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The increase in renewable energy penetration on the grid has accelerated the need to transition conventional fossil-based energy sources from their traditional base load operation to more flexible operational regimes. The mode of operation changed dramatically in terms of number of starts, operating hours per annum, and variation in load level. This results in greater thermal transients on operational equipment leading to an increase in Low Cycle Fatigue damage. To ensure the continued integrity of the steam turbine components, it is essential to assess the lifetime status by applying residual lifetime analysis methods. Depending on the amount of lifetime consumption and the extend of potential crack findings, different component repair options are possible. The rework or repair options can be divided into two main groups, namely, cold- and hot-rework. These two options can also be carried out consecutively. All rework or repair options provide the opportunity to improve the application of a component by applying profiling with improved stress fields and even superior materials, in the case of hot rework. The aim of the rework/reconditioning is to ensure that the steam turbine component is suitable for future operation. This ensures that plants are well placed to deliver more flexible operation in the energy industry through carefully tailored refurbishments and reworks. [ABSTRACT FROM AUTHOR]

Acute Pesticide Poisoning (APP) is a significant problem in developing countries, causing loss of productivity and fatalities in the agricultural sector. However, limited information on the connection between pesticide use, APP, and deaths in Zimbabwe is available. This study aimed to evaluate incidents that resulted in APP and identify the specific pesticides that caused them at Health Care Facilities (HCFs) in Mashonaland Central Province. Researchers conducted a survey asking standardized questions to gather information on APP cases from 93 HCFs. Descriptive statistics and chisquare association tests for APP cases in the targeted HCFs were calculated using IBM SPSS version 22. The study found that 43% of APP cases were due to pesticides belonging to the World Health Organization (WHO) class II acute toxicity category, while 26.1% were caused by Highly Hazardous Pesticides (HHPs). Most of the cases were due to intentional poisoning (87.1%), with the majority (55.9%) of APP incidents being males. The highest APP cases were recorded in the 21-30 age group (38.8%), followed by the 31-40 age group (32.8%). These results emphasize the significant impact of intentional poisoning by WHO class II type pesticides, particularly HHPs, on the incidence of APP in Zimbabwe. To mitigate the impact of HHPs on human health, it is recommended that the government of Zimbabwe consider pesticide risk reduction measures, such as stricter pesticide registration criteria, import restrictions, and the promotion of less toxic alternatives. These findings highlight the urgent need for policymakers, researchers, and other stakeholders in the agricultural sector to work collaboratively towards creating a safer and more sustainable farming environment in Zimbabwe. [ABSTRACT FROM AUTHOR]

The cast coarse-grained polycrystalline Alloy 247 is investigated, which is typically used in the rear turbine blades of land-based gas turbines. High rotational speeds up to 10,000 rpm in combination with high temperatures induce creep deformation. Additionally, gas turbine blades are subjected to high-frequency cyclic stresses. This complex loading state requires the investigation of the interaction of creep damage and high-cycle fatigue (HCF). Therefore, HCF tests with a stress ratio of Rσ = −1 were carried out on as-received and pre-crept specimens. In comparison, an HCF test series with high mean stresses (Rσ = 0.5) was conducted to consider the superposition of creep and fatigue. Since nickel-base alloys exhibit a pronounced elastic anisotropy, the grain orientations were considered in the damage analysis. The results show that creep-induced grain boundary damage is a dominant structural parameter for the HCF behaviour of Alloy 247 in both, sequential and superpositioned creep-fatigue loading. [ABSTRACT FROM AUTHOR]

The influence of pre‐strain on the tensile and fatigue properties of a dual phase DP600 steel was studied. The material was pre‐strained by uni‐axial tension in rolling and transverse direction. Thereafter, specimens were cut from the deformed plates in parallel or orthogonal to pre‐strain direction. It was found that pre‐strain increases yield and tensile strength. Results suggested that strain path change primarily affects the elastic‐plastic transition during early stage of reloading. Pre‐strained specimens showed an increase in high cycle regimes as a consequence of yield strength increment, irrespective of imposed pre‐straining direction. A modified stress life equation that accounts for pre‐strain was proposed and showed good agreement with experimental data. Bake hardening enhanced both tensile and high cycle fatigue resistance. Walker equation was successfully fitted to account for tensile mean stress. In low cycle fatigue, negligible influence of pre‐strain was observed due to cyclic softening and residual stress relaxation. Highlights: A DP600 steel sheet is characterized under different pre‐strain conditions and after baking.Experiments indicate that pre‐strain and bake hardening are beneficial in HCF.Modified Basquin equations to account for the effect of pre‐strain and bake hardening are proposed.Walker mean stress correction shows good agreement with experimental data. [ABSTRACT FROM AUTHOR]

