Dissertation Announcement for Pedram Gharghabi • 04/26/18 at 10:00 AM
April 16, 2018
Faculty, graduate and undergraduate students,
You are invited to attend the PhD Dissertation Defense of Pedram Gharghabi
Title: Experimental and numerical studies of lightning strike induced damage to carbon fiber epoxy composites
When: Thursday, April 26, at 10:00 A.M.
Where: Simrall Hall, Room 228 (Conference Room).
Candidate: Pedram Gharghabi
Committee:
Dr. Joni Kluss
Assistant Professor of Department of Electrical and Computer Engineering (Major Professor)
Dr. Thomas Lacy
Professor of Department of Aerospace Engineering (Co-Major Professor)
Dr. Michael Mazzola
Director of the Energy Production and Infrastructure Center (EPIC) and the Duke Energy Distinguished Chair in Power Engineering Systems at UNC Charlotte
Dr. J. Patrick Donohoe
Professor of Electrical and Computer Engineering
Abstract:
The objective of this study is to investigate the interaction between a lightning strike and carbon/fiber composites. The first approach is to characterize the damage development in a composite structure subjected to simulated lightning strikes. Several existing literatures have acknowledged that the lightning induced damaged can be categorized into two separate domains of damage; the primary domain of damage that occurs at the attachment point, and the secondary domain of damage that is typically formed around the attachment point. Quantitative studies of the causes of the primary damage domain are not satisfactory for explaining the secondary damage domain and thus, these two domains are produced by presumably different mechanisms. There have been many reports and studies focused on the inspection of the primary damaged area. However, the secondary domain of damage has not yet been fully explained and understood.
An experimental setup was configured with the recommissioned lightning current simulator to generate artificial lightning strikes consistent with the existing standard for lightning protection testing used in the aerospace industry. Carbon/epoxy composite laminates in various layups and Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) structure were subjected to high impulse currents of different magnitudes. The lightning induced-damage to the protected and non-protected composite laminates and PRSEUS panel were evaluated, and the influence of different variables such as current magnitude, strike location, and laminate layup were studied. An interesting observation was the damaged area that expanded laterally beyond the intense damage are a. The structure of a composite panel is such that it forces the current to flow linearly parallel lines along carbon fibers aligned in fabric plies, as opposed to metals where the relatively homogenous conductivity of the metal allows current to distribute radially. It is argued in this work that the secondary domain of damage may be related to the anisotropic current conduction property of the composite panels. A comprehensive theory based on multidimensional electromagnetic field simulations were proposed to reveal the root cause mechanisms of the unique patterns of secondary damage in the carbon composite structural materials tested with simulated lightning current impulses.
Best regards
Pedram