Spontaneous symmetry breaking can result in emergence of complicated patterns in nature. Simple symmetry arguments can be used to describe beautiful and periodic rippled and wavy edges of flowers and leaves as well as fractal structure at the edge of a torn plastic sheet. In this paper, I will first discuss simple physical and geometrical arguments based on symmetry breaking and metrics on a cu...

Although understanding the collective migration of cells, such as that seen in epithelial sheets, is essential for understanding diseases such as metastatic cancer, this motion is not yet as well characterized as individual cell migration. Here we adapt quantitative metrics used to characterize the flow and deformation of soft matter to contrast different types of motion within a migrating shee...

In this paper, the study of efficient bonding characteristics of AA6014 and AA1050 metal strips is carried out for Accumulative Roll Bonding (ARB) process. Among various Severe Plastic Deformation (SPD) techniques, ARB process is widely used due to its ability to produce ultra-fine grained ( UFG) or nanostructured bulk material. It has been observed that, if the experimental pressure and corres...

Stretching process of sheet metals in both cases of axisymmetric and non-axisymmetric is analyzed. A rigid-plastic, normal anisotrop material is assumed and large strain formulation is applied. Triangular elements are used and stiffness equations of elements are obtained from virtual work principle. These nonlinear equations are linearized by Newton-Raphson's method and are solved by Gaussian e...

An intelligent V-bending process developed by the authors is briefly described and the importance of change in Young's modulus due to plastic deformation, which influences the amount of springback and therefore the accuracy, is emphasized. The change in Young's modulus in simple tension of a cold rolled steel sheet is experimentally investigated by affixing strain gauges on the specimen. It is ...

In this Thesis crumpling of thin sheets is explored when they are confined into a small volume by external forcing. To this end a simulation model based on a discrete element method is constructed. The Thesis begins with an introductory part reviewing the related elasticity theory and previous results on the properties of relevant geometric structures, ridges and cones, which appear in crumpled...

BACKGROUND Sepsis accounts for up to 15% of an estimated 3.3 million annual neonatal deaths globally. We used data collected from the control arms of three previously conducted cluster-randomised controlled trials in rural Bangladesh, India, and Nepal to examine the association between clean delivery kit use or clean delivery practices and neonatal mortality among home births. METHODS AND FIN...

We have measured the multiscale wrinkling that occurs along the edge of torn plastic sheets. The plastic deformations produced by tearing define a new metric on the sheet, which then relaxes elastically. The resultant patterns of wrinkles correspond to a superposition of waves of different wavelengths. Measurements of the variation of the pattern as a function of the distance from the edge reve...

Stretching process of sheet metals in both cases of axisymmetric and non-axisymmetric is analyzed. A rigid-plastic, normal anisotrop material is assumed and large strain formulation is applied. Triangular elements are used and stiffness equations of elements are obtained from virtual work principle. These nonlinear equations are linearized by Newton-Raphsons method and are solved by Gaussian el...

Equal channel angular rolling (ECAR) process is one of the severe plastic deformation (SPD) methods that have been used to make ultra-fine grain (UFG) materials with improving the mechanical properties of samples. After performing the process at several paths, a large strain is applied to the material that can cause decreasing the grain size and improving the mechanical and physical properties ...