Development and Verification of an Orthotropic Three-Dimensional Model with Tabulated Input Suitable for Use in Composite Impact Problems

Implementation of a Tabulated Failure Model into a Generalized Composite Material Model Suitable for Use in Impact Problems

“…An implication of a diagonal damage tensor is that loading the composite in a particular coordinate direction only leads to a stiffness reduction in the direction of the load due to the formation of matrix cracks perpendicular to the direction of the load. However, as discussed in detail in Goldberg, et al [3], in actual composites, particularly those with complex fiber architectures, a load in one coordinate direction can lead to stiffness reductions in multiple coordinate directions. To maintain a diagonal damage tensor while still allowing for the damage interaction in at least a semi-coupled sense, each term in the diagonal damage matrix should be a function of the plastic strains in each of the normal and shear coordinate directions.…”

“…While there are several material models currently available within commercial transient dynamic codes such as LS-DYNA [1] to analyze the impact response of composites, areas have been identified where the predictive capabilities of these models can be improved. These limitations have been extensively discussed in Goldberg, et al [2,3]. Of particular relevance to the current study, one major limitation of the currently existing models is that the input to these models generally consists of point-wise properties (such as the modulus, failure stress or failure strain in a particular coordinate direction) that leads to curve fit approximations to the material stress-strain curves and simplified approximations to the actual material failure surfaces.…”

“…The deformation model, described extensively in Goldberg, et al [2], is based on extending the commonly used Tsai-Wu composite failure model [4] to a strain hardening plasticity model with a non-associative flow rule. For the damage model, described extensively in Goldberg, et al [3], a strain equivalent formulation is used in which the deformation and damage calculations can be uncoupled. A significant feature in the developed damage model is that a semicoupled approach has been utilized in which a load in a particular coordinate direction results in damage (and thus stiffness reduction) in multiple coordinate directions.…”

“…A significant feature in the developed damage model is that a semicoupled approach has been utilized in which a load in a particular coordinate direction results in damage (and thus stiffness reduction) in multiple coordinate directions. This semi-coupled approach, while different from the methodology used in many existing damage mechanics models [3], has the potential to more accurately reflect the damage behavior that actually takes place, particularly for composites with more complex fiber architectures.…”

Verification and Validation of a Three-Dimensional Composite Impact Model With Tabulated Input

“…Furthermore, most of the existing models apply either a plasticity based approach (such as that used by Sun and Chen (2)) or a continuum damage mechanics approach (such as that used by Matzenmiller et al (3)) to simulate the nonlinearity that takes place in the composite response. As documented in detail by Goldberg,et al (4,5), either of these approaches can capture certain aspects of the actual composite behavior. However, optimally, combining a plasticity based deformation model (to capture the rate dependence and significant nonlinearity, particularly in shear, observed in the composite response) with a damage model (to account for the changes in the unloading modulus observed as the material is unloaded from various stress levels, as well as to account for strain softening observed after the peak stress is reached) can provide advantages over using one approach or the other.…”