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1.
《Geotextiles and Geomembranes》2020,48(6):897-911
Dynamic responses of the geosynthetic-encased stone column (GESC) supported embankment under traffic loads have become a hot topic. This study investigates the responses of GESC improved ground under vertical cyclic loading. A series of laboratory tests in a designed model test tank have been carried out with different loading parameters (varied loading amplitudes and frequencies), different column dimensions (varied encasement lengths and column diameters). In the tests, the soil-column stress distribution, accumulated settlement of loading plate, excess pore water pressure in the surrounding soil and lateral bulging of the stone column are monitored. Experimental results indicate that the vertical stress on the stone column increases with the increment of encasement length, and decreases with the increment of column diameter, loading amplitude and loading frequency. The increasing stress on the surrounding soil leads to a greater accumulated settlement of the loading plate and excess pore water pressure, while the increasing stress on the column leads to larger lateral bulging of the column. Excess pore water pressure dissipates effectively through vertical and horizontal drainage channels provided by the stone column and the sand bed. The geosynthetic encasement prevents the clay from obstructing the drainage channel by filtration and guarantees the drainage effect. 相似文献
2.
High amplitude non-linear acoustic methods have shown potential for the identification of micro damage in brittle materials such as concrete. Commonly, these methods evaluate a non-linearity parameter from the relative change in frequency and attenuation with strain amplitude. Here, a novel attenuation model is introduced to describe the free reverberation from a standard impact resonance frequency test, together with an algorithm for estimating the unknown model coefficients. The non-linear variation can hereby by analyzed over a wider dynamic range as compared to conventional methods. The experimental measurement is simple and fully compatible with the standardized free-free linear impact frequency test. 相似文献
3.
In recent years, many tidal turbine projects have been developed using composites blades. Tidal turbine blades are subject to ocean forces and sea water aggressions, and the reliability of these components is crucial to the profitability of ocean energy recovery systems. The majority of tidal turbine developers have preferred carbon/epoxy blades, so there is a need to understand how prolonged immersion in the ocean affects these composites. In this study the long term behaviour of different carbon/epoxy composites has been studied using accelerated ageing tests. A significant reduction of composite strengths has been observed after saturation of water in the material. For longer immersions only small further changes in these properties occur. No significant changes have been observed for moduli nor for composite toughness. The effect of sea water ageing on damage thresholds and kinetics has been studied and modelled. After saturation, the damage threshold is modified while kinetics of damage development remain the same. 相似文献
4.
A method for simultaneous measurement of the thickness and density for Glass Fiber-Reinforced Polymer (GFRP) laminate plates with ultrasonic waves in C-Scan mode is presented in the form of maps. The method uses three different signals in immersion pulse-echo C-Scan mode. The maps obtained based on the density show the heterogeneity of the material at high resolution at the pixel level (1 × 1 mm2) and therefore they represent an efficient tool to assess and evaluate the damage of the composite structures after manufacturing and after an applied mechanical loading. 相似文献
5.
6.
This paper addresses the nonlinear stress-strain response in glass fibre non-crimp fabric reinforced vinylester composite laminates subjected to in-plane tensile loading. The nonlinearity is shown to be a combination of brittle and plastic failure. It is argued that the shift from plastic to brittle behaviour in the vinylester is caused by the state of stress triaxiality caused by the interaction between fibre and vinylester. A model combining damage and plasticity is calibrated and evaluated using data from extensive experimental testing. The onset of damage is predicted using the Puck failure criterion, and the evolution of damage is calibrated from the observed softening in plies loaded in transverse tension. Shear loading beyond linear elastic response is observed to result in irreversible strains. A yield criterion is implemented for shear deformation. A strain hardening law is fitted to the stress-strain response observed in shear loaded plies. Experimental results from a selection of laminates with different layups are used to verify the numerical models. A complete set of model parameters for predicting elastic behaviour, strength and post failure softening is presented for glass fibre non-crimped fabric reinforced vinylester. The predicted behaviour from using these model parameters are shown to be in good agreement with experimental results. 相似文献
7.
