LS-OPT is widely used to optimize designs or parameters using a number of experiments obtained by running LS-DYNA simulations. The number of experiments (simulations) per iteration is dependent on the number of variables defined in LS-OPT in addition to the type of point-selection (DOPT, LatinHyperCube, etc). When a large number of simulations are involved, it…
LSTC has introduced a free limited LS-DYNA version for U.S. unemployed LS-DYNA users as a result of the current poor economic conditions. A free LS-DYNA course may also be introduced in the coming months. Please contact Marsha Victory at 925 449 2500 or send her an email at marsha@lstc.com.
In LS-OPT, one can run a multi-disciplinary optimiztion or a multi-solver type optimization problem, where the variables can be shared among the different solvers. In performing DOE or any optimization using LS-OPT, it is important that consistent experimental points are used in the evaluations. To ensure this, one can use solver experiment duplicate solver_1 command…
In a previous post about a simple Python script that scans a LS-DYNA input file to package all INCLUDED files recursively so the entire model can be compressed and sent to the recipient. Based on some new suggestions, largely by Brian Wainscott, I have attached a revised script that handles the included files a little…
TIED contacts help “bond” two surfaces of different mesh densities. When using the default constraint method, the projection distance of the slave node onto to the closest master segment must be zero and this is achieved by LS-DYNA by updating the slave node coordinates such that it lies on the master surface. This coordinate update…
Material parameter identification of GURSON material requires a process of fitting using an optimization package such as LS-OPT to match against a measured response such as a test. Following is a stress-strain curve that is achieved as a process of parameter identification using LS-OPT and LS-DYNA.
In cases where a monotonically increasing curve such as pressure_vs_leakage in *AIRBAG or effective_stress_vs_effective_strain in plasticity models in *MAT are to be parametrically identified by an optimization software such as LS-OPT to match against a physical test, it is important to ensure that the points identified by LS-OPT satisfy the non-negative slope. To satisfy this,…
It is common to perform a uni-axial tensile test on a material sample to generate stress-strain curve for use in numerical models in LS-DYNA. The problem frequently encountered by analysts is the cleaning of the test data that is usually noisy. I recently wrote a small Python utility that takes any test generated force-deflection curve…
In older versions of LS-DYNA (950 and lower) , when mass-scaling was active and over the course of the simulation when the percentage of added mass was greater than ENDMASS in *CONTROL_TERMINATION , LS-DYNA would terminate that job with no additional message. However, recent versions of LS-DYNA terminate the job AND provide a list of…
In these days, a finite element model consists of several INCLUDE files either relative or absolute. When collaborating with other people, it is very difficult to remember sending the included files and also if we do remember, it is cumbersome if not difficult to find them and zip them as one file. I recently encountered…
