Laser Based Pre-treatment of Secondary Bonded Composite T-joints for Improved Energy Dissipation

  • Mjed H. Hashem

Student thesis: Master's Thesis


This study demonstrates an experimental investigation into the efficacy of a novel surface pre-treatment technique to improve the toughness and energy dissipation of composite CFRP T-joints. This novel technique optimizes CO2 laser irradiations to remove surface contaminations and modify the surface morphology of CFRP T-joint adherents. Pull-off tests were performed on T-joints that experienced peel-ply (PP) treatment and to those that were ablated with 10% (LC) and 30% (LA) laser power respectively. A further developed alternative pattern between LA and LC surface pre-treatment was examined. Two different quasi-isotropic stacking sequences have been studied by having surface fibers aligned in 0° and 45° direction. A series of surface roughness analysis, optical microscopy, SEM, CT scan and pictorial findings have been carried out to characterize the surface morphologies and failure modes prior to and after the failure. The patterning technique promoted non-local damage mechanisms which resulted in large improvements in the toughness and energy dissipation as compared to the other pre-treatment techniques. Up to ~12 times higher energy dissipation compared to peel-ply pre-treated T-joint were achieved with patterned T-joint structures that are stacked with a 0° surface fiber direction.
Date of AwardApr 6 2021
Original languageEnglish (US)
Awarding Institution
  • Physical Sciences and Engineering
SupervisorGilles Lubineau (Supervisor)


  • CFRT
  • T-joints
  • Composites
  • pulsed laser irradiation
  • Pull-off
  • Adhesive Joints

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