MSc Thesis Defense: İbrahim Bahadır, INTEGRATING MULTI-SENSOR EXPERIMENTAL AND NUMERICAL APPROACHES FOR DAMAGE LOCALIZATION AND CRACK PROPAGATION MONITORING IN COMPOSITE LAMINATES, Date & Time: 16 July, 2026 – 2:00 PM, Place: FENS L062

INTEGRATING MULTI-SENSOR EXPERIMENTAL AND NUMERICAL APPROACHES FOR DAMAGE LOCALIZATION

AND CRACK PROPAGATION MONITORING IN COMPOSITE LAMINATES

İbrahim Bahadır
Manufacturing Engineering, MSc Thesis, 2026

Thesis Jury

  Assoc. Prof. Adnan Kefal (Thesis Advisor)

  Assoc. Prof. Bertan Beylergil

  Asst. Prof. Bekir Dizman

Date & Time: 16th June, 2026 – 2:00 PM

Place: FENS L062

Keywords : Digital image correlation; Acoustic emission, Composite laminates;

Crack propagation; Damage localization

Abstract

This thesis presents an integrated methodology for damage characterization and crack propagation monitoring in pre-cracked carbon/epoxy composite laminates. To address the numerical sensitivity of full-field optical measurements, a dual-stage smoothing element analysis (SEA) assisted digital image correlation (DIC) methodology is developed to formulate a gradient-enhanced, bounded damage-sensitive localization index. This numerical formulation identifies spatially localized damage zones without relying on constitutive material models. Utilizing a unified experimental campaign on seven composite laminates with varying stacking sequences (0/90/0, 90/0/90, 0/0/0, 90/90/90) and initial crack orientations (45º and 90º), the crack propagation behavior is comprehensively investigated through a multi-instrument approach combining DIC, acoustic emission (AE), and strain gauges. Results demonstrate that the macroscopic mechanical response and microscopic damage evolution are strongly governed by both ply architecture and initial crack angle. Specifically, 0º-dominated laminates exhibit progressive horizontal crack propagation, whereas 90º-dominated laminates display delayed but abrupt vertical fracture. AE clustering analysis identifies two distinct acoustic event populations corresponding to tensile crack-tip activity and high-energy mixed-mode sliding mechanisms. By synthesizing the spatial deformation from DIC, temporal damage activity from AE, and local mechanical response from strain gauges, the proposed assessment provides a comprehensive evaluation of progressive, delayed, and fracture-dominated damage stages. Ultimately, this thesis establishes a robust, physically consistent basis for monitoring spatial and temporal crack evolution in composite structures.