AZ91 is one of the most broadly used Mg alloys because of its good castability and reasonable mechanical properties. Strengthening AZ91 with carbon short fibers aims to increase tensile and fatigue strength, creep, and wear resistance. One of the proposed applications of reinforced AZ91 is the production of pistons for trucks. Such reciprocating parts are subjected to alternating fatigue loads which can lead to fatigue failure. In this respect, studying the tensile and fatigue behavior of materials subjected to such loading conditions is of great interest. The alternating low-cycle fatigue (LCF) and high-cycle fatigue (HCF) of unreinforced AZ91 and carbon fiber-reinforced AZ91 (AZ91-C) were investigated at 20 °C and 250 °C. Tensile tests were carried out at the same testing temperature to find the appropriate fatigue testing stress and strain for stress-controlled and strain-controlled tests, respectively. The fatigue curves of stress against the number of cycles (S–N) revealed that the composite AZ91-C's fatigue strength was 55 MPa under HCF, while that of the matrix alloy AZ91 was only 37 MPa at 250 °C. Fracture investigations were conducted on the broken test samples. The fracture approach in the matrix material (AZ91) is mixed ductile/brittle containing fatigue serration, fiber fracture, and separation in the reinforced material (AZ91-C). [ABSTRACT FROM AUTHOR]

The helical cruciform fuel (HCF) rod assembly is a new type of fuel for the lead-bismuth (LBE) fast reactor. It can be self-positioned and realize a coolant mixing without wrapped wire or grid spacer. This kind of fuel assembly can not only realize the function of the traditional wire-wrapped fuel assembly, but also omit the wire -wrapped structure, which provides a satisfactory prospect for the development of LBE reactor. In this study, the coolant mixing in the LBE cooled reactor with HCF assembly was analyzed numerically. The influence of the Reynolds number and different coolant mediums were investigated. Advantages and disadvantages of the HCF assembly were analyzed and compared with the wire-wrapped fuel.

This paper presents the results of a comprehensive effort to characterize the properties of Inconel 718 produced by a form of laser powder bed fusion (LPBF) additive manufacturing (AM) or three-dimensional (3D)-printing, subsequently subjected to hot isostatic pressing (HIP) and heat treatment according to standards F3055-14a and AMS 5663, respectively. Material property data, while broadly available for traditional Inconel 718 presentations (e.g., forgings or castings) is currently lacking for the 3D-printed material. It is expected that while limited in size, the experimental data sets presented provide sufficient information to glean the capability of LPBF Inconel 718. These include: (1) chemical composition, electron backscatter diffraction (EBSD), and X-ray energy dispersive spectroscopy (XEDS) characterization of 3D-printed material structure; (2) tensile properties--0.2% yield stress, ultimate stress, modulus of elasticity, and elongation to failure--based on 108 samples, as functions of temperature and sample print orientation; (3) creep rupture data including the Larson-Miller parameter, based on 21 samples; and (4) high cycle fatigue data based on 21 samples as a function of temperature. Results are compared to available standards and/or data for forged, cast, and other AM Inconel 718. A key observation of this study, based on the EBSD results, is that while the material appears to approach full recrystallization following heat treatment, there is a detectable fraction of the material that does not fully recrystallize, resulting in a material with mechanical properties (e.g., yield stress and creep rupture) measurably lower than those of forgings, but higher than those of castings. [ABSTRACT FROM AUTHOR]

LG Electronics, es un fabricante líder de productos comerciales y de consumo que van desde televisores, electrodomésticos, soluciones de aire acondicionado, monitores, robots de servicio, componentes automotrices y sus marcas premium LG SIGNATURE y LG ThinQ inteligente son nombres familiares en todo el mundo. LG Electronics siempre a la vanguardia en tecnología, ya cuenta en Panamá con el Centro de Soluciones de Negocios para Latinoamérica. Esta unidad de Negocios de categoría mundial, está destinada a brindar servicios de capacitación y entrenamiento especializado en el rubro de HVAV; tanto de forma presencial, como en línea, para todos los países de Latinoamérica. El Ing. César Penailillo, vocero del Business Solutions Leader de LG Electronics, con más de 10 años experiencia trabajando en diferentes países con la empresa Trane, una de las marcas líderes de aires acondicionados de Estados Unidos y desde el 2019 forma parte del equipo de LG, nos hablará de los avances, expectativas y convenios para el nuevo Centro de Soluciones de Negocios para Latinoamérica.

Lightweight magnesium alloys and magnesium matrix composites have recently become more widespread for high-efficiency applications, including automobile, aerospace, defense, and electronic industries. Cast magnesium and magnesium matrix composites are applied in many highly moving and rotating parts, these parts can suffer from fatigue loading and are consequently subjected to fatigue failure. Reversed tensile-compression low-cycle fatigue (LCF) and high-cycle fatigue (HCF) of short fibers reinforced and unreinforced AE42 have been studied at temperatures of 20 °C, 150 °C, and 250 °C. To select suitable fatigue testing conditions, tensile tests have been carried out on AE42 and the composite material AE42-C at temperatures of up to 300 °C. The Wohler curves σa (NF) have shown that the fatigue strength of the reinforced AE42-C in the HCF range was double that of unreinforced AE42. In the LCF range at certain strain amplitudes, the fatigue life of the composite materials is much less than that of the matrix alloys, this is due to the low ductility of this composite material. Furthermore, a slight temperature influence up to 150 °C has been established on the fatigue behavior of the AE42-C. The fatigue life curves Δεtotal (NF) were described using the Basquin and Manson–Coffin approaches. Fracture surface investigations showed a mixed mode of serration fatigue pattern on the matrix and carbon fibers fracturing and debonding from the matrix alloy. [ABSTRACT FROM AUTHOR]

