|
Stress/Displacement Elements
Stress/displacement elements are used in the modeling of linear or complex
nonlinear mechanical analyses that possibly involve contact, plasticity, and/or
large deformations. Stress/displacement elements can also be used for
thermal-stress analysis, where the temperature history can be obtained from a
heat transfer analysis carried out with diffusive elements.
Analysis Types
Stress/displacement elements can be used in the following analysis types:
Active Degrees of Freedom
Stress/displacement elements have only displacement degrees of freedom. See
Conventions
for a discussion of the degrees of freedom in
Abaqus.
Choosing a Stress/Displacement Element
Stress/displacement elements are available in several different element
families.
Pore Pressure Elements
Pore pressure elements are provided in
Abaqus/Standard for
modeling fully or partially saturated fluid flow through a deforming porous
medium. The names of all pore pressure elements include the letter P (pore
pressure). These elements cannot be used with hydrostatic fluid elements.
Analysis Types
Pore pressure elements can be used in the following analysis types:
Active Degrees of Freedom
Pore pressure elements have both displacement and pore pressure degrees of
freedom. In second-order elements the pore pressure degrees of freedom are
active only at the corner nodes. See
Conventions
for a discussion of the degrees of freedom in
Abaqus.
Interpolation
These elements use either linear- or second-order (quadratic) interpolation
for the geometry and displacements in two or three directions. The pore
pressure is interpolated linearly from the corner nodes. Curved element edges
should be avoided; exact linear spatial pore pressure variations cannot be
obtained with curved edges.
For output purposes the pore pressure at the midside nodes of second-order
elements is determined by linear interpolation from the corner nodes.
Choosing a Pore Pressure Element
Pore pressure elements are available only in the following element family:
Coupled Temperature-Displacement Elements
Coupled temperature-displacement elements are used in problems for which the
stress analysis depends on the temperature solution and the thermal analysis
depends on the displacement solution. An example is the heating of a deforming
body whose properties are temperature dependent by plastic dissipation or
friction. The names of all coupled temperature-displacement elements include
the letter T.
Analysis Types
Coupled temperature-displacement elements are for use in fully coupled
temperature-displacement analysis (Fully Coupled Thermal-Stress Analysis).
Active Degrees of Freedom
Coupled temperature-displacement elements have both displacement and
temperature degrees of freedom. In second-order elements the temperature
degrees of freedom are active at the corner nodes. In modified triangle and
tetrahedron elements the temperature degrees of freedom are active at every
node. See
Conventions
for a discussion of the degrees of freedom in
Abaqus.
Interpolation
Coupled temperature-displacement elements use either linear or parabolic
interpolation for the geometry and displacements. The temperature is always
interpolated linearly. In second-order elements curved edges should be avoided;
exact linear spatial temperature variations for these elements cannot be
obtained with curved edges.
For output purposes the temperature at the midside nodes of second-order
elements is determined by linear interpolation from the corner nodes.
Choosing a Coupled Temperature-Displacement Element
Coupled temperature-displacement elements are available in the following
element families:
Coupled Thermal-Electrical-Structural Elements
Coupled thermal-electrical-structural elements are used when a solution for
the displacement, electrical potential, and temperature degrees of freedom must
be obtained simultaneously. In these types of problems, coupling between the
temperature and displacement degrees of freedom arises from
temperature-dependent material properties, thermal expansion, and internal heat
generation, which is a function of inelastic deformation of the material. The
coupling between the temperature and electrical degrees of freedom arises from
temperature-dependent electrical conductivity and internal heat generation
(Joule heating), which is a function of the electrical current density. The
names of the coupled thermal-electrical-structural elements begin with the
letter Q.
Analysis Types
Coupled thermal-electrical-structural elements are for use in a fully
coupled thermal-electrical-structural analysis (Fully Coupled Thermal-Electrical-Structural Analysis).
Active Degrees of Freedom
Coupled thermal-electrical-structural elements have displacement, electrical
potential, and temperature degrees of freedom. In second-order elements the
electrical potential and temperature degrees of freedom are active at the
corner nodes. In modified tetrahedron elements the electrical potential and
temperature degrees of freedom are active at every node. See
Conventions
for a discussion of the degrees of freedom in
Abaqus.
Interpolation
Coupled thermal-electrical-structural elements use either linear or
parabolic interpolation for the geometry and displacements. The electrical
potential and temperature are always interpolated linearly. In second-order
elements curved edges should be avoided; exact linear spatial electrical
potential and temperature variations for these elements cannot be obtained with
curved edges.
