Civil Engineering Reference
In-Depth Information
5.6.2.3 Sequentially Coupled Thermal-Stress Analysis
A sequentially coupled heat transfer analysis available in ABAQUS [1.29] is
used when the stress/deformation field in a structure depends on the tem-
perature field in that structure, but the temperature field can be found
without knowledge of the stress/deformation response. The analysis is
usually performed by first conducting an uncoupled heat transfer analysis
and then a stress/deformation analysis. The analysis is a thermal-stress
analysis in which the temperature field does not depend on the stress field.
Nodal temperatures are stored in ABAQUS as a function of time in the
heat transfer results (.fil) file or output database (.odb) file. The tempera-
tures are read into the stress analysis as a predefined field; the temperature
varies with position and is usually time-dependent. It is predefined because
it is not changed by the stress analysis solution. Such predefined fields are
always read into ABAQUS (Standard) at the nodes. They are then in-
terpolated to the calculation points within elements as needed. The tem-
perature interpolation in the stress elements is usually approximate and one
order lower than the displacement interpolation to obtain a compatible
variation of thermal and mechanical strain. Any number of predefined
fields can be read in, and material properties can be defined to depend
on them.
Appropriate initial conditions for the thermal and stress analysis
problems are described in the heat transfer and stress analysis sections.
Appropriate boundary conditions for the thermal and stress analysis prob-
lems are described in the heat transfer and stress analysis sections. Also,
appropriate loading for the thermal and stress analysis problems is
described in the heat transfer and stress analysis sections. In addition to
the temperatures read in from the heat transfer analysis, user-defined field
variables can be specified; these values only affect field-variable-
dependent material properties. The materials in the thermal analysis must
have thermal properties such as conductivity defined. Any mechanical
properties such as elasticity will be ignored in the thermal analysis, but
they must be defined for the stress analysis procedure. Thermal strain will
arise in the stress analysis if thermal expansion is included in the material
property definition. Any of the heat transfer elements in ABAQUS
(Standard) can be used in the thermal analysis. In the stress analysis, the
corresponding continuum or structural elements must be chosen. For
continuum elements, heat transfer results from a mesh using first-order
elements can be transferred to a stress analysis with a mesh using
second-order elements.
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