The rich and complex arrangements of metal atoms in high‐index metal facets afford appealing physical and chemical properties, which attracts extensive research interest in material science for the ...applications in catalysis and surface chemistry. However, it is still a challenge to prepare large‐area high‐index single crystals in a controllable and cost‐efficient manner. Herein, entire commercially available decimeter‐sized polycrystalline Cu foils are successfully transformed into single crystals with a series of high‐index facets, relying on a strain‐engineered anomalous grain growth technique. The introduction of a moderate thermal‐contact stress upon the Cu foil during the annealing leads to the formation of high‐index grains dominated by the thermal strain of the Cu foils, rather than the (111) surface driven by the surface energy. Besides, the designed static gradient of the temperature enables the as‐formed high‐index grain seed to expand throughout the entire Cu foil. The as‐received high‐index Cu foils can serve as the templates for producing high‐index single‐crystal Cu‐based alloys. This work provides an appealing material basis for the epitaxial growth of 2D materials, and the applications that require the unique surface structures of high‐index metal foils and their alloys.
Large single‐crystal Cu foils with high‐index facets are successfully achieved by using strain‐engineered anomalous grain growth, in which a graphite susceptor provides moderate strain on the Cu foil. The minimization of the strain energy leads to the formation of anomalous Cu grains with high‐index facets, which is investigated by the theoretical calculations.
•A novel approach for extending uniaxial LITS model to 3D is presented.•A bilinear uniaxial LITS model, conceived to be extended to 3D, is presented.•The presented model is verified and validated ...against experiments.•LITS plays a key role for nuclear concrete vessels under transient high temperatures.
The paper presents a novel thermomechanical 3D Load-Induced Thermal Strain (LITS) model that captures the experimentally demonstrated behavior of concrete in the case of heating under multiaxial mechanical load, for temperatures up to 250 °C. In contrast to the models available in the literature, the new model takes into account the observed dependency of LITS on stress confinement. Such a dependency is introduced through a confinement coefficient which makes LITS directly proportional to the confinement of the stress state. Also, a new practical bilinear LITS model is proposed and proved to be suitable for fitting the general trend of the curves experimentally obtained for different loading conditions. The presented model is embedded in a thermoelastic material constitutive law, and then verified and validated against experiments performed on concrete specimens subjected to transient temperatures up to 250 °C under uniaxial, biaxial and triaxial compressive stress states. Once calibrated and validated, the constitutive model is used to evaluate the effects of LITS on the structural behavior of a Prestressed Concrete Pressure Vessel (PCPV) of a typical Advanced Gas cooled Reactor (AGR) subjected to a heating-cooling cycle simulating a temporary fault in its cooling system. The results of this study indicate that the development of LITS significantly influences the stress redistribution in the structure. Moreover, it is shown that in the case of PCPVs (and by extension similar structures) it is crucial to consider the LITS dependence on the stress confinement.
Whenever people spend time outdoors during hot weather, they are putting themselves in potentially stressful situations. Being able to predict whether a person is overheating can be critical in ...preventing heat-health issues. There is a clear relationship between body core temperature and heat health. However, measuring body core temperature is expensive. Identifying a non-invasive measure that could indicate a person's thermal strain would be valuable. This study investigated five physiological measures as possible surrogates: finger mean skin temperature (FSKT), finger maximum skin temperature (FMSKT), skin conductance level (SCL), heart rate (HR), and heart rate variability (HRV). Furthermore, they were compared against the results of participants' subjective thermal sensation and thermal comfort in a range of hot microclimatic conditions in a hot and humid climate. Results showed that except for SCL, each of the other four physiological measures had a positive significant relationship with thermal sensation, but a negative relationship with thermal comfort. Furthermore, through testing by cumulative link mixed models, HRV was found to be the most suitable surrogate for predicting thermal sensation and thermal comfort through a simple, non-invasive measure in outdoor environment in summer in a hot and humid area. This study highlights the method for predicting human thermal strain and contributes to improve the public health and well-being of urban dwellers in outdoor environments.
