Imaging stress and strain in the fracture of drying colloidal films

Xu, Yun; German, Guy K.; Mertz, Aaron F.; Dufresne, Eric R.

doi:10.1039/c3sm27912j

Cited by 48 publications

(57 citation statements)

References 46 publications

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“…In these cases, the development of analytical and numerical methods for the growth dynamics of multiple cracks has been a decades-long challenge 10 . More recently, the study of fracture patterns in soft materials has become a topic of specific interest due to the novel applications of these materials 2,[11][12][13][14] . Particular attention has been paid to the formation and paths of cracks in gels and colloids.…”

Section: Introductionmentioning

confidence: 99%

Modeling growth paths of interacting crack pairs in elastic media

Ghelichi

Kamrin

2015

Soft Matter

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The problem of predicting the growth of a system of cracks, each crack influencing the growth of the others, arises in multiple fields. We develop an analytical framework toward this aim, which we apply to the 'En-Passant' family of crack growth problems, in which a pair of initially parallel, offset cracks propagate nontrivially toward each other under far-field opening stress. We utilize boundary integral and perturbation methods of linear elasticity, Linear Elastic Fracture Mechanics, and common crack opening criteria to calculate the first analytical model for curved En-Passant crack paths. The integral system is reduced under a hierarchy of approximations, producing three methods of increasing simplicity for computing crack paths. The last such method is a major highlight of this work, using an asymptotic matching argument to predict crack paths based on superposition of simple, single-crack fields. Within the corresponding limits of the three methods, all three are shown to agree with each other. We provide comparisons to exact results and existing experimental data to verify certain approximation steps.

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Section: Introductionmentioning

confidence: 99%

Modeling growth paths of interacting crack pairs in elastic media

Ghelichi

Kamrin

2015

Soft Matter

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“…For example, during film processes, which are important for optoelectronics, magnetic and electronic materials [6][7][8][9], internal stresses often arise affecting the mechanical stability and strength of the film [9][10][11][12][13][14][15][16][17][18]. Here we study increasingly confined colloidal crystals to investigate how changes in their microstructure affect the microscopic stresses ultimately responsible for their bulk mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

Relating microstructure and particle-level stress in colloidal crystals under increased confinement

Lin

Cohen

2016

Soft Matter

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The mechanical properties of crystalline materials can be substantially modified under confinement. Such modified macroscopic properties are usually governed by the altered microstructures and internal stress fields. Here, we use a parallel plate geometry to apply a quasi-static squeeze flow crushing a colloidal polycrystal while simultaneously imaging it with confocal microscopy. The confocal images are used to quantify the local structure order and, in conjunction with Stress Assessment from Local Structural Anisotropy (SALSA), determine the stress at the single-particle scale. We find that during compression, the crystalline regions break into small domains with different geometric packing. These domains are characterized by a pressure and deviatoric stress that are highly localized with correlation lengths that are half those found in bulk. Furthermore, the mean deviatoric stress almost doubles, suggesting a higher brittleness in the highly-confined samples.

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“…Xu et al have also measured the Young’s Modulus of films of the same type of silica particles that were used in this study and found it to be ~100 MPa19. These values predict d ~ 3.3 h, as opposed to the data in Fig.…”

Section: Resultsmentioning

confidence: 54%

The interplay of crack hopping, delamination and interface failure in drying nanoparticle films

Yang

Sharp

Smith

2016

Sci Rep

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Films formed through the drying of nanoparticle suspensions release the build-up of strain through a variety of different mechanisms including shear banding, crack formation and delamination. Here we show that important connections exist between these different phenomena: delamination depends on the dynamics of crack hopping, which in turn is influenced by the presence of shear bands. We also show that delamination does not occur uniformly across the film. As cracks hop they locally initiate the delamination of the film which warps with a timescale much longer than that associated with the hopping of cracks. The motion of a small region of the delamination front, where the shear component of interfacial crack propagation is believed to be enhanced, results in the deposition of a complex zig-zag pattern on the supporting substrate.

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Imaging stress and strain in the fracture of drying colloidal films

Cited by 48 publications

References 46 publications

Modeling growth paths of interacting crack pairs in elastic media

Modeling growth paths of interacting crack pairs in elastic media

Relating microstructure and particle-level stress in colloidal crystals under increased confinement

The interplay of crack hopping, delamination and interface failure in drying nanoparticle films

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