Main ideas introduced in soil plasticity constitutive model. The remainder of the dissertation is divided into two parts, dealing respectively with a theoretical and experimental study of the applicability of plasticity theory to soils. Balance laws, variational formulation, and linearization. A variational constitutive model for porous metal plasticity article pdf available in computational mechanics 372. Since plastic collapse of mcc soils cannot be embedded in the classical limit analysis theory. A variational formulation of the mcc evolution equations is proposed in this paper. This model provides a reasonable match to the experimentally observed behavior of saturated clays. This is a pdf file of an unedited manuscript that has been accepted for. Adaptive viscous regularization, dilated time and numerical integration across stressstrain jump.
Use of plane stress and plane strain formulation, solution of typical boundary value problems. The approach to plasticity theory developed here is firmly. This cited by count includes citations to the following articles in scholar. An energy approach to modified camclay plasticity and. Soil plasticity and the structured cam clay model dr. When casting a camclay model within the framework of finite deformation theory, a central issue concerns the existence of a stored energy, or potential. Regarding the nonstandard form of the model, the partial normality is exploited and an implicit variational formulation of the modified camclay model is derived.
We present a finite deformation constitutive theory for noncohesive granular media. Borja department of civil and environmental engineering, stanford university, stanford, ca 943054020, usa. These concepts are used to revisit the camclay model. We extend the stress update algorithms from smallstrain plasticity to finite plasticity through the logarithmic and exponential mappings and adopt a fully variational characterization of the viscoplastic constitutive updates. A mathematical framework for threephase deformation and strain localization analyses of partially saturated porous media ronaldo i. A variational camclay theory of plasticity the essential concepts underlying camclay models derive from the observation of the soil in laboratory tests. Particular attention is paid to the issue of dilatancy as relating to the flow rule. Pdf we introduce a regularized anisotropic modified camclay mcc. Graduate course descriptions structural engineering. For instance, it is usually based on variational formulations, possible. Variational formulation of the camclay model springerlink. M ortiz and a pandolfi, a variational camclay theory of plasticity, computer methods in applied mechanics and engineering, 193, 2729, 2645, 2004. We model snow based on the critical state plasticity theory for soil mechanics 25,26.
Liu school of civil engineering university of new south wales sydney, nsw 2052, australia tel 293855474 fax. Viscoenergetic solutions to some rateindependent systems. The immediate plastic deformation is evaluated by employing the. In any case, nonassociative elastoplasticity is a widely used model in both soil and rock me. Mathematical theory of plasticity for frictional materials.
Iutam symposium on variational concepts with applications to the mechanics of materials, k. A variational camclay theory of plasticity request pdf. A variational formulation of the coupled thermomechanical boundaryvalue problem for general dissipative solids. Dynamic anticrack propagation in snow nature communications. Assumed yield locus in pressure p mises shear stress q plane and criticalstate line csl irreversible. As typical of camclay models, soil is assumed to be frictional with a logarithmictype compression. Abstract a variational camclay theory of plasticity core. The anomalous elastic and yield behavior of fused silica glass. Plasticity theory is widely used to describe the behaviour of soil and rock in many engineering situations. Due to collisions, brittle fracture and threshold e. The classical and gradientdependent versions of the theory and their numerical.
Potentials for the modified camclay model request pdf. Our knowledge of soil mechanics comes from human practice. Implicit integration of elastoplastic constitutive relations. The anomalous elastic and yield behavior of fused silica. In conventional camclay, a stressbased yield criterion is the primitive postulate. The material model falls in the family of the socalled camclay theories. Computer methods in applied mechanics and engineering, vol. Sorry, we are unable to provide the full text but you may find it at the following locations. Existence and regularity of solutions for an evolution.
You can define the inelastic material behavior by a yield function that depends on the three stress invariants, an associated flow assumption to define the plastic strain rate, and a strain. Potentials for the modified camclay model archive ouverte hal. Development, formulation and application of field equations of elasticity and variational principles for structural applications in civil and aerospace area. Metal plasticity is described and elementary theories are. Soil plasticity and the structured cam clay model i. Maier, quadratic programming theory for elastic perfectly plastic. Pdf a variational constitutive model for porous metal. A variational camclay theory of plasticity sciencedirect. Citeseerx abstract a variational camclay theory of.
Plastic collapse, camclay, variational principles, soil. Transport phenomena in porous media mcgill university. On the other hand, deformations of solids and motions of. Plasticity and geomechanics plasticity theory is widely used to describe the behaviour ofsoil and rock in. This paper revolves around a newly introduced weak solvability concept for rateindependent systems, alternative to the notions of energetic e and balanced viscosity bv solutions. Request pdf a variational camclay theory of plasticity we present a finite deformation constitutive theory for noncohesive granular media. Computer methods in applied mechanics and engineering, 193. A variational and multiscale perspective michael ortiz california institute of technology and. F, we can easily write the eulerlagrangian form of eqn.
