume of the part. An equivalent stress is used to capture the relevant fiber and matrix failure modes and the maximum value within the specimen volume is the random variable of the model. The method is applied to open-hole tension tests of a woven twill carbon fiber–epoxy composite. Two specimen widths and three width-to-diameter ratios, from 3 to 12, are considered. Specimen width produced an observable size effect, whereas the variation of hole size in the range considered did not. The statistical model is found to accurately describe the experimental observations, efficiently replicating an inverse size effect, regardless of hole size, while wider specimens lead to a lower probability of failure. [ABSTRACT FROM AUTHOR]

It is currently a challenge to accurately predict the deformation and fracture behavior of metal parts in automobile crashes. Many studies have shown that the deformation and fracture behavior of materials are significantly affected by the stress state during automobile crashes with complex stress state characteristics. In order to further promote the application of die-cast magnesium alloys in automobiles, it is particularly important to study the material deformation and fracture behavior of die-cast magnesium alloys. In this paper, the mechanical properties of the AM60B die-cast magnesium alloy sheet under four stress states (shear, tension, R10 notch tension, and cupping) were designed and tested. Based on the von Mises isotropic constitutive model and Swift weighted Hockett–Sherby hardening model, the plastic constitutive model of die-cast magnesium alloy was established. Based on the plastic model and the fracture model (JC, MMC, and DIEM) considering the influence of three stress states, the deformation and fracture behavior of the AM60B die-cast magnesium alloy front-end members in three-point bending were predicted by experiments and finite element simulation. The experimental results show that the deformation mode and loading–displacement curve trend of the AM60B die-cast magnesium alloy front members are the same, the crack initiation point and crack initiation time are the same, and the crack shape is similar. The results show that the complex stress state constitutive model parameters and the DIEM fracture model obtained in this paper can accurately predict the deformation and fracture failure behavior of the AM60B die-cast magnesium alloy sheet. [ABSTRACT FROM AUTHOR]

Rock naturally contains numerous defects, and both loading rate and defect geometry affect the loading capacity of rock structures when subjected to dynamic impact loads. Understanding the rate-dependent mechanical response and characterizing geometry-related fracture parameter of defected rocks are crucial to safety assessment of rock engineering. In this paper, the effects of loading rate and notch parameter on dynamic brittle fracture behavior of Fangshan granite weakened by a blunt V-notch are experimentally studied. First, the dynamic fracture experiments on blunt V-notched semi-circular bend (BVNSCB) specimen of Fangshan granite with different notch geometries are performed using the split Hopkinson pressure bar (SHPB) system. Second, the dynamic fracture processes of blunt V-notched rocks are recorded using an ultrahigh-speed camera, and the mechanical responses to different impact loading conditions are obtained via digital image correlation (DIC) method. Third, the effects of loading rate and notch parameter on the dynamic fracture parameters including notch fracture toughness, crack propagation toughness, and crack velocity are discussed to reveal the fracture mechanism of blunt V-notched rocks subjected to impact loads. It is found that dynamic notch fracture toughness obtained from DIC method is usually larger than that measured directly from conventional maximum impact load method. The maximum tangential stress (MTS) criterion eliminating the effect of the fracture process zone (FPZ) at blunt V-notch tip is used to correct the apparent notch fracture toughness value measured from the maximum load method. The results show that corrected notch fracture toughness values are in good agreements with those obtained from the DIC method. This study is significant for dynamic fracture analyses and strength assessments of rock masses containing notches or other defects with complex geometry. Highlights: Effects of loading rate and notch geometry on dynamic fracture behavior of blunt V-notched rocks are studied. Dynamic notch fracture toughness and crack propagation toughness are simultaneously determined. DIC method is used to track the development of FPZ at blunt V-notch tip and quantify the FPZ length. [ABSTRACT FROM AUTHOR]

This article focuses on the modeling of crack propagation in miniaturized and normal SENB specimens to determine the fracture toughness of reactor pressure vessel (RPV) beltline materials in nuclear power plants. The study combines a brittle and ductile model using the Gurson-Tvergaard-Needleman (GTN) model and the Virtual Crack Closure Technique (VCCT) in simulations. The article also discusses the use of an artificial neural network (ANN) method to determine GTN parameters. Tensile tests were conducted on test materials, and finite element simulations were performed to analyze stress-strain curves. The GTN parameters were validated using mini and normal SENB test specimens, with good agreement between simulations and measured data for normal SENB specimens. However, further investigation is needed to understand discrepancies for miniaturized specimens. The ASTM E1820-20 standard was used to evaluate the fracture toughness results. [Extracted from the article]

