The effects of dilatational phase transformation on the target strength of ceramic materi- als are investigated based on Tate's model.The constitutive behavior of materials in different regions (elastic,cracked,pl...The effects of dilatational phase transformation on the target strength of ceramic materi- als are investigated based on Tate's model.The constitutive behavior of materials in different regions (elastic,cracked,plastic and phase transformation)are taken into account.It is found that,with a proper choice of material parameters,the dilatational phase transformation can increase effectively the target strength R_t.This would be of importance in penetration-resistance design.展开更多
Experimental investigations of the dilatancy and particle breakage of gravelly material from the Zipingpu concrete-faced rock- fill dam, which was subjected to high-intensity seismic load during the 2008 Wenchuan eart...Experimental investigations of the dilatancy and particle breakage of gravelly material from the Zipingpu concrete-faced rock- fill dam, which was subjected to high-intensity seismic load during the 2008 Wenchuan earthquake, were conducted through a series of large-scale drained triaxial compression tests. A hyperbolic relation between the input plastic work and the degree of particle breakage was found for Zipingpu gravel, independent of the initial void ratio and confining pressures. The stress-dilatancy for Zipingpu gravel was analyzed and compared with data from two rounded alluvial and three angular quar- ried gravelly and rockfill materials in the literature. A nearly linear relationship between the dilatancy Dp and the stress ratio η was found at medium-to-large stress ratios before the peak stress ratio. The slope of the stress-dilatancy line before peak had slight dependence on the void ratio and confining pressure of the gravel. After peak, the stress-dilatancy relation shifts down compared with that before peak for the gravel specimen. The phase-transformation stress ratio decreased with increased con- fining pressure, with the exception of sub-rounded gravel with little particle breakage. A nearly linear relationship was found between the phase-transformation stress ratio Mf and the state parameter ψ for the Zipingpu gravel, regardless of the void ratio and confining pressure of the specimens.展开更多
Measuring the thickness of steel plates during the hot rolling process IS crucial tor getnng me necessary feedback to obtain the desired values at room temperature. The dilatation and the phase transformations of stee...Measuring the thickness of steel plates during the hot rolling process IS crucial tor getnng me necessary feedback to obtain the desired values at room temperature. The dilatation and the phase transformations of steel occur during heating and subsequent cooling and rolling strongly influences the results of thickness measurements. The radiometrie method provides the necessary means for making real-time and fully automatized measurements of steel thickness during rolling, if only the temperature correction is precisely known and taken into consideration. This article proves that the experimental results concerning the relative variation of steel thickness and corresponding massthickness variation can be correctly explained by means of the theory of metal dilatation correlated with the theory of nuclear radiation absorption when passing through a metal or metallic alloy, such as steel.展开更多
The structure of a steel changes with temperature due to phase transformations. This phase change is generally companied by a variation in the specific volume which is exhibited as a departure from the behaviour of th...The structure of a steel changes with temperature due to phase transformations. This phase change is generally companied by a variation in the specific volume which is exhibited as a departure from the behaviour of the thermal expansion or contraction, at the temperature at which the change occurs. This behaviour can be detected as a change in the dimensions of a suitable test piece, and forms the operating principle of dilatometry. The dilatometric technique may be applicable to the investigation of the phase transformation kinetics if the relation between the fractions of phases, the temperature, the compositions of phases and the dilatation can be built up. Efforts have been made to analyze the dilatation during an isothermal transformation or to calculate the dilatation during the heating of plain carbon steels using the thermodynamic function. The existing models are, however, not directly applicable to the determination of the phase transformation kinetics from a dilatation curve. A detailed analysis has been made of the length change of a hypoeutectoid steel during a continuous cooling. A model has been developed in which the transient dilatation is calculated based on the fraction of the phases present. The model takes into account the redistribution of carbon and is applicable to the determination of the phase transformation kinetics from the dilatation data during a cooling of a hypo-eutectoid steel. The model was validated by comparing the model results with the experimental results of an interstitial free steel. Experiments have been done with an interstitial-free steel and a C-Mn steel. The model has been applied to the calculation of the transformation kinetics indicated by the dilatation curves. Excellent agreements between the model and the experiments have been obtained.展开更多
基金the Excellent Youth Foundation of Harbin Institute of Technology
文摘The effects of dilatational phase transformation on the target strength of ceramic materi- als are investigated based on Tate's model.The constitutive behavior of materials in different regions (elastic,cracked,plastic and phase transformation)are taken into account.It is found that,with a proper choice of material parameters,the dilatational phase transformation can increase effectively the target strength R_t.This would be of importance in penetration-resistance design.
