Date of Award

Spring 2022

Document Type

Open Access Dissertation


Mechanical Engineering

First Advisor

Zafer Gürdal


The objective of the work presented in this thesis is to propose and validate a numerical solution to quantify the influence of Automated Fiber Placement (AFP) induced defects on the mechanical behavior of conventional composite laminates in fatigue. The work presented here will be divided in six sections. At first, a description of the Automated Fiber Placement process and its associated defects is proposed. In association, two tools developed for a rapid analysis and a progressive damage analysis respectively are discussed and used as an introduction to the work conducted in this thesis. In the second section, an extensive literature review on AFP defects, their influence on the quasi-static behavior of conventional composite laminates, and as well as their influence in fatigue is conducted. Then, the third section of this document mainly focuses on AFP induced defects and two potential modeling approaches: a "simple" model versus an "advanced" modeling solution. The modeling approaches presented in the previous section are put to the test within the following two sections of this document. Section four of this thesis focuses on the modeling and simulation of the influence of AFP induced defects on quasi-static tensile test of Open Hole specimens to identify critical configurations to be used for the analysis in fatigue. The following portion of this document is dedicated to the presentation of the modeling approach and the results of fatigue analysis on configurations identified in the quasi-static portion of the work conducted. Finally, the last section presents the implementation of a new capability to incorporate a stochastic representation of the material properties in a progressive damage analysis tool. This allows for a propagation of uncertainty from the material level to the number of cycles to failure.