Plane strain cylindrical indentation of functionally graded half-plane with exponentially varying shear modulus in the presence of residual surface tension

A functionally graded half-plane with shear modulus varying exponentially along the direction normal to the surface and surface effects accounted through Gurtin Murdoch model, indented by long rigid smooth cylindrical indenter is solved to understand the effect of material inhomogeneity and surface effects on indentation response. The Green's function relating surface load to surface displacement under plane strain condition is obtained semi analytically through the combination of Airy stress function approach and Fourier transforms and utilized to solve the contact problem. The solution is used to study the effect of inhomogeneity through grading parameter and surface effects through residual surface tension based intrinsic length scale on the contact pressure, contact size and in-plane normal stress on the surface responsible for cracks during indentation. (C) 2017 Elsevier Ltd. All rights reserved

Analytical Investigation of Binder's Role on the Diffusion Induced Stresses in Lithium Ion Battery through a Representative System of Spherical Isolated Electrode Particle Enclosed by Binder

Binder which serves to maintain mechanical and electrical integrity of Lithium ion batteries and occupies as much as 50% of battery weight is rather relatively less explored in terms of its effect on electrode and binder stresses during charging-discharging operation and hence motivates the present work. Closed form solution of diffusion induced stresses in an isolated spherical linear elastic, perfectly plastic electrode particle encapsulated by a linear viscoelastic binder during galvanostatic charging-discharging cycle under two sets of boundary conditions for the binder surface viz. traction free and fully constrained are developed. It is proved that the stresses in binder are unchanged even if electrode deforms elastically or plastically and whether diffusion in electrode is driven by concentration gradient or combination of concentration gradient and hydrostatic stress. The analysis identifies that current density not only directly controls the diffusion induced stress in electrode but affects it indirectly through change in stiffness of the binder depending upon the cycle time. Furthermore analysis reveals lower viscosity, lower stiffness and faster relaxation behavior as the recommended binder properties for lower diffusion induced stresses in electrode and binder. (C) 2017 The Electrochemical Society. All rights reserved

Plane strain indentation on finite thickness bonded layer in couple stress elasticity

Contact of flat, cylindrical and wedge indenter on a finite thickness layer obeying couple stress elasticity and bonded to a rigid base under plane strain conditions is solved. The method of stress functions and Fourier transforms is employed to reduce the mixed boundary value contact problem to a singular integral equation in terms of the unknown contact pressure and contact size. For a given load on the indenter, the solution is obtained iteratively through numerical inversion of the integral equation and the effect of layer thickness and intrinsic length inherent in couple stress elastic material on the contact pressure and contact size is studied. Finally a map described in terms of the intrinsic length and layer thickness is proposed which can be used as a guiding tool to decide appropriate combination of geometry i.e. layer or half space and material behavior i.e. classical elasticity or couple stress elasticity to obtain accurate indentation response for a given system.(C) 2016 Elsevier Ltd. All rights reserved

Stress enhanced calcium kinetics in a neuron

Accurate modeling of the mechanobiological response of a Traumatic Brain Injury is beneficial toward its effective clinical examination, treatment and prevention. Here, we present a stress history-dependent non-spatial kinetic model to predict the microscale phenomena of secondary insults due to accumulation of excess calcium ions (Ca) induced by the macroscale primary injuries. The model is able to capture the experimentally observed increase and subsequent partial recovery of intracellular Ca concentration in response to various types of mechanical impulses. We further establish the accuracy of the model by comparing our predictions with key experimental observations