Showing papers by "Shmuel M. Rubinstein published in 2023"
TL;DR: In this paper , the authors examined the global response of thin shells to poking through the energy landscape and showed that by analyzing the dynamics of the shell, which gives the correct point of poking for accurate ridge tracking, and identified two kinds of buckling points.
Abstract: Recent research into the buckling load of thin shells has focused on local poking of the shell. In this approach, the shell is poked under load to extract its stability landscape, and a ridge tracking method is performed to estimate the buckling load of the shell. It is the current understanding that the stability landscape measures the local stability of the shell and, as a result, that the accuracy of ridge tracking greatly relies on the location of poking. Currently, there is no method that can predict where poking should be performed on an experimental system. Here, we examine the global response of thin shells to poking through the energy landscape. We present an experimental method for measuring the energy landscape of thin shells and demonstrate its application on a thin plate strip. We show that by analysing the dynamics of the shell in the energy landscape we can experimentally measure the buckling mode of the system, which gives the correct point of poking for accurate ridge tracking, and identify two kinds of buckling points. Finally, we propose how this approach can be applied to more complex systems such as thin cylinders. This article is part of the theme issue ‘Probing and dynamics of shock sensitive shells’.
2 citations
TL;DR: In this article , the failure of real cylindrical shells by experimentally poking soda cans with a large imparted dimple was examined, revealing that larger dimples tend to set the initial buckling location.
Abstract: Geometric imperfections are understood to play an essential part in the buckling of a thin shell, but how multiple defects interact to control the onset of failure remains unclear. Here, we examine the failure of real cylindrical shells by experimentally poking soda cans with a large imparted dimple. By high-speed imaging of the can’s surface, the initiation of buckling from axial loading is directly observed, revealing that larger dimples tend to set the initial buckling location. However, the influence of the shell’s background geometric imperfections can still occasionally dominate, causing initiation to occur far from the dimple. In this situation, probing at the dimple leads to an over-prediction of the axial capacity. Using finite-element simulations, we understand our experimental results as a competition between the large dimple and the shell’s inherent defect structure. In our simulations, we empirically observe a deformation-based criterion that connects the ideal poking location to the initiation site. This article is part of the theme issue ‘Probing and dynamics of shock sensitive shells’.
1 citations
TL;DR: In this paper , the statistics of noise emitted by ultrathin crumpled sheets are measured while they exhibit logarithmic relaxations under load, and the authors find that the log-Poisson relaxation advanced via a series of discrete, audible, micromechanical events that are log Poisson distributed (i.e., the process becomes a Poisson process when time stamps are replaced by their log-arithms).
Abstract: The statistics of noise emitted by ultrathin crumpled sheets is measured while they exhibit logarithmic relaxations under load. We find that the logarithmic relaxation advanced via a series of discrete, audible, micromechanical events that are log-Poisson distributed (i.e., the process becomes a Poisson process when time stamps are replaced by their logarithms). The analysis places constraints on the possible mechanisms underlying the glasslike slow relaxation and memory retention in these systems.
TL;DR: In this paper , the authors examine step interactions and show that interaction outcomes depend on the geometry of the incoming steps and the rules that govern step interactions can be categorized into three unique classes and fully described, providing a complete framework for predicting fracture roughness.
Abstract: The roughness of a fracture surface records a crack's complex path through a material and can affect the resultant frictional or fluid transport properties of the broken medium. For brittle fractures, some of the most prominent surface features are long, step-like discontinuities called step lines. In heterogeneous materials, the mean crack surface roughness created by these step lines is well captured by a simple, one-dimensional ballistic annihilation model, which assumes the creation of these steps is a random processes with a single probability that depends on the heterogeneity of the material, and that their destruction occurs via pairwise interactions. Here, through an exhaustive study of experimentally generated crack surfaces in brittle hydrogels, we examine step interactions and show that interaction outcomes depend on the geometry of the incoming steps. The rules that govern step interactions can be categorized into three unique classes and are fully described, providing a complete framework for predicting fracture roughness.
TL;DR: In this paper , a transparent experimental fault that allows direct observation of thousands of slip events, with ruptures that are fully contained within the fault, was developed and the observed stress drops are largely independent of both the magnitude of normal stress and its heterogeneity, capturing the independence seen in nature.
Abstract: Seismic moment and rupture length can be combined to infer stress drop, a key parameter for assessing earthquakes. In natural earthquakes, stress drops are largely depth‐independent, which is surprising given the expected dependence of frictional stress on normal stresses and hence overburden. We have developed a transparent experimental fault that allows direct observation of thousands of slip events, with ruptures that are fully contained within the fault. Surprisingly, the observed stress drops are largely independent of both the magnitude of normal stress and its heterogeneity, capturing the independence seen in nature. However, we observe larger, normal stress‐dependent stress drops when the fault area is reduced, which allows slip events to frequently reach the edge of the interface. We conclude that confined ruptures have normal stress independent stress drops, and thus the depth‐independent stress drops of tectonic earthquakes may be a consequence of their confined nature.