The explicit solution method is a true dynamic procedure originally
developed to model high-speed impact events in which inertia plays a dominant
role in the solution. Out-of-balance forces are propagated as stress waves
between neighboring elements while solving for a state of dynamic equilibrium.
Since the minimum stable time increment is usually quite small, most problems
require a large number of increments.
The explicit solution method has proven valuable in solving quasi-static
problems as well—Abaqus/Explicit
solves certain types of static problems more readily than
Abaqus/Standard
does. One advantage of the explicit procedure over the implicit procedure is
the greater ease with which it resolves complicated contact problems. In
addition, as models become very large, the explicit procedure requires fewer
system resources than the implicit procedure. Refer to
Comparison of implicit and explicit procedures
for a detailed comparison of the implicit and explicit procedures.
Applying the explicit dynamic procedure to quasi-static problems requires
some special considerations. Since a static solution is, by definition, a
long-time solution, it is often computationally impractical to simulate an
event in its natural time scale, which would require an excessive number of
small time increments. To obtain an economical solution, the event must be
accelerated in some way. The problem is that as the event is accelerated, the
state of static equilibrium evolves into a state of dynamic equilibrium in
which inertial forces become more dominant. The goal is to model the process in
the shortest time period in which inertial forces remain insignificant.
Quasi-static analyses can also be conducted in
Abaqus/Standard.
Quasi-static stress analysis in
Abaqus/Standard
is used to analyze linear or nonlinear problems with time-dependent material
response (creep, swelling, viscoelasticity, and two-layer viscoplasticity) when
inertia effects can be neglected. For more information on quasi-static analysis
in
Abaqus/Standard,
see
Quasi-static analysis.