April 8, 2024 at 4:16 am
Puneeth Bagaria
Ansys Employee

Hello, 

A shell element may have multiple integration points through thickness defined under *SECTION_SHELL > NIP. The output of "upper" and "lower" Ipt strains correspond to strains in these integration points. 

The default integration scheme in LS-DYNA is gaussian which does not place integration points on the top and bottom surface of the shell element. Hence, they are not really the strains at top and bottom surfaces. You may refer to *SECTION_SHELL description in LS-DYNA manual volume-1 for more details on thickness integration.

Also, please refer to Shell Strain — Welcome to the LS-DYNA support site for a general overview of strain output for shell elements.

 

Regards

Puneeth