Date of Award

Spring 2023

Document Type

Open Access Dissertation

Department

Mechanical Engineering

First Advisor

Ramy Harik

Abstract

Process planning represents an essential stage of the Automated Fiber Placement (AFP) workflow. It develops useful and efficient machine processes based upon the working material, composite design, and manufacturing resources. The current state of process planning requires a high degree of interaction from the process planner and could greatly benefit from increased automation. Therefore, a list of key steps and functions are created to identify the more difficult and time-consuming phases of process planning. Additionally, a set of metrics must exist by which to evaluate the effectiveness of the manufactured laminate from the machine code created during the Process Planning stage.

Layup strategies, in addition to dog ears, stagger shifts, steering constraints, and starting points, represented the group of functions labeled as process optimization and ranked the highest in terms of priority for automation. The laminates resulting from the selected parameters are evaluated through the occurrences of principal defect metrics such as fiber gaps, overlaps, angle deviation and steering violations.

This document presents an automated software solution to the layup strategy and starting point selection phase of process planning. A series of ply scenarios are generated with variations of these ply parameters and evaluated according to a set of metrics entered by the Process Planner. These metrics are generated through use of the Analytical Hierarchy Process (AHP), where relative importance between each of the fiber features are defined. The ply scenarios are selected which reduce the overall fiber feature scores based on the defects the Process Planner wishes to minimize.

An extensive evaluation of the ply scoring algorithms was performed with various tool surfaces. The evaluation provided insight into the interaction of the different layup strategies and the underlying geometry of the tool surface. Additionally, the relationship of the various fiber defects with the tool surface curvature were also investigated.

Furthermore, the document covers the incorporation of inspection data for the validation of fiber defect predictions, in addition to a new laminate evaluation tech-nique which begins to consider how undesirable features within the composite may interact through the thickness of the laminate. Utilizing the in-depth understanding of fiber path generation with the evaluation methods within CAPP, a new dynamic layup strategy is devised which considers the assigned relative importance of various defect types to take some of the guess work out of layup strategy selection, which can be a challenging task when complex tool geometry is involved.

Rights

© 2023, Joshua Allen Halbritter

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