Mechanical Engineering MS Thesis Defense by Hasan Çağlar

KOÇ UNIVERSITY

GRADUATE SCHOOL OF SCIENCES & ENGINEERING

MECHANICAL ENGINEERING

MS THESIS DEFENSE BY HASAN ÇAĞLAR

Title: Permeability Characterization of Fiber Reinforcements Used in Liquid Composite Molding

Speaker: Hasan Çağlar 

Time: July 5, 2018, 10.00 

Place: SOS B11

Koç University

Rumeli Feneri Yolu

Sariyer, Istanbu

Thesis Committee Members:

Assoc. Prof. E. Murat Sözer (Advisor, Koç University)

Research Asst. Prof. Melis Şerefoğlu (Koç University)

Asst. Prof. Hatice Sinem Şaş Çaycı (Sabancı University)

Abstract:

Experimental setups were designed and constructed to characterize permeability of fabric preforms used in liquid composite molding processes for three different flow dimensions (linear, radial and through-thickness). They allow measuring both unsaturated and saturated permeabilities in linear and radial flows, but only steady permeability in through-thickness direction. Four common curve fitting methods (global, single-step, reference time step, elementary methods) are used to fit the analytically expected formulas that are driven by Darcy’s Law and conservation of mass experimental data. It is investigated how closely these four curve fitting methods fit the experimental data by comparing their R-squared values. In agreement with the previous literature, in general, there is a very significant variation between the results of the repeated experiments due to inherent variations in the material used and labor of fabric cutting, stacking and placement in the mold.  This study contributes to the composite research by investigating which setups, conditions and curve-fitting method are more suitable to model the resin flow through fabric preforms used in LCM, and also help to decrease the mentioned variation in permeability measurements.