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172 results on '"Lyu, Zhiyang"'

19. Experimental Investigation of High-temperature Crack Propagation Behaviors for Ti-6Al-4V/ELI at 250 ℃

Author

LYU Zhiyang, XIONG Junjiang, ZHAO Yanguang, and MA Shaojun

Subjects
titanium alloy, crack propagation, fatigue, high temperature, SEM, Motor vehicles. Aeronautics. Astronautics, TL1-4050
Abstract

Fatigue crack propagation behaviors at high temperature are important preconditions for damage tolerance design in aircraft and engine structures.Therefore, fatigue tests were carried out on titanium alloy Ti-6Al-4V/ELI subjected to constant amplitude loading at two temperatures of 25 ℃ and 250 ℃ and three stress radios of 0.06, 0.5, -1 to determine fatigue crack propagation behaviors. Fatigue crack propagation da/dN-ΔK curves and da/dN-ΔK-R surfaces were obtained from experimental data by secant method. Those behaviors at different temperatures were compared and analyzed, and the interaction mechanism between high-temperature and fatigue load was deduced from fractographical study by SEM analysis.The results show that the larger the stress ratio R, the faster the rate of crack propagation of Ti-6Al-4V/ELI under the same temperature and stress intensity factors rangeΔK. Oxidation products and large numbers of secondary cracks are found on the fatigue fracture surfaces at high temperature and the destruction mode of crack propagation is gradually changed form cleavage to quasi-cleavage. Acceleration effect of oxidation and deceleration effect of secondary cracks combine affecting the crack propagation rate; when R is 0.5 or 0.06, those two seem equal and the effect of temperature is not obvious, while R is -1, more and deeper secondary cracks caused by fully interaction of high temperature and fatigue load make crack propagation rate at high temperature lower than that at room temperature.

Published
2018
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35. Support-based modulation strategies in single-atom catalysts for electrochemical CO2 reduction: graphene and conjugated macrocyclic complexes.

Author

Fu, Zhanzhao, Wu, Mingliang, Zhou, Yipeng, Lyu, Zhiyang, Ouyang, Yixin, Li, Qiang, and Wang, Jinlan

Abstract

The electrochemical CO2 reduction reaction (CO2RR) is a promising method to decrease the CO2 concentration in the atmosphere and produce high value-added chemicals simultaneously. Catalysts play a central role in the CO2RR system, and can determine the conversion efficiency and product species. Single-atom catalysts (SACs), a new class of catalysts, have been extensively employed in the CO2RR due to their high activities, selectivity and maximum atom utilization efficiency. In this review, an overview of the recent progress of SACs for the CO2RR is provided with respect to two types of catalyst supports including graphene (Gr)-based nanomaterials and conjugated macrocycle (CM)-based complexes. Specifically, we focus on significant influencing factors on the activity and selectivity of the modeled catalysts, such as heteroatom doping, ligand effects and bimetals. Insights on the intrinsic connection between electronic structures and catalytic properties are summarized. Moreover, the stability and the dynamic structural change of SACs under operating conditions are also discussed. Finally, some challenges and perspectives are raised for the future development of efficient SACs based on Gr and CM supports. [ABSTRACT FROM AUTHOR]

Published
2022
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43. High-cycle fatigue behavior of Co-based superalloy 9CrCo at elevated temperatures

Author

Kuang Li, Aoshuang Wan, Chen Kejiao, Junjiang Xiong, Lyu Zhiyang, Man Ziyu, and Du Yisen

Subjects
Materials science, Stress ratio, Mechanical Engineering, Metallurgy, Fatigue testing, Aerospace Engineering, TL1-4050, 02 engineering and technology, Metals and alloys, 021001 nanoscience & nanotechnology, Nominal stress, Superalloy, Stress (mechanics), 020303 mechanical engineering & transports, 0203 mechanical engineering, SEM, Composite material, 0210 nano-technology, Fatigue, Test data, Elevated temperature, Motor vehicles. Aeronautics. Astronautics
Abstract

A modified model is developed to characterize and evaluate high-cycle fatigue behavior of Co-based superalloy 9CrCo at elevated temperatures by considering the stress ratio effect. The model is informed by the relationship surface between maximum nominal stress, stress ratio and fatigue life. New formulae are derived to deal with the test data for estimating the parameters of the proposed model. Fatigue tests are performed on Co-based superalloy 9CrCo subjected to constant amplitude loading at four stress ratios of −1, −0.3, 0.5 and 0.9 in three environments of room temperature (i.e., about 25 °C) and elevated temperatures of 530 °C and 620 °C, and the interaction mechanisms between the elevated temperature and stress ratio are deduced and compared with each other from fractographic studies. Finally, the model is applied to experimental data, demonstrating the practical and effective use of the proposed model. It is shown that new model has good correlation with experimental results.

Published
2016

44. Stretchable fiber-shaped lithium metal anode

Author

Wang, Xianshu, primary, Pan, Zhenghui, additional, Yang, Jie, additional, Lyu, Zhiyang, additional, Zhong, Yaotang, additional, Zhou, Guangmin, additional, Qiu, Yongcai, additional, Zhang, Yuegang, additional, Wang, John, additional, and Li, Weishan, additional

Published
2019
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