On the stability of delamination growth at scratching of thin film structures

Abstract

Scratching of thin film/substrate structures is studied theoretically and numerically. The results are discussed in connection to delamination initiation and in particular subsequent growth at scratching. The material behavior of the film is described by classical elastoplasticity accounting for large deformations. The deformation of the substrate is neglected indicating that the results are pertinent to soft thin films. The numerical investigation is performed using the finite element method (FEM) and the numerical strategy is discussed in some detail. The results from this study show that delamination growth at thin film scratching is a stable feature with crack arrest occurring at a decreasing load.

A comparison of adsorbed and grafted fibronectin coatings under static and dynamic conditions

“…In the case of CF x , the presence of oxygen after the plastic deformation could be explained by a slight oxidation of the fluorocarbon polymer during its exposure to air. 24,25 It is important to highlight that no metal was detected, meaning that no crack or delamination on the CF x film occurred during the deformation step. In the case of FNa conditions, even if an increase of F concentration is observed, the percentage is not significantly different from the amount before the test.…”

On the correlation of scratch testing using separated elastoplastic and rigid plastic descriptions of the representative stress

“…e.g. [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44], considering different aspects of the problem such as fracture, delamination, the behaviour of different global and local scratch variables (global scratch variables include normal and tangential hardness, apparent coefficient of friction and contact area) and alternative constitutive behaviour. In the present investigation, however, it was thought advisable to restrict the analysis to scratching of homogeneous materials as otherwise a characteristic length would be introduced into the problem.…”