Oral submucous fibrosis (OSF) is a chronic disorder with a high malignant transformation rate. Epithelial-mesenchymal transition (EMT) and angiogenesis are key events in OSF. The Notch signaling plays an essential role in the pathogenesis of various fibrotic diseases, including OSF. Our study aimed to explore the effects of Notch on the EMT and angiogenesis processes during the development of OSF. The expression of Notch in OSF tissues versus normal buccal mucosa samples was compared. Arecoline was used to induce myofibroblast transdifferentiation of buccal mucosal fibroblasts (BMFs). Short hairpin RNA technique was used to knockdown Notch in BMFs. Pirfenidone and SRI-011381 were used to inhibit and activate the TGF-β1 signaling pathway in BMFs, respectively. The expression of Notch was markedly upregulated in OSF tissues and fibrotic BMFs. Knockdown of Notch significantly decreased the viability and promoted apoptosis in BMFs subjected to arecoline stimulation. Downregulation of Notch also significantly suppressed the EMT process, as shown by the reduction of N-cadherin and vimentin with concomitant upregulation of E-cadherin. In addition, knockdown of Notch upregulated VEGF and enhanced the angiogenic activity of fBMFs. Moreover, inhibition of TGF-β1 suppressed viability and EMT, promoted apoptosis, and induced angiogenesis of fBMFs, while activation of TGF-β1 significantly diminished the effects of Notch knockdown on fBMFs. Knockdown of Notch suppressed EMT and induced angiogenesis in OSF by regulating TGF-β1, suggesting that the Notch-TGF-β1 pathway may serve as a therapeutic intervention target for OSF. Highlights: Notch is upregulated in oral submucous fibrosis tissues and fibrotic buccal mucosal fibroblasts (fBMFs). Knockdown of Notch suppresses the viability and epithelial-mesenchymal transition, promotes apoptosis, and induces angiogenesis in fBMFs. Activation of the transforming growth factor beta 1 signaling diminished the effects of Notch knockdown on fBMFs. [ABSTRACT FROM AUTHOR]

The fracture behavior of specimens made of polylactic acid and weakened by inclined double keyhole notches is investigated by both experimental and numerical methods. The test specimens are fabricated by two different methods; fused deposition modeling and traditional methods. The mechanical behavior of specimens was investigated under mixed‐mode loading with different notch inclination angles, various notch tip radius, and multiple raster angles. An experimental program was performed, and 72 new experimental data were provided. A fracture criterion based on the strain energy density is used to assess the critical fracture loads of the tested specimens. Good agreement is found between experimental and numerical data. The results showed that increasing the notch inclination angle and notch tip radius led to a decrease in the fracture load of the specimens. Also, fracture loads of the classical specimens are higher than the 3D‐printed specimens. In the 3D‐printed specimens, fracture loads for the samples with raster angles of 0°, 45°, and 90° have the highest value, respectively. Highlights: Fracture assessment of polylactic acid specimensSpecimens were weakened by using an eccentric inclined double keyhole notchSpecimens manufactured by fused deposition modeling and traditional methodInvestigation of different notch inclination angles and notch tip radiusEvaluation of specimens using experimental and numerical analysis methods [ABSTRACT FROM AUTHOR]

Thermal interface materials (TIMs) used between the chip and the heat spreader play an indispensable role in effective heat removal to ensure the chip's performance and reliability. As they suffer from stresses in practical applications, TIMs need to have high toughness to resist fracture. The notch sensitivity of TIMs is considered an important parameter to evaluate its toughness. However, the notch sensitivity of TIMs is seldom mentioned, and the mechanism to enhance the toughness is still unclear. Here, using polymer-based TIMs consisting of polydimethylsiloxane/aluminum as a model, we specifically investigate notch sensitivity of TIMs and analyze the mechanical mechanism in detail from the macroscopic and microscopic scales. It was found that a transition from notch insensitive to notch sensitive will happen with a notch length of 2.0 mm, which is much higher than typical soft materials, such as hydrogels. We interpret the notch sensitivity of the TIM by finite element analysis at macroscopic scales and the Lake–Thomas theory at microcosmic scales. The relationship between the area of the strain concentration region to the notch length in finite element analysis is in good agreement with the fracture stretch ratio with different notch lengths measured in a uniaxial tensile experiment. This investigation gives an insight into designing notch-insensitivity TIM and understanding their fracture behavior. [ABSTRACT FROM AUTHOR]

