Integration rule for 2D plane stress element

- June 30, 2025 at 5:57 pm
  
  sockalin
  Subscriber
  
  Hello,
  I am trying to understand what specific in-plane integration rule is used for 2D plane stress element (elform = 12) in LS-DYNA? Single point quadrature? Full quadrature? or?
  Thanks.
- July 1, 2025 at 12:41 pm
  
  Ram Gopisetti
  Ansys Employee
  
  Hi,
  Based on the NIP value given in *SECTION_SHELL, for a 2D plane stress element in LS-DYNAelform = 12, single-point quadrature (i.e., reduced integration) is used for in-plane integration by default. The NIP parameter, which controls the number of in-plane integration points, only supports full integration (e.g., 2×2 Gaussian quadrature) for elform = 13 and elform = 15. Therefore, elform = 12 does not support full in-plane integration via the NIP parameter and uses reduced (single-point) integration.
  Also, elfrom 12 is seldom used as it is similar to standard shell elements in 3D
  Cheers, Ram