Isogeometric Analysis of Damage and Residual-Strength in Aerospace Composite Structures Subjected to Low-Velocity Impact

摘要

multi-layered shell modelling approach is developed in the framework of theIsogeometric Analysis (IGA), based on a higher-order accurate and higher-ordercontinuous Non-Uniform Rational B-Splines (NURBS), which allows us to adopt acomputationally efficient rotation-free shell formulation.The proposed model is capable of predicting the interlaminar damage modes suchas delamination, and the intralaminar damage modes such as matrix cracking due totransverse shear stress and fiber breaking. The IGA shell layers, which represent asingle lamina or a groups of lamina, are connected through cohesive interfacesgoverned by local traction-separation laws. The intralaminar elasto-plastic damageresponse and the in-plane damage modes related to tension, compression and shear,are evaluated layer by layer at the level of each ply.Two numerical examples are shown. The End-Notched Flexure (ENF) test is firstpresented as a benchmark case to validate the cohesive-interface formulation. Then, asimple low-velocity impact scenario is considered. The smoothness of the NURBSshell discretization is shown to be beneficial for the penalty formulations adopted forboth the cohesive interface and contact with the impactor. Also, due to the higheraccuracygeometry and solution representation enabled via NURBS basis functions, itis found that with the proposed IGA approach, issues that typically affect impactproblems, such as through-thickness element distortion/inversion which may causeaccuracy loss, shortening of time steps, and numerical instability/crashing of the code,are often circumvented.