Direct Stress-Strain Measurements from Bulged Membranes Using Topography Image Correlation

Neggers, Jan; Hoefnagels, Jpm Johan; Hild, François; Roux, Stéphane; Geers, Mgd Marc

doi:10.1007/s11340-013-9832-4

Cited by 57 publications

(53 citation statements)

References 26 publications

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“…Global regularization is used in the DIC algorithm, meaning that instead of using local correlation of individual subsets, global shape functions are applied to describe the full displacement field. These shape functions are based on polynomials up to the third degree, which can accurately describe bending kinematics [20].…”

Section: Pure Bending Validationmentioning

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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Section: Pure Bending Validationmentioning

confidence: 99%

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

2015

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“…Here, the displacements of one large facet on the substrate and of another on the gauge end are tracked by a recently developed global DIC (GDIC) code [89][90][91], which is based on a DIC algorithm developed for 2D images by Hild and Roux [92]. During long term testing, lighting conditions may change, thereby affecting the DIC performance, which depends on the image brightness and contrast.…”

Section: Displacement Measurementmentioning

confidence: 99%

“…The contrast and brightness are added as an intensity scaling factor, α I and an offset I 0 respectively. The exact implementation is straigtforward when considering the details by Sutton et al and the GDIC-basis [89,90]. Employing GDIC for displacement measurements enables high resolution.…”

Section: Displacement Measurementmentioning

confidence: 99%

“…Therefore, here, optical profilometry is employed, which is well suited for measuring the 3D configuration of the chip and the gripper in a limited field of view. From 3D profiles and 2D images these directions can be adequately determined by a novel image processing strategy that combines plane-fitting and (quasi-3D) GDIC applied to full field displacement data [89][90][91]. After establishing the misalignment, the rotation manipulators allow for a precise correction.…”

Section: Misalignment Controlmentioning

confidence: 99%

“…The gripper is moved along the full range of the loading axis, while registering surface profiles of the gripper surface in its extreme positions. The quasi-3D GDIC algorithm [89,90] is used to extract the 3D displacement vector of a ROI, ⃗ ⃗ ⃗ ⃗ = + + u u e u e u e x x y y z z LA , i.e. the loading axis direction is measured and θ y,LA = atan(u z /u x ) can be calculated, see figures 9(c) and (d).…”

Section: Misalignment Controlmentioning

confidence: 99%

See 2 more Smart Citations

On-wafer time-dependent high reproducibility nano-force tensile testing

Bergers¹,

Hoefnagels²,

Geers³

2014

J. Phys. D: Appl. Phys.

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Time-dependent mechanical investigations of on-wafer specimens are of interest for improving the reliability of thin metal film microdevices. This paper presents a novel methodology, addressing key challenges in creep and anelasticity investigations through on-wafer tensile tests, achieving highly reproducible force and specimen deformation measurements and loading states. The methodology consists of a novel approach for precise loading using a pinin-hole gripper and a high-precision specimen alignment system based on three-dimensional image tracking and optical profilometry resulting in angular alignment of <0.1 mrad and near-perfect co-linearity. A compact test system enables in situ tensile tests of on-wafer specimens under light and electron microscopy. Precision force measurement over a range of 0.07 µN to 250 mN is realized based on a simple drift-compensated elastically-hinged load cell with high-precision deflection measurement. The specimen deformation measurement, compensated for drift through image tracking, yields displacement reproducibility of <6 nm. Proof of principle tensile experiments are performed on 5 µm-thick aluminum-alloy thin film specimens, demonstrating reproducible Young's modulus measurement of 72.6 ± 3.7 GPa. Room temperature creep experiments show excellent stability of the force measurement and underline the methodology's high reproducibility and suitability for time-dependent nanoforce tensile testing of on-wafer specimens.

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Time‐resolved integrated digital image correlation

Neggers

Hoefnagels

Geers

et al. 2015

Numerical Meth Engineering

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SUMMARYThis paper discusses a method that provides the direct identification of constitutive model parameters by intimately integrating the finite element method (FEM) with digital image correlation (DIC), namely, directly connecting the experimentally obtained images for all time increments to the unknown material parameters. The problem is formulated as a single minimization problem that incorporates all the experimental data. It allows for precise specification of the unknowns, which can be, but are not limited to, the unknown material properties. The tight integration between FEM and DIC enables for identification while providing necessary regularization of the DIC procedure, making the method robust and noise insensitive. Through this approach, the versatility of the FE method is extended to the experimental realm, enhancing the analyses of existing experiments and opening new experimental opportunities.

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Direct Stress-Strain Measurements from Bulged Membranes Using Topography Image Correlation

Cited by 57 publications

References 26 publications

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

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

On-wafer time-dependent high reproducibility nano-force tensile testing

Time‐resolved integrated digital image correlation

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