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Spatio-temporal evolution of pore and fracture structures in coal induced by initial damage and creep behavior:A real-time NMR-based approach OA
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作者 Lei Zhang Yimeng Wang +5 位作者 Mingzhong Gao Wenhao Jia Senlin Xie Wei Hou Xiangyu Wang Hao Zhang 《International Journal of Mining Science and Technology》 SCIE EI CAS 2024年第10期1409-1425,共17页
Understanding the impact of mining disturbances and creep deformation on the macroscopic deformation and the microscopic pore and fracture structures(MPFS)of coal is paramount for ensuring the secure extraction of coa... Understanding the impact of mining disturbances and creep deformation on the macroscopic deformation and the microscopic pore and fracture structures(MPFS)of coal is paramount for ensuring the secure extraction of coal resources.This study conducts cyclic loading-unloading and creep experiments on coal using a low-field nuclear magnetic resonance(NMR)experimental apparatus which is equipped with mechanical loading units,enabling real-time monitoring the T2spectrum.The experiments indicated that cyclic loading-unloading stress paths initiate internal damage within coal samples.Under identical creep stress conditions,coal samples with more initial damages had more substantial instantaneous deformation and creep deformation during the creep process.After undergoing nearly 35 h of staged creep,the total strains for coal samples CC01,CC02,and CC03 reach 2.160%,2.261%,and 2.282%,respectively.In the creep stage,the peak area ratio of seepage pores and microfractures(SPM)gradually diminishes.A higher degree of initial damage leads to a more pronounced compaction trend in the SPM of coal samples.Considering the porosity evolution of SPM during the creep process,this study proposes a novel fractional derivative model for the porosity evolution of SPM.The efficacy of the proposed model in predicting porosity evolution of SPM is substantiated through experimental validation.Furthermore,an analysis of the impact mechanisms on key parameters in the model was carried out. 展开更多
关键词 Coal microscopic pore and fracture structures Initial damage Creep behavior Fractional porosity model of seepage pores and microfractures Nuclear magnetic resonance
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Research on the intermediate phase of 40CrMnSiB steel shell under different heat treatments 被引量:1
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作者 Wei-bing Li Zhi-chuang Chen +1 位作者 Xiao-ming Wang Wen-bin Li 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2021年第3期1032-1041,共10页
In this study, 40 Cr Mn Si B steel cylindrical shells were tempered at 350, 500 and 600 ℃ to study the effect of tempering temperature on the dynamic process of expansion and fracture of the metal shell. A midexplosi... In this study, 40 Cr Mn Si B steel cylindrical shells were tempered at 350, 500 and 600 ℃ to study the effect of tempering temperature on the dynamic process of expansion and fracture of the metal shell. A midexplosion recovery experiment for the metal cylinder under internal explosive loading was designed, and the wreckage of the casings at the intermediate phase was obtained. The effects of different tempering temperatures on the macroscopic and microscopic fracture characteristics of 40 Cr Mn Si B steel were studied. The influence of tempering temperatures on the fracture characteristic parameters of the recovered wreckage were measured and analyzed, including the circumferential divide size, the thickness and the number of the circumferential divisions. The results show that as the tempering temperature was increased from 350 to 600 ℃, at first, the degree of fragmentation and the fracture characteristic parameters of the recovered wreckage changed significantly and then became essentially consistent. Scanning electron microscopy analysis revealed flow-like structure characteristics caused by adiabatic shear on different fracture surfaces. At the detonation initiation end of the casing, fracturing was formed by tearing along the crack, which existed a distance from the initiation end and propagated along the axis direction. In contrast, the fracturing near the middle position consists of a plurality of radial shear fracture units. The amount of alloy carbide that was precipitated during the tempering process increased continuously with tempering temperature, leading to an increasing number of spherical carbide particles scattered around the fracture surface. 展开更多
关键词 Explosive mechanics Mid-explosion recovery experiment Explosion and fracture Heat treatment SEM(Scanning electron microscope)fracture analysis
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