A numerical turbine-blade fatigue-life analysis method is suggested. This method comprises a stationary thermal 3D finite element (FE) analysis of the hot run for the combined high-cycle fatigue (HCF) and creep analysis, and a follow-on (one-way coupled) quasi-stationary structural 3D FE analysis (including six load steps) of a single and two half turbine blades and the related disk and rotor section and a (modified Goodman equation based) post-processing fatigue life analysis for the highest HCF-loaded point of the turbine blade. For the low-cycle fatigue (LCF) analysis, this includes a transient thermal 3D FE analysis of two full loading cycles, a follow-on (one-way coupled) quasi-stationary structural 3D finite element analysis of a single and two half turbine blades and the related disk and rotor section and a (modified-Langer-equation-based) post-processing fatigue life analysis approach for the highest LCF-loaded point of the turbine blade. Finally, this approach is demonstrated by the numerical HCF, LCF and creep analysis of a generic turbine blade of the first rotor row of a full admission hydrogen turbo pump of a 1 MN thrust class gas generator LOX-LH2 liquid rocket engine (LRE). For this numerical example, the LCF loading turned out to be dominant. Creep turned out to be negligible. [ABSTRACT FROM AUTHOR]

In the automotive environment, the need to increase the performance of materials requires extra engineering efforts. The possibility of developing new materials is strategically important. Indeed, alternative solutions in terms of material choice allow designers to optimise their projects and keep competitive production costs. Traditional quenched and tempered steels are usually used for highly stressed components, and possible alternatives could be important competitive opportunities. One possible substitute is using bainitic steels to exploit their economic advantages while maintaining acceptable mechanical performances. This paper explores the fatigue life behaviour of a new low-carbon bainitic steel for applications requiring case hardening treatment obtained by the nitriding process. A high-cycle fatigue (HCF) strength assessment is conducted through a test campaign to compare treated and untreated material. The improvement in fatigue strength is evaluated as well as the study of fracture surfaces, residual stress, and microhardness profiles to assess in detail the effectiveness of the nitriding process. It is found that the nitriding leads to an improvement in fatigue life but not as much as expected because of the low ductile behaviour of this steel, the high speed of stress application added, and the embrittlement of the nitriding treatment, as confirmed through fracture surface analysis. [ABSTRACT FROM AUTHOR]

This study examines how build orientation and heat treatment affect microstructure and, consequently, the mechanical properties in tensile and high cycle fatigue of additively manufactured AlSi10Mg. Specimens were manufactured in two orientations (0° and 45°) using a laser-based powder bed fusion and subsequently subjected to two heat treatments: (i) direct aging at 170 °C for 2 h (A170) and (ii) stress relief at 300 °C for 2 h (SR300). Two routes for direct aging were previously explored to determine the ideal time and temperature for heat treatment: direct aging at 155 °C and direct aging at 170 °C, both for up to 10 h. It was found that aging at 170 °C for 2 h resulted in higher hardness, yield strength, and ultimate tensile strength than aging at 155 °C for 6 h (A155). Based on the run-out specimens, the specimens subjected to heat treatment A170 exhibited similar stress amplitude at 106 fatigue strength than SR300, with 43.8 MPa and 45.6 MPa, respectively. At similar stress amplitudes, below 106 cycles, the build orientation (0° and 45°) slightly affect the high cycle fatigue properties. [Display omitted] • HT's led to a minor enlargement of grain size without altering their morphology. • The results suggest that the fatigue strength at 106 cycles of AlSi10Mg approaches 45 MPa. • Fast HT to increase the mechanical strength of AlSi10Mg alloy processed by PBF. [ABSTRACT FROM AUTHOR]

Fatigue failure driven by stress gradients associated to casting defects was studied in two cast nickel-based superalloys. The experimental campaign revealed complex damage phenomena linked to spongeous shrinkages, characterized by their intricate arrangement of defects in the material medium, forming defect clusters. Multiple cracks were observed to initiate from defect volumes, coalescing with neighbouring void surfaces along crystallographic planes. Defects were characterized using X-ray computed tomography, and image-based finite element (FE) models were constructed as digital representations of each experimental sample explicitly containing all real casting defects. Numerical simulations of these FE models under the same conditions as the experiments revealed that tortuous defects contain small ligaments where very high local stresses develop. These ligaments initiate early cracks, but due to the limited stressed volumes, these cracks do not drive the life of the material. A thorough comparison of simulations with experiments led to the development of an original method to define stressed volumes and address small ligaments. Finally, a novel energy-based non-local model was proposed, using two parameters to predict the fatigue lives of samples containing casting defects at the mesoscopic scale. The model was validated against samples with varying porosity levels, sizes, and geometries, accurately predicting fatigue lives within a factor of 3 compared to experimental results. This new approach generalizes the application of non-local methods to real casting defects by considering their shape and stressed volumes to estimate fatigue properties. • Tortuous defects create small ligaments that act as false hotspots in simulations. • Novel energy-based fatigue model using non-local methods is proposed. • Model accounts for stressed volume and eliminates small ligaments of casting defects. • The model fits accurately for samples of varying porosity levels, shape and volume. [ABSTRACT FROM AUTHOR]

