Electrorheological(ER) and magnetorheological(MR) dampers, which are active damping devices, stand out for their exceptional performance in mitigating vibrations in mechanical systems and construction engineering....
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Electrorheological(ER) and magnetorheological(MR) dampers, which are active damping devices, stand out for their exceptional performance in mitigating vibrations in mechanical systems and construction engineering. Their prowess lies in the inherent ability of ER/MR fluids to change their mechanical properties, particularly viscosity and shear stress, in response to the influence of electric or magnetic fields. In this study, a damper filled with Giant-ER(GER) fluid, a modified product of ER fluid,is employed in the rotor system for vibration suppression. This damper operates in a Cut submode derived from the conventional working modes. This mode results in an effective enhancement of the damping performance by integrating the advantages of these modes, thereby achieving a damping force density of 1.2 × 10~4 N/m2and a modulation coefficient of 15 within a multilayered cylindrical damper. Whereafter, the dynamics of the rotor system are modeled and analyzed based on the Jeffcott rotor model, which incorporates a parallelogram-structured motion decoupling mechanism equipped with the proposed Cut submode dampers that are introduced to reduce the vibration of the transmission shaft in the rotor system. Furthermore, to evaluate the damping effect, a vibration-damping performance validation testbed is constructed. The results are noteworthy, demonstrating that by leveraging the superior properties of the GER fluid, the Cut submode damper effectively suppresses the vibrations of the transmission shaft, particularly at the resonant frequencies, achieving an impressive 88.9% reduction when subjected to an electric field of 3 kV/mm compared to the action of 0 kV/mm. This performance highlights the exceptional effectiveness of the proposed Cut submode, underscoring its vast potential for various engineering applications.
The novel Co-based superalloys are extensively used in gas-powered and jet engine turbines due to their excellent high-temperature performance, achieved by strengthening the L12-γ′ ordered phase. This review present...
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The novel Co-based superalloys are extensively used in gas-powered and jet engine turbines due to their excellent high-temperature performance, achieved by strengthening the L12-γ′ ordered phase. This review presents an overview of the research progress on oxidation behavior of Co-based superalloys, including oxidation kinetics, oxides morphology, the formation and spallation of oxide layers, and importantly, the synergistic effects of alloying elements on oxidation resistance—a critical area considering the complex interactions with multiple alloying elements. Additionally, this review compares the oxidation resistance of single crystal versus polycrystalline alloys. The effect of phase interface and dislocations on oxidation behavior is also discussed. While significant progress has been achieved, areas necessitating further investigation include optimizing alloy compositions for enhanced oxidation resistance and understanding the long-term stability of oxide layers. The future prospects for Co-based superalloys are promising as ongoing research aims to address the existing challenges and unlock new applications at even higher operating temperatures.
Eutectic high entropy alloys are noted for their excellent castability and comprehensive mechanical *** excellent mechanical properties are closely related to the activation and evolution of deformation mechanisms at ...
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Eutectic high entropy alloys are noted for their excellent castability and comprehensive mechanical *** excellent mechanical properties are closely related to the activation and evolution of deformation mechanisms at the atomic *** this work,AlCoCrFeNi2.1 alloy is taken as the research *** mechanical behaviors and deformation mechanisms of the FCC and B2 single crystals with different orientations and the FCC/B2 composites with K-S orientation relationship during nanoindentation processes are systematically studied by molecular dynamics *** results show that the mechanical behaviors of FCC single crystals are significantly orientation-dependent,meanwhile,the indentation force of[110]single crystal is the lowest at the elastic-plastic transition point,and that for[100]single crystal is the lowest in plastic deformation *** with FCC,the stress for B2 single crystals at the elastic-plastic transition point is ***,more deformation systems such as stacking faults,twins and dislocation loops are activated in FCC single crystal during the plastic deformation process,resulting in higher indentation *** composites,the flow stress increases with the increase of B2 phase thickness during the initial stage of *** indenter penetrates heterogeneous interface,the significantly increased deformation system in FCC phase leads to a significant increase in indentation *** mechanical behaviors and deformation mechanisms depend on the component single *** the thickness of the component layer is less than 15 nm,the heterogeneous interfaces fail to prevent the dislocation slip and improve the indentation *** results will enrich the plastic deformation mechanisms of multi-principal eutectic alloys and provide guidance for the design of nanocrystalline metallic materials.
Carbide dispersion reinforcing has been demonstrated to be an effective way of strengthening metal ma-trix ***,plagued by the nerve-wracking fact that the carbide particles tend to aggregate at the grain boundary of t...
