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Presents a study which presented analytical and probabilistic models for predicting pitting corrosion and corrosion-fatigue life in aluminum alloy used in aircraft structures. Development of an analytical model; Information on several models developed for the prediction of corrosion-fatigue life; Results and conclusions.

Investigates the development of experimental and analytical techniques to understand high-cycle fatigue behavior of steel wires. Use of ultrasonic fatigue test; Fatigue strength of the steel wires; Crack initiation and propagation behavior.

Investigates the long fatigue life of ferrous alloys. Occurrence of fatigue failure; Relationship between temperature and stress amplitudes; Observations of fracture surfaces.

This paper reports the study of hydrogen and carbon monoxide produced by radiation degradation of N, N-dimethylhydroxylamine (DMHA). The results show that when the concentration of DMHA is between 0.1M–0.5M and the dose is between 10–1000 kGy, the volume fraction of hydrogen is very high and increases with the dose. The volume fraction of hydrogen is little dependent on the concentration of DMHA at lower dose but increases with increasing concentration of DMHA at higher dose. The volume fraction of carbon monoxide is very low. [ABSTRACT FROM AUTHOR]

Discusses the fatigue characterization of a spheroidal graphite cast iron under ultrasonic loading. Uses of spheroidal graphite cast iron; Brief discussion of fatigue crack initiation; Fatigue testing in a piezoelectric resonance system; Investigation of fracture surfaces of tested specimens by scanning electron microscopy.

Highlights: [•] Kilometre level, Nb reinforced MgB2 wires was fabricated by in situ PIT method. [•] Higher stress–strain properties were acquired in this Nb reinforced MgB2 wires. [•] Good homogeneity of I c distribution was acquired in this MgB2 wires. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this paper is to investigate compositions on the interface between LiCoO2 and electrolyte when trimethyl phosphite TMP(i) is used as an additive in 1M LiPF6/EC+DEC electrolyte system and the thermal stability of the electrolyte as well as Li0.5CoO2 mixed with the electrolyte. The electrochemical performance of LiCoO2 electrode in the two electrolyte systems was also studied. It is found that the electrochemical performance, including capacity, cycle performance and 3.6V plateau efficiency, has been improved in the electrolyte with TMP(i) additive. FTIR analysis indicates that Li x PO y is an important surface film composition on the cathode in TMP(i) containing system. A thicker and more passivating surface layer is formed when using TMP(i) additive as an additive. The thermal stability of the cathode is substantially improved in the electrolyte containing TMP(i) additive in the system, especially the exothermic peak around 190°C, which is associated with the reaction between active surface of cathode and solvents, is obviously restrained. [Copyright &y& Elsevier]

Abstract This paper presents a study focusing on the perforation resistance of glass fibre-reinforced PEKK composites. Woven S-glass fibre (GF) reinforced poly-ether-ketone-ketone (PEKK) thermoplastic prepreg materials were manufactured using a dry powder prepregging method. Prior to impact testing and modelling, the properties of the composites were evaluated by conducting a series of quasi-static tests at room and elevated temperatures. Quasi-static tensile and perforation tests showed that the optimum weight fraction of PEKK, w f , is approximately 0.4, which gives the peak tensile strength and perforation resistance. Tests at elevated temperatures highlighted the excellent stability of these materials under extreme conditions. As expected, the energy required to perforate the targets increased with projectile diameter. Subsequent tests highlighted the severity of conically-shaped projectiles with the perforation resistance dropping under sharp object impact loading. A series of finite element models were also developed to predict the response of the glass fibre/PEKK composites to impact by projectiles based on different diameters and shapes. The predictions were validated against the experimental force-displacement traces and failure modes with good agreement. Highlights • Manufacture S-glass fibre/PEKK prepreg materials using a dry powder prepregging method. • The optimum weight fraction of PEKK is approximately 0.4 to offer high mechanical behaviour. • There is no tensile strength reduction at 100 °C and only 10% reduction at 200 °C. • Perforation resistance was studies with projectiles in various sizes and shapes. • The finite element modelling outputs show good correlation with the related test results. [ABSTRACT FROM AUTHOR]

