Interface Delamination Studied using Advanced DIC Techniques

Interfacial delamination is a key reliability challenge in composites and micro-electronic systems due to (high-density) integration of dissimilar materials. Therefore, we developed a number of advanced methodologies to study interface delamination in detail, which are all based on Global [1] or Integrated [2,3] Digital Image Correlation (DIC). To measure quantitative 3D displacement fields of interface delamination kinematics, a novel self-adaptive NURBS-based isogeometric global digital height correlation (DHC) was developed.[4] The deformation kinematics of interface failure in stretchable electronics was measured and compared to cohesive-zone modeling, revealing that device failure initiates by delamination of metal interconnect lines from the substrate [5]. In-situ high-resolution ESEM imaging elucidated that delamination progresses through formation of 30µm-long fibrils. DHC at the surface roughness scale revealed that the permanent fibril deformation is negligible, however, upon rupture fibrils dynamically release much elastically stored energy, explaining the observed high fracture toughness of >2 kJ/m 2 .[5,6] In addition, an advanced Integrated Global Digital Image Correlation (I-GDIC) strategy was developed for direct, accurate determination of interface behavior from simple mixed-mode in-situ delamination experiments.[7] The problem is cast into a transparent single-minimization formulation with explicit expression of the unknowns, being the material properties and, optionally, experimental uncertainties such as misalignments.[2,3] This method has been validated on virtual and real delamination experiments, demonstrating high accuracy and  noise robustness, and compared to a more indirect mechanical interface characterization method.[8] Moreover, preliminary results show that this IDIC methodology enables characterization of spatially varying interface properties. Furthermore, a quantitative comparison of the suitability of cohesive zone models versus cohesive band models is ongoing. [1]  J. Neggers, B. Blaysat, J.P.M. Hoefnagels, M.G.D. Geers, On image gradients in digital image correlation , Int. J. Num. Meth. Engng. 105 , 243–260 (2015) [2]  J. Neggers, J.P.M. Hoefnagels, F. Hild, S. Roux, M.G.D. Geers, Time-Resolved Integrated Digital Image Correlation , Int. J. Num. Meth. Engng. 103 , 157–182 (2015) [3]  A.P. Ruybalid, J.P.M. Hoefnagels, O. van der Sluis, M.G.D. Geers, Comparison of the identification performance of conventional FEM-Updating and Integrated DIC , accepted for publication in Int. J. Num. Meth. Engng. (2015) [4]  S. Kleinendorst, J.P.M. Hoefnagels, C.V. Verhoosel, A.P. Ruybalid, On the use of adaptive refinement in isogeometric digital image correlation , Int. J. Num. Meth. Engng. 104 , 944–962 (2015). [5]  J. Neggers, J.P.M. Hoefnagels, O. van der Sluis, M.G.D. Geers, Multi-scale experimental analysis of rate dependent metal-elastomer interface mechanics , Journal of the Mechanics and Physics of Solids 80 , 26–36 (2015). [6]  J. Neggers, J.P.M. Hoefnagels, O. van der Sluis, O. Sedaghat, M.G.D. Geers, Analysis of the dissipative mechanisms in metal–elastomer interfaces , Engng. Frac. Mech. 149 , 412–424 (2015) [7]  B. Blaysat, J.P.M. Hoefnagels, M. Alfano, G. Lubineau, M.G.D. Geers, Interface debonding characterization by image correlation integrated with double cantilever beam kinematics , Int. J. Solid. Struct. 55, 79–91 (2015). [8]  M. Kolluri, J.P.M. Hoefnagels, M. Samimi, J.A.W. van Dommelen, O. van der Sluis, and M.G.D. Geers, An in-situ experimental-numerical approach for characterization and prediction of interface delamination: application to CuLF-MCE systems , Advanced Engineering Materials, 14(11) , 1034–1041 (2012)