Author

Zhennan He

Date of Award

12-2020

Document Type

Thesis - Open Access

Degree Name

Master of Science in Aerospace Engineering

Department

Aerospace Engineering

Committee Chair

Dr. Mandar Kulkarni

First Committee Member

Dr. Marwan Al-Haik

Second Committee Member

Dr. David J. Sypeck

Abstract

Low-velocity impact (LVI) on composites may cause Barely Visible Impact Damage (BVID), which is one of the most common damage types and may result in a decrease in strength of the composite. The objectives of this research were (a) to identify the characteristics of a carbon/epoxy composite plate after low-velocity impact, (b) to create a validated model to simulate the impact process and progressive failure, and (c) to perform sizing and shape optimization of the laminate for improving the damage resistance of the plate. As a part of this thesis, composite plates were fabricated using carbon fiber reinforced polymer (CFRP) prepreg. The LVI testing was performed on the samples with different impactors and different impact energy levels. The X-Ray Micro-tomography technique helped to reveal the internal fiber damage and matrix damage of the impacted plate. Numerical models with nonlinear dynamic responses were developed in ABAQUS, which validated the LVI experiments. Further, the modified model was created in MSC. PATRAN/NASTRAN to optimize the ply thickness, ply orientation, and dimensional properties of the plate to minimize the weight while abiding by the structural response constraints. Moreover, the possibility of the OpenMDAO framework in nonlinear dynamic analysis and size optimization was explored.

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