An improved miniature mixed-mode delamination setup for in situ microscopic interface failure analyses

Kolluri, M.; Hoefnagels, Jpm Johan; Dommelen, J.A.W. van; Geers, M.G.D.

doi:10.1088/0022-3727/44/3/034005

Cited by 22 publications

(20 citation statements)

References 33 publications

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“…local crack opening displacement fields at the delamination front) to quantify the input parameters needed for CZ models. (18) SEM chamber [32,33].…”

Section: Resultsmentioning

confidence: 99%

An in-situ experimental-numerical approach for interface delamination characterization

Hoefnagels

Kolluri

Dommelen

et al. 2011

Experimental and Applied Mechanics, Volume 6

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Interfacial delamination is a key reliability challenge in composites and micro-electronic systems due to (high density) integration of dissimilar materials. Predictive finite element models are used during the design and optimization stage to minimize delamination failures, however, they requires a relevant interface model to capture the (irreversible) crack initiation and propagation behavior observed in experiments. Therefore, a set of experimental-numerical tools is presented to enable accurate characterization of delamination mechanism(s) and prediction of the interface mechanics. First, a novel Miniature Mixed Mode Bending (MMMB) delamination setup is presented that enables in-situ SEM characterization of interface delamination mechanisms while sensitively measuring global load-displacement curves for the full range of mode mixities. Accurate determination of the critical energy release rate from the global load-displacement curve requires, however, identification and separation of bulk plastic contributions from the measured total energy dissipation; to this end, an analytical procedure is presented. Finally, a cohesive zone model suitable for mixed mode loading with realistic coupling is presented that can capture the range of interface failure mechanisms from damage to plasticity, as observed in-situ with SEM, as well as a parameter identification procedure. The set of experimental-numerical tools is validated on delamination measurements of a glue interface.

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“…local crack opening displacement fields at the delamination front) to quantify the input parameters needed for CZ models. (18) SEM chamber [32,33].…”

Section: Resultsmentioning

confidence: 99%

An in-situ experimental-numerical approach for interface delamination characterization

Hoefnagels

Kolluri

Dommelen

et al. 2011

Experimental and Applied Mechanics, Volume 6

View full text Add to dashboard Cite

show abstract

“…Although elegant in design, friction of the sliders induces parasitic loads to the bent sample, causing the state of pure bending to be lost. Moreover, friction introduces hysteresis in cyclic tests which is nontrivial to calibrate out, and the influence of friction increases when the setup would be miniaturized to enable in-situ microscopic observation [13]. Therefore, Boers et al…”

Section: Design Considerations and Criteriamentioning

confidence: 99%

“…In-situ SEM characterization of mechanical behavior of materials at the microscopic scale requires miniaturization of the testing device and adaptation to additional constraints, such as vacuum compatibility of all setup components, an increased influence of friction, and a horizontal working plane for the vertical SEM viewing direction. Sufficiently high load application can be challenging due to the limited space in a SEM vacuum chamber (e.g., 260 × 225 × 90 mm 3 for a FEI Quanta 600 SEM) [17], while the mitigation of friction can trigger unconventional design choices, such as electron discharge machined elastic hinges [13]. Ideally, the contactless, frictionless pure bending setup for large amplitude, cyclic loading, developed by Boers et al, should simply be miniaturized.…”

Section: Design Considerations and Criteriamentioning

confidence: 99%

A Small-Scale, Contactless, Pure Bending Device for In-situ Testing

2015

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The introduction of flexible electronics calls for new ways of measuring the mechanical limits and failure mechanisms resulting from (large) bending loads during manufacturing and application. Therefore, an autonomous, miniaturized, pure bending test apparatus was developed to investigate material systems at the microscopic level. Improvements to conventional bending test methods are: (1) well-defined pure moment application without friction or local pressure contacts, through active feedback control of parasitic axial and transverse forces at the specimen edges, (2) continuous reversibility of the loading direction within an angular range of −114 • ≤ θ ≤ 114 • (minimum radius of 2 mm), (3) no view-obstruction from both the thickness and in-plane perspective, enabling in-situ optical and scanning electron microscopic studies of failure mechanisms under constant field-of-view. The pure bending test setup was validated by moment-curvature measurements of monocrystalline silicon. The setup's continuous load-reversibility and strain determination were validated by cyclic tests and in-situ digital image correlation, respectively, on polyethylene napthalate specimens. Furthermore, in-situ microscopic failure analysis was demonstrated on

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“…The microscopic information obtained from these experiments is used for the research on mechanical behavior at the microscale. Kolluri et al [7] reports an example of the relevance of such an investigation with a miniaturized mixed-mode delamination setup, with which quantitative delamination characteristics can be measured while simultaneously the delamination mechanisms can be observed during real-time in situ SEM visualization. Wiklund et al [8], Frei et al [9] and Buchanan et al [10] already performed in situ bending tests in a SEM, relying on the four-point bending principle.…”

Section: Requirements Of the Bending Testmentioning

confidence: 99%