Crack Detection in Beams of Layered Composite Materials

Abstract

Composites, as anisotropic materials with high strength-to-weight ratios and excellent stiffness-to-weight ratios, are widely used in a variety of industrial applications, including the aerospace and marine structures, automobile industry, bridge structures and high-speed turbine machinery. Composite beams are commonly employed in various applications due to their ease of fabrication, efficiency, and variety in fiber and reinforcement orientation. However, due to their layered nature, and the interaction between different materials (fibers, matrix, etc.), composite materials are subject to different types of failure. Delamination and cracks are the most typical types of failure, which can result in irreparable damage. Cracks in the beam results in the loss of mechanical strength due to the separation of layers. Cracks are the most dangerous defect in composites because they can occur without warning and cause structural collapse, loss of stiffness and variations in modal properties such as natural frequencies, mode shapes and damping ratio. Therefore, researching the various failure modes of these materials could be extremely beneficial. As the dynamic behavior, stiffness, and damping characteristics of a structural element are altered by cracks and other defects, the natural frequencies and mode shapes of the structure offer information about the location and size of the damage. newlineNon-Destructive Testing (NDT) methods like ultrasonic, acoustic, and magnetic field testing are time-consuming. The vibration analysis-based approach for finding cracks has proven to be efficient and cost-effective. The fundamental principle behind vibration-based damage detection is that measurable changes in modal features will result from changes in physical properties (mass, stiffness, and damping) induced by damage (natural frequencies, mode shapes, and modal damping). The primary objective of the present work is to understand the vibration analysis of laminated composite beams using theoretical, numerical, and experimental vibratio