The behaviour of concrete filled steel tube (CFST) columns has been investigated intensively against lateral and axial impact loading. However, there is a lack of knowledge on the impact response of the connection between such the column and steel beam. In order to close this gap, the most common connections with a partial depth end plate (PDEPCs), as a simple connection, and a flush plate (FPCs), as a moment resisting connection, were investigated under lateral impact loads. The long bolts were used to connect the CFST column to the beam as an alternative technique to the ordinary bolts. Here, eight specimens were tested under loading conditions with different locations and plate thicknesses. 3D finite element models were then developed and validated against the corresponding experimental results. Full range analyses of the connection response under the loading regime were then carried out using the validated FE models to examine the internal forces and the energy dissipation of the connections. The main findings are as follows: (1) the failure modes of both connection types investigated were similar at both loading locations only with slightly higher tearing fracture on the PDEPC; (2) using a thicker end plate increases the moment capacity of the connection but decreases its energy absorption; (3) the performance of long bolts provides the connection with appropriate ductility up to failure. [ABSTRACT FROM AUTHOR]

Microstructure, mechanical properties and microhardness of electron beam welded Nimonic 80A sheets and base metal were studied using various tools, i.e. scanning electron microscopy, field emission scanning electron microscope with energy dispersive spectroscopy and electron backscatter diffraction, X-ray diffraction analysis and Vickers microhardness. Very high cycle fatigue behavior of base metal and welded joint under push – pull condition at room temperature was also investigated using ultrasonic fatigue tests. Examination of microstructure shows that weld zone was mainly composed of columnar dendritic, and solidification modes can be changed according to the cooling rate. Moreover, there is little precipitates and MC carbides observed in the weld zone. X-ray diffraction results show that the phase structure of weld zone has not changed after electron beam welding. Additionally, electron backscatter diffraction results show that the weld zone and base metal has a clear difference in grain boundaries characterization and kernel average misorientation. Therefore, microhardness, tensile and very high cycle fatigue behavior of welded joint is lower than base metal. [ABSTRACT FROM AUTHOR]

• Residual mechanical behaviour of RAC and basalt fibre reinforced RAC subjected to high temperature was studied. • Incorporation of inner steel tube and BF improved compressive behaviour of RAC columns. • Temperature of exposure significantly influence residual fatigue behaviour of BSRC and CFRP confined specimens. • Inner steel tube and basalt fibre reinforcements effectively enhance the residual HTE and post-fatigue strength of RAC. Experimental and numerical investigations were carried out to evaluate the effects of incorporating recycled coarse aggregates (RCA) on the mechanical behaviour of inner steel-tube reinforced concrete columns exposed to high temperature. The specimens were reinforced with basalt fibres (BF) and strengthened by carbon fibre reinforced polymer (CFRP) sheets, which were subjected to mechanical loading in monotonous and cyclic arrangements. Test results show that at room temperature (RT), incorporation of the chopped BF has reduced both the tensile strength and flexural strength of concrete specimens prepared with recycled aggregate concrete (RAC) but not their static elastic modulus. On the other hand, the BF has improved crack resistance of the steel tube reinforced RAC (STRC) column specimens. Also, the reduction in mass and dynamic elastic modulus of BF reinforced STRC specimens are lower than those of STRC at a given RCA replacement ratio and exposure temperature. Furthermore, improvements in mechanical performance under monotonous and fatigue loading was observed for STRC columns reinforced with BF and externally bonded CFRP sheets with high-temperature exposure (HTE). Therefore, it is possible that BF reinforced STRC columns could be used to reduce risk of brittle structural collapse when exposed to fire or elevated temperature. [ABSTRACT FROM AUTHOR]

Here we fabricate a heterostructure in CrCoNi medium entropy alloy consisting of deformed substructures (the hard zone) and recrystallized ultrafine/fine grains (the soft zone). Mechanical tests reveal that the heterogeneous structure displays an exceptional combination of strength and ductility, especially at cryogenic condition, with a yield strength up to 1480 MPa and a uniform elongation of 28%. Such mechanical performance is primarily attributed to the zone boundary-dictated inhomogeneous deformation. Strain incompatibility-induced inter-zone interaction produces high internal stress near zone boundary, which leads to quick piling-up of geometrically necessary dislocations and consequently extra back stress strengthening. Cryogenic deformation further improves the internal stress, which helps to activate additional mechanical twinning and promotes the multiplication and interaction of defects, thereby contributing to high strain hardening at the large plastic stage. These findings suggest that heterostructured CrCoNi medium entropy alloy is a promising candidate for structural application over a wide temperature range. • Design heterogeneous microstructure on H/MEA is aimed to understand the coupling of multiple factors including microstructure heterogeneity, intrinsic material properties and cryogenic deformation temperatures. • The heterogeneous CrCoNi MEA presents deformed substructures (the hard zone) and recrystallized ultrafine/fine grains (the soft zone). • Heterostructured CrCoNi MEA displays an exceptional combination of yield strength (1480 MPa) and tensile ductility (28%) at 77 K. • Strain incompatibility-induced inter-zone interaction produces quick accumulation of geometrically necessary dislocations and extra strengthening. • Cryogenic temperature and microstructure heterogeneity collectively promote the deformation twinning and interaction of defects that contribute to high strain hardening. [ABSTRACT FROM AUTHOR]

