ABSTRACT
Nowadays, rapid growth of fiber composite material applications in machine design is observed. These materials have many advantages in comparison with isotropic materials like, for example, structural steel. The most important can be quoted as namely: high value of the ratio of the strength to weight, the possibility of tailoring the mechanical and physical properties. Thus, they are widely used in thin – walled shell structures, especially in aircraft industry. However, in case of composite materials the process of the damage gradually growth is much more complex than in case of isotropic materials. The most common types of flaws are matrix cracking, fiber breakage and delaminations. Hence, it is necessary do develop the effective methods of detecting of any kind of damage inside the composite structures in time. Moreover, it should be also possible to indicate the localization and the size of the flaw. It is obvious that these techniques should not damage the analyzing structure. Currently, several nondestructive testing (NDT) techniques are available: ultrasonic inspection, acoustic emission, thermography, Eddy current or tomography. The advantages and shortcomings of NDT techniques are discussed by Hellier (2001).