Sustainable composites are presently employed in applications where structural demands are minimal. Basalt fiber reinforced PLA (BFPLA) and polybutylene succinate (BFPBS) composites, incorporates bio-based materials, offer the potential to reduce non-renewable resource consumption and improve end-of-life disposal practices. Given the significance of thermal aging in semi-structural applications and the necessity for open holes (notches) for installation and assembly, little is known about how thermal cycling (TC) affects the open-hole strength of sustainable composites. This experimental work establishes a quantitative relationship between open-hole strength and TC, taking into account varying abrasive waterjet pressures, and explores the impacts of thermal aging on the notch sensitivity, thermal, mechanical, and physical properties. BFPBS displayed better unnotched tensile strength and notched strength than prethermal BFPLA specimens after they have been subjected to 100 TC ranging from -20 to 55°C. Thermal aging significantly influenced notch sensitivity, emphasizing its consideration in evaluating notch performance. This research provides a significant contribution to our current understanding of the effects of thermal aging on sustainable composites, enabling their informed application in a variety of industries and the results highlight their promising potential, in particular BFPBS, as strong alternative for medium load applications. Highlights • Evaluated thermal aging effects on basalt fiber (BF) composites, revealing improved properties in BF/PBS composites after thermal cycles. • Established quantitative link between mechanical behavior and thermal cycling using varying waterjet pressure values. • Basalt fibers enhanced crystallinity and thermal stability of PLA and PBS polymers, showing promise for sustainable composites. • Notch sensitivity impacted by thermal aging, underlining the importance of considering these effects in notch performance evaluation. • BF/PBS composites demonstrated potential as robust alternatives for indoor products and sports equipment. [ABSTRACT FROM AUTHOR]

Background/aim: Distal radius fractures (DRFs) are frequently associated with distal radioulnar joint (DRUJ) instability. The purpose of this study is to evaluate the effect of the sigmoid notch and ulna styloid fracture types on DRUJ subluxation following closed reduction and casting of DRFs via calculating radioulnar ratio (RUR) on postreduction computed tomography (CT) images. Materials and methods: In our study, postreduction CT images of 202 patients with distal radius fractures were evaluated retrospectively. CT images were evaluated for RUR, sigmoid notch fracture, and ulna styloid types. Sigmoid notch fractures were classified as nondisplaced in the sigmoid notch fractures (NDS) and displaced sigmoid notch (DS) fractures; ulna styloid fractures were grouped as the proximal half ulna styloid (PHUS) and distal half ulna styloid (DHUS) fractures. Results: The mean age of Rozental type 3b (62.8 years) was significantly higher among others. The mean RUR value was significantly higher in Rozental type 3a in compared to type 1a and type 2 fractures. PHUS fractures were more common with DS fractures than DHUS fractures. Conclusion: DS fractures and higher patient age are associated with DRUJ subluxation on postreduction CT images following DRFs. DS fractures are seen more commonly with PHUS fractures than DHUS. Patients with PHUS should be carefully assessed for sigmoid notch fractures and DRUJ congruency. These findings could be helpful for preoperative decision making in the treatment of DRFs. [ABSTRACT FROM AUTHOR]

In order to raise the hardness and strength of the surface layer of mechanical components and induce favorable residual compressive stresses, case‐hardening procedures have become established in the heat treatment of steel. In this work, a calculation concept for the fatigue strength of components that have been case‐hardened through carburizing heat treatment is being developed. The residual stress and the load stresses in complex‐shaped, carburized materials are determined using a finite element (FE) model. The fatigue limit of the components is derived using probabilistic methods and taking into account hardness gradients, residual stresses, and non‐metallic inclusions. The model is validated with available axial bending fatigue test data and then used to predict the rotating bending fatigue limit of samples with various geometries and heat‐treatment conditions. This work demonstrates the capability of combining probabilistic and FE‐based modeling to represent complex interactions between variables that affect the fatigue of heat‐treated components, such as steel cleanliness, notch shape, case‐hardening depth, or loading conditions. Highlights: Combined FE‐based and probabilistic methods can predict fatigue strength accurately.Interplay of heat‐treatment output, geometry, load, and material is considered.Crack initiation position gets shifted by increased case‐hardness depth.Fatigue strength reduction due to defects in steel depends on load concentration. [ABSTRACT FROM AUTHOR]