Reliably predicting and estimating roof collapse in underground cavities such as mine goafs and power caverns is a serious concern in mining and geotechnical engineering fields. An analytical expression for a three-dimensional (3D) failure mode of a generic-shaped cavity crown is derived according to the upper bound theorem via limit analysis, where the Hoek-Brown yield criterion represents rock mass strength. The proposed method is validated by comparison against the extant research; the comparison also suggests that the roof profile plays a crucial role in cavity stability. Specific example is given to ellipsoidal cavity and the stability graph with respect to roof profile and cavity span is obtained and discussed. The effects of numerous factors on potential collapse are investigated based on the numerical calculation results. These results may provide workable guidelines for the optimization of roof shapes and support designs in minimizing rock detachment above cavity roofs in practice. [ABSTRACT FROM AUTHOR]

Particulate air pollution is a severe environmental problem in China, affecting visibility, air quality, climate and human health. However, previous studies focus mainly on large cities such as Beijing, Shanghai, and Guangzhou. In this study, an Aerodyne Aerosol Chemical Speciation Monitor was deployed in Baoji, a middle size inland city in northwest China from 26 February to 27 March 2014. The non-refractory submicron aerosol (NR-PM 1 ) was dominated by organics (55%), followed by sulfate (16%), nitrate (15%), ammonium (11%) and chloride (3%). A source apportionment of the organic aerosol (OA) was performed with the Sofi (Source Finder) interface of ME-2 (Multilinear Engine), and six main sources/factors were identified and classified as hydrocarbon-like OA (HOA), cooking OA (COA), biomass burning OA (BBOA), coal combustion OA (CCOA), less oxidized oxygenated OA (LO-OOA) and more oxidized oxygenated OA (MO-OOA), which contributed 20%, 14%, 13%, 9%, 23% and 21% of total OA, respectively. The contribution of secondary components shows increasing trends from clean days to polluted days, indicating the importance of secondary aerosol formation processes in driving particulate air pollution. The formation of LO-OOA and MO-OOA is mainly driven by photochemical reactions, but significantly influenced by aqueous-phase chemistry during periods of low atmospheric oxidative capacity. [ABSTRACT FROM AUTHOR]

High-entropy alloys (HEAs) are considered as potential structural materials for aerospace and defense applications where impacts are recurrently encountered. The dynamic mechanical properties and the underlying deformation and damage mechanisms are significant for safety assessment and structural design optimization, but are underinvestigated. In this work, two types of plate impact experiments, i.e., shock compression and spallation, are performed on typical quaternary CoCrFeNi HEA (at%), to investigate its dynamic mechanical properties and microscopic deformation/damage mechanisms. Free-surface velocity histories are measured to evaluate the mechanical properties and damage processes, including the Hugoniot elastic limit (HEL; ∼0.8 GPa), spall strength (∼3.2 GPa) and pullback rates. The spall strength of the CoCrFeNi HEA is higher than those of most medium- and high-entropy alloys ever reported, except for the Al 0.1 CoCrFeNi HEA. The deformed samples are characterized with scanning electron microscopy, electron backscatter diffraction and transmission electron microscopy. Shock-induced dislocation slip and deformation twinning dominate plastic deformation. With increasing impact velocity, dislocation density increases significantly and twin bundles appear instead of individual twins. For incipient spallation, voids nucleate preferentially at grain boundaries, especially at grain boundary triple junctions. Damage in the CoCrFeNi HEA is ductile in nature. [Display omitted] • CoCrFeNi HEA demonstrates an excellent spall strength-ductility combination. • Nano-twin bundles, rather than individual nano-twins, apper at u f = 901 m s−1. • Voids nucleate at grain boundaries, especially at grain boundary triple junctions. • Heterogeneous-structured dimples reveal ductile damage in CoCrFeNi HEA. [ABSTRACT FROM AUTHOR]