In this study, the crystal structure, thermal, oxygen transport, electrical conductivity and electrochemical properties of the perovskite NdBa0.5Sr0.5Co2O5+δ (NBSC55) are investigated. In the temperature range of 250 °C–350 °C, the weight loss upon heating was due to a partial loss of lattice oxygen and along with a reduction of Co4+ to Co3+. The tend of weight-loss slows down as temperature increased above 350 °C indicating a reduction of Co3+ to Co2+ during this stage. The oxygen migration is dominated by surface exchange process at high temperature range (650-800 °C); however, the bulk diffusion process prevails at low temperature range (500–600 °C). For long-term testing, the polarization resistance of NBSC55 increases gradually form 3.13 Ω cm2 for 2 h to 3.34 Ω cm2 for 96 h at 600 °C and an increasing-rate for polarization resistance is around 0.22% h?1. The power density of the single cell with NBSC55 cathode reached 341 mW cm?2 at 800 °C. 相似文献
8.
对甲乙酮装置剩余丁烯的循环利用进行了研究,采用聚结器脱水-净化的方法,脱除了剩余丁烯中的仲丁醇、仲丁醚、甲乙酮和水分等杂质,使得剩余丁烯得到了循环使用,满足了水合工段的进料要求,同时提高了甲乙酮的产品质量。 相似文献
9.
Simone Grassi Oscar Campuzano Mnica Coll Francesca Cazzato Georgia Sarquella-Brugada Riccardo Rossi Vincenzo Arena Josep Brugada Ramon Brugada Antonio Oliva 《International journal of molecular sciences》2021,22(8)
Inherited cardiomyopathies are frequent causes of sudden cardiac death (SCD), especially in young patients. Despite at the autopsy they usually have distinctive microscopic and/or macroscopic diagnostic features, their phenotypes may be mild or ambiguous, possibly leading to misdiagnoses or missed diagnoses. In this review, the main differential diagnoses of hypertrophic cardiomyopathy (e.g., athlete’s heart, idiopathic left ventricular hypertrophy), arrhythmogenic cardiomyopathy (e.g., adipositas cordis, myocarditis) and dilated cardiomyopathy (e.g., acquired forms of dilated cardiomyopathy, left ventricular noncompaction) are discussed. Moreover, the diagnostic issues in SCD victims affected by phenotype-negative hypertrophic cardiomyopathy and the relationship between myocardial bridging and hypertrophic cardiomyopathy are analyzed. Finally, the applications/limits of virtopsy and post-mortem genetic testing in this field are discussed, with particular attention to the issues related to the assessment of the significance of the genetic variants. 相似文献
10.
Baofu Qiu Xiaoming Duan Zhuo Zhang Delong Cai Ning Liao Peigang He Dechang Jia Yu Zhou 《Ceramics International》2021,47(1):73-79
The effects of La2O3–Al2O3–SiO2 addition on the thermal conductivity, coefficient of thermal expansion (CTE), Young's modulus and cyclic thermal shock resistance of hot-pressed h-BN composite ceramics were investigated. The samples were heated to 1000 °C and then quenched to room temperature with 1–50 cycles, and the residual flexural strength was used to evaluate cyclic thermal shock resistance. h-BN composite ceramics containing 10 vol% La2O3–Al2O3 and 20 vol% SiO2 addition exhibited the highest flexural strength, thermal conductivity and relatively low CTE, which were beneficial to the excellent thermal shock resistance. In addition, the viscous amorphous phase of ternary La2O3–Al2O3–SiO2 system could accommodate and relax thermal stress contributing to the high thermal shock resistance. Therefore, the residual flexural strength still maintained the value of 234.3 MPa (86.9% of initial strength) after 50 cycles of thermal shock. 相似文献