Abstract
Carbon fiber reinforced plastic (CFRP) has been widely used to manufacture components of bicycles, in particular of those high-performance and high-value ones. However, by following the current inspection codes, the defect inspection technique is to apply mechanical load to the assembled bicycle CFRP components to check whether failure occurs. If defects present in the CFRP components could be detected during its manufacturing process and before assembly, both the efficiency of productivity and quality can be significantly improved. A nondestructive testing system is urgently needed to inspect defects of bicycle components. Among several nondestructive techniques, advantages of optical methods are their real-time, full-field, remote sensing, high precision and noncontact characteristics. In this paper, two optical methods, electronic shearography (ES) and electronic speckle pattern interferometry (ESPI) were employed to nondestructively investigate the defects in the circular CFRP tube prepared by the blowing process and circular sandwiched composite tube by the foaming process. The artificial defects were placed at selected layers and locations in the CFRP tubes. The defects can be detected directly and effectively by applying compressed air, vacuum, or heating. The optical sensitivity was further increased by employing the phase-shifting technique. The investigated results of this paper have proven the potential development of an on-line real-time nondestructive inspection system for the CFRP components of bicycles.