Any of the mechanical constitutive models available in abaqus standard can be used to model the porous solid material. It also allows you to iterate, if necessary, to obtain equilibrium. For complex problems abaqus can be extended via user subroutines. Ideally, the loads and initial stresses should exactly equilibrate and produce zero. Geostatic stressvoid ratio saturationpore pressure. The entities from which you can select depend on whether the part instance is an abaqus native part or an orphan mesh part and on the modeling space of the part. In the initial step a geostatic stress field is applied. Given the large number of possible configuration permutations, even for a single platform, simulia tests only a sample of the possible configurations.
The installation of the 2019 abaqus release is quite straigtforward, similar to abaqus 2018. For abaqus explicit analyses, elevationdependent initial stresses cannot be specified for beams and shells. One thing we need to pay attention in abaqus cae while setting the geostatic stress as the predefined field is that the direction of geostatic stress is set in zdirection as default. For non abaqus users could be very hard to define a model. Html version of this manual contains the same information as the pdf version as well as. All downloaded files need to be extracted to a common file structure. How to use abaquscae geostatic step to simulate lateral and. All test configurations for a particular platform are supported using the same abaqus software build. Our new crystalgraphics chart and diagram slides for powerpoint is a collection of over impressively designed datadriven chart and editable diagram s guaranteed to impress any audience. Abaqus also offers two druckerprager models, with and without a compression cap, to model this class of material behavior. There are 7 arguments, of which at least one must be entered.
Chart and diagram slides for powerpoint beautifully designed chart and diagram s for powerpoint with visually stunning graphics and animation effects. This manual is not meant to be a complete abaqus script manual. Its running and finishing step one in 50 increments and aborted in 2nd step. This step also establishes the initial distribution of pore pressure. Regional contact information is listed in the front of each abaqus manual and is accessible from the locations page at support for simulia products. Geostatic stress state massachusetts institute of technology. I have a very simple plain strain 2d model and i applied the following initial stress that balances the gravity load of g10 ms2 operating in z direction throughout a zone that extends vertically from z0 to z100 m i am estimating the intial vertical stress as follows. Users manual getting started manual release notes supported platforms windowsx8664 linuxx8664 product support maintenance and support quality monitoring service installation training and users meetings related products abaqus cae topology optimization module atom, cad associative. Because geostatic stresses cannot be defined directly in abaqus cae, they are added to the model using the keywords editor.
The radius of the well is 81 m 265 ft, and the well extends from a depth of 335 m 1100 ft to 732 m 2500 ft. How to use abaquscae geostatic step to simulate lateral. If a porous medium will be analyzed subsequent to the geostatic procedure, pore fluid flow quantities such as permeability and sorption should be defined see about pore fluid flow properties. Plugin for tunneling and geotechnical analysis in abaqus. Any of the stressdisplacement elements in abaqus standard can be used in a geostatic procedure. Automatic and manual element library beam truss solidworks, and connector proengineershell. The plastic poissons ratio, is expected to be less than 0. For more information, see geostatic stress state, section 6. Pdf abaqus analysis users manual prakash k academia. Examples manual pdf enfem is a generalpurpose finiteelementanalysis fea software for simulating 2d mechanical behaviors of solid materials subjected to various loads. Abaqus cae data sheet geometry geometry creation tools solid features extrude loft revolve. The abaqus mohrcoulomb model is described in mohrcoulomb plasticity, section 23. This guide is a complete reference for all of the capabilities of abaqus standard, abaqus explicit, and abaqus cfd and contains a description of the elements, material models, procedures, input specifications, etc. One of the features of the infinite elements is that they will apply the proper tractions on the boundary to maintain an initial equilibrium stress field.
The initial geostatic stress field is defined using the initial conditions option. The example considers an axisymmetric model of an oil well and the surrounding soil, as shown in figure 9. For the potential to be welldefined, must be greater than 1. How to define abaqus geostatic stress on 2d models. The abaqus manual explains only the theoretical part, as per the description, from the experimental data of triaxial test, i am not able to generate the required function. In this case abaqus assigns pore pressure according to what the user has specified and the stresses are calculated accordingly. The paper explores the steps to define a geotechnical analysis and abaqus cae capabilities. Abaqusstandard can be used for modeling reinforced soils and. These elements have pore pressure degree of freedom 8 in addition to displacement. Assign geostatic variation of pore pressure initially bottom 8 kpa, top 19. Abaqus standard will restrict the time step to ensure that this value is not exceeded at any node during any increment of the step. Geostatic step not completing in abaqus after deactivating.
The different abaqus constitutive models applicable to geotechnical materials are presented in lecture 3. Introduction overview of geotechnical applications. However, i dont know how to achieve a correct geostress field. Settings you can configure with these tabbed pages include controls to include nonlinear effects of large displacements and equation. Abaqus, soil mechanics, soil plasticity, hypoplasticity, pile penetration analysis, soil. This example simulates a semiinfinite granular medium under initial geostatic stress, subject to pressure suddenly applied to part of its surface. Abaqus will issue a warning message if the procedure is used with a nonsupported material model.
Figure 203 abaqus computes the contour integral at each node along the crack line. If a porous medium will be analyzed subsequent to the geostatic procedure, pore fluid flow quantities such as permeability and sorption should be defined see pore fluid flow properties, section 20. What is the requirement of geostatic step in abaqus. The abaqus druckerprager model without a cap provides a choice of three yield criteria. Continuum pore pressure elements can also be used for modeling fluid in a deforming porous medium. Regional contact information is listed in the front of each abaqus manual.
