Mechanical characterizations of intact and open-hole tensile GFRP and GLARE composite beams subjected to different low-rate monotonic loads

In the recent decades, an important class of materials the so-called fiber metal laminate (FML) composites has been considered for the fabrication of complex structures, which requires scientific investigation to overcome mechanical and design challenges. This research aimed to study the mechanical behavior of FRP composite and its extended FML configuration to highlight the characteristics of the material. In this regard, glass fiber-reinforced plastic (GFRP) composite and glass laminate aluminum reinforced epoxy (GLARE) composite beams were fabricated and tested to characterize the behavior and highlight the mechanical characteristics. A systematic study was planned to have a minimum of five different conditions; two types of samples as intact and open-hole tensile beam configurations, each subjected to various 1, 2, and 3 mm/min loading rates. Results indicated a brittle-like behavior for plain and perforated GFRP specimens with a linear response followed by specimen rupture. The effect of 1 to 3 mm/min load rates on the ultimate stresses of the GFRP specimens (with and without holes) was measured 9.2 and 8.1%, respectively. While the fracture strain failed, it had a decreasing trend. The ultimate strain and stress and the ultimate stress and fracture strain of the perforated samples intact specimens of GFRP increased compared to the perforated specimens of GFRP with loading rates of 1, 2, and 3 mm/min. While the elastic modulus of perforated GFRP case increased by 9% for loading rates of 1 to 3 mm/min, when compared to the plain sample, the GLARE composite samples shown full elastic–plastic behavior in all cases reflecting the effect of aluminum constituent. A higher loading rate resulted in the perforated GLARE to enter the plastic stage later, while the trend was reversed in the intact GLARE specimen. The mechanism of fracture in the plane GLARE sample was cracking delamination, while the perforated GLARE specimens mainly failed at the perforation hole cross section. Scanning electron microscopy of the perforated area of GLARE‌ specimens shows local separation around the hole as the cause to structural rupture. The key novelty of this work is the direct, systematic comparison of the base materials (Al 6061-T6 and GFRP) with their hybrid GLARE configuration, under both intact and open-hole conditions, across multiple low-rate monotonic loading speeds. This approach provides a fundamental dataset that isolates the contribution of each constituent and their interactions, offering critical insights for material selection in applications where stress concentrators, such as holes for mechanical fastening, are present.