Implementing deformation, damage, and failure in an orthotropic plastic material model

Abstract

Theoretical and implementation details of an orthotropic plasticity model are presented. The model is comprised of three sub-models dealing with elastic and inelastic deformations, damage, and failure. The input to the three sub-models involves tabulated data that can be obtained from laboratory and/or virtual testing. In this article, the focus is on the development of the failure sub-model and its links to the other components. Details of how the user-selected failure criterion is used, and what steps are implemented post-failure are presented. The well-known Puck failure criterion is used in the numerical examples. Three validation tests are used to illustrate the strengths and weaknesses of the failure sub-model—10°, 15°, and 30° off-axis tests, a stacked-ply test carried out at room temperature under quasi-static loading, and finally, a high-speed impact test. Results indicate that while the deformation and damage sub-models give reasonably accurate results, the failure predictions are a huge challenge especially for high-speed impact tests.

Improving failure sub-models in an orthotropic plasticity-based material model

“…For the sake of brevity, details of the convergence analyses used in generating the optimal mesh (one that balances accuracy and computational cost) for the impact validation test are not presented here but can be found in Hoffarth et al 9 In the impact validation tests, cohesive zone elements (CZE) have been used for modeling the delamination behavior and the details can be found in an earlier publication. 19 PFC Parameters: The same input parameters used in our previous research 3…”

“…The implementation of PFC in MAT_213 has been discussed in an earlier publication. 3 The failure modes are used to predict the failure onset in the finite element. Furthermore, a stress degradation model (SDM) which gradually degrades the material behavior after failure onset, and ultimately predicts when element erosion needs to take place, is used.…”

“…The grey colored regions represent the portion of the specimen which were tabbed using glass fiber tabs and gripped in the test fixture. 3,27 Finite Element Modeling: The tabbed regions in the specimen were excluded from the finite element model to create a computationally efficient model. Figure 9 shows the FE models with the fine mesh used for the stacked-ply validation tension test (SPVTT) and stacked-ply compression validation test (SPVCT).…”

“…An orthotropic elasto-plastic damage material model suitable for impact analysis of composite materials has been developed through a joint research project funded by the Federal Aviation Administration and the National Aeronautics and Space Administration. [3][4][5][6] The material model is implemented into LS-DYNA 7 as MAT_ COMPOSITE_TABULATED_PLASTICITY_ DAMAGE, also known as MAT_213. MAT_213 is a constitutive model with a modular architecture comprised of three sub-models -deformation, damage and failure.…”

“…In an earlier work, 3 the well-known Puck Failure Criterion (PFC) was discussed, verified and validated. PFC was implemented as a part of the failure submodel in MAT_213.…”