Open Access. Powered by Scholars. Published by Universities.®
- Discipline
- Institution
Articles 1 - 4 of 4
Full-Text Articles in Engineering
Why The Crackling Deformations Of Single Crystals, Metallic Glasses, Rock, Granular Materials, And The Earth’S Crust Are So Surprisingly Similar, Karin A. Dahmen, Jonathan T. Uhl, Wendelin J. Wright
Why The Crackling Deformations Of Single Crystals, Metallic Glasses, Rock, Granular Materials, And The Earth’S Crust Are So Surprisingly Similar, Karin A. Dahmen, Jonathan T. Uhl, Wendelin J. Wright
Faculty Journal Articles
Recent experiments show that the deformation properties of a wide range of solid materials are surprisingly similar. When slowly pushed, they deform via intermittent slips, similar to earthquakes. The statistics of these slips agree across vastly different structures and scales. A simple analytical model explains why this is the case. The model also predicts which statistical quantities are independent of the microscopic details (i.e., they are "universal"), and which ones are not. The model provides physical intuition for the deformation mechanism and new ways to organize experimental data. It also shows how to transfer results from one scale to another. …
From Critical Behavior To Catastrophic Runaways: Comparing Sheared Granular Materials With Bulk Metallic Glasses, Alan A. Long, Dmitry Denisov, Peter Schall, Todd C. Hufnagel, Xiaojun Gu, Wendelin J. Wright, Karin A. Dahmen
From Critical Behavior To Catastrophic Runaways: Comparing Sheared Granular Materials With Bulk Metallic Glasses, Alan A. Long, Dmitry Denisov, Peter Schall, Todd C. Hufnagel, Xiaojun Gu, Wendelin J. Wright, Karin A. Dahmen
Faculty Journal Articles
The flow of granular materials and metallic glasses is governed by strongly correlated, avalanche-like deformation. Recent comparisons focused on the scaling regimes of the small avalanches, where strong similarities were found in the two systems. Here, we investigate the regime of large avalanches by computing the temporal profile or “shape” of each one, i.e., the time derivative of the stress-time series during each avalanche. We then compare the experimental statistics and dynamics of these shapes in granular media and bulk metallic glasses. We complement the experiments with a mean-field model that predicts a critical size beyond which avalanches turn into …
Force Oscillations Distort Avalanche Shapes, Louis W. Mcfaul, Wendelin J. Wright, Jordan Sickle, Karin A. Dahmen
Force Oscillations Distort Avalanche Shapes, Louis W. Mcfaul, Wendelin J. Wright, Jordan Sickle, Karin A. Dahmen
Faculty Journal Articles
Contradictory scaling behavior in experiments testing the principle of universality may be due to external oscillations. Thus, the effect of damped oscillatory external forces on slip avalanches in slowly deformed solids is simulated using a mean-field model. Akin to a resonance effect, oscillatory driving forces change the dynamics of avalanches with durations close to the oscillation period. This problem can be avoided by tuning mechanical resonance frequencies away from the range of the inverse avalanche durations. The results provide critical guidance for experimental tests for universality and a quantitative understanding of avalanche dynamics under a wide range of driving conditions.
Bending Nanoindentation And Plasticity Noise In Fcc Single And Polycrystals, Ryder Bolin, Hakan Yavas, Hengxu Song, Kevin J. Hemker, Stefanos Papanikolaou
Bending Nanoindentation And Plasticity Noise In Fcc Single And Polycrystals, Ryder Bolin, Hakan Yavas, Hengxu Song, Kevin J. Hemker, Stefanos Papanikolaou
Faculty & Staff Scholarship
Abstract: We present a high-throughput nanoindentation study of in situ bending effects on incipient plastic deformation behavior of polycrystalline and single-crystalline pure aluminum and pure copper at ultranano depths (< 200 nm). We find that hardness displays a statistically inverse dependence on in-plane stress for indentation depths smaller than 10 nm, and the dependence disappears for larger indentation depths. In contrast, plastic noise in the nanoindentation force and displacement displays statistically robust noise features, independently of applied stresses. Our experimental results suggest the existence of a regime in Face Centered Cubic (FCC) crystals where ultranano hardness is sensitive to residual applied stresses, but plasticity pop-in noise is insensitive to it.