基金supported by the State Key Program of the National Natural Science Foundation of China(Grant No.51138001)the National Natural Science Foundation of China(Grant Nos.51279025+1 种基金91215301&51508071)the Program for New Century Excellent Talents in University(Grant No.NCET-12-0083)
文摘Experimental investigations of the dilatancy and particle breakage of gravelly material from the Zipingpu concrete-faced rock- fill dam, which was subjected to high-intensity seismic load during the 2008 Wenchuan earthquake, were conducted through a series of large-scale drained triaxial compression tests. A hyperbolic relation between the input plastic work and the degree of particle breakage was found for Zipingpu gravel, independent of the initial void ratio and confining pressures. The stress-dilatancy for Zipingpu gravel was analyzed and compared with data from two rounded alluvial and three angular quar- ried gravelly and rockfill materials in the literature. A nearly linear relationship between the dilatancy Dp and the stress ratio η was found at medium-to-large stress ratios before the peak stress ratio. The slope of the stress-dilatancy line before peak had slight dependence on the void ratio and confining pressure of the gravel. After peak, the stress-dilatancy relation shifts down compared with that before peak for the gravel specimen. The phase-transformation stress ratio decreased with increased con- fining pressure, with the exception of sub-rounded gravel with little particle breakage. A nearly linear relationship was found between the phase-transformation stress ratio Mf and the state parameter ψ for the Zipingpu gravel, regardless of the void ratio and confining pressure of the specimens.
文摘Measuring the thickness of steel plates during the hot rolling process IS crucial tor getnng me necessary feedback to obtain the desired values at room temperature. The dilatation and the phase transformations of steel occur during heating and subsequent cooling and rolling strongly influences the results of thickness measurements. The radiometrie method provides the necessary means for making real-time and fully automatized measurements of steel thickness during rolling, if only the temperature correction is precisely known and taken into consideration. This article proves that the experimental results concerning the relative variation of steel thickness and corresponding massthickness variation can be correctly explained by means of the theory of metal dilatation correlated with the theory of nuclear radiation absorption when passing through a metal or metallic alloy, such as steel.
文摘The structure of a steel changes with temperature due to phase transformations. This phase change is generally companied by a variation in the specific volume which is exhibited as a departure from the behaviour of the thermal expansion or contraction, at the temperature at which the change occurs. This behaviour can be detected as a change in the dimensions of a suitable test piece, and forms the operating principle of dilatometry. The dilatometric technique may be applicable to the investigation of the phase transformation kinetics if the relation between the fractions of phases, the temperature, the compositions of phases and the dilatation can be built up. Efforts have been made to analyze the dilatation during an isothermal transformation or to calculate the dilatation during the heating of plain carbon steels using the thermodynamic function. The existing models are, however, not directly applicable to the determination of the phase transformation kinetics from a dilatation curve. A detailed analysis has been made of the length change of a hypoeutectoid steel during a continuous cooling. A model has been developed in which the transient dilatation is calculated based on the fraction of the phases present. The model takes into account the redistribution of carbon and is applicable to the determination of the phase transformation kinetics from the dilatation data during a cooling of a hypo-eutectoid steel. The model was validated by comparing the model results with the experimental results of an interstitial free steel. Experiments have been done with an interstitial-free steel and a C-Mn steel. The model has been applied to the calculation of the transformation kinetics indicated by the dilatation curves. Excellent agreements between the model and the experiments have been obtained.
