The dynamic response of vitreous carbon to uniaxial strain loading has been investigated by means of the plate impact experiments. The two x cut shorted quartz gauges assembled with impactor and target were used ...The dynamic response of vitreous carbon to uniaxial strain loading has been investigated by means of the plate impact experiments. The two x cut shorted quartz gauges assembled with impactor and target were used to obtain the wave speeds in material and the stress histories at the sample gauge interface. The wave speed and stress histories were analyzed to determine the peak state in the sample. For compressive stress up to 4 0 GPa, the wave profiles were observed to be simple and steady, the uniaxial strain response is essentially nonlinear elastic, and no inelastic deformation has been found. All the experiment results indicate that the Hugoniot curve of vitreous carbon is concave downward just like that of fused silicon. There is no shock wave but the compressed wave propagating in the impacted samples.展开更多
The paper follows from the theory of explosion and interaction of an impact wave formed by the explosion and a structure. Firstly, the paper determines the parameters of the blast wave excited by a small charge explos...The paper follows from the theory of explosion and interaction of an impact wave formed by the explosion and a structure. Firstly, the paper determines the parameters of the blast wave excited by a small charge explosion. The empirical formulas on the basis of our own experimental results are shown and used for the structure analysis. Evaluations of structures loaded by an explosion based on dynamic response in rotations round the central line of plate or beam systems during the dynamic load of this type is discussed in the paper and comparison of own limit values and published ones is presented. Blast loads typically produce very high strain rates in the range of 102 to 10-4 s-1. The effect of strain rate for concrete material is discussed. The formulas for increased compressive strength of concrete and steel reinforcement are presented. The ductility of structural members is influenced by the corresponding values under high strain rate of reinforcement, Damage to the structure is assessed accordingly firstly by the angle of rotation of the middle axis/surface, and secondly by the limit internal forces of the selected structure. The extreme nature of blast resistance makes it necessary to accept that structural members have some degree of inelastic response in most cases. This enables the application of structure dissipation using the ductility factor and increased of concrete strength. The limits are correlated with qualitative damage expectations. The methodology of dynamic response assessment and its application to the simple bridge structure is discussed.展开更多
文摘The dynamic response of vitreous carbon to uniaxial strain loading has been investigated by means of the plate impact experiments. The two x cut shorted quartz gauges assembled with impactor and target were used to obtain the wave speeds in material and the stress histories at the sample gauge interface. The wave speed and stress histories were analyzed to determine the peak state in the sample. For compressive stress up to 4 0 GPa, the wave profiles were observed to be simple and steady, the uniaxial strain response is essentially nonlinear elastic, and no inelastic deformation has been found. All the experiment results indicate that the Hugoniot curve of vitreous carbon is concave downward just like that of fused silicon. There is no shock wave but the compressed wave propagating in the impacted samples.
文摘The paper follows from the theory of explosion and interaction of an impact wave formed by the explosion and a structure. Firstly, the paper determines the parameters of the blast wave excited by a small charge explosion. The empirical formulas on the basis of our own experimental results are shown and used for the structure analysis. Evaluations of structures loaded by an explosion based on dynamic response in rotations round the central line of plate or beam systems during the dynamic load of this type is discussed in the paper and comparison of own limit values and published ones is presented. Blast loads typically produce very high strain rates in the range of 102 to 10-4 s-1. The effect of strain rate for concrete material is discussed. The formulas for increased compressive strength of concrete and steel reinforcement are presented. The ductility of structural members is influenced by the corresponding values under high strain rate of reinforcement, Damage to the structure is assessed accordingly firstly by the angle of rotation of the middle axis/surface, and secondly by the limit internal forces of the selected structure. The extreme nature of blast resistance makes it necessary to accept that structural members have some degree of inelastic response in most cases. This enables the application of structure dissipation using the ductility factor and increased of concrete strength. The limits are correlated with qualitative damage expectations. The methodology of dynamic response assessment and its application to the simple bridge structure is discussed.
