| Research was completed to characterize the root behavior of the LS-DYNA MAT54 composite orthotropic material model. This primarily involved investigating the constitutive relations, ply failure (damage onset), ply deletion, damage factors, and element deletion. A single shell element under uniaxial tensile and compressive loading was employed to isolate MAT54 behavior for three different idealized laminates. Simulation results were compared against expected behavior from published material properties and experimental testing. A parametric study was also conducted to confirm the behavior of all other MAT54 inputs. Overall the LS-DYNA MAT54 material model adequately predicted Unidirectional (UD), cross-ply, and fabric laminate behavior for the majority of cases. However, results showed pronounced plasticity when the strength-based Chang-Chang ply-failure criteria was reached prior to the strain-based ply-deletion parameters. This led to significant energy and failure strain errors in some cases. |
