research

Ericksen's problem consists of determining all equilibrium deformations that can be sustained solely by the application of boundary tractions for an arbitrary incompressible isotropic hyperelastic material whose stress-free configuration is geometrically flat. We generalize