### 2.2.8. Limitations & Recommendations

Interlaminar shear strains of linear triangular shell elements can not be evaluated. Interlaminar shear stresses of linear triangular shell elements can be evaluated by ANSYS but not by ACP. By default, the ANSYS .RST results file contains stress and strain data, however, they may be excluded. In the case of excluded stresses and strains, ACP can evaluate stresses and strains on the basis of the deformation and rotation fields in the results file. Nonlinear effects are not considered by ACP and can induce inaccurate stresses and strains. In general, it is recommended to include the stress and strain data in the .RST data. More information can be found in Solutions.

ACP provides a unique method to evaluate interlaminar normal stresses (INS) for shell elements. This calculation of the INS requires the evaluation of the shell curvature. It is therefore recommended to use quadratic shell elements when INS are of interest. The quadratic elements contain the curvature information per element and offer a better approximation than linear elements. The curvature for a linear shell element is determined from its neighboring elements. This evaluation does not consider INS induced by edge effects or out-of-plane loads (e.g. inserts, pressures, etc.).

Release 18.2 - © ANSYS, Inc. All rights reserved.