Isogeometric Analysis for the Prediction of Damage and Residual-Strength in Laminated Composite Structures

摘要

The concept of the Isogeometric Analysis (IGA) is adopted in the framework ofstructural analysis, where the Kirchhoff-Love theory is used for the development ofefficient shell elements for the simulation of full scale components. The proposedmulti-layer modeling approach consists of the representation of composite laminatesat the level of individual plies, or group of similar plies, connected through cohesiveinterfaces. The novel cohesive interface formulation, which is specifically developedto be used in combination with thin shell elements, is equipped with a Mixed-ModeCohesive Model (MMCM) in order to predict the onset and the propagation of thedelamination.The interlaminar damage, such as matrix cracking, fiber breaking and pullout, aremodeled at the lamina level by degrading the pristine elastic properties of the material.This methodology introduces mesh-dependency and damage localization. A nonlocaldamage model is therefore investigated in order to alleviate the dependency ofthe solution with respect to the adopted discretization.The formulation is validated through the correlation with an experimental testfrom the literature. The model aims to simulate the damage caused by a low-velocityimpact on a flat composite coupon. The richness of the isogeometric design-toanalysisconcept is then illustrated. A commercial NURBS-based CAD softwareis used to create the multi-layer model of a reinforced composite panel typical ofaerospace structures. The IGA analysis framework is then used to predict the damagecaused by a mid-energy impact.It is found that the higher-order continuity of the NURBS shape functions translatesinto a better representation of the strains, which drive the intralaminar damagemodel, and of the displacement jumps in the area of the delamination front, whichdrive the MMCM. Therefore, IGA simulations remain stable and accurate at lownumber of DOFs even when severe intralaminar damage and delamination occurs.