The hydrogen storage alloys are selected as tritium s torage and boost materials. The alloy’s lattice swells and compresses in the hyd rogen ab /desorption cycle, and the wall stress is induced as a result of ununi f...The hydrogen storage alloys are selected as tritium s torage and boost materials. The alloy’s lattice swells and compresses in the hyd rogen ab /desorption cycle, and the wall stress is induced as a result of ununi form deformation. The pulverization of the bulk material leads to self compacti on and concentration of stress. The relationships of wall stress of hydrogen sto rage bed with cycle number of hydrogen ab /desorption, capacity of hydrogen sto rage, packing fraction and thickness of the wall are studied using strain gauges . In the paper, the relationship of wall stress and capacity of hydrogen storage is mainly discussed.展开更多
Modal strain energy based methods for damage detection have received much attention. However, most of published articles use numerical methods and some studies conduct modal tests with simple 1D or 2D structures to ve...Modal strain energy based methods for damage detection have received much attention. However, most of published articles use numerical methods and some studies conduct modal tests with simple 1D or 2D structures to verify the damage detection algorithms. Only a few studies utilize modal testing data from 3D frame structures. Few studies conduct performance comparisons between two different modal strain energy based methods. The objective of this paper is to investigate and compare the effectiveness of a traditional modal strain energy method(Stubbs index) and a recently developed modal strain energy decomposition(MSED) method for damage localization, for such a purpose both simulated and measured data from an offshore platform model being used. Particularly, the mode shapes used in the damage localization are identified and synthesized from only two measurements of one damage scenario because of the limited number of sensors. The two methods were first briefly reviewed. Next, using a 3D offshore platform model, the damage detection algorithms were implemented with different levels of damage severities for both single damage and multiple damage cases. Finally, a physical model of an offshore steel platform was constructed for modal testing and for validating the applicability. Results indicate that the MSED method outperforms the Stubbs index method for structural damage detection.展开更多
Due to the difficulty and weakness of current stress measurement methods in deep soft rock, a new rheological stress recovery method of the determination of the three-dimensional(3D) stress tensor is proposed. It is s...Due to the difficulty and weakness of current stress measurement methods in deep soft rock, a new rheological stress recovery method of the determination of the three-dimensional(3D) stress tensor is proposed. It is supposed that rock stresses will recovery gradually with time and can be measured by embedding transducers into the borehole. In order to explore the applicability and accuracy of this method, analytical solutions are developed for stress measurement with the rheological stress recovery method in a viscoelastic surrounding rock, the rheological properties of which are depicted as both the Burger's model and a 3-parameter solid model. In such conditions, explicit analytical expressions for predicting time-dependent pressures on the transducer are derived. A parametric analysis is then adopted to investigate the influences of the grout solidification time and the mechanical properties of the grout layer. The results indicate that this method is suitable for stress measurement in deep soft rock, the characteristics of which are soft, fractured and subjected to high geo-stress.展开更多
文摘The hydrogen storage alloys are selected as tritium s torage and boost materials. The alloy’s lattice swells and compresses in the hyd rogen ab /desorption cycle, and the wall stress is induced as a result of ununi form deformation. The pulverization of the bulk material leads to self compacti on and concentration of stress. The relationships of wall stress of hydrogen sto rage bed with cycle number of hydrogen ab /desorption, capacity of hydrogen sto rage, packing fraction and thickness of the wall are studied using strain gauges . In the paper, the relationship of wall stress and capacity of hydrogen storage is mainly discussed.
基金supported by the National Basic Research Program of China (2011CB013704)863 project (2008AA092701-5)+1 种基金the National Natural Science Foundation of China (50909088, 51010009, 51379196)the Program for New Century Excellent Talents in University (NCET-10-0762)
文摘Modal strain energy based methods for damage detection have received much attention. However, most of published articles use numerical methods and some studies conduct modal tests with simple 1D or 2D structures to verify the damage detection algorithms. Only a few studies utilize modal testing data from 3D frame structures. Few studies conduct performance comparisons between two different modal strain energy based methods. The objective of this paper is to investigate and compare the effectiveness of a traditional modal strain energy method(Stubbs index) and a recently developed modal strain energy decomposition(MSED) method for damage localization, for such a purpose both simulated and measured data from an offshore platform model being used. Particularly, the mode shapes used in the damage localization are identified and synthesized from only two measurements of one damage scenario because of the limited number of sensors. The two methods were first briefly reviewed. Next, using a 3D offshore platform model, the damage detection algorithms were implemented with different levels of damage severities for both single damage and multiple damage cases. Finally, a physical model of an offshore steel platform was constructed for modal testing and for validating the applicability. Results indicate that the MSED method outperforms the Stubbs index method for structural damage detection.
基金supported by the National Basic Research Program of China (No.2014CB046904)the National Natural Science Foundation of China (Nos.41130742 and 11302242)
文摘Due to the difficulty and weakness of current stress measurement methods in deep soft rock, a new rheological stress recovery method of the determination of the three-dimensional(3D) stress tensor is proposed. It is supposed that rock stresses will recovery gradually with time and can be measured by embedding transducers into the borehole. In order to explore the applicability and accuracy of this method, analytical solutions are developed for stress measurement with the rheological stress recovery method in a viscoelastic surrounding rock, the rheological properties of which are depicted as both the Burger's model and a 3-parameter solid model. In such conditions, explicit analytical expressions for predicting time-dependent pressures on the transducer are derived. A parametric analysis is then adopted to investigate the influences of the grout solidification time and the mechanical properties of the grout layer. The results indicate that this method is suitable for stress measurement in deep soft rock, the characteristics of which are soft, fractured and subjected to high geo-stress.
