The drucker prager failure segment is a perfectly plastic yield surface no hardening. In addition, monotonic and low cycle fatigue tests were. A study on the plasticity and fracture of the aisi 4340. When abaqus cae begins, the start session dialog box appears.
A modified drucker prager model implemented in the fe code abaqus is used to describe. The guideline of the methodology to determine the parameters is provided in. Effect of soil behavior model on drilling response of anchor. The function approaches the linear drucker prager flow potential asymptotically at high confining pressure stress and intersects the hydrostatic pressure axis at. B physical interpretations for cap parameters of the modified drucker prager cap model in relation to the deviator stress curve of a particulate compact in conventional triaxial testing. Existing research works have identified that drucker prager dp plasticity model is capable of modeling the stress strain behavior of confined concrete. The stress invariants and other terms in each of the three related yield criteria are. The model is described in detail in drucker prager cap model for geological materials. Keywords drucker prager, triaxial test, silicon, finite. The drucker prager model has been used to model polymers such as polyoxymethylene and polypropylene citation needed. Hi, there i am writting a umat modeling drucker prager constitutive model nonassociated flow rule in abaqus.
Constitutive model development for powder compaction and. Initial stress geostatic stress void ratio saturationpore pressure loads mechanical bolt load thermal acoustic. Thus, the models will not reproduce some localization effects exhibited by real materials, which are assumed to behave more in accordance with a vertex model than with a smooth model when the. In this study, the linear model is considered because of its relationship with the parameters of the mohrcoulomb behavior model 1719.
Abaqus standard to abaqus explicit cosimulation abaqus cfd to abaqus standard or abaqus explicit fluid structure interaction fsi conjugate heat transfer cht flow analysis incompressible laminar and turbulent linear perturbation analyses static stress displacement analysis linear static stress displacement analysis. Yield surfaces for the drucker prager cap model in the space of hydrostatic, p,deviatoric, q, stresses, with the transition region implemented by abaqus 10. Drucker prager massachusetts institute of technology. Data lines to define a linear druckerprager plasticity model shear criterion linear first line. Druckerprager 1952 yield theory and incorporates combined multilinear. We propose a simple elasticplastic contact model by considering the interaction of two spheres in the normal direction, for use in discrete element method dem simulations of geomaterials. Due to the complex behavior of the soil stressstrain, influence from stress path and loading. An abaqus user material subroutine umat was developed to investigate. The deviatoric stress s and plastic strain increment. One easy method of addressing mohrcoulomb is proposed in the abaqus theory manual.
Application of druckerprager plasticity model for stress. The dp model was proposed by drucker and prager 1952. Extensive researches have been done on the plastic dilation rate for steel confined concrete. Stress strain plot with different confining pressures is presented in fig. The exponent drucker prager is a more complex elasticplastic model, which is better able to describe behaviour under stress states in which there is a high component of hydrostatic tension.
It is clearly observed from the figure that increase in the confining pressure resulted. Where k is the ratio of yield stress in the triaxial tension. Explicit finite element analysis of springenergized. The initiative of this work comes from the need to develop a user defined constitutive model in abaqus explicit v6. In abaqus, the flow potential is written in the form as. Glasgow, uk, 1112 september 2015 numerical simulation of. Even if a local coordinate system has been defined at a node transformed coordinate systems, section 2. The druckerprager yield criterion is a pressuredependent model for determining whether a material has failed or undergone plastic yielding. Plastic flow potential in drucker prager model \\mathrm i\. K flow stress ratio related to shape of yield surface in deviatoric plane p mean total normal stress p. It is, therefore, preferred as a flow potential for the drucker prager models over the straight line potential, which has a vertex on the hydrostatic pressure axis. The stress invariants and other terms in each of the three related yield criteria are defined later in this section.
The drucker prager shear failure surface function can be represented as. Extended drucker prager plasticity capped drucker prager plasticity camclay plasticity. A variant of the drucker prager cap model is developed to more realistically capture the behaviour of sand under large deformation. Implementation of a piecewise druckerprager model in abaqus. This paper investigates the capability of drucker prager creep model, based on a sensitivity of the equiv alent creep stress to. Damage and plastic deformation of reservoir rocks the university. Associative plasticity was assumed for defining the flow rule, with the angle of dilation assumed to be the same as the angle of friction. Miretalicac2015numericalsimulationoftriaxialtest strathprints. Triaxial compression and tension tests at different levels of confining pressures are required to obtain these parameters. Experimental and numerical investigation of the asymmetric primary. Extended drucker prager plasticity capped drucker prager plasticity. For polyoxymethylene the yield stress is a linear function of the pressure. This model assumes nonassociated potential plastic flow and the flow potential used for this model is the drucker prager hyperbolic function.
The abaqus drucker prager and mohrcoulomb models restrict possible flow patterns when the stress point is at a vertex of the mohrcoulomb yield surface. On the cap surface plastic flow causes the material to compact. It can well describe pressuresensitive materials such as rock, soil and concrete. Pdf identification of material parameters for druckerprager. Extended drucker prager plasticity capped drucker prager plasticity camclay plasticity mohrcoulomb plasticity crushable foam plasticity jointed materials concrete progressive damage and failure ductile shear forming limit diagram fld forming limit stress diagram flsd muschenbornsonne forming limit. Their definitions are the same as that defined in 2.
