Numerical analysis of indentation-induced cracking of brittle coatings on ductile substrates

Abstract Cracking of hard coatings during indentation is studied using the finite element method. The coating is assumed to be linear elastic, the substrate is elastic-perfectly plastic and the indenter is spherical and rigid. Through-thickness cracks are modeled using cohesive surfaces, with a finite strength and fracture energy. The interface between the coating and the substrate is also modeled by means of cohesive zones but with interface properties. The primary potential locations for the initiation of coating cracks are the coating surface close to the contact edge and the coating side of the interface in the contact region, where high values of tensile radial stress are found. Circumferential cracks are found to initiate from the coating surface and to propagate towards the interface. The initiation and advance of a crack is imprinted on the load–displacement curve as a kink. The spacing between successive cracks is found to be of the order of the coating thickness. The influence of other material and cohesive parameters on the initiation of the first crack and spacing between successive cracks is also investigated.

[1]  A. G. Evans,et al.  The mechanical performance of DLC films on steel substrates , 1998 .

[2]  R. Borst.  Computation of post-bifurcation and post-failure behavior of strain-softening solids , 1987 .

[3]  P. V. D. Varst.  Energy based approach to the failure of brittle coatings on metallic substrates , 2001 .

[4]  M. Kanninen,et al.  Advanced Fracture Mechanics , 1986 .

[5]  W. Nix,et al.  Analysis of elastic and plastic deformation associated with indentation testing of thin films on substrates , 1988 .

[6]  R. King,et al.  Elastic analysis of some punch problems for a layered medium , 1987 .

[7]  Elastic modulus , indentation pressure and fracture toughness of hybrid coatings on glass , 2000 .

[8]  van der Erik Giessen,et al.  Delamination of a strong film from a ductile substrate during indentation unloading , 2001 .

[9]  M. Munawar Chaudhri,et al.  Accurate determination of the mechanical properties of thin aluminum films deposited on sapphire flats using nanoindentations , 1999 .

[10]  Xiaopeng Xu,et al.  Void nucleation by inclusion debonding in a crystal matrix , 1993 .

[11]  William D. Nix,et al.  A method for interpreting the data from depth-sensing indentation instruments , 1986 .

[12]  G. Pharr,et al.  An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments , 1992 .

[13]  Huajian Gao,et al.  Elastic contact versus indentation modeling of multi-layered materials , 1992 .

[14]  Bharat Bhushan,et al.  Fracture Mechanisms of Thin Amorphous Carbon Films in Nanoindentation , 1997 .

[15]  Xiaopeng Xu,et al.  Numerical simulations of fast crack growth in brittle solids , 1994 .

[16]  Bharat Bhushan,et al.  Measurement of fracture toughness of ultra-thin amorphous carbon films , 1998 .

[17]  Amilton Sinatora,et al.  Numerical and experimental study of the circular cracks observed at the contact edges of the indentations of coated systems with soft substrates , 2001 .

[18]  M. Ortiz,et al.  Computational modelling of impact damage in brittle materials , 1996 .

[19]  E. van der Giessen,et al.  Indentation-induced interface delamination of a strong film on a ductile substrate , 2001 .