Non-Destructive Technique for Determination of Material Properties

It is well known that material properties determined from the standard tests of small specimens, which are made by cutting samples, may differ from the actual material properties in structure. Therefore, the determination of realized material properties using non-destructive evaluation techniques has become actual problem. The determination of stiffness parameters for complex materials is much more complicated than for isotropic materials. A number of various non-destructive evaluation techniques have been proposed for determining the material properties of materials. In the present study, attention is focused on the identification of the material properties using vibration test data. The problem associated with vibration testing is converting the measured modal frequencies to elastic constants. A standard method for solving this problem is the use of a numerical-experimental model and optimization techniques. The numerical-experimental method proposed in the present investigation consists of the experimental set-up, numerical model, and material identification procedure. The work comprises two main experimental parts. The first part, deals with the identification of material properties of composite plate. Elastic constants of laminated composite plates are identified via modal frequencies by using a mixed numerical-experimental technique. The presented method derives the properties from the measured modal frequencies of unidirectional as well as multidirectional reinforced laminated composite plates and is able to identify four out of five major elastic constants of a transversally isotropic material. In the second part, identification technique is applied for determination of elastic material properties of aluminium alloys with different Carbon nanotubes (CNT) volume content. Nowadays CNT-reinforced aluminium alloys have promising perspectives for an application in many industrial sectors such as aerospace, automotive and electronics industries