Date of Award

Summer 2021

Document Type


Degree Name

Master of Science (MS)


Mechanical & Aerospace Engineering


Aerospace Engineering

Committee Director

Oleksandr Kravchenko

Committee Member

Krishnand Kaipa

Committee Member

Mileta Tomovic


Investigation of this study is to the determine the crack propagation and disbonding in the bonded region of the skin and stringer specimen. An adhesive layer has been used to bond the skin and stringer by using a heat press operation. After the bonding, a drilling method has been adopted to install the through thickness reinforcement in the specimen. The key role of the through thickness reinforcement is to increase the stiffness and strength of the panels and to prevent the crack propagation or disbonding of the panels. The reinforcement was installed in pure (Pristine) samples and in defect samples where an initial defect was placed in between the skin and stringer panels before the bonding process to compare the efficiency of the through thickness reinforcement in both the cases. The effect of spacing of the through thickness reinforcement along the longitudinal direction of the specimens were studied. Two different spacing of the reinforcement was installed in both pure and defect samples. A three point bending test and Tensile tests were carried out to inspect the crack propagation and failure of the specimens. The strength and stiffness of the specimens for both the spacings are compared using the respective Load-Displacement plots. Also, an Ultrasonic scanner was used to analyze the location and size of the crack in the specimen after the tests were completed. In addition, Digital Image Correlation (DIC) was equipped to understand the displacement measurements during the experiment.