I used the geostatic step first, defining the material properties as follows. To model a semiinfinite halfspace, one option is to generate a mesh that. The abaqus manual explains only the theoretical part, as per the description, from the experimental data. Learn abaqus script in one hour harvard university. This manual is a complete reference for all of the capabilities of abaqus standard, abaqus explicit, and abaqus cfd and contains a description of the elements, material models, procedures, input specifications, etc. Regional contact information is listed in the front of each abaqus manual and is accessible. Abaqus references for additional information on the abaqus capabilities referred to in this brief please see the following abaqus 6. In abaqus standard elevationdependent initial stresses should be specified for beams and shells in user subroutine sigini, as explained earlier. A file containing the pore pressure in each eclipse block is read for each time step analyzed by abaqus. Abaqus builtin features enable a wide range of simulating such problems. Geostatic step stress calculation university of cambridge. Headings for each test configuration list the operating system and processor architecture. The first step of the analysis is a geostatic step to equilibrate geostatic loading of the finite element model.
Abaqus technology brief analysis of reinforced and. Prior to external effect, ususlly a system is subject to its gravity load and one in this step has to describe intial stress condition that at least roughly equliberates the stress state produced by the gravity load. Its use in all but the simplest test examples will require considerable coding by the userdeveloper. Abaquscae 2016 data sheet geometry geometry creation tools solid features extrude loft revolve. Abaqus cae 2017 data sheet geometry geometry creation tools solid features extrude loft revolve. The first step in this problem is of a duration of 5 milliseconds. Multiple temperature values are used in association with beam section points and throughthickness shell locations.
When you configure a geostatic stress field procedure, the step editor displays the basic and other tabs. Mar 23, 2007 does any one have some remarks on how can i establish equilibrium and get zero displacement out of geostatic step. I digged a vertical hole and insert the pile into that with general contact. In the first step geostatic equilibrium is obtained by applying the. Several extensions for soil mechanics purposes are discussed and corresponding case studies are presented.
In abaqus explicit elevationdependent initial stresses cannot be specified for beams and shells. No fixing of the pore pressures at the geostatic step. Enfem is able to perform planestrain, planestress, and axisymmetric analyses with an emphasis on solving problems in geotechnical engineering. Abaqus user subroutine reference manual disp, section 1. Abaqus user subroutine reference manual describes 55 different user subroutines for abaqus standard, 21 abaqus explicit subroutines, and all available utility routines 18 in detail. In lecture 4 we outline the treatment of porous media in abaqus and discuss the coupling between.
Please have a look at enclosed pdfvery interesting. Geostatic initial stresses are for use with continuum elements only. The geostatic stress state specified initially should be in equilibrium with the applied loads such as gravity and boundary conditions. This paper shows a plugin for abaqus cae that helps the user to define a tunneling, excavation and temporary structures, with support facility and other geotechnical analysis. Any help or documentation related to geostatic analyses is greatly appreciated. In this method the modes of the linear system are extracted in an eigenfrequency extraction step natural frequency extraction, section 6. Abaqus uses the initial stresses specified by the user initial conditions, typestress, geostatic as an initial guess or as a start in the process of. In the abaqus standard, we just create a step named geostatic and then set the pregeostress field. Abaqus is a general purpose finite element program. Abaqus cae also provides a set of tools in the mesh module that allow you to verify the quality of your mesh and to obtain information about the nodes and elements in the mesh.
Due to many reasons, i prefer using abaqus explicit for this simulation. Their usage, calibration, implementation, and limitations are discussed. Modeling vertical bearing capacity of pile foundation by using. A geostatic stress field procedure allows you to verify that the initial geostatic stress field is in equilibrium with applied loads and boundary conditions. Since gravity loading is defined with distributed load type bz and not with gravity load type grav, the pore fluid pressure reported by abaqus is defined as the pore pressure in. Geostatic step the goal of this step is to make sure that the system under analysis is under equlibrium state prior to analyzing it under any external effect. Geostatic stressvoid ratio saturationpore pressure loads mechanical bolt load thermal. Abaqus cae has an addon optimizer called tosca that can be used in this way.
The eulerian part is meshed with ec3d8r elements using a global mesh seed of 5 mm. Geostatic stress fields are applicable only to continuum elements. The initial geostatic stress field must be in equilibrium with the applied loads and boundary conditions. In abaqus standard any procedure that determines the initial static steadystate equilibrium conditions is suitable as the first step of the analysis. Getting started manual release notes supported platforms windowsx8664 linuxx8664.
We will start by running a simple 2d plane stress structural optimization problem. Ppt abaqus i powerpoint presentation free to view id. When a geostatic stress field is prescribed for a particular region, the stress in the vertical direction assumed to be the zdirection in threedimensional and axisymmetric models and the ydirection in twodimensional models is assumed to vary piecewise linearly with this vertical coordinate. If this parameter, the cetol parameter, and the utol parameter are all omitted in a transient analysis, fixed time increments will be used, with a constant time increment equal to the initial time increment. Overvelde december 12, 2010 introduction scripting is a powerful tool that allows you to combine the functionality of the graphical user interface gui of abaqus and the power of the programming language python. As quoted from the manual abaqus standard manual prescribed conditionsinitial conditions. Our goal is to find the optimal shape of a plate that will be clamped near one corner, and will support a load specified as a traction near another. Abaqus uses the initial stresses specified by the user initial conditions, typestress, geostatic as an initial guess or as a start in the process of getting a converged stresses for the start. Briefly describes the step by step instruction of abaqus fem package software. How to reset displacement to zero after a geostatic step. An example of adding a gui plug in to the plugins menu. For more information, see initial conditions in abaqus standard and abaqus explicit. Highperformance abaqus simulations in soil mechanics.
1150 929 727 1406 1358 66 1271 1498 1291 388 1440 305 1687 1417 280 1563 273 1341 134 1481 470 546 770 507 458 1826 1022 160 1534