• Freeze-thaw behaviour of basalt fibre reinforced RAC filled CFRP tube column under freeze–thaw were studied. • The influence of the freeze–thaw cycles on the residual mechanical properties of constrained BFRC columns. • The basalt fibre and CFRP tube could be used in RAC to upgrade the frost resistance of the composite structures. This paper is focused on the behaviour of basalt fibre reinforced recycled aggregate concrete (BFRC) short specimens confined by carbon fibre reinforced polymer (CFRP) tubes under freeze–thaw conditions. The main parameters investigated are the replacement rate of recycled coarse aggregate (RCA), the number of freeze–thaw cycle (FTC), the related temperature range, and the shape of short specimen section. The failure mode, dynamic elastic modulus, ultimate bearing capacity and the load–strain response of the specimens are studied. The results show that the failure mode and the load–strain response of CFRP tube confined recycled aggregate concrete (RAC) specimen have insignificant change due to FTCs. However, with the increase of the FTCs, the bearing capacity of the specimen decreases, and the specimen with square cross-section is much more sensitive than that of the circular cross-section counterpart. The smaller the range of freeze–thaw temperature changed, the smaller loss of the dynamic modulus and the smaller decrease range of the ultimate bearing capacity after FTCs. [ABSTRACT FROM AUTHOR]

Nano-grained ceramics have their unique mechanical characteristics that are not commonly found in their coarse-grained counterparts. In this study, nano-grained YAG transparent ceramics (NG-YAG) were prepared by low-temperature high-pressure technique (LTHP). The peak profile analysis of the X-ray diffraction was employed to investigate the compressive yield strength of NG-YAG. During the temperature at 450 °C, the residual micro-strain (RMS) increased with increasing loading pressure. However when the loading pressure was exceeded to 4.0 GPa the RMS exhibited a severe negative slop. The temperature effects on the compressive yield strength were also studied. It shows that the compressive yield strength of NG-YAG is 4.0 GPa and 5.0 GPa respectively at 450 °C and 350 °C. More importantly according to this investigation, a feasible technique to study the nano-grained ceramics is provided. [ABSTRACT FROM AUTHOR]

The thermal shock resistance is a major concern of the Yb:Y 3 Al 5 O 12 (Yb:YAG) transparent ceramic considered as a potential solid-state laser material. Its thermal shock behavior was investigated by the standard water-quenching and indentation-quenching thermal shock measuring methods. The residual flexural strength and Vickers radial cracks were measured as a function of thermal shock temperature difference (Δ T ). It showed that after the thermal shocking of Δ T =130 °C a reduction in residual flexural strength was observed, and there was a Δ T of 120 °C at which the longitudinal cracks (aligned parallel to the sample's length) grew radically. A good correspondence was found between the results of the thermal shock critical temperature difference (Δ T c ) obtained by the standard water-quenching method and estimated by the indentation-quenching test. The analysis of the indentation fracture mechanics was used to account for the cracking responses. The analysis confirmed that the thermal stress induced by the thermal shock is much greater in the transverse direction than in the longitudinal direction, resulting in the unstable longitudinal cracks propagated at first. [ABSTRACT FROM AUTHOR]

Carbonaceous aerosol is an important component that influences the environment, climate, and human health. Organic and elemental carbon (OC and EC) are the two main constituents of carbonaceous aerosols that have opposite, i.e., cooling versus warming, effects on the Earth's radiation balance. Knowledge on the variability of OC/EC splits measured by different thermal/optical protocols is useful for understanding the uncertainty in the climate models. This study shows good correlations within OC or EC (r 2 > 0.83, P < 0.001) across the IMPROVE, IMPROVE_A, and EUSAAR_2 protocols for both ambient aerosol samples and biomass burning samples. However, EC concentrations differ by more than two folds, and OC/EC ratios differ up to a factor of 2.7. The discrepancies were attributed to the selection between the reflectance and transmittance corrections and the different peak inert-atmosphere temperature. The IMPROVE and IMPROVE_A protocols also quantified different char and soot concentrations, two subtypes of EC with distinct chemical and optical properties. Char, but not soot, was found to correlate with the humic-like substances (HULIS) content in the samples, suggesting that both char and HULIS originate mainly from biomass burning. A one-year (2012–2013) ambient aerosol monitoring in Xi'an, China, shows that OC, EC, and char displayed winter highs and summer lows, while soot had no seasonal trend. The char/soot ratios showed a “single peak” in winter, while OC/EC ratios exhibited “dual peak” feature due to the influence of secondary organic aerosol formation. In addition to commonly measured OC and EC, we recommend both char and soot from a common reference method to be considered in the chemical transport and climate models. [ABSTRACT FROM AUTHOR]

