Learning Forum

[Marense]

We're going to use abaqus to check a plate that's been subjected to a load. The material properties are to consist of a variety of parameters. We heard we could do this using LS-opt. However, we dont want the model to be optimized. We need the results (forece displacement stress-strain) for each type of material. Does someone know if it is possible and how we can to this?

[Ram Gopisetti]

check the responses for the selected solver,
then from these responses from ABACUS solver, find the response which can output the forces (SPCFORC in dyna) displacement and relevent stress and stain output for an element and then define a crossplot from Multihistories
from here, its a direct, this will be written out in the solver directory.
Cheers, Ram

[Imtiaz Gandikota]

It is possible. You can select DOE task and generate different stress-strain curves for different parameter combinations. You can even optimize the material model to match computed stress-strain with experimental stress-strain curves.
In terms of the setup, you need to 1. define solver settings, 2. parameterize input file, and 3. extract computed stress-strain curves.
You can use "user-defined" solver as stage package in LS-OPT. Note that ls-opt will expect N o r m a l string in standard output of the solver job to know whether a job terminated normally or not. For user-defined solvers, you can use a script as solver command. The script will run abaqus in batch mode and echo N o r m a l after the job is completed. (or) If you are using ls-opt v7.0, select "use queuing -> Simple" under remote tab and then define termination criteria in "termination" tab.
The input file can be parameterized using LS-OPT generic format i.e. any field of the input file defined using double bracket format (<>) will be read as design variable in ls-opt.
For extracting stress-strain curves, you have a few options. a. If abaqus can write the curves to a file in two column format, copy this file as "LsoptHistory" and read it in LS-OPT using "user-defined" history option. For example, say abaqus dumps a file stress.txt with two coloumns of data (stress vs time), you can go to "histories" tab and define "user-defined" history. The command in Linux will be: cp stress.txt ./LsoptHistory; cat LsoptHistory (or) b. Use GenEx tool in ls-opt to extract columns of data from ascii files. You will have one history for stress, one for strain, then use "crossplot" to create stress vs. strain. The experimental data can be imported using "File history" option (located bottom right in "history" tab).