Thus, laboratory tests show that soils loaded from some initial condition eventually reach a critical state characterized by the ability to sustain plastic deformation at constant volume. A standard version of the model is first discussed. The provided hyperelastoplasticdamage framework is motivated by a desire to ensure thermodynamic consistency of model predictions, and is shown to satisfy the principle of maximum plastic dissipation, enabling enforcement of the plastic. Plasticity and geomechanics presents a concise introduction to the general subject of plasticity with a particular emphasis on applications in geomechanics. We remark that conventional critical state plasticity models, including the modi. Enter the initial yield surface size, units of fl 2, if hardening exponential. In metal plasticity the theory necessary for describing plastic. We extend the previous existence result by introducing nonzero external forces in the model, and we discuss the regularity of the solutions thus obtained. Quasistatic evolution in nonassociative plasticity 3 camclay, but, more commonly especially in soils, it is a byproduct of intergranular friction, and this without any kind of hardeningsoftening phenomenon. Offers a selfcontained text that allows the reader to learn computational plasticity theory and its implementation from one volume. Pdf gradientenhanced camclay model in simulation of strain.
The ones marked may be different from the article in the profile. Abstract this paper describes a fully implicit stresspoint integration algorithm for a class of anisotropic bounding surface plasticity models with ellipsoidal loading function. We have applied ortiz and stainiers variational framework to the formulation and timediscretization of a finitedeformation model of camclay plasticity. Data lines to define camclay plasticity data lines to define camclay plasticity. The analytical model is cast within the framework of finite deformation theory based on. A variational camclay theory of plasticity article in computer methods in applied mechanics and engineering 1932729.
Viscoenergetic ve solutions have been recently obtained by passing to the timecontinuous limit in a timeincremental scheme, akin to that for e solutions, but perturbed by a viscous correction. In theories of elasticity and plasticity the sign of volumetric strain. Pdf a micromorphically regularized camclay model for capturing. We continue the study of a dynamic evolution model for perfectly plastic plates, recently derived in 19 from threedimensional prandtlreuss plasticity. The computation of the exponential and logarithmic. The same state boundary surfacedescribed by ellipsesis taken as yield and plastic potential surface. In particular, we discuss the camclay family of yield surfaces, developed for granular materials, as a proponent of plasticity models that display quite general nonassociative hardening.
There, the model features an explicit dependence of the elastic domain upon an. We extend the stress update algorithms from smallstrain plasticity to finite plasticity through the logarithmic and exponential mappings and adopt a fully variational characterization of the viscoplastic. In chapter 12 we discuss elasticviscoplastic material response, which is characterized by. The contributions of particulate mechanics are briefly summarised. A variational camclay theory of plasticity caltechauthors.
The plasticity model is coupled with a nonlinear hyperelastic model to ensure that the elastic component of the combined model is energyconserving. Models based on a volumetricdeviatoric split, international journal of solids and structures on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Isotropic and kinematic hardening with bauschingers. Alternatively, the variational equation for the balance of linear momentum can be written in. A variational camclay theory of plasticity, computer. Fung, computation of the matrix exponential and its derivatives by scaling and squaring, international journal for numerical methods in engineering, 59, 10, 12731286. However, the hardening rule is nonassociated in the sense that the evolution equation for. The model adopts the concept of separating the total deformation into immediate and delayed components. The new theory can be viewed as an extension of the conventional mathematical theory of plasticity which. Numerical investigation of the dynamic behavior of advanced ceramics. The cam clay model outlined above operates with an associated flow rule which is a necessary prerequisite to arrive at a variational formulation. Theory, abstract a constitutive model for the stressstraintime behavior of cohesive soils is developed using camclay plasticity theory extended to include timedependent effects.
Beginning with elementary theory and progressing to advanced, complex theory and computer implementation, it is suitable for use at both introductory and advanced levels. Absent a standard, stateindependent, normality postulate, energetic formulations are also relevant in spite of their variational bias. In conventional camclay, a stressbased yield criterion is the primitive postulate of the theory and the flow rule is a derived law. The abaqusstandard clay plasticity model describes the inelastic response of cohesionless soils. A key feature of the integration algorithm for the. Adaptive viscous regularization, dilated time and numerical integration across stressstrain jump discontinuities, computer methods in applied mechanics and engineering, 258, 118, 20. Desimone, critical softening in camclay plasticity. Read towards variational constitutive updates for nonassociative plasticity models at finite strain. The large deformation theory is based on the multiplicative decomposition of the deformation gradient into elastic and inelastic parts. Study of plasticity theories and their applicability to soils. Computational cam clay plasticity using secondorder cone. An alternative approach to modified camclay mcc critical state plasticity coupled with damage is proposed. Selvadurai transport phenomena in porous media aspects of micromacro behaviour 123. Moreover, softening models imply a nonconvex variational principle and.
328 285 1228 305 310 1008 81 1352 1365 1274 1256 945 771 954 824 819 1431 837 1166 1275 1481 1385 1122 1561 1368 1490 401 383 218 1070 56 867 780 79 352 1049 187 141 238 1139 290 211