In metals with homogeneous microstructure, whether there is a critical grain size, and exactly at which, that enables the optimal strength-ductility synergy alongside the trade-off relation? Here, this issue is investigated in the recrystallized CrCoNi medium entropy alloys across a wide grain size range of 0.23-108 μm. Results reveal that there is indeed a critical grain size of ∼2 μm at which the product of yield strength (∼800 MPa) and uniform elongation (>30%) reaches the maximum, i.e., achieving the optimal strength-ductility synergy. Physics behind this critical grain size are explored by microstructure examination: (i) reduced grain size renders short dislocation slip path for high strength; (ii) low initial dislocation density and dense grain/twin boundaries enables effective accumulation of defects for consistent work hardening during plastic deformation. [Display omitted] [ABSTRACT FROM AUTHOR]

Highlights: [•] AlMgB14–TiB2 was synthesized by the two-step heat treatment. [•] AlMg6B14–xTiB2 shows a significantly improved critical current density. [•] The grain size of AlMgB14 decreases with increasing Ti doping content. [•] The stepwise synthesis method can produce practical AlMgB14–TiB2 materials. [ABSTRACT FROM AUTHOR]

Abstract: The fracture behavior of 6+1 filamentary MgB2 superconductive wires is presented here. The composite wires were fabricated by in situ Powder-in-Tube method using Nb as a barrier and copper as a stabilizer. The microstructure of the material has a great influence on its fracture behavior. The microstructural aspects of crack nucleation and propagation are discussed. It shows that there are complicated correlations between fracture behavior and the main influencing parameters, which contain specific drawing conditions (drawing velocity, reduction in area per pass), materials properties (strength, yield stress, microstructure) as well as the extent of bonding between the metal sheaths at their interface. [Copyright &y& Elsevier]

Abstract: Pure copper and copper–aluminum alloys (aluminum content of 2.3at%, 7.2at%, and 11.6at% with stacking fault energies (SFEs) of about 48mJ/m2, 21mJ/m2, and 8mJ/m2, respectively) were processed by equal channel angular pressing (ECAP) at room temperature for 8 passes to generate a nanoscale grain size. The effect of SFE on microstructure refinement and tensile properties of these materials were investigated. Microstructural observations indicated that the grain size of as-ECAPed alloy decreased monotonically with increasing Al concentration, i.e. with decreasing SFE. A very low SFE was especially favorable for achieving a true nanocrystalline structure (e.g. d≈57nm in Cu–11.6at% Al) by twinning and shear banding. The tensile strength and uniform elongation of nanostructured copper–aluminum alloys were simultaneously enhanced owing to the significant grain size refinement, solid solution strengthening and enhanced strain hardening capability. [Copyright &y& Elsevier]

Abstract: Six mixtures with different recycled aggregate (RA) replacement ratios of 0%, 50% and 100% were designed to manufacture recycled aggregate concrete (RAC) and alkali-activated fly ash geopolymeric recycled concrete (GRC). The physical and mechanical properties were investigated indicating different performances from each other. Optical microscopy under transmitted light and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX) were carried out in this study in order to identify the mechanism underlying the effects of the geopolymer and RA on concrete properties. The features of aggregates, paste and interfacial transition zone (ITZ) were compared and discussed. Experimental results indicate that using alkali-activated fly ash geopolymer as replacement of ordinary Portland cement (OPC) effectively improved the compressive strength. With increasing of RA contents in both RAC and GRC, the compressive strength decreased gradually. The microstructure analysis shows that, on one hand, the presence of RA weakens the strength of the aggregates and the structure of ITZs; on the other hand, due to the alkali-activated fly ash in geopolymer concrete, the contents of Portlandite (Ca(OH)2) and voids were reduced, as well as improved the matrix homogeneity. The microstructure of GRC was changed by different reaction products, such as aluminosilicate gel. [Copyright &y& Elsevier]

