Marine geological disasters occurred frequently in the deep-water slope area of the northern South China Sea,especially submarine landslides,which caused serious damage to marine facilities.The cyclic elastoplastic mo...Marine geological disasters occurred frequently in the deep-water slope area of the northern South China Sea,especially submarine landslides,which caused serious damage to marine facilities.The cyclic elastoplastic model that can describe the cyclic stress-strain response characteristic for soft clay,is embedded into the coupled Eulerian-Lagrangian(CEL)algorithm of ABAQUS by means of subroutine interface technology.On the basis of CEL technique and undrained cyclic elastoplastic model,a method for analyzing the dynamic instability process of marine slopes under the action of earthquake load is developed.The rationality for cyclic elastoplastic constitutive model is validated by comparing its calculated results with those of von Mises model built in Abaqus.The dynamic instability process of slopes under different conditions are analyzed.The results indicate that the deformation accumulation of soft clay have a significant effect on the dynamic instability process of submarine slopes under earthquake loading.The cumulative deformation is taken into our model and this makes the calculated final deformation of the slope under earthquake load larger than the results of conventional numerical method.When different contact conditions are used for analysis,the smaller the friction coefficient is,the larger the deformation of slopes will be.A numerical analysis method that can both reflect the dynamic properties of soft clay and display the dynamic instability process of submarine landslide is proposed,which could visually predict the topographies of the previous and post failure for submarine slope.展开更多
In situ TiB2 reinforced 6351 Al alloy composites were subjected to compression testing at strain rates and temperatures ranging from 0.001 to 10 s -1 and from 300 to 550？欲espectively,using Gleeble-1500D system.And t...In situ TiB2 reinforced 6351 Al alloy composites were subjected to compression testing at strain rates and temperatures ranging from 0.001 to 10 s -1 and from 300 to 550？欲espectively,using Gleeble-1500D system.And the associated microstructural transformations and instability phenomena were studied by observations of the optical and transmission electron microscope.The power dissipation efficiency and instability parameter were calculated following the dynamic material model and plotted with the temperature and logarithm of strain rate to obtain processing maps for strains of 0.2,0.4,and 0.6.The processing maps present the instability zones at higher strain rates.The result shows that with increasing strain,the instability zones enlarge.The microstructural examination shows that the interface separates even the particle cracks or aligns along the shear direction of the adiabatic shear band in the instability zones.Two domains of higher efficiencies correspond to dynamic recovery and dynamic recrystallization during the hot deformation.Using the processing maps,the optimum processing parameters of stain rates and temperatures can be chosen for effective hot deformation of TiB2/6351 composites.展开更多
基金This work was supported by the National Natural Science Foundation of China(NSFC)(No.51179174).
文摘Marine geological disasters occurred frequently in the deep-water slope area of the northern South China Sea,especially submarine landslides,which caused serious damage to marine facilities.The cyclic elastoplastic model that can describe the cyclic stress-strain response characteristic for soft clay,is embedded into the coupled Eulerian-Lagrangian(CEL)algorithm of ABAQUS by means of subroutine interface technology.On the basis of CEL technique and undrained cyclic elastoplastic model,a method for analyzing the dynamic instability process of marine slopes under the action of earthquake load is developed.The rationality for cyclic elastoplastic constitutive model is validated by comparing its calculated results with those of von Mises model built in Abaqus.The dynamic instability process of slopes under different conditions are analyzed.The results indicate that the deformation accumulation of soft clay have a significant effect on the dynamic instability process of submarine slopes under earthquake loading.The cumulative deformation is taken into our model and this makes the calculated final deformation of the slope under earthquake load larger than the results of conventional numerical method.When different contact conditions are used for analysis,the smaller the friction coefficient is,the larger the deformation of slopes will be.A numerical analysis method that can both reflect the dynamic properties of soft clay and display the dynamic instability process of submarine landslide is proposed,which could visually predict the topographies of the previous and post failure for submarine slope.
文摘In situ TiB2 reinforced 6351 Al alloy composites were subjected to compression testing at strain rates and temperatures ranging from 0.001 to 10 s -1 and from 300 to 550？欲espectively,using Gleeble-1500D system.And the associated microstructural transformations and instability phenomena were studied by observations of the optical and transmission electron microscope.The power dissipation efficiency and instability parameter were calculated following the dynamic material model and plotted with the temperature and logarithm of strain rate to obtain processing maps for strains of 0.2,0.4,and 0.6.The processing maps present the instability zones at higher strain rates.The result shows that with increasing strain,the instability zones enlarge.The microstructural examination shows that the interface separates even the particle cracks or aligns along the shear direction of the adiabatic shear band in the instability zones.Two domains of higher efficiencies correspond to dynamic recovery and dynamic recrystallization during the hot deformation.Using the processing maps,the optimum processing parameters of stain rates and temperatures can be chosen for effective hot deformation of TiB2/6351 composites.