Tensar geogrid sr2 used in the wall exhibits slightly nonlinear stress strain properties with a breaking load of 63 knm netlon ltd, 1984. The criterion was introduced to deal with the plastic deformation of soils. The values of angle of friction and the flow stress ratio were calculated according to formulas presented in. Abaqus cae is asking for angle of friction, flow stress ratio and dilation angle. The parameters needed for the extended druckerprager. The yield surface is described by a shear failure line and a compaction surface, as illustrated in figure 1b in the effective stress e and hydrostatic stress m space, where m ax 2 rad 3 1 1 e. Analytical and numerical analyses of tunnel excavation problem. To learn about abaqus the best resource is getting started with abaqus. Plastic potential function in drucker prager model. Other material parameters for drucker prager model are derived from soil cohesion, angle of internal friction and dilation angle abaqus manual, 1990. However, the accuracy of the model largely depends on the adequate evaluation of its parameters that determine the yield criterion, hardeningsoftening rule and flow rule. However, polypropylene shows a quadratic pressuredependence of the yield stress. None of the existing dp type models possesses all three features, so they cannot be expected to lead.
Many uniaxial creep laws exist that relate the strain rate to the. Figure 1 shows the yield surface described by the cap model in the pq hydrostatic pressure deviatoric stress plane abaqus, 1998. Explicit finite element analysis of springenergized rotary. Identification of material parameters for druckerprager plasticity. For example, a comprehensive nonlinear finite element analysis of vertically loaded pile was carried out using abaqus tm trochanis et al. Raper and erbach, 1990, drucker prager linear yield criterion fig. Since it was first introduced, drucker prager type model drucker and prager, 1952 has been successfully adopted in analysis of geomaterials due to its relative simplicity. Interim report on the laboratory and theoretical work in modeling the. Plastic flow on this segment produces inelastic volume increase dilation that causes the cap to soften.
Effect of soil behavior model on drilling response of. The ratio of the flow stress in triaxial tension to the flow stress in triaxial. Development of a pressuredependent constitutive model with. Analysis users manual abaqus aquakeywords manual getting started manual example problems manual. It is also found that the influence of flow stress ration k on the results of the drucker prager criterion is negligible when comparing the result of and. Existing research works have established that drucker prager dp plasticity. The abaqus calculations were performed at the office.
Statistical analysis of modified druckerprager cap model. The main failure mechanisms are cracking in tension and crushing in compression. A simple model for elasticplastic contact of granular. Revision of druckerprager cap creep modelling of pebble beds in. Viscoelasticviscoplastic combined hardening constitutive model. In the current dp model, plastic potential function g that governs the flow rule is. The initial void ratio e0, defined as the ratio between the pore volume and the solid volume, is related to the porosity n through. Drucker prager matrix model the stress state within the matrix between the fibres is highly complex due to its triaxial. This model has been developed by using the finite element method fem and nonlinear fitting methods, in the form of powerlaw relation of the dimensionless normal force and displacement. If you are performing an abaqus standard analysis, enter a value for the flow potential. Plane strain deformation and an associated plastic flow rule, where the dilation angle is equal to the material friction angle, are assumed for. Piecewise drucker prager yield model, numerical implementation, constitutive. This surface is shown in the qp space in which p and q are the mean stress and the equivalent stress and s is the stress deviator tensor. Similar to other plasticity models, there are three criteria controlling the framework of a dp type model, and hence accuracy of predictions by the model.
Jan 01, 2011 with the implementation of this model, the finite element analysis results fit well with the experimental stress strain curves for columns with both low and high confinement. Mechanical tests were performed to characterize the material properties of two metals, in100 and 2024t851. A study on the plasticity and fracture of the aisi 4340 steel. The ratio of the flow stress in triaxial tension to the flow stress in triaxial compression, k. Pdf existing research works have established that drucker prager dp. Numerical modeling of compaction of particulate systems. Drucker prager model 45 degree flow stress ratio for drucker prager. The manner of introducing rate dependence is described in the users manual.
Abaqus users abaqus drucker prager and drucker prager. Pdf application of druckerprager plasticity model for. The values of angle of friction and the flow stress ratio were calculated according to formulas presented in sui, 1999a. The drucker prager model in abaqus software consists of three types of linear, exponential, and hyperbolic models. The lectures in mane 4240cilv 4240 will cover the basics of linear. Although it is quite straightforward to make a reasonable extension of the conventional druckerprager model that allows for simultaneously.
Drucker prager, plasticity model, frp confined concrete, plastic dilation, abaqus. K, the ratio of the flow stress in triaxial tension to the flow stress in triaxial compression. Data lines to define a linear druckerprager plasticity model shear criterion linearfirst line. Nonlinear finite element analysis of cone penetration in. To model this behaviour a drucker prager material model including hardening was specified in abaqus. Manual for the calculation of elasticplastic materials. For nodal variables, 1, 2, and 3 refer to the global directions 1x, 2y, 3z except for axisymmetric elements, in which case 1r, 2z. The models in this group are characterized by reversible deformations upon unloading. Poissons ratio and q and p may be expressed in terms. Identification of material parameters for druckerprager. Can anyone tell me where can i get the dilation angle.
1059 1464 1075 98 322 862 1213 743 1182 272 1334 1079 758 410 817 1072 119 610 672 590 876 1145 295 493 9 841 1190 820 355 530 775 19 299 144 23