Conclusion: Preconcentration of metals are derived from sulfide-enriched cumulates in the lower arc crust; transcrustal structures imaged by geophysical data shows their roles for time–space window of mineralization in arc. [Display omitted] • Lower-crustal conductor relates sulfide-enriched cumulates beneath Hatu Au-deposit. • No such cumulates present beneath Baogutu porphyry Cu-Au deposit. • Baogutu deposit formed during active delamination/relamination in forearc. • Hatu deposits formed during transition from compression to extension. • Metal preconcentration in arc crust leave footprints on geophysical structures. Previous studies showed that metal preconcentration in fluids and/or magma is critical to the formation of gold deposit in arcs and is closely related to the segregation of sulfide phases. However, the depth range and the magnitude of and associated mechanism by which the deep crust controls the metal preconcentration of arc mineralization remain enigmatic. Here we present geophysical observations of the medium-scale Baogutu porphyry copper–gold deposit and the large-scale Hatu epithermal gold deposit from the late Paleozoic arc in the western Junggar, NW China. During the closure of Paleo-Asian Ocean, Baogutu deposit formed at ∼313 Ma relating to the adakitic intrusions driven by the ridge-related subduction, and Hatu deposit formed at ∼300 Ma just before the subduction termination. The transcrustal structures of resistivity and shear-wave velocity would show the signatures of metal preconcentration by reasoning the cause of low-resistivity anomaly to the persisting sulfide phases and the change of shear-wave velocity to the garnet proportion, respectively. Our results showed that the sulfide phases persisted in the entire deep crust and thus the metal preconcentration could occur in the base cumulates and mush reservoir beneath Hatu deposit, but the signatures were not fully reflected beneath the Baogutu deposit. These observations suggest that the reduced permeability of brittle-ductile transition and the water flux associated with magma likely affect the rising rate of melt, resulting in different efficiency of the metal preconcentration. Thus, the endowments of mineralization in arcs are controlled by crustal structures and contemporaneous arc magmatism during subduction. [ABSTRACT FROM AUTHOR]

Abstract: We have investigated the phase evolution and microstructure of carbon doped MgB2 by using differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscope (SEM). The analysis of DSC and XRD indicate that both the reaction temperature between Mg and B and the MgB2 phase stability increase for the carbon doped samples. The reaction rate between Mg and B decreases with the carbon content increase in the Mg–B system. SEM observation has shown that the carbon doping degenerates the grain connectivity of MgB2. In order to improve denseness of MgB2 sample, the two-step reaction method is proposed. [Copyright &y& Elsevier]

Abstract: A novel testing methodology on three-point bending fatigue test at 20kHz has been developed based on ultrasonic vibration theory to determine the bending fatigue strength of structural materials in very high cycle regime. In this paper, the working feature of the testing machine has been introduced. On the basis of vibration theory analysis, the differential equation of longitudinal and flexural vibration were given, finite element model was introduced to design and calculate the amplifier, specimen and the connector in the testing system. Furthermore, to produce the shapes of the components necessary to achieve the required displacement and stress states. Longitudinal cyclic load was transferred to transverse vibration of specimen by the tip in the testing system. In order to understand the effect of the tip on the testing system, matching analysis between amplifier and tip in the bending vibration system has been discussed. Finally, a successful application of the methodology is demonstrated by the experimental results from TiAl alloy specimens subjected to three-point bending stress states. [Copyright &y& Elsevier]

• Fatigue crack modes of tubular flanges connecting corrugated webs are evaluated. • Bending stress gradient across the depth of the tubular flange is properly assessed. • Proposed residual life model allowing for eccentric cracks is shown to be desired. This paper is devoted to experimentally and analytically evaluate the fatigue life behaviour of composite girders with concrete-filled tubular flanges and corrugated webs. Typical fatigue crack manner and stress distribution under repeated bending moment are analyzed and compared between the first and subsequent cycles. The fatigue life results are evaluated with S - N curves related to codified detail classes which are analogous to those dealing with the corrugated web girders with plain flange plates consisting of similar critical welded details. The remaining fatigue life analytical model is also developed to offer supplementary data for general fatigue behaviour of test girders. To this end, a formulation permits the tensile stress gradient along the depth and length of flange surface and combined correction factors is developed in the determinations of stress ranges. Also, the fatigue crack initiations are properly accounted at the upper surface of the bottom tubular flange where the longitudinal stress concentrates at the welded toes close to the end of the inclined fold adjoining longitudinal fold of the corrugation. The proposed formula is demonstrated to be effective in the remaining fatigue life assessment of test girders with multiple cracks based on a consistent trend between the predicted results and the test data. [ABSTRACT FROM AUTHOR]

