Several different experiments,including freezing-thawing,freezing-thawing+drying-wetting,and drying-wetting,in salt solution and in water respectively,were designed to determine the durability of concrete.The durabili...Several different experiments,including freezing-thawing,freezing-thawing+drying-wetting,and drying-wetting,in salt solution and in water respectively,were designed to determine the durability of concrete.The durability damage features of concrete in the above experiments were studied.It is demonstrated that the damage extent of concrete under freezing-thawing and freezing-thawing+drying-wetting in salt solution is larger than that in water.Thus,freezing-thawing and freezing-thawing+drying-wetting in salt solution are stricter and more effective methods to evaluate the durability of concrete in salt-existing environment in cold regions.The damage extent of concrete under freezing-thawing+drying-wetting shows an ultra-superposition effect.The order of concrete durability deterioration degree in these experiments is determined.It shows that effects of multi-damage factors are greater than those of single-damage factor.展开更多
The computational modeling of fracture in solids using damage mechanics faces challenges with complex crack topology.This can be addressed by using a variational framework to reformulate the damage mechanics.In this p...The computational modeling of fracture in solids using damage mechanics faces challenges with complex crack topology.This can be addressed by using a variational framework to reformulate the damage mechanics.In this paper,we propose several mathematically elegant variational damage models(VDMs)for fracture mechanics without explicitly using damage variables.Based on the energy densityϕ,the fracture energy density is formulated as=ϕ/(1+ℓϕ/G_(c))and the damage variable is expressed as s=ϕ/(ϕ+G_(c)/ℓ),which satisfy|_(ϕ→∞)=G_(c)/ℓand s|_(ϕ→∞)=1 asϕapproaches infinity.These limits demonstrate that the new energy density converges to the Griffith energy release rate at full-damage state.The VDM profoundly modified the energy functional,implicitly incorporating the damage field.As a generalization of previous model,we propose a family of VDMs of varying orders.Additionally,we develop a multidamage model to account for different types of energy densities,such as elastic thin plate and gradient elasticity.Using this functional,it is straightforward to deduce the governing equation for automatically evolving fractures.These formulations can be employed in conventional finite element method or other numerical methods with minimal modifications.Compared to the phase field method with the same mesh density,a sharper crack interface can be achieved.We demonstrate the capabilities of the proposed variational damage formulations using representative numerical examples.展开更多
文摘Several different experiments,including freezing-thawing,freezing-thawing+drying-wetting,and drying-wetting,in salt solution and in water respectively,were designed to determine the durability of concrete.The durability damage features of concrete in the above experiments were studied.It is demonstrated that the damage extent of concrete under freezing-thawing and freezing-thawing+drying-wetting in salt solution is larger than that in water.Thus,freezing-thawing and freezing-thawing+drying-wetting in salt solution are stricter and more effective methods to evaluate the durability of concrete in salt-existing environment in cold regions.The damage extent of concrete under freezing-thawing+drying-wetting shows an ultra-superposition effect.The order of concrete durability deterioration degree in these experiments is determined.It shows that effects of multi-damage factors are greater than those of single-damage factor.
文摘The computational modeling of fracture in solids using damage mechanics faces challenges with complex crack topology.This can be addressed by using a variational framework to reformulate the damage mechanics.In this paper,we propose several mathematically elegant variational damage models(VDMs)for fracture mechanics without explicitly using damage variables.Based on the energy densityϕ,the fracture energy density is formulated as=ϕ/(1+ℓϕ/G_(c))and the damage variable is expressed as s=ϕ/(ϕ+G_(c)/ℓ),which satisfy|_(ϕ→∞)=G_(c)/ℓand s|_(ϕ→∞)=1 asϕapproaches infinity.These limits demonstrate that the new energy density converges to the Griffith energy release rate at full-damage state.The VDM profoundly modified the energy functional,implicitly incorporating the damage field.As a generalization of previous model,we propose a family of VDMs of varying orders.Additionally,we develop a multidamage model to account for different types of energy densities,such as elastic thin plate and gradient elasticity.Using this functional,it is straightforward to deduce the governing equation for automatically evolving fractures.These formulations can be employed in conventional finite element method or other numerical methods with minimal modifications.Compared to the phase field method with the same mesh density,a sharper crack interface can be achieved.We demonstrate the capabilities of the proposed variational damage formulations using representative numerical examples.
