GISSMO card for 1D Beam elements : ELFORM 1
PRATHAMESH DEHADRAY
Has anyone worked on GISSMO material for 1 D beams ?
James Kennedy
Dear Prathamesh,
Some notes taken from an AI Overview,
GISSMO (Generalized Incremental Stress-State dependent damage MOdel) can be used for 1D beams in LS-DYNA, but it requires careful consideration of how to represent the beam's behavior and how to define the material parameters. The key is to understand that while GISSMO is often associated with shell and solid elements, it can be adapted for 1D elements like beams by defining the material properties and failure criteria appropriately.
Here's a breakdown of how to use GISSMO with 1D beams in LS-DYNA:
1. Choose the appropriate element type:
For beams, you'll typically use *SECTION_BEAM or *SECTION_SHELL elements, depending on the desired level of detail and complexity.
When using shell elements, you'll need to define the shell thickness and material orientation.
2. Select the material model:
Use *MAT_ADD_EROSION to activate the GISSMO damage model.
Within *MAT_ADD_EROSION, set IDAM=1 to activate the damage model and DMGTYP=1 to accumulate damage and define element failure at D=1.
You'll also need to define the material's constitutive behavior (e.g., plasticity, strain rate dependency) using other material models like *MAT_PIECEWISE_LINEAR_PLASTICITY.
3. Calibrate GISSMO parameters:
GISSMO parameters, such as damage exponent (DMGEXP), fading exponent (FADEXP), and load curves (LCSDG and ECRIT), need to be calibrated based on experimental data.
This often involves using experimental tests (e.g., tensile tests, notched tensile tests) to determine stress-strain curves and failure strains under different stress triaxiality conditions.
LS-OPT can be used to optimize these parameters.
4. Define failure criteria:
GISSMO defines failure based on damage accumulation and the equivalent plastic strain.
The critical equivalent plastic strain (ECRIT) vs. triaxiality curve is crucial for defining failure.
When damage (D) reaches 1, the material is considered failed, and stress is reduced to zero.
5. Account for cross-sectional properties:
For 1D elements, the cross-sectional area and other geometric properties must be defined in the section definition (*SECTION_BEAM or *SECTION_SHELL).
These properties are essential for accurate stress and strain calculations within the beam element.
6. Consider mesh refinement:
Fine mesh is crucial for capturing localized damage and failure, especially near stress concentrations or where material behavior changes rapidly.
However, mesh refinement can also increase computational cost.
*In summary, using GISSMO with 1D beams involves activating the damage model within MAT_ADD_EROSION, defining the material's constitutive behavior, calibrating the GISSMO parameters based on experimental data, and ensuring accurate cross-sectional properties are defined for the beam element.
Sincerely,
James M.. Kennedy
KBS2 Inc.
July 17, 2025
--
You received this message because you are subscribed to the Google Groups "LS-DYNA2" group.
To unsubscribe from this group and stop receiving emails from it, send an email to
ls-dyna2+u...@googlegroups.com.
To view this discussion visit
https://groups.google.com/d/msgid/ls-dyna2/a8b3dff1-0259-461a-aee7-a320f32abc6dn%40googlegroups.com.