Effects of cracking on the tensile properties of glass and carbon fiber composites

Abstract Glass and carbon fiber composites were selected for this comparative study due to their exceptional strength, durability, lightweight nature, thermal resistance, and insulation properties, which make them highly attractive for a wide range of applications, including locomotives, aerospace, structural reinforcements, and other high-performance engineering domains. Both glass and carbon fibers are considered advanced composite materials. Despite extensive research on composite materials, the combined influence of notch size and fiber orientation on tensile performance remains a key area of interest. This study investigates the effects of notch size and fiber orientation on the ultimate tensile strength, stress concentration, and failure mechanisms of carbon/epoxy and glass/epoxy composite panels. Experimental tensile tests were conducted on specimens with varying notch geometries and fiber angles, complemented by finite element simulations to analyze stress distribution and predict failure behavior. The results highlight that both notch size and fiber orientation significantly affect mechanical response, offering valuable insights into the structural integrity and damage tolerance of composite materials in engineering applications. A comparison between glass/epoxy and carbon/epoxy laminates in terms of maximum tensile stress ( σ max ) shows that, although carbon/epoxy exhibits a much higher σ max in the uncracked state, it is more sensitive to crack orientation. For a 15 mm crack, σ max reductions in carbon/epoxy reach up to 88%, whereas glass/epoxy shows a more moderate and stable decrease. Consequently, glass/epoxy demonstrates better damage tolerance, while carbon/epoxy retains superior σ max under healthy material.