•Advanced materials are selected. W-ZrC material exhibits high strength, high ductility, high thermal conductivity, low DBTT, excellent resistance to high thermal-loads and to high flux plasma ...etching as well as enhanced high-temperature stability.•The mock-up successfully endured the stepped loading (5 - 10 Mw m−2) and cyclical loading (10 MW m−2 1000 cycles).•A thermomechanical measurements for the W-ZrC mono-block mock-up, thermal strain data had been analyzed in detail to explore the mechanism of deformation during thermal cycles.
Mono-blocks are important components of plasma-facing components (PFCs) in nuclear fusion engineering. W-ZrC shows superior performance as a novel plasma-facing material (PFM) and may be a better choice as a promising armor material. A W-ZrC mono-block mock-up developed for the divertors of future fusion reactors was tested and analyzed. The displacement, strain, and temperature of the model were obtained using a comprehensive experimental platform combining an electron beam scanning high-heat-flux (HHF) test system with digital image correlation (DIC). The mock-up was successfully subjected to stepped loading (5–10 MW m−2) and cyclical loading (10 MW m−2 for 1000 cycles). The bending effect that caused the mock-up to arch upward was observed. The mock-up was maintained in an elastic deformation state during the entire cyclic process. Linear fitting of the strain data revealed that the strain grew slowly at a growth rate of 0.3 and linear extrapolation found that one of the conditions limiting the lifetime of the mock-up was 24,135 cycles.
This study proposes a mesoscopic thermo-mechanical (TM) lattice model to describe the transient thermal strain (TTS) behaviour of concrete and to predict the attenuation of its TM properties as a ...function of temperature. In such a model, concrete includes three constituents: cement, aggregates and interfacial transition zones (ITZ). A damage model including softening behaviour is used to describe the behaviour of the cement matrix and the ITZ, while the aggregates are assumed to be elastic. The thermal response within mesoscopic concrete is represented by a non-linear heat transfer equation, where the mechanical effect on thermal conductivity is taken into account. Mismatch of thermal expansions and stiffness between material phases (cement, aggregate) causes damage of concrete subjected to thermal and/or mechanical loadings, which makes decrease the concrete properties. Five parameters are envisaged: Young's modulus, compressive strength, direct tensile strength, thermal conductivity and thermal expansion coefficient.
TM responses of concrete, especially TTS phenomenon and evolution of some key properties appear to be captured by the proposed mesoscale TM model (without consideration of moisture effects). Comparisons with experimental studies are drawn through this paper to show the ability of the present model.
•A TM mesoscale lattice model is proposed to describe concrete behaviour.•Transient thermal strain phenomenon is well captured.•Some key parameters appear to be rooted in the TM mesoscale model.•Difference in results during heating and after cooling is shown.
An experimental LaNi5 alloy’s hydrogen absorption/desorption system was established to explore the strain generation process mechanism on the reactor wall during the cyclic hydrogen ...absorption/desorption process of LaNi5 alloy powders at room temperature after different cycles and periods. On this basis, the influence of the hydrogen pressure on the wall strain of the reactor was verified. Results showed that with the increase in cycles, the reactor wall was subjected to an expansion strain, and the closer to the reactor bottom, the greater the strain value. As the hydrogen pressure grew from 3.0 to 4.0 MPa, the strain value at the reactor bottom increased obviously. Still, it did not grow during cycling experiments with hydrogen, indicating that the agglomeration phenomenon was mainly attributed to the pulverization effect after hydrogen absorption by the alloy instead of the gas pressure itself. After 24 cyclic reactions, the wall strain at the 1/5 position from the bottom experienced changes in growth laws since the thermal strain was not enough to influence the expansion strain triggered by agglomeration, and the closer to the reactor top, the more greatly the wall strain was influenced by reaction heat.
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