Energy consumption has become one of the main costs of the stone processing industry and results in substantial stress on the environment. Consequently, the energy-saving issue has drawn increasing attention in the stone processing industry. Cutting power modeling is the crucial technology of energy prediction of stone machining process, being the foundation of energy-saving optimization in this sector. The cutting power changes dynamically during the variable material removal rate process (V-MRR process). Therefore, the power characteristic of the V-MRR process is more complicated than that of the constant material removal rate process (C-MRR process). In the stone processing industry, various machining processes belong to the V-MRR process, such as block sawing, slab chamfering, curved surface milling and grinding. In this paper, a modeling methodology of cutting energy consumption for variable-MRR process is proposed. The dynamic power characteristic can be reflected in this methodology, and the influences of cutting parameters on stone-cutting energy consumption are also fully considered. Based on the specially designed test system, experimental studies were conducted to obtain the fitting coefficients of the proposed energy consumption model. Then, energy calculations of four stone blocks sawing processes were performed. The results show that the predictive accuracy of all tested stone block sawing cases is above 90%. Finally, a case application is elaborated to demonstrate that the proposed method can help stone manufacturers determine the energy-optimal process plan. The detailed results of energy-saving & benefits-improving with using the proposed method are also proved in the case study. • This paper proposes a new modeling method of cutting energy consumption for V-MRR process. • The dynamic power characteristic can be fully considered in the I -model. • The power simulation using I -model is more in accordance with the actual situation. • The I -model can help stone manufacturers determine the energy-optimal process plan. • It shows that the effects of energy-saving & benefit-improving using the I -model are remarkable. [ABSTRACT FROM AUTHOR]

Sulfate, nitrate and ammonium are the most abundant secondary inorganic aerosols (SIA) in atmospheric fine particle matter (PM 2.5). Meteorological conditions, gas-particle transportation process, and aerosol acidity (pH) can influence SIA formation. In this study, we conducted semi-continuous measurements of water-soluble inorganic ions during a winter extreme pollution event (from January 9th to January 17th, 2015, average PM 2.5 concentrations of ~250 μg m−3 and peak concentrations of ~700 μg m−3) in Xi'an to elucidate on the SIA formation mechanism. The hourly mean level of the total water-soluble ion was 137.4 μg m−3, accounting for 55.3% of PM 2.5 on average. The dominant ions concentrations of SO 4 2−, NO 3 − and NH 4 + accounted for 15.8%, 19.0% and 13.2% of PM 2.5 mass, respectively. PM 2.5 was moderately acidic, with an average pH of 4.8 ± 0.4. Compared to the clean periods, sulfate content decreased by 6.9% during the polluted periods, while those of nitrate and ammonium increased by 2.2% and 5.0%, respectively. The increase in nitrogen oxidation ratios (NOR) and ammonia conversion ratio (NHR) from normal days to haze days were greater when comparison to sulfur oxidation ratios (SOR). In the polluted periods, sulfate and nitrate formations were facilitated by water content increase. Strong linear correlation coefficients between SOR (R2 = 0.81) and NOR (R2 = 0.55) with aerosol water content indicated that the gas-liquid reaction of SO 2 and NO 2 is the major pathway of sulfate and nitrate formation during severe haze episodes. In contrast, the NHR and aerosol water content exhibited a logarithmic relationship, which reveals that when water content was greater than 100 μg m−3, the gas-particle partitioning ratio of ammonium was basically unchanged following an increase in water content. • Large amount formation of secondary aerosol contributes to a significant increase in haze PM 2.5 concentration. • Compared to SOR, NOR and NHR significantly increase during heavy pollution periods. • Heterogeneous SO 2 reaction is the main pathway of sulfate generation during severe haze episodes. • The gas-particle partitioning ratio of ammonium and aerosol water content has a logarithmic relationship. [ABSTRACT FROM AUTHOR]

• An innovative composite repair technology with a stitched scarf panel. • Significant enhancement on load carrying capacity of the repaired laminates. • There is a balance between scarf patch size and thread hole size. • The scarf ratio has a limited effect on the failure load and failure mechanisms. • Repaired laminate with 2.5 mm stitch size and 1:10 scarf ratio offer the highest failure load. In order to increase the service life and maintain the residual strength of damaged composite structures, it is necessary to investigate effective repairing techniques. In this paper, an innovative stitch-reinforced scarf patch is developed in order to reduce the amount of parent material that is removed during the repair. Carbon fibre threads are used to stitch the scarf patch to a damaged carbon fibre laminate via pre-drilled holes. Following stitching, the vacuum resin infusion technique is used to infuse the carbon fibre threads, thereby fixing the patch to the parent part. Here, the effects of varying both the hole diameter and the scarf angle on the load-carrying capacity of the repaired laminates are studied. The tensile strength, strain distribution and failure mechanisms are investigated using the digital image correlation (DIC) technique. The results show that by introducing a 2.5 mm diameter stitching hole, the ultimate tensile strength of repaired laminates related to three scarf angles is increased by up to 20, 27 and 45% respectively, relative to traditional laminates with an equivalent scarf ratio. [ABSTRACT FROM AUTHOR]

