Exact solutions in elementary functions are derived for the stress and electric displacement intensity factors of a half-plane crack in a transversely isotropic piezoelectric space interacting with various resultant s...Exact solutions in elementary functions are derived for the stress and electric displacement intensity factors of a half-plane crack in a transversely isotropic piezoelectric space interacting with various resultant sources, including force dipole, electric dipole, moment, force dilatation and rotation. Such force and charge sources may model defects like vacancies, foreign particles and dislocations. The locations and orientations of the stress and charge sources with respect to the crack are arbitrary.展开更多
Exact solutions in form of elementary functions were derived for the stress and electric displacement intensity factors of a circular crack in a transversely isotropic piezoelectric space interacting with various stre...Exact solutions in form of elementary functions were derived for the stress and electric displacement intensity factors of a circular crack in a transversely isotropic piezoelectric space interacting with various stress and charge sources： force dipoles, electric dipoles, moments, force dilatation and rotation. The circular crack includes penny-shaped crack and external circular crack and the locations and orientations of these resultant sources with respect to the crack are arbitrary. Such stress and charge sources may model defects like vacancies, foreign particles, and dislocations. Numerical results are presented at last.展开更多
In order to meet the requirement of structural inspection,the crack spacing and crack width at various heights in the tensile zone of six large depth reinforced concrete beams were measured under several loading level...In order to meet the requirement of structural inspection,the crack spacing and crack width at various heights in the tensile zone of six large depth reinforced concrete beams were measured under several loading levels of serviceability state.The effects of the depth of normal section beams on the crack spacing and crack width were analyzed,and the modified model is proposed for calculating the average crack spacing by thinking about the depth of normal section,the reinforcement arrangement and the effective reinforcement ratio.The relationships of crack widths at any position in the tensile zone and at the reinforcement level on the side surface of beam were studied.By theoretical and statistical analysis,a method is proposed to calculate the ratios of crack widths between any position and the reinforcement level on the side surface of large depth reinforced concrete beams.展开更多
In view of the periodic bending deformation of solid-liquid interface in the solidification process for continuous casting slab, the variation of temperature gradient and dendritic spacing in the front edge of the sol...In view of the periodic bending deformation of solid-liquid interface in the solidification process for continuous casting slab, the variation of temperature gradient and dendritic spacing in the front edge of the solid-liquid interface, and the nucleation and propagation process of crack were studied. It is shown that the bending deformation of the interface results in the temperature field change in the front edge of solid-liquid interface, and the occurrence of temperature gradient along drawing direction results in the growth of secondary dendrites. The initial crack formed during the middle and final stage of solidification may extend to the surface of the casting slab and become an internal crack. The results of the theoretical analysis are basically in agreement with that of the experiment.展开更多
基金Project supported by the National Natural Science Foundation of China (No. 10172075)the Yu-Ying Foundation of Hunan University.
文摘Exact solutions in elementary functions are derived for the stress and electric displacement intensity factors of a half-plane crack in a transversely isotropic piezoelectric space interacting with various resultant sources, including force dipole, electric dipole, moment, force dilatation and rotation. Such force and charge sources may model defects like vacancies, foreign particles and dislocations. The locations and orientations of the stress and charge sources with respect to the crack are arbitrary.
基金Project supported by the National Natural Science Foundation of China (No.10472102)Special Foundation of City University of HongKong (No.9610022)Outstanding Young Teacher Foundation of Hunan Province (No.521105236)the Yu-Ying Foundation of Hunan University (No.531103011110)
文摘Exact solutions in form of elementary functions were derived for the stress and electric displacement intensity factors of a circular crack in a transversely isotropic piezoelectric space interacting with various stress and charge sources： force dipoles, electric dipoles, moments, force dilatation and rotation. The circular crack includes penny-shaped crack and external circular crack and the locations and orientations of these resultant sources with respect to the crack are arbitrary. Such stress and charge sources may model defects like vacancies, foreign particles, and dislocations. Numerical results are presented at last.
基金Sponsored by the Outstanding Youth Scientific Fund of Henan Province(Grant No.04120002300)Program for Innovation in University of Henan Province(Grant No.[2004]294)
文摘In order to meet the requirement of structural inspection,the crack spacing and crack width at various heights in the tensile zone of six large depth reinforced concrete beams were measured under several loading levels of serviceability state.The effects of the depth of normal section beams on the crack spacing and crack width were analyzed,and the modified model is proposed for calculating the average crack spacing by thinking about the depth of normal section,the reinforcement arrangement and the effective reinforcement ratio.The relationships of crack widths at any position in the tensile zone and at the reinforcement level on the side surface of beam were studied.By theoretical and statistical analysis,a method is proposed to calculate the ratios of crack widths between any position and the reinforcement level on the side surface of large depth reinforced concrete beams.
基金supported by the National Natural Science Foundation of China(No.50374043).
文摘In view of the periodic bending deformation of solid-liquid interface in the solidification process for continuous casting slab, the variation of temperature gradient and dendritic spacing in the front edge of the solid-liquid interface, and the nucleation and propagation process of crack were studied. It is shown that the bending deformation of the interface results in the temperature field change in the front edge of solid-liquid interface, and the occurrence of temperature gradient along drawing direction results in the growth of secondary dendrites. The initial crack formed during the middle and final stage of solidification may extend to the surface of the casting slab and become an internal crack. The results of the theoretical analysis are basically in agreement with that of the experiment.
