Vibration-Based Methods for the Identification of the Elastic Properties of Layered Materials (Trillingsgebaseerde methodes voor de identificatie van de elastische eigenschappen van gelaagde materialen)

This thesis develops a vibration-based identification technique todetermine the elastic properties of the constituent layers of layeredmaterials. The presented mixed numerical-experimental technique (MNET)derivesthe layer properties from the resonant frequencies of rectangular beam-or plate-shaped specimens, and is able to identify the in-plane elasticproperties of both isotropic and orthotropicmaterials. An optional post-processing step allows the estimation of the uncertainty of the identified elastic parameters.Thethesis comprises three main parts. The first part, chapters 1 to 4,introduces the mathematical tools that are required to construct anMNET procedure. The second part, chapters 5 to 7, uses thesemathematicaltools to build a series of vibration-based identification proceduresfor the identification of the elastic properties of layered materials.The last part, chapters 8 and 9, provides an experimentalvalidation together with a number of applications of the developed identification routines.status: publishe

Identifying the elastic properties of the individual layers of layered materials from vibration data

status: publishe

A multi-model updating routine for layered material identification

status: publishe

Layered material identification using multi-model uptdating

status: publishe

Identification of distributed material properties using measures modal data

status: publishe

Damage identification in beams using inverse methods

status: publishe

Determination of the in-plane elastic properties of the different layers of laminated plates by means of vibration testing and model updating

status: publishe

Resonant-based identification of the elastic properties of layered materials: Application to air-plasma sprayed thermal barrier coatings

This work introduces a resonant-based, mixed numerical-experimental method for the determination of the in-plane elastic properties of the constituent materials of laminates. This non-destructive method identifies elastic properties from the resonant frequencies of beam-shaped layered specimens, using a set of finite element models. The method is demonstrated on a thermal barrier coating system made of NiCoCrAlY bondcoat and yttria-stabilised zirconia topcoat deposited by air-plasma spraying on stainless steel. The stainless steel was found to be elastically anisotropic, while both bondcoat and topcoat exhibited in-plane isotropy. Moreover, the topcoat Poisson's ratio approached zero, and the bondcoat properties varied with the coating thickness. Scanning electron microscopy was used to correlate the identified elastic properties with the coating microstructure. (c) 2007 Elsevier Ltd. All rights reserved.status: publishe

Validation of the resonalyser method: an inverse method for material identification

The Resonalyser method uses resonance frequencies measured on rectangular plate specimens to identify orthotropic material properties. An inverse technique is used to update the material properties in a numerical model of the test plate. The obtained material properties of steel and aluminum test plates are validated with the results of standard impulse excitation tests and standard tensile tests. Impulse excitation tests (IET) were performed on beam specimens cut in different material directions of the plates. IET uses in-plane and torsional vibration modes to identify the Young's moduli, shear moduli and Poisson's ratios in the orthotropic material axes and off-axis directions. It was found that the obtained results were situated well within the error intervals of the tensile test results and that the results from IET were in good agreement with the Resonalyser results. The error bounds of the Resonalyser tests have the same small magnitude as impulse testing. Both methods based on vibration measurements are accurate and produce repeatable results.status: publishe