[Display omitted] • The S-N curves showed poorer fatigue properties in GA2/GA3 compared to GA1. • Crack initiation mechanism changes between GA1 and GA2/GA3 relative to stress. • Intergranular crack initiation is observed only in GA3. • Change in slip character as a function of stress/alloy variant influences fatigue life. • The fracture mechanism map underlines the different fatigue crack initiation mechanisms. The paper investigates the influence of different impurity/scrap elements on the high cycle fatigue (HCF) properties of 6082 Al-alloy. Accordingly, HCF tests are carried out on the different variants- GA1, GA2 and GA3 (designed as a function of varying impurity content)- of this alloy, which resulted in a lower fatigue limit in GA2/GA3 compared to GA1. To explain such behavior, detailed fractographic and microstructural investigations are conducted which bring out that although the crack initiation and propagation modes are mostly transgranular irrespective of alloy variant and stress levels, intergranular crack initiation is promoted in GA2/GA3 at 150 MPa in contrast to occurrence of run-out in GA1 at the same stress level. This phenomenon is found to be facilitated by intermetallic particles anchoring the grain boundaries. These observations point out the possibility of strong sensitivity of stress and alloy variant (varying impurity content) to fatigue life. The difference in fatigue properties as a function of alloy variant could be attributed to the variation in initial microstructure/particle size distribution as well as the slip character. In light of these, a fracture mechanism map is generated which underlines the different mechanisms responsible for fatigue crack initiation among different alloy variants. [ABSTRACT FROM AUTHOR]

Mammalian KMT2C , KMT2D , and HCFC1 are expressed during heart development and have been associated with congenital heart disease, but their roles in heart development remain elusive. We found that the Drosophila Lpt and trr genes encode the N-terminal and C-terminal homologs, respectively, of mammalian KMT2C or KMT2D. Lpt and trr mutant embryos showed reduced cardiac progenitor cells. Silencing of Lpt , trr , or both simultaneously in the heart led to similar abnormal cardiac morphology, tissue fibrosis, and cardiac functional defects. Like KMT2D , Lpt and trr were found to modulate histone H3K4 mono- and dimethylation, but not trimethylation. Investigation of downstream genes regulated by mouse KMT2D in the heart showed that their fly homologs are similarly regulated by Lpt or trr in the fly heart, suggesting that Lpt and trr regulate an evolutionarily conserved transcriptional network for heart development. Moreover, we showed that cardiac silencing of Hcf , the fly homolog of mammalian HCFC1 , leads to heart defects similar to those observed in Lpt and trr silencing, as well as reduced H3K4 monomethylation. Our findings suggest that Lpt and trr function together to execute the conserved function of mammalian KMT2C and KMT2D in histone H3 lysine K4 mono- and dimethylation required for heart development. Possibly aided by Hcf , which we show plays a related role in H3K4 methylation during fly heart development. [Display omitted] • Lpt and trr are required for Drosophila heart development. • Fly Lpt and trr encode the N- and C-terminal homologs proteins of mammalian KMT2D. • KMT2D and Lpt ​+ ​Trr regulate similar downstream genes during heart development. • Lpt and trr modulate H3K4 mono- and di- (not tri-) methylation in the fly heart. • Hcf deficiency led to Lpt/trr -like cardiac defects and reduced H3K4 monomethylation. [ABSTRACT FROM AUTHOR]

Lightweight magnesium alloys and magnesium matrix composites have recently become more widespread for high-efficiency applications, including automobile, aerospace, defense, and electronic industries. Cast magnesium and magnesium matrix composites are applied in many highly moving and rotating parts, these parts can suffer from fatigue loading and are consequently subjected to fatigue failure. Reversed tensile-compression low-cycle fatigue (LCF) and high-cycle fatigue (HCF) of short fibers reinforced and unreinforced AE42 have been studied at temperatures of 20 °C, 150 °C, and 250 °C. To select suitable fatigue testing conditions, tensile tests have been carried out on AE42 and the composite material AE42-C at temperatures of up to 300 °C. The Wohler curves σa (NF) have shown that the fatigue strength of the reinforced AE42-C in the HCF range was double that of unreinforced AE42. In the LCF range at certain strain amplitudes, the fatigue life of the composite materials is much less than that of the matrix alloys, this is due to the low ductility of this composite material. Furthermore, a slight temperature influence up to 150 °C has been established on the fatigue behavior of the AE42-C. The fatigue life curves Δεtotal (NF) were described using the Basquin and Manson–Coffin approaches. Fracture surface investigations showed a mixed mode of serration fatigue pattern on the matrix and carbon fibers fracturing and debonding from the matrix alloy.

