Learning Forum

[euklidespl]

Hi.

1) I dont have experemental data from tensile test so I performed a simulation of a tensile test of a sheet metal piece. 

2) I used the material model "mat power plasticity" 018 with the parameter k = 530 and the parameter n = 0.26.

3) After performing the simulation of the tensile test of a sheet metal piece, I saved the Huber-Von Mises stress graph in the txt file format. I called this graph "stress-time" - it is a graph, one could say, a reference-target graph, i.e. a reference graph that is aimed at.

 I want the OptisLang program to find the correct value of the parameter "n" (the correct value, i.e. the reference value is 0.26) starting from the value 0.2. I got stuck in a place called "Ls extractor definition".

Another question is the stress vs. time graph created in ls-prepost (txt format) is correct ? I mean correct format data ? 

Is Von Mises stress vs. time graph is good for "histories" and "responses" ?

 

[Marco Grosse]

Hi euklidespl,

the LS-Extractor tool can be used to extract histories (signals: values over time) or scalar Responses from LS-DYNA binary result files (eg. d3plot, binout). To be able to define a senseful result extraction from such binary files you must know what is stored in those files. Unfortunately, you cannot see the file content within that LS-Extractor dialog. Please have a look at the LS-DYNA help for Keywords *DATABASE_ and *DATABASE_BINARY to learn more about binary output files and possible content. Or use LS-PREPOST to control the content of the binary files. Please note, the LS-DYNA-Output-node (or LS-Extractor) cannot be used to read TXT or ASCII files.

The LS-DYNA-Output-node (or LS-Extractor) is automatically added when using the Solver Wizard to enable a response extraction without the need to integrate a LS-PREPOST or any other postprocessing tool. But if you like you can replace the LS-DYNA-Output-node with a batch node (eg. to start LS-PREPOST with a command file writing specific results to TXT files as you described) followed by ETK-node (to read the content from that TXT file). With ETK node you are free to adapt the given TXT file format (delimiter, number of columns, length of columns, …).

For running LS-PREPOST in batch please see How execute an LS-PrePost command file? | Ansys Knowledge or in the Ansys LS-DYNA help: LS-PREPOST | Commands. Please read in the optiSLang user’s guide how to use the ETK node: ETK. Please read the section “Plain text files”.

Best regards

Marco

[euklidespl]

Hi Marco, 

Thank you for your answer. So, if Ls-Extractor cant read txt file my stress history file should be in csv format file ?  

If I want to fit "n" parameter using reference stress (von mises) time history (not in txt format file)  what data  I should chose in "history" window and what I data I  should chose  in  "response" window ?