Experimental study for the effect of hole notched in fracture mechanics of GLARE and GFRP composites subjected to quasi-static loading

Abstract

The requirements for the use of lightweight structures, damage-resistant materials, and optimal fuel consumption in various industries such as aerospace, marine, and automotive structures have increased the need for designing new structural systems to meet these demands. According to research, Fiber Metal Laminates (FMLs) are excellent candidates to meet the above needs. In this study, the tensile test specimens were fabricated according to ASTM D 3039 standard from plain textured glass fibers, aluminum sheet Al 6061-T6 with a thickness of 0.5 mm, and epoxy resin with lay-up of [AL/(GFRP [0,90]4)/Al/(GFRP [0,90]4)/Al]. Glass Fiber Reinforced Plastic (GFRP) specimens were also constructed using E-GLASS fibers with [0,90]20 lay-up. GLARE and GFRP specimens were subjected to tensile testing in two types of simple and open-hole at ambient temperature at the loading rate of 2 mm/min. Failure modes of the simple specimens were studied with open-hole specimens. The failure mechanism in simple glass laminate aluminum reinforced epoxy (GLARE) was delamination, however, in open-hole GLARE, no delamination occurred except for some areas around the hole, and the specimen was broken in the hole area. Open-hole GFRP‌ specimens were all broken in the hole area and simple specimens mainly in several regions in the gauge length range. Scanning Electron Microscopy (SEM) images recorded from the hole area of ​​GLARE‌ specimens clearly show that local debonding in the area around the hole caused the breakage of the specimen. In addition, the ratio of the ultimate stress of the simple GFRP‌ specimen to the open-hole specimen is 1.18 and the same ratio is 1.07 for GLARE‌ specimens. This indicates less hole effect on the ultimate stress in GLARE specimens than in GFRP. Furthermore, curved fibers around the hole can be used to reduce damage due to fracture and delay in its occurrence.