This paper aimed to study the soil–water characteristics and stability evolution law of rainfall-induced landslide. Taking the two landslide events in Siwan village as an example, the formation conditions of the disaster and landslide characteristics were analyzed. Additionally, the deformation characteristics and destruction mechanisms of landslides were discussed in-depth. The soil–water characteristics and hydraulic conductivity of the landslides were analyzed based on TRIM experiment results. Geo-Studio numerical software was further used for typical sections to analyze the stability of the evolution of the landslide events under rainfall conditions. The results showed that (1) The soil–water characteristic curve (SWCC) inversely varies with water content volume, and the sliding body has lower saturated water content and matrix suction than the sliding zone. The hydraulic conductivity function (HCF) increases with water content volume, and the sliding body has higher hydraulic conductivity (0.43 m/d) than the sliding zone (0.03 m/d). (2) Rainfall is the primary cause of landslides, and there is a hysteretic effect. Heavy rainfall will inevitably accelerate the formation of landslides in the analysis of the deformation characteristics and destruction mechanisms of rainfall-induced landslides. (3) Compared with the engineering analogy of the Fredlund and Xing (FX) model, the Van Genuchten–Mualem (VGM) model of the soil–water characteristics test based on the TRIM experimental system can better reflect the actual field situation. The numerical simulation method based on the TRIM experiments of the soil–water characteristics test is scientifically sound and reliable for the stability evolution of overburden rainfall-induced landslides.

A numerical turbine-blade fatigue-life analysis method is suggested. This method comprises a stationary thermal 3D finite element (FE) analysis of the hot run for the combined high-cycle fatigue (HCF) and creep analysis, and a follow-on (one-way coupled) quasi-stationary structural 3D FE analysis (including six load steps) of a single and two half turbine blades and the related disk and rotor section and a (modified Goodman equation based) post-processing fatigue life analysis for the highest HCF-loaded point of the turbine blade. For the low-cycle fatigue (LCF) analysis, this includes a transient thermal 3D FE analysis of two full loading cycles, a follow-on (one-way coupled) quasi-stationary structural 3D finite element analysis of a single and two half turbine blades and the related disk and rotor section and a (modified-Langer-equation-based) post-processing fatigue life analysis approach for the highest LCF-loaded point of the turbine blade. Finally, this approach is demonstrated by the numerical HCF, LCF and creep analysis of a generic turbine blade of the first rotor row of a full admission hydrogen turbo pump of a 1 MN thrust class gas generator LOX-LH2 liquid rocket engine (LRE). For this numerical example, the LCF loading turned out to be dominant. Creep turned out to be negligible.

In the automotive environment, the need to increase the performance of materials requires extra engineering efforts. The possibility of developing new materials is strategically important. Indeed, alternative solutions in terms of material choice allow designers to optimise their projects and keep competitive production costs. Traditional quenched and tempered steels are usually used for highly stressed components, and possible alternatives could be important competitive opportunities. One possible substitute is using bainitic steels to exploit their economic advantages while maintaining acceptable mechanical performances. This paper explores the fatigue life behaviour of a new low-carbon bainitic steel for applications requiring case hardening treatment obtained by the nitriding process. A high-cycle fatigue (HCF) strength assessment is conducted through a test campaign to compare treated and untreated material. The improvement in fatigue strength is evaluated as well as the study of fracture surfaces, residual stress, and microhardness profiles to assess in detail the effectiveness of the nitriding process. It is found that the nitriding leads to an improvement in fatigue life but not as much as expected because of the low ductile behaviour of this steel, the high speed of stress application added, and the embrittlement of the nitriding treatment, as confirmed through fracture surface analysis.

Terahertz (THz) radiation has recently gained much attention in diverse fields ranging from short-range wireless communication to biomedical applications. In general, THz radiation is much difficult to transmit through conventional waveguides due to experiencing higher transmission losses. Many waveguide-based technologies have been proposed in recent decades; among these, hollow-core fiber (HCF) is one of the best options due to the lower material absorption and dispersion. Recently, metamaterial-based HCF shows great promise to transmit THz radiation due to its unique and tunable optical properties. This work focuses on the effect of different metal wires (e.g. indium, silver, and gold) on the confinement loss (CL) of metamaterial-based HCFs. Numerical simulations are carried out from 0.24 to 1.5 THz with a 1 mm diameter core and metamaterial cladding made of subwavelength size metal wires embedded in Zeonex. The impact of the diameter, position, and number of metal wires have been thoroughly investigated. It is observed that the effect of increasing the wire diameter and the number of wires around the core have similar effects as the fraction of metal increases in the cladding layer for both the cases. However, there is an optimal position of wires embedded in a dielectric, where the loss is found to be the lowest. Thus, the metamaterial-based HCF design needs to be optimized to achieve the lowest loss at a specific spectral range. This analysis could help to select metal wires with associated parameters for designing low-loss metamaterial-based HCF in the THz region.

