An official website of the United States government
We investigate the spatial correlations of microscopic stresses in soft particulate gels using 2D and 3D numerical simulations. We use a recently developed theoretical framework predicting the analytical form of stress–stress correlations in amorphous assemblies of athermal grains that acquire rigidity under an external load. These correlations exhibit a pinch-point singularity in Fourier space. This leads to long-range correlations and strong anisotropy in real space, which are at the origin of force-chains in granular solids. Our analysis of the model particulate gels at low particle volume fractions demonstrates that stress–stress correlations in these soft materials have characteristics very similar to those in granular solids and can be used to identify force chains. We show that the stress–stress correlations can distinguish floppy from rigid gel networks and that the intensity patterns reflect changes in shear moduli and network topology, due to the emergence of rigid structures during solidification.
more »
« less
Toward Robust Stress Prediction in the Age of Wearables: Modeling Perceived Stress in a Longitudinal Study with Information Workers
More Like this
-
-
null (Ed.)Abstract A micromechanics-based ductile fracture initiation theory is developed and applied for high-throughput assessment of ductile failure in plane stress. A key concept is that of inhomogeneous yielding such that microscopic failure occurs in bands with the driving force being a combination of band-resolved normal and shear tractions. The new criterion is similar to the phenomenological Mohr–Coulomb model, but the sensitivity of fracture initiation to the third stress invariant constitutes an emergent outcome of the formulation. Salient features of a fracture locus in plane stress are parametrically analyzed. In particular, it is shown that a finite shear ductility cannot be rationalized based on an isotropic theory that proceeds from first principles. Thus, the isotropic formulation is supplemented with an anisotropic model accounting for void rotation and shape change to complete the prediction of a fracture locus and compare with experiments. A wide body of experimental data from the literature is explored, and a simple procedure for calibrating the theory is outlined. Comparisons with experiments are discussed in some detail.more » « less
-
As part of the first stage of a community-based participatory research project with two communities in the Canadian Arctic—Kangiqsujuaq, Nunavik, and Ulukhaktok, Northwest Territories—we conducted 57 interviews eliciting residents’ perceptions of pressing issues facing their communities, problems affecting health and wellbeing, and how researchers or other organized groups could help alleviate those problems. A recurrent theme that emerged during these interviews was having “no one to talk to.” Here, we focus on understanding why communication was a central theme using a grounded-theory approach to develop a model of Inuit stress management. Inuit in both Kangiqsujuaq and Ulukhaktok codify stress as isumaaluttuq, or excess worry, which often manifests physically and leads to social withdrawal. Because stress is believed to accumulate in the body, managing it involves decisions about whether to “Get It Out” or “Keep It In.” Keep It In is a potentially dangerous strategy because, if the problem does not resolve itself, accumulated stress may have harmful consequences. Inuit viewed talking to others as the most effective means to Get It Out, but respondents also identified numerous barriers to doing so. One important reason for this is that stress is transferable: Talking to others about a problem potentially increases the burden of stress on them. Consequently, Inuit may choose to Keep It In to avoid the potential negative consequences (for others or for oneself) of sharing bad thoughts. Based on this preliminary model, we consider questions for further inquiry and implications for community-based mental health programming in Inuit communities.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1109/TAFFC.2022.3188006
