Executive Summary : | The proposed research aims to study mechanical damage in fiber reinforced laminated composite materials using a multicontinuum theory (MCT). Laminated composites have gained importance in aerospace and civil engineering structures due to their structural and functional properties. The research aims to investigate the damage mechanisms, evolutions, and stiffness degradation of these materials to facilitate damage-tolerant design. Several models have been proposed in the literature, but most are limited to small-strain theories and large deformation damage models. The proposed research employs MCT to study the intrinsic geometry of laminated composites and derive three damage variables: matrix and fiber, and the interaction between them (delamination). The developed theoretical model will require numerical analysis to obtain results under simple loading conditions. The proposed model will be implemented using Abaqus/standard, with an in-house 'umat' subroutine. The predictions from this semi-analytical model will be verified through experiments. The stiffness degradation will be investigated for undamaged and artificially damaged laminated composites under uniaxial tension, compression, and shear loading. A vibration-based technique will be used to characterize the damage content in the sample, and vibration deflection shapes will be analyzed instead of traditional mode shapes for better accuracy. |