LS-DYNA3D is an easy to use yet sophisticated multi-physics
analysis tool for highly nonlinear dynamic problems.
It is a 3-D finite element analysis (FEA)-based code
that uses an explicit time integration scheme (Central
Difference Method). Explicit integration enables the
solution at time (t+dt) to be based on equilibrium conditions
at time (t) rather than (t+dt). This means there is
no factorization of stiffness matrices at each time
step, which greatly reduces both solution time and hard
disk usage, and limits model sizes. Engineers involved
with virtually any large deformation or contact/impact
problem will appreciate LS-DYNA3D's robustness.
Model generation can be done totally within the Finite
Element Model Builder (FEMB) preprocessor or in conjunction
with imported IGES, DXF, or NASTRAN files. Interfacing
is also available with ANSYS, I-DEAS PATRAN, etc. FEMB
is CAD-like and allows the user to generate 3-D wireframes
and surfaces, nodes, elements, and contacting interfaces.
Models of up to 100,000 elements can be developed with
FEMB. Necessary data such as material properties, element
real constants, and boundary conditions can be fully
assigned. FEMB provides selective control over the model
by enabling the user to designate part names to any
section or component. Features can be toggled on/off
through part-name control or by material property, element
sets, interfaces, etc.
Coupling of LS-DYNA3D's extensive element library with
a host of interface types to more than 30 standard and
advanced material models provides the user with a wide
range of solutions. Once model generation is completed,
the user saves the model in a database file and LS-DYNA3D
input deck. Dialog boxes prompt the user to specify
problem title, solution end time, type, and output interval
times for writing time history data, restarts, etc.
These boxes were structured with keyword abbreviations
that I often found awkward, forcing me to refer to the
on-line documentation outside of FEMB for explanation.
Proper selection of the time step size is critical
for stability and accuracy of the integration scheme
since the Central Difference Method is only conditionally
stable. Dynamic programs without auto-time stepping
controls require the user to perform a modal analysis
to establish a suitable (dt). LS-DYNA3D eliminates this
burden from the user. It automatically computes the
critical time step based on the highest frequency of
all elements within the model.
After the solution is obtained, the user returns to
FEMB to begin post processing the results. FEMB's post
processor is very simple to use and conveniently structured.
It performs animation of deformed shapes in wireframe
form, rendered form, and shaded surfaces with stress/strain
contours. The user has total control over which time
steps will be animated. He or she can also freeze the
model at a specified time step for contouring the results,
for example, at the initiation of contact between parts.
Section cuts can be made to the model for a review of
responses through the structure's thickness. Also, by
importing time history results, the user can plot selected
time-dependent responses such as velocities with impressive
LS-DYNA3D is geared toward large deformation behavior
involving nonlinear structural dynamics. It is impossible
to discuss the full wealth of LS-DYNA3D's extensive
element formulations, material models, and coupled physics
capabilities here. Although a few quirks were discovered
with LS-DYNA3D operating in Windows 95, I was impressed
with its robustness, speed and performance of its solver,
and ease of use. I recommend LS-DYNA3D to engineers
faced with nonlinear structural problems in automotive,
aircraft, transportation, research, and defense industries.
LS-DYNA3D is available for use with 486 or Pentium
PCs, Unix workstations, supercomputers, and other platforms.
Minimum requirements for a 486 or Pentium system: Windows
95 or NT, 16 Mbytes RAM, 500 Mbytes hard drive space,
an NE 2000-compatible network card, and an SVGA display
adapter with 800x600 resolution and 1 Mbyte RAM.
KBS2 Inc., 455 S. Frontage Rd., Suite 112, Burr Ridge,
IL 60521; ph: (630) 850-7878; fax: (630) 850-9455;e-mail:firstname.lastname@example.org
Livermore Software Technology Corp., 2876 Waverly Way,
Livermore, CA 94550; ph: (510) 449-2500; fax: (510)
A similar product:
MSC NASTRAN -- The MacNeal Schwendler Corp., 815 Colorado
Blvd., Los Angeles, CA 90041; ph. (213) 258-9111; fax: