Title page for ETD etd-520112859651791


Type of Document Master's Thesis
Author Waldhart, Chris
URN etd-520112859651791
Title Analysis of Tow-Placed, Variable-Stiffness Laminates
Degree Master of Science
Department Engineering Science and Mechanics
Advisory Committee
Advisor Name Title
Jones, Robert M.
Ribbens, Calvin J.
Gürdal, Zafer Committee Chair
Keywords
  • tow placement machine
  • curvilinear fibers
  • variable-stiffness laminates
  • buckling
Date of Defense 1996-06-05
Availability unrestricted
Abstract
It is possible to create laminae that have spatially varying fiber orientation with a tow placement machine. A laminate which is composed of such plies will have stiffness properties which vary as a function of position.

Previous work had modelled such variable-stiffness laminae by taking a reference fiber path and creating subsequent paths by shifting the reference path. This thesis introduces a method where subsequent paths are truly parallel to the reference fiber path. The primary manufacturing constraint considered in the analysis of variable-stiffness laminates was limits on fiber curvature which proved to be more restrictive for parallel fiber laminae than for shifted fiber. The in-plane responses of shifted and parallel fiber variable-stiffness laminates to either an applied uniform end shortening or in-plane shear were determined. Both shifted and parallel fiber variable-stiffness laminates can redistribute the applied load thereby increasing critical buckling loads compared to traditional straight fiber laminates. The primary differences between the two methods is that parallel fiber laminates are not able to redistribute the loading to the degree of the shifted fiber. This significantly reduces the increase in critical buckling load for parallel fiber variable-stiffness laminates over straight fiber laminates.

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