For output purposes the electrical potential and temperature at the midside
nodes of second-order elements are determined by linear interpolation from the
corner nodes.
Choosing a Coupled Thermal-Electrical-Structural Element
Coupled thermal-electrical-structural elements are available only in the
following element family:
Coupled Temperature–Pore Pressure Elements
Coupled temperature–pore pressure elements are used in
Abaqus/Standard
for modeling fully or partially saturated fluid flow through a deforming
porous medium in which the stress, fluid pore pressure, and temperature fields
are fully coupled to one another. The names of all coupled temperature–pore
pressure elements include the letters T and P. These elements cannot be used
with hydrostatic fluid elements.
Analysis Types
Coupled temperature–pore pressure elements are for use in fully coupled
temperature–pore pressure analysis (Coupled Pore Fluid Diffusion and Stress Analysis).
Active Degrees of Freedom
Coupled temperature–pore pressure elements have displacement, pore pressure,
and temperature degrees of freedom. See
Conventions
for a discussion of the degrees of freedom in
Abaqus.
Interpolation
These elements use either linear- or second-order (quadratic) interpolation
for the geometry and displacements. The temperature and pore pressure are
always interpolated linearly.
Choosing a Coupled Temperature–Pore Pressure Element
Coupled temperature–pore pressure elements are available in the following
element family:
Diffusive (Heat Transfer) Elements
Diffusive elements are provided in
Abaqus/Standard
for use in heat transfer analysis (Uncoupled Heat Transfer Analysis),
where they allow for heat storage (specific heat and latent heat effects) and
heat conduction. They provide temperature output that can be used directly as
input to the equivalent stress elements. The names of all diffusive heat
transfer elements begin with the letter D.
Analysis Types
The diffusive elements can be used in mass diffusion analysis (Mass Diffusion Analysis)
as well as in heat transfer analysis.
Active Degrees of Freedom
When used for heat transfer analysis, the diffusive elements have only
temperature degrees of freedom. When they are used in a mass diffusion
analysis, they have normalized concentration, instead of temperature, degrees
of freedom. See
Conventions
for a discussion of the degrees of freedom in
Abaqus.
Interpolation
The diffusive elements use either first-order (linear) interpolation or
second-order (quadratic) interpolation in one, two, or three dimensions.
Choosing a Diffusive Element
Diffusive elements are available in the following element families:
Forced Convection Heat Transfer Elements
Forced convection heat transfer elements are provided in
Abaqus/Standard
to allow for heat storage (specific heat) and heat conduction, as well as the
convection of heat by a fluid flowing through the mesh (forced convection). All
forced convection heat transfer elements provide temperature output, which can
be used directly as input to the equivalent stress elements. The names of all
forced convection heat transfer elements begin with the letters
DCC.
Analysis Types
The forced convection heat transfer elements can be used in heat transfer
analyses (Uncoupled Heat Transfer Analysis),
including cavity radiation modeling (Cavity Radiation in Abaqus/Standard).
The forced convection heat transfer elements can be used together with the
diffusive elements.
Active Degrees of Freedom
The forced convection heat transfer elements have temperature degrees of
freedom. See
Conventions
for a discussion of the degrees of freedom in
Abaqus.
Interpolation
The forced convection heat transfer elements use only first-order (linear)
interpolation in one, two, or three dimensions.
Choosing a Forced Convection Heat Transfer Element
Forced convection heat transfer elements are available only in the following
element family:
Fluid Pipe and Fluid Pipe Connector Elements
Fluid pipe elements suitable for modeling incompressible pipe flow and
fluid pipe connector elements suitable for modeling the junction between two
pipes are available in
Abaqus/Standard.
These elements have only pore pressure degree of freedom. The names of all
fluid pipe elements begin with the letters FP.
The names of all fluid pipe connector elements begin with the letters
FPC.
Analysis Types
The fluid pipe and fluid pipe connector elements can be used in the
following analyses:
Active Degrees of Freedom
The fluid pipe and fluid pipe connector elements provide primarily pore
pressure degree of freedom. See
Conventions
for a discussion of the degrees of freedom in
Abaqus.
Choosing a Fluid Pipe Element
The fluid pipe elements are available only in the following element family:
Choosing a Fluid Pipe Connector Element
The fluid pipe connector elements are available only in the following
element family:
Coupled Thermal-Electrical Elements
Coupled thermal-electrical elements are provided in
Abaqus/Standard for
use in modeling heating that arises when an electrical current flows through a
conductor (Joule heating).
Analysis Types
The Joule heating effect requires full coupling of the thermal and
electrical problems (see
Coupled Thermal-Electrical Analysis).
The coupling arises from two sources: temperature-dependent electrical
conductivity and the heat generated in the thermal problem by electric
conduction.
These elements can also be used to perform uncoupled electric conduction
analysis in all or part of the model. In such analysis only the electric
potential degree of freedom is activated, and all heat transfer effects are
ignored. This capability is available by omitting the thermal conductivity from
the material definition.
The coupled thermal-electrical elements can also be used in heat transfer
analysis (Uncoupled Heat Transfer Analysis),
in which case all electric conduction effects are ignored. This feature is
quite useful if a coupled thermal-electrical analysis is followed by a pure
heat conduction analysis (such as a welding simulation followed by cool down).
The elements cannot be used in any of the stress/displacement analysis
procedures.
Active Degrees of Freedom
Coupled thermal-electrical elements have both temperature and electrical
potential degrees of freedom. See
Conventions
for a discussion of the degrees of freedom in
Abaqus.
Interpolation
Coupled thermal-electrical elements are provided with first- or second-order
interpolation of the temperature and electrical potential.
Choosing a Coupled Thermal-Electrical Element
Coupled thermal-electrical elements are available only in the following
element family:
Coupled Thermal-Electrochemical Elements
Coupled thermal-electrochemical elements are provided in Abaqus/Standard for use in modeling battery electrochemistry.
Analysis Types
The modeling of battery electrochemistry requires full coupling of the thermal,
electrical, and electrochemical problems (see Coupled Thermal-Electrochemical Analysis). The coupling
arises from the flow of electrons and ions in the solid and electrolyte phases of the
battery and the intercalation process at the solid-liquid interphase.
You can also use these elements to perform an electrochemical analysis where the thermal
effects are ignored. This capability is available by omitting the thermal conductivity
from the material definition.
You can use the coupled thermal-electrochemical elements only in the coupled
thermal-electrochemical analysis procedure.
Active Degrees of Freedom
Coupled thermal-electrochemical elements have temperature, electrical potential in the
solid and liquid phases, and ion concentration degrees of freedom. See Conventions for a
discussion of the degrees of freedom in Abaqus.
Interpolation
Coupled thermal-electrochemical elements are provided with first-order interpolation of
the four fields; namely, temperature, electrical potential in the solid and liquid phases,
and ion concentration.
Choosing a Coupled Thermal-Electrochemical Element
Coupled thermal-electrochemical elements are available only in the following element
family:
Coupled Thermal-Electrochemical-Structural Elements
Coupled thermal-electrochemical-structural elements are provided in Abaqus/Standard for use in modeling battery electrochemistry.
Analysis Types
The modeling of battery electrochemistry allows for full coupling of the structural,
thermal, electrical, and electrochemical problems (see Fully Coupled Thermal-Electrochemical-Structural Analysis). The coupling
arises from the flow of electrons and ions in the solid and electrolyte phases of the
battery and the intercalation process at the solid-liquid interphase. The coupling to the
mechanical degrees of freedom arises from thermal effects and particle swelling during the
intercalation/deintercalation process.
You can also use these elements to perform an electrochemical analysis where the thermal
effects are ignored. This capability is available by omitting the thermal conductivity
from the material definition.
You can use the coupled thermal-electrochemical-structural elements only in the coupled
thermal-electrochemical-structural analysis procedure.
Active Degrees of Freedom
Coupled thermal-electrochemical-structural elements have displacement, temperature,
electrical potential in the solid and liquid phases, and ion concentration degrees of
freedom. The temperature degree of freedom is inactive if thermal conductivity is omitted
from the material definition. See Conventions for a
discussion of the degrees of freedom in Abaqus.
Interpolation
Coupled thermal-electrochemical-structural elements are provided with first-order
interpolation of the five fields; namely, displacements, temperature, electrical potential
in the solid and liquid phases, and ion concentration.
Choosing a Coupled Thermal-Electrochemical-Structural Element
Coupled thermal-electrochemical-structural elements are available only in the following
element family:
Piezoelectric Elements
Piezoelectric elements are provided in
Abaqus/Standard for
problems in which a coupling between the stress and electrical potential (the
piezoelectric effect) must be modeled.
Analysis Types
Piezoelectric elements are for use in piezoelectric analysis (Piezoelectric Analysis).
Active Degrees of Freedom
The piezoelectric elements have both displacement and electric potential
degrees of freedom. See
Conventions
for a discussion of the degrees of freedom in
Abaqus.
The piezoelectric effect is discussed further in
Piezoelectric Analysis.
Interpolation
Piezoelectric elements are available with first- or second-order
interpolation of displacement and electrical potential.
Choosing a Piezoelectric Element
Piezoelectric elements are available in the following element families:
Electromagnetic Elements
Electromagnetic elements are provided in
Abaqus/Standard for
problems that require the computation of the magnetic fields (such as a
magnetostatic analysis) or for problems in which a coupling between electric
and magnetic fields must be modeled (such as an eddy current analysis).
Analysis Types
Electromagnetic elements are for use in magnetostatic and eddy current
analyses (Magnetostatic Analysis
and
Eddy Current Analysis).
Active Degrees of Freedom
Electromagnetic elements have magnetic vector potential as the degree of
freedom. See
Conventions
for a discussion of the degrees of freedom in
Abaqus.
Magnetostatic analysis is discussed further in
Magnetostatic Analysis,
while the electromagnetic coupling that occurs in an eddy current analysis is
discussed further in
Eddy Current Analysis.
Interpolation
Electromagnetic elements are available with zero-order element edge–based
interpolation of the magnetic vector potential.
Choosing an Electromagnetic Element
Electromagnetic elements are available in the following element family:
Acoustic Elements
Acoustic elements are used for modeling an acoustic medium undergoing small
pressure changes. The solution in the acoustic medium is defined by a single
pressure variable. Impedance boundary conditions representing absorbing
surfaces or radiation to an infinite exterior are available on the surfaces of
these acoustic elements.
Acoustic infinite elements, which improve the accuracy of analyses involving
exterior domains, and acoustic-structural interface elements, which couple an
acoustic medium to a structural model, are also provided.
Analysis Types
Acoustic elements are for use in acoustic and coupled acoustic-structural
analysis (Acoustic, Shock, and Coupled Acoustic-Structural Analysis).
Active Degrees of Freedom
Acoustic elements have acoustic pressure as a degree of freedom. Coupled
acoustic-structural elements also have displacement degrees of freedom. See
Conventions
for a discussion of the degrees of freedom in
Abaqus.
Choosing an Acoustic Element
Acoustic elements are available in the following element families:
The acoustic elements can be used alone but are often used with a structural
model in a coupled analysis.
Acoustic Interface Elements
describes interface elements that allow this acoustic pressure field to be
coupled to the displacements of the surface of the structure. Acoustic elements
can also interact with solid elements through the use of surface-based tie
constraints; see
Acoustic, Shock, and Coupled Acoustic-Structural Analysis.
Poroelastic Acoustic Elements
Volumetrically coupled poroelastic acoustic elements (or simply poroelastic
elements) are used for modeling porous media undergoing small displacement and
small pressure changes. The solution is defined by displacements and pressure
variables. Interface boundary conditions connecting the poroelastic to
poroelastic elements, poroelastic to elastic elements, and poroelastic to
acoustic elements are available using surface-based tie constraints.
Analysis Types
Poroelastic elements are used in acoustic and coupled acoustic-structural
analysis (Acoustic, Shock, and Coupled Acoustic-Structural Analysis).
They are available only in direct steady-state dynamic linear perturbation
procedures.
Active Degrees of Freedom
Poroelastic elements have translational displacements and acoustic pressure
degrees of freedom as primary variables. See
Conventions
for a discussion of the degrees of freedom in
Abaqus.
Choosing a Poroelastic Acoustic Element
Poroelastic elements are available only in the following element family:
Poroelastic elements can be used alone but are often used with a structural
and acoustic model in a coupled analysis. Only first-order interpolation
elements for both displacements and pressure are available.
Using the Same Mesh with Different Analysis or Element Types
You may want to use the same mesh with different analysis or element types.
This may occur, for example, if both stress and heat transfer analyses are
intended for a particular geometry or if the effect of using either reduced- or
full-integration elements is being investigated. Care should be taken when
doing this since unexpected error messages may result for one of the two
element types if the mesh is distorted. For example, a stress analysis with C3D10 elements may run successfully, but a heat transfer analysis using
the same mesh with DC3D10 elements may terminate during the
datacheck portion of the analysis with an error
message stating that the elements are excessively distorted or have negative
volumes. This apparent inconsistency is caused by the different integration
locations for the different element types. Such problems can be avoided by
ensuring that the mesh is not distorted excessively.
|