Title
Enhanced characterization of tow gaps in fiber steered laminates: Advanced specimen design for better representation of defects in structures
Author
Czél, László (TU Delft Aerospace Engineering)
Contributor
Peeters, D.M.J. (mentor) 
Castro, Saullo G.P. (mentor)
Degree granting institution
Delft University of Technology
Programme
Aerospace Engineering | Structures and Materials
Date
2024-03-28
Abstract
The thesis aimed to characterize the effects of manufacturing-induced defects, particularly gaps in variable stiffness laminates. The primary focus centered on designing a specimen capable of accurately characterizing gap effects. A refined, element-level specimen design featuring a controlled gauge zone was developed, based on pre-defined requirements to represent common variable stiffness structures accurately. The specimens were manufactured and tested. The experimental work featured Digital Image Correlation, Dye Penetrant Testing, and Optical Microscopy. Experimental observations revealed deformation peaks induced by gaps, along with trends in void formation and ply deformation during curing processes. Furthermore, digital image correlation (DIC) analysis unveiled distinct out-of-plane tendencies associated with gap locations. Discrepancies between finite element method (FEM) results and experimental strain distributions highlighted the need for improved modeling, particularly accounting for ply waviness. The main hypothesis presumes that the effects of gaps are influencing off-axis plies through matrix failures. The hypothesis was not proven true based on insufficient proof.
Subject
Variable Stiffness Laminate
Fiber Steering
Automated Fibre Placement
Manufacturing Induced Defects
Ply Drop-off
Tow Gaps
To reference this document use:
http://resolver.tudelft.nl/uuid:03aea8b1-e8dd-43f4-8b67-78adcd3d4e2a
Embargo date
2024-09-01
Part of collection
Student theses
Document type
master thesis
Rights
© 2024 László Czél