Single-sample decohesion test: mechanics and implementation

• Published in: International journal of fracture Vol. 129; no. 1; pp. 1 - 20
• Main Authors: MODI, Mitul B, SITARAMAN, Suresh K
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01.09.2004; Springer Nature B.V
• Subjects: Biaxial loads; Bifurcation theory; Condensed matter: structure, mechanical and thermal properties; Crack propagation; Crack tips; Curvature; Energy release rate; Exact sciences and technology; Finite element method; Fracture mechanics (crack, fatigue, damage...); Fracture toughness; Fundamental areas of phenomenology (including applications); Mechanical and acoustical properties; Mechanics (physics); Microelectromechanical systems; Model testing; Nonlinear analysis; Physical properties of thin films, nonelectronic; Physics; Plate theory; Solid mechanics; Structural and continuum mechanics; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin films; High strain; Energy release; Mode coupling; nonlinear plate theory; microelectronics; Biaxial load; Crack propagation; Thin films; Finite element method; Crack tip; Modelling; Analytical mechanics; Delamination; Microelectromechanical device; Plates; Interfacial fracture toughness; Peel test; Layered materials; Experimental study; Steady state; Fracture toughness; fracture test; thin film; Non linear effect; Curvature; Surface cracks; Breaking test
• ISSN: 0376-9429; 1573-2673
• DOI: 10.1023/B:FRAC.0000038907.94272.e5

The Single-Sample Decohesion Test (SSDT), developed by the authors, eliminates shortcomings of current interfacial fracture toughness testing methods. In this approach, a highly stressed super layer is used to drive delamination and create any mode mix at the crack tip. SSDT uses the change in crack surface area to vary the available energy per unit area for crack growth and thus to bound the steady state interfacial fracture toughness. Therefore, this technique uses a single sample to measure the interfacial fracture toughness and maintains the advantages of the original decohesion test: (1) SSY conditions, (2) micro-electronics and MEMS representative interfaces, and (3) ability to generate any mode mix. Critical to the usefulness of this test is the availability of a mechanics based analytical model to calculate the test site energy release rate. The test sites are cantilevered thin film strips, which undergo large, nonlinear deflection, consist of multilayered materials, are subject to in-plane biaxial loading, have varying in-plane dimensions, and can be loaded from pure shear to pure peel. In this paper, one dimensional and linear and nonlinear classical laminate plate theories are compared to a finite element representation of the SSDT test site. The regions of applicability of linear and nonlinear analytical models are discussed and nonlinear effects such as the importance of capturing the bifurcation of curvature are highlighted. Application of the nonlinear plate theory model to the test is shown and interfacial fracture toughness results are provided for a Ti/Si interface at several mode mixes.