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Carbide dispersion reinforcing has been demonstrated to be an effective way of strengthening metal ma-trix ***,plagued by the nerve-wracking fact that the carbide particles tend to aggregate at the grain boundary of the metal matrix,grow up,and form an incoherent interface with it,their im-provement in mechanical strength tends to be *** this study,spark plasma sintering(SPS)was used to prepare the bulk alloy Ni20Cr and its composites with different carbides including TiC,SiC,and *** leads to discharge and elevates temperature at the interface to melt the Ni20Cr alloy par-ticles *** cooled down,the alloy is heterogeneously solidified on the surface of the carbide and builds up a coherent interface with *** to the decomposition of Ti3SiC2 during sintering,it completely transformed into nanosized TiC particles,which are engulfed by the outer melted layer of Ni20Cr and well dispersed within the alloy *** comparison to the Ni20Cr alloy,the composite with merely 4 wt%Ti3SiC2 gains over three times enhancement in yield strength to 879 MPa,while keeping a moderate high elongation of 17.8%.Finite element analysis demonstrated that the combination of SPS and precursor MAX phase of Ti3SiC2,which results in the in-situ precipitation of coherent ultrafine TiC particles in alloy grains,plays the key role in getting a good balance between mechanical strength and ductility for the Ni20Cr matrix composites.
Low thermal conductivity and excellent mechanical strength are essential to pyrochlore A2B2O7 ceramic for environmental/thermal barrier coating *** collaboratively tailor the me-chanical and thermal properties of A2B2...
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Low thermal conductivity and excellent mechanical strength are essential to pyrochlore A2B2O7 ceramic for environmental/thermal barrier coating *** collaboratively tailor the me-chanical and thermal properties of A2B2O7 ceramic,a novel high entropy pyrochlore ceramic(La0.3Gd0.3Ca0.4)2(Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)2O7 with significant atomic radius and mass fluctuation is pro-posed by simultaneously introducing various elements with different valence states at A and B cation *** as-synthesized(La0.3Gd0.3Ca0.4)2(Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)2O7 exhibits enhanced fracture tough-ness(1.68 MPa m1/2),amorphous-like low thermal conductivity(1.45 W m-1 K-1 at 900 ℃)and matched thermal expansion coefficient(9.0 × 10-6 K-1 at 1200 ℃)with Al2O3/Al2O3 *** extensive mis-fits in atomic weight,ionic radius among the substitutional cations in combination with the intrinsic oxygen vacancies in the anion sublattice play significant roles in the thermal conductivity reduction of(La0.3Gd0.3Ca0.4)2(Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)2O7 *** combination of outstanding mechanical and thermal properties indicates that this type of material has a good application prospect for environmen-tal/thermal barrier coatings.
As a representative of the third generation advanced high-strength steels(AHSSs),medium Mn steels(MMS)have broad development prospects in the field of automobile *** with typical austenite reversion treatment have a s...
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As a representative of the third generation advanced high-strength steels(AHSSs),medium Mn steels(MMS)have broad development prospects in the field of automobile *** with typical austenite reversion treatment have a soft duplex microstructure,***+austenite,presenting a high ductility but a low yield *** we show that a flash heating and cooling after austenite reversion treatment can replace the ferrite with strong martensite,which greatly enhances the yield strength of a 0.25C-4Mn steel by about 461–886 *** adjusting the reversion temperature before the flash treatment,the C and Mn concentrations of reverted austenite can be altered,which determine the fraction of reverted austenite surviving the flash *** addition,the mechanical stability of final retained austenite is also linked to the reversion temperature,resulting different work hardening behaviors due to transformation induced plasticity(TRIP)*** tweaking the reversion temperature before the flash treatment,an optimized combination of strength and ductility can be *** micromechanical differences caused by the replacement of the matrix are also investigated via in-situ digital image correlation method.
The mechanical and corrosion characteristics of aluminum alloys can be influenced not only by the addition of grain refiners but also by heat treatment that modifies the microstructure and introduces variations in the...
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With the increasing use of micro-manufactured devices and the demand for low-cost fabrication techniques, this study presents a simple and scalable surface polishing method for laser etched acrylic using WELD-ON 4 acr...
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Emerging machine learning(ML)approaches have been adopted in various material systems to predict novel properties with the assistance of the corresponding large *** new materials,however,collecting sufficient data poi...
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Emerging machine learning(ML)approaches have been adopted in various material systems to predict novel properties with the assistance of the corresponding large *** new materials,however,collecting sufficient data points for model training is not feasible,which is the case for gold nanoparticle/polymer hybrid *** this study,an ML approach coupled with finite element modeling was proposed for predicting the optical and photothermal properties of gold nanoparticle/polymer hybrid *** datasets of the optical and photothermal properties were built using results from the ***,finite element analyses were conducted to generate synthetic data to satisfy the quality and quantity of the data required for training *** analysis and model training were performed using the datasets with and without synthetic data to evaluate their effects on predicting the performance of the ML *** relative importance of features to targets(properties)was evaluated by correlation *** models with high accuracy were obtained by training various models from conventional to newly developed ***,weaknesses,and improvement of the synthetic data addition were *** proposed workflow and framework offer reliable prediction of optical and photothermal properties over different combinations of gold nanoparticles and polymer matrices,which can be extended to include more features related to processing parameters and microstructures.
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