• Stress gradients and inhomogeneous porosity distribution control the fatigue behavior, • Murakami parameter is pertinent for estimating the criticality of porosity networks, • It is likely that the atmosphere within the casting porosity affects the fatigue behavior, • Good correlation is seen between El Haddad's parameter and microstructurally based parameters. In order to expand the number of possible applications of High Pressure Die Cast (HPDC) components using the AlSi9Cu3 alloy, the automotive industry is giving greater attention to the fatigue design of components produce by this process-material combination. The process is well known for introducing a heterogeneous distribution of casting defects. This study explores the impact of the heterogeneous porosity distribution and stress gradients on the high cycle fatigue behavior of HPDC AlSi9Cu3 components. Fatigue tests under fully-reversed tension–compression and fully-reversed bending loads are used to investigate the influence of porosity and stress gradients on the fatigue behavior, by machining different specimen thicknesses. The results demonstrate that stress gradients and the heterogeneous porosity distribution determine the material's fatigue response, including both the fatigue strength and crack initiation mechanisms. The Murakami parameter and local stress level at the critical defect make it possible to interpret the gradient effects. The nature of the entrapped gas in internal defects may influence the in-bulk crack propagation behavior. The comparison of fracture mechanics models (El Haddad, Murakami, Kitagawa-Takahashi) make it possible to highlight the link between the El Haddad's parameter to parameters that are more microstructurally based. [ABSTRACT FROM AUTHOR]

Prediction of cyclic life under low cycle fatigue - high cycle fatigue (LCF-HCF) interaction is of paramount importance in the context of structural integrity of components in the primary side of fast reactors where such damage under LCF-HCF interaction occurs. The present investigation deals with the crack growth behavior of a type 316LN austenitic stainless steel subjected to simultaneous application of LCF and HCF cycles (block-loading). Tests were performed over a wide range of temperatures from ambient to 923 K. Experimental results indicate that a critical crack-length (acr) exists, beyond which the LCF-HCF interaction becomes significant. An attempt was made to predict life under block cycling by estimating the acr using fatigue crack threshold (?Kth) since the latter is known to be affected significantly by the loading history. A universal equation, based on the concept of an equivalent critical crack length (acr.,eq) which incorporates the damage contribution from DSA and ratcheting under combined LCF-HCF loading, was proposed for life estimation.

Two cracks, initiated from the opposite tips of a central notch inclined by 45䒰, were considered in cruciform specimens made of Ti6246. A static load was applied to a cruciform arm while a cyclic load was applied along the other arm. Fatigue propagation of cracked specimens was performed by means of Dual Boundary Element Method (DBEM) and Finite Element Method (FEM) codes. For crack path assessment, the Minimum Strain Energy Density (MSED) and the Maximum Tensile Stress (MTS) criteria were adopted in DBEM and FEM approaches, respectively. Moreover, the J and M integrals� formulations were used to evaluate the SIFs along the crack fronts for DBEM and FEM codes, respectively. Crack-growth rates were predicted by using a Walker law, calibrated on mode I fracture experimental data. A good agreement between numerical and experimental crack paths was obtained.

The microstructural origins of premature fatigue failures were investigated on a variety of forged components manufactured from AZ80 and ZK60 magnesium, both at the test specimen level and the full-scale component level. Both stress and strain-controlled approaches were used to characterize the macroscopically defect-free forged material behaviour as well as with varying levels of defect intensities. The effect of thermomechanical processing defects due to forging of a industrially relevant full-scale component were characterized and quantified using a variety of techniques. The fracture initiation and early crack growth behaviour was deterministically traced back to a combination of various effects having both geometric and microstructural origins, including poor fusion during forging, entrainment of contaminants sub-surface, as well as other inhomogeneities in the thermomechanical processing history. At the test specimen level, the fracture behaviour under both stress and strain controlled uniaxial loading was characterized for forged AZ80 Mg and a structure-property relationship was developed. The fracture surface morphology was quantitatively assessed revealing key features which characterize the presence and severity of intrinsic forging defects. A significant degradation in fatigue performance was observed as a result of forging defects accelerating fracture initiation and early crack growth, up to 6 times reduction in life (relative to the defect free material) under constant amplitude fully reversed fatigue loading. At the full-scale component level, the fatigue and fracture behaviour under combined structural loading was also characterized for a number of ZK60 forged components with varying levels of intrinsic thermomechanical processing defects. A novel in-situ non-contact approach (utilizing Digital-Image Correlation) was used as a screening test to establish the presence of these intrinsic defects and reliably predict their effect on the final fracture behaviour in an accelerated manner compared to conventional methods.

The microstructural origins of premature fatigue failures were investigated on a variety of forged components manufactured from AZ80 and ZK60 magnesium, both at the test specimen level and the full-scale component level. Both stress and strain-controlled approaches were used to characterize the macroscopically defect-free forged material behaviour as well as with varying levels of defect intensities. The effect of thermomechanical processing defects due to forging of an industrially relevant full-scale component were characterized and quantified using a variety of techniques. The fracture initiation and early crack growth behaviour was deterministically traced back to a combination of various effects having both geometric and microstructural origins, including poor fusion during forging, entrainment of contaminants sub-surface, as well as other inhomogeneities in the thermomechanical processing history. At the test specimen level, the fracture behaviour under both stress and strain-controlled uniaxial loading was characterized for forged AZ80 Mg and a structure-property relationship was developed. The fracture surface morphology was quantitatively assessed revealing key features which characterize the presence and severity of intrinsic forging defects. A significant degradation in fatigue performance was observed as a result of forging defects accelerating fracture initiation and early crack growth, up to 6 times reduction in life (relative to the defect free material) under constant amplitude fully reversed fatigue loading. At the full-scale component level, the fatigue and fracture behaviour under combined structural loading was also characterized for a number of ZK60 forged components with varying levels of intrinsic thermomechanical processing defects. A novel in-situ non-contact approach (utilizing Digital-Image Correlation) was used as a screening test to establish the presence of these intrinsic defects and reliably predict their effect on the final fracture behaviour in an accelerated manner compared to conventional methods. [ABSTRACT FROM AUTHOR]