Due to the rapid economic development and urbanization in China, the ornamental stone industry is developing fast, resulting in several environmental problems. Compared with the marble, granite is more difficult to be processed with greater environmental impacts. At present, many advanced and clean technologies are emerging in granite processing field, such as new processing technologies, wastewater treatment system and solid waste reusing technologies. Therefore, a reasonable clean technology planning is crucial for granite processing companies to achieve cleaner production (CP) mode. The purpose of this study is to develop a methodology for evaluating sawability of ornamental granite and constructing the relational model between sawability and environmental impacts from sawing process. The relation model can be used to predict key environmental impacts and support the clean technology planning. This paper firstly develops a characterization mechanism to describe the granite sawability based on Multiple Attribute Decision Making (MADM) theory. The characterization mechanism provides a specialized score system as uniform metric of sawability for ornamental granite. Secondly, definition of sawability function is proposed in this paper to make sawability evaluating process with better operability and applicability. The method for developing the sawability function is investigated combining the characterization mechanism with the design of experiment (DOE) theory. Thirdly, relational models between the granite sawability and the key environmental impacts are investigated by numerical fitting. The uncertainty analysis method for the modeling process is also provided in this paper. The methodology has been applied in a granite processing plant in Laizhou stone industrial park in Shandong province of China. Energy consumption, water consumption and solid waste generation of the plant have been estimated based on the relational models. The models have been proved to be helpful in providing basis for the cleaning technology planning in the plant. [ABSTRACT FROM AUTHOR]

• Combined temperature and moisture microsensors are embedded in two types of helmets. • In-helmet thermal and moisture mappings have been obtained for the first time. • Human perceptions on warmth, moisture and thermal comfort have been recorded. • Comfort index is linked to the measured in-helmet temperature and relative humidity. Based on microsensor technology, a novel test rig was developed for the first time to measure real-time multi-point temperatures and relative humidities inside a cricket helmet worn by a human subject for obtaining the corresponding thermal and moisture mapping. Two types of helmets with and without ventilation openings were investigated to visualise the hot and wet spots clearly inside the helmet. The results show the clear influence of ventilation openings on effective reduction of the temperature as well as the relative humidity inside the helmet. Also, the subjective data were linked to the digital temperature and relative humidity measurements for possible assisting design of helmet with improved thermal comfort. The technology developed is a useful measurement approach to other head gears such as safety, fire fighter and motorcycle helmets, and further to study microclimate environments in close contact with human body. [ABSTRACT FROM AUTHOR]

This paper presents a study on the mechanical properties of spherical egg-box core sandwich panels subjected to compression. Initial attention focuses on the effect that constraining the core, via the introduction of skins, and increasing the thickness of the cell walls has on the compressive properties of GFRP and CFRP structures. Tests were also undertaken on foam-filled samples in order to investigate the influence of additional support on the crushing behaviour of the cores. Low velocity impact tests were subsequently undertaken in order to investigate the rate-sensitivity of these core structures. Finally, blast tests were conducted on the core materials to investigate their response at high strain rates. It has been shown that constraining the lateral movement of the cores, by bonding composite skins to the upper and lower surfaces, serves to enhance the mechanical properties of the core in compression. In addition, quasi-static compression testing has shown that the compressive strength of the core increases rapidly with increasing cell wall thickness, with effects being more pronounced in the GFRP structures. Tests on foam-filled panels have shown that adding a low density filler to the core serves to enhance the energy-absorbing properties of the GFRP systems. Subsequent tests at dynamic rates of loading have shown that the values of energy absorption were slightly higher than those measured at quasi-static rates, due to rate effects in the failure processes within the composite material. Finally, it has been shown that when subjected to blast loading, extensive crushing of the spherical egg-box was observed, indicating that these structures are capable of absorbing significant energy under this extreme loading condition. • The compressive strength of the spherical egg-box sandwich panels increases rapidly with increasing cell wall thickness. • Tests on foam-filled panels have shown enhanced energy-absorbing properties. • A load sensitivity effect was noticed at high strain compression. • The extensive crushing of the spherical egg-box was observed under blast loading. [ABSTRACT FROM AUTHOR]