Speaker
Description
In the field of electronics, there is a strong push towards miniaturization of current devices. Modern electronics consist of various combinations of layered materials with different material properties, enabling the desired device properties. Their interfaces are assumed to be a weak-points and, therefore, must be investigated.
Measurements of the adhesion energy of the thin film on the different substrate materials can be made using the spontaneous buckling method described by Hutchinson and Suo [1]. However, the method to form delaminated buckles induces lateral deformation of the thin film with respect to the substrate, which causes a significant shear loading contribution to the delamination crack front and therefore, the inevitable mode II appearance. Mode II loading may be even more pronounced with use of modern materials, such as in flexible devices.
The influence of several parameters of the investigated substrate and thin film (e.g. mismatch of elastic material properties, influence of film thickness h variation, the crack length 2b, etc.) on the mode-mixity at the delamination crack front for the case of buckling-delamination will be examined.
In this work, the finite element (FE) modelling is combined with analytical solutions to evaluate parameters describing the mode-mixity of the delaminated buckles as a function of model parameters, unraveling the main influencing factors. The FE approach enables relatively simple and quick evaluation of stress intensity factors for arbitrary models via domain integration method. Therefore, several FE model configurations can be analyzed together with numerically obtained stress/strain fields in the buckled samples.
The results can be used to further improve the original model, which is nowadays still widely used to experimentally measure the adhesion energies of the thin films.
[1] J.W. Hutchinson, Z. Suo, Mixed Mode Cracking in Layered Materials, Adv. Appl. Mech. 29 (1992) 63–191.
| Speaker Country | Czech Republic |
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