The present study aims at understanding the mechanisms of fatigue endurance through high-cycle fatigue (HCF) behavior of Alloy 617M at varying temperatures, ranging from 300 to 1023 K. Dynamic strain aging (DSA) was a key feature observed in this alloy at high temperatures (853-973 K), which also affects the cyclic life as well as the endurance limit. Furthermore, in situ precipitation of Cr23C6 and γ′ phase (Ni3(Al,Ti)) at 973 K during the course of HCF cycling is found to impart a beneficial effect on the HCF life of the alloy. At T > 973 K, effect of creep damage was found to be prominent, resulting in a deteriorating effect on HCF life. The role of DSA, precipitation and creep on the fatigue damage is assessed through in-depth microstructural characterization of the tested specimens, which is further utilized to develop a damage map across the temperatures 300-1023 K. [ABSTRACT FROM AUTHOR]

Water, sanitation and hygiene (WASH) is important to improve and maintain the quality of health care services. Improving and managing WASH services require strong and consistent monitoring mechanisms to measure progress and direct efforts where needs are greatest. Although several tools are available to assess WASH in health care facilities (HCFs), there is always a dilemma among the program managers to select an appropriate tool for the assessment of WASH. Thus, it was aimed to perform a descriptive review of all available WASH assessment tools and assist in reaching a consensus for an optimal tool to assess WASH in HCFs. For this descriptive review, PubMed, ScopeMed and Google Scholar were used to search all available tools for the assessment of WASH. All the tools available online since 1991 till July 2018 were included in the review. Globally, nine different WASH assessment tools were retrieved. The majority of them have their self-limitations on the basis of 11 selected indicators and were examined in all the retrieved tools. There are variability and overlapping components within the specific tools. Very few survey instruments including human resource (HR), supply, budget, patient/staff satisfaction and documentation for appropriateness of WASH were found to be neglected. The majority of instruments were based on the subjective assessment of WASH validating with microbiological surveillance and photo documentation. The descriptive review suggests that various tools are available for the assessment of WASH but none of them seem to be complete with all indicators and to have consensus for the elements. Therefore, there is a need to develop a robust and comprehensive tool for the assessment of WASH in HCFs. [ABSTRACT FROM AUTHOR]

A closed die forging process was developed to successfully forge an automotive suspension component from AZ80 Mg at a variety of different forging temperatures (300 °C, 450 °C). The properties of the forged component were compared and contrasted with other research works on forged AZ80 Mg at both an intermediate forging and full-scale component forging level. The monotonic response, as well as the stress and strain-controlled fatigue behaviours, were characterized for the forged materials. Stress, strain and energy-based fatigue data were used as a basis for comparison of the durability performance. The effects of the starting material, forging temperature, forging geometry/configuration were all studied and aided in developing a deeper understanding of the process-structure-properties relationship. In general, there is a larger improvement in the material properties due to forging with cast base material as the microstructural modification which enhances both the strength and ductility is more pronounced. In general, the optimum fatigue properties were achieved by using extruded base-material and forging using a closed-die process at higher strain rates and lower temperatures. The merits and drawbacks of various fatigue damage parameters (FDP’s) were investigated for predicting the fatigue behaviour of die-forged AZ80 Mg components, of those investigated, strain energy density (SED) proved to be the most robust method of comparison.

Prediction of cyclic life under low cycle fatigue - high cycle fatigue (LCF-HCF) interaction is of paramount importance in the context of structural integrity of components in the primary side of fast reactors where such damage under LCF-HCF interaction occurs. The present investigation deals with the crack growth behavior of a type 316LN austenitic stainless steel subjected to simultaneous application of LCF and HCF cycles (block-loading). Tests were performed over a wide range of temperatures from ambient to 923 K. Experimental results indicate that a critical crack-length (acr) exists, beyond which the LCF-HCF interaction becomes significant. An attempt was made to predict life under block cycling by estimating the acr using fatigue crack threshold (ΔKth) since the latter is known to be affected significantly by the loading history. A universal equation, based on the concept of an equivalent critical crack length (acr.,eq) which incorporates the damage contribution from DSA and ratcheting under combined LCF-HCF loading, was proposed for life estimation.

The reversible posttranslational O-GlcNAc modification of serine or threonine residues of intracellular proteins is involved in many cellular events from signaling cascades to epigenetic and transcriptional regulation. O-GlcNAcylation is a conserved nutrient-dependent process involving two enzymes, with O-GlcNAc transferase (OGT) adding O-GlcNAc and with O-GlcNAcase (OGA) removing it in a manner that’s protein- and context-dependent. O-GlcNAcylation is essential for epigenetic regulation of gene expression through its action on Polycomb and Trithorax and COMPASS complexes. However, the important role of O-GlcNAc in adult life and health span has been largely unexplored, mainly due the lack of available model systems. Cataloging the O-GlcNAc proteome has proven useful in understanding the biology of this modification in vivo. In this study, we leveraged a recently developed oga knockout fly mutant to identify the O-GlcNAcylated proteins in adult Drosophilamelanogaster. The adult O-GlcNAc proteome revealed many proteins related to cell and organismal growth, development, differentiation, and epigenetics. We identified many O-GlcNAcylated proteins that play a role in increased growth and decreased longevity, including HCF, SIN3A, LOLA, KISMET, ATX2, SHOT, and FOXO. Interestingly, oga mutant flies are larger and have a shorter life span compared to wild type flies, suggesting increased O-GlcNAc results in increased growth. Our results suggest that O-GlcNAc alters the function of many proteins related to transcription, epigenetic modification and signaling pathways that regulate growth rate and longevity. Therefore, our findings highlight the importance of O-GlcNAc in growth and life span in adult Drosophila.

Prediction of cyclic life under low cycle fatigue - high cycle fatigue (LCF-HCF) interaction is of paramount importance in the context of structural integrity of components in the primary side of fast reactors where such damage under LCF-HCF interaction occurs. The present investigation deals with the crack growth behavior of a type 316LN austenitic stainless steel subjected to simultaneous application of LCF and HCF cycles (blockloading). Tests were performed over a wide range of temperatures from ambient to 923 K. Experimental results indicate that a critical crack-length (acr) exists, beyond which the LCF-HCF interaction becomes significant. An attempt was made to predict life under block cycling by estimating the acr using fatigue crack threshold (ΔKth) since the latter is known to be affected significantly by the loading history. A universal equation, based on the concept of an equivalent critical crack length (acr.,eq) which incorporates the damage contribution from DSA and ratcheting under combined LCF-HCF loading, was proposed for life estimation.. [ABSTRACT FROM AUTHOR]

• Microstructural crack growth on single bcc slip system in small martensite blocks. • Alternating crack growth on two bcc slip systems in coarse martensite blocks. • High-angle block boundaries show a strong barrier effect on plastic deformation. • Prior austenite grain boundaries show a low barrier effect on plastic deformation. • Brittle crack propagation on block boundaries was observed below ΔKth. With increasing requirements for high service life and mechanical strength of components undergoing cyclic deformation, identification of quantitative relationships between material properties and its microstructure is of substantial significance. To understand the interaction mechanisms between microstructure, the fatigue crack initiation and the early stage fatigue crack growth fundamental fatigue experiments at 95 Hz and a stress ratio of R = −1, applied to a 0.5C-1.25Cr-Mo tempered martensitic steel were carried out. The present study is focused on both the observation of the crack initiation and, as main objective, the subsequent short crack growth by in-situ observations of a well-selected surface area. With the help of the in-situ crack observations, the correlation with the local microstructure and FIB cross-sections, it was shown that early crack propagation is driven by different damage mechanisms, which take place within martensite blocks as well as on block boundaries. A transgranular crack growth mechanism on the hierarchical martensite block level was correlated to single slip system activities within small blocks or alternating slip system activities within coarse blocks. Interestingly, also intergranular crack propagation on martensite block boundaries was observed within single martensite packets with nearly perpendicular spatial orientation of the crack path to the loading direction. This indicates not only the crack propagation by shear mechanisms, but also brittle crack propagation below the stress intensity threshold value and a high interaction with the underlying microstructure. [ABSTRACT FROM AUTHOR]

Highlights • Crack growth in cruciform specimens depends on the static to cyclic loading ratio. • Ratios belong 0.5 trigger crack growth orthogonal to the cyclic load. • Ratios above 0.75 makes cracks grow orthogonal to the static load. • Both FEM and DBEM predict crack growth well for both low and for high ratios. • State-of-the-art approaches do not predict crack growth for ratios in-between well. Abstract Two cracks, initiated from the opposite tips of a 45° inclined central notch, were considered in cruciform specimens made of Ti6246. A static load was applied along one arm of the specimen and a cyclic load (R = −1) was applied along the other arm. Crack propagation was carefully monitored by optical means for different ratios of static to cyclic load. The observed crack propagation was simulated using two numerical tools, involving two different mixed-mode crack propagation prediction methods. The experimental evidence shows that there is a switch in crack propagation direction from orthogonal to the cyclic load at low static load levels to orthogonal to the static load for high static load levels. Both numerical procedures were able to predict this switch, albeit at slightly different static to cyclic load ratios. [ABSTRACT FROM AUTHOR]

Combined influence of mean stress and alternating stress on the high cycle fatigue (HCF) behaviour of Alloy 617 M at 973 K is discussed in the present study. Constant life Haigh diagrams have been generated using different combinations of alternating stress (σ a) and mean stress (σ m). The alloy exhibited dynamic strain aging (DSA) which is found to strongly influence the cyclic life as well as the fatigue limit. Apart from DSA, presence of annealing twins and carbide precipitation at high temperature during fatigue deformation is also found to positively influence the fatigue life of the alloy. • Constant life Haigh diagram is generated at 973 K. • The alloy exhibited strong dynamic strain aging (DSA). • DSA led to allowable stresses higher than YS. • DSA delayed the transition in Stage-I to Stage-II crack propagation. • Precipitation of Cr 23 C 6 also contributes to the extensive strengthening of the alloy. [ABSTRACT FROM AUTHOR]