Measurement of the local displacement field produced by a microindentation using speckle

DOLINKO, A. E.; KAUFMANN, G. H.

Stuttgart, Germany

Congreso; Fringe 2009; 2009

Stuttgart University

The definition of adhesion is not a simple issue and its characterization generates considerable debate in the technical literature. Many of the existing tests to determine the adhesion of a given coating-substrate combination are qualitative or semi-quantitative and the adhesion is assessed from the appearance of the fracture surface. In this work we present a technique to investigate coating adhesion based on digital speckle pattern interferometry (DSPI), which is used to measure the out-of-plane deflections of the buckling generated by the introduction of a conical microindentation. The buckling generates a circular delamination, whose magnitude is directly related to the strain energy release rate that is a parameter that can be used to evaluate the adhesion. Experiments performed in coated specimens with different interface conditions demonstrate that DSPI enables the measurement of the tiny buckling generated in the coating after the introduction of a microindentation and allows the determination of the radius of the delaminated region, which is directly related to the adhesion strength of the coating.