On the Residual Stresses and Fracture Toughness of Glass/Carbon Epoxy Composites

M A Umarfarooq; P S Shivakumar Gouda; N R Banapurmath; M I Kittur; Tabrej Khan; Irfan Anjum Badruddin; Sarfaraz Kamangar; Mohamed Hussien

doi:10.3390/ma15207135

On the Residual Stresses and Fracture Toughness of Glass/Carbon Epoxy Composites

Materials (Basel). 2022 Oct 13;15(20):7135. doi: 10.3390/ma15207135.

Authors

M A Umarfarooq¹, P S Shivakumar Gouda², N R Banapurmath^{1

3}, M I Kittur^{4

5}, Tabrej Khan⁶, Irfan Anjum Badruddin⁷, Sarfaraz Kamangar⁷, Mohamed Hussien^{8

9}

Affiliations

¹ Center of Excellence in Material Science, School of Mechanical Engineering, KLE Technological University, Hubballi 580031, India.
² Department of Mechanical Engineering, SDM College of Engineering & Technology, Dharwad 580002, India.
³ School of Mechanical Engineering, KLE Technological University, Hubballi 580031, India.
⁴ Centre of Advanced Materials, Faculty of Engineering, Universiti Malaya, Kuala Lumpur 50603, Malaysia.
⁵ Department of Mechanical Engineering, Faculty of Engineering, Universiti Malaya, Kuala Lumpur 50603, Malaysia.
⁶ Department of Engineering Management, College of Engineering, Prince Sultan University, Riyadh 11586, Saudi Arabia.
⁷ Mechanical Engineering Department, College of Engineering, King Khalid University, Abha 61421, Saudi Arabia.
⁸ Department of Chemistry, Faculty of Science, King Khalid University, P.O. Box 9004, Abha 61413, Saudi Arabia.
⁹ Pesticide Formulation Department, Central Agricultural Pesticide Laboratory Agricultural Research Center, Dokki, Giza 12618, Egypt.

Abstract

The resistance to delamination in polymer composite depends on their constituents, manufacturing process, environmental factors, specimen geometry, and loading conditions. The manufacturing of laminated composites is usually carried out at an elevated temperature, which induces thermal stresses in composites mainly due to a mismatch in the coefficient of thermal expansion (CTE) of fiber and matrix. This work aims to investigate the effect of these process-induced stresses on mode-I interlaminar fracture toughness (G_I) of Glass-Carbon-Epoxy (GCE) and Glass-Epoxy (GE) composites. These composites are prepared using a manual layup technique and cured under room temperature, followed by post-curing using different curing conditions. Double cantilever beam (DCB) specimens were used to determine G_I experimentally. The slitting technique was used to estimate residual stresses (longitudinal and transverse direction of crack growth) inherited in cured composites and the impact of these stresses on G_I was investigated. Delaminated surfaces of composites were examined using a scanning electron microscopy (SEM) to investigate the effect of post-curing on the mode-I failure mechanism. It was found that G_I of both GE and GEC composites are sensitive to the state of residual stress in the laminas. The increase in the G_I of laminates can also be attributed to an increase in matrix deformation and fiber-matrix interfacial bond with the increase in post-curing temperature.

Keywords: SEM; hybrid composites; interlaminar fracture toughness; residual stresses; slitting method.

Grants and funding

RGP. 2/101/43/Deanship of Scientific Research at King Khalid University for funding this work through the Large Groups Project under grant number RGP. 2/101/43.