Simulation Of The Impact Damage Characteristics Of Composite Laminates For Aerospace Applications

Structures and structural components of aircrafts are presently made with large proportion of composite materials due to their exceptional high material properties.Indisputably,composites have become the material of choice in the 21 st century for efficient and innovative design in aero-structures.However,these materials are vulnerable to impact and induced damage substantially which reduces the residual mechanical performance and safeservice life of the composite structures.In this dissertation,a finite element model based on continuum damage mechanics is developed to study the damage formation and behavior of composite component in aircraft structure under transverse loading.A commercial finite element solver ABAQUS/Explicit version 6.11 was used for the 3D structural design.Hashin criteria as well as gradual or sudden degradation schemes were adopted to predict intra-laminar damage initiation and evolution;whiles interface constitutive model was employed to predict the inter-laminar delamination induced by impact loading conditions.A user-material subroutine VUMAT involving these constitutive models of intra-laminar and inter-laminar damages were coded and implemented in the finite element package ABAQUS/Explicit.Numerical results show that the damage models vary with respect to the properties of the material to be degraded under a specific damage mode.Numerical results of impact damage responses of intra-laminar behavior and interface delamination as well as damage formulations for different impact energy levels were detail discussed.The damage assessment was also introduced to compare the failure modes of composites laminates under different impact energy thresholds.The impact resistance and damage characteristics of composite laminates under low and high velocities were also analyzed.In all models,when prediction results were compared with physical test,an acceptable match was observed validating the efficiency and applicability of the proposed models.This study has comprehensively deepens understanding of impact damage behavior and performance of composite aero-structures.Finally,the dissertation results could be used by engineers and researchers to improve and optimize the design processes of composite materials in the automobile and aviation structural applications.