Cyclic Relaxation, Impact Properties and Fracture Toughness of Carbon and Glass Fiber Reinforced Composite Laminates

Mohammed Y Abdellah; Mohamed K Hassan; Ahmed F Mohamed; Ahmed H Backar

doi:10.3390/ma14237412

Cyclic Relaxation, Impact Properties and Fracture Toughness of Carbon and Glass Fiber Reinforced Composite Laminates

Materials (Basel). 2021 Dec 3;14(23):7412. doi: 10.3390/ma14237412.

Authors

Mohammed Y Abdellah^{1

2}, Mohamed K Hassan^{1

3}, Ahmed F Mohamed^{1

4}, Ahmed H Backar^{1

5}

Affiliations

¹ Mechanical Engineering Department, College of Engineering and Islamic Architecture, Umm Al-Qura University, Makkah 21955, Saudi Arabia.
² Mechanical Engineering Department, Faculty of Engineering, South Valley University, Qena 83521, Egypt.
³ Production Engineering& Design Department, Faculty of Engineering, Minia University, Minia 61111, Egypt.
⁴ Mechanical Engineering Department, Faculty of Engineering, Sohag University, Sohag 82524, Egypt.
⁵ Production Engineering Department, Faculty of Engineering, Alexandria University, Alexandria 21544, Egypt.

Abstract

In this paper, the mechanical properties of fiber-reinforced epoxy laminates are experimentally tested. The relaxation behavior of carbon and glass fiber composite laminates is investigated at room temperature. In addition, the impact strength under drop-weight loading is measured. The hand lay-up technique is used to fabricate composite laminates with woven 8-ply carbon and glass fiber reinforced epoxy. Tensile tests, cyclic relaxation tests and drop weight impacts are carried out on the carbon and glass fiber-reinforced epoxy laminates. The surface release energy G_IC and the related fracture toughness K_IC are important characteristic properties and are therefore measured experimentally using a standard test on centre-cracked specimens. The results show that carbon fiber-reinforced epoxy laminates with high tensile strength give high cyclic relaxation performance, better than the specimens with glass fiber composite laminates. This is due to the higher strength and stiffness of carbon fiber-reinforced epoxy with 600 MPa compared to glass fiber-reinforced epoxy with 200 MPa. While glass fibers show better impact behavior than carbon fibers at impact energies between 1.9 and 2.7 J, this is due to the large amount of epoxy resin in the case of glass fiber composite laminates, while the impact behavior is different at impact energies between 2.7 and 3.4 J. The fracture toughness K_IC is measured to be 192 and 31 MPa √m and the surface energy G_IC is measured to be 540.6 and 31.1 kJ/m² for carbon and glass fiber-reinforced epoxy laminates, respectively.

Keywords: composites; cyclic; drop weight; fiber; relaxation.