Civil Engineering Reference
In-Depth Information
provided in ABAQUS (Explicit) has some important advantages including
the following:
(1) The analysis cost rises only linearly with problem size, whereas the cost
of solving the nonlinear equations associated with implicit integration
rises more rapidly than linearly with problem size. Therefore, ABAQUS
(Explicit) is attractive for very large problems.
(2) The explicit integration method is often more efficient than the implicit
integration method for solving extremely discontinuous short-term
events or processes.
(3) Problems involving stress wave propagation can be far more efficient
computationally in ABAQUS (Explicit) than in ABAQUS (Standard).
(4) In choosing an approach to a nonlinear dynamic problem, modelers
must consider the length of time for which the response is sought
compared to the stability limit of the explicit method; the size of the
problem; and the restriction of the explicit method to first-order,
pure displacement method or modified second-order elements.
In some cases, the choice is obvious, but in many problems of practical
interest, the choice depends on details of the specific case.
Direct-solution procedures must be used for dynamic analyses that
involve a nonlinear response. Modal superposition procedures are a cost-
effective option for performing linear or mildly nonlinear dynamic analyses.
The direct-solution dynamic analyses procedures available in ABAQUS
include the following:
(1) Implicit dynamic analysis, in which implicit direct-integration dynamic
analysis is used to study (strongly) nonlinear transient dynamic response
in ABAQUS (Standard).
(2) Subspace-based explicit dynamic analysis, in which the subspace projec-
tion method in ABAQUS (Standard) uses direct, explicit integration of
the dynamic equations of equilibrium written in terms of a vector space
spanned by a number of eigenvectors. The eigenmodes of the system
extracted in a frequency extraction step are used as the global basis vec-
tors. This method can be very effective for systems with mild nonline-
arities that do not substantially change the mode shapes. However, it
cannot be used in contact analyses.
(3) Explicit dynamic analysis, in which explicit direct-integration dynamic
analysis is performed in ABAQUS (Explicit).
(4) Direct-solution steady-state harmonic response analysis, in which
thesteady-stateharmonicresponseofasystemcanbecalculatedin
ABAQUS (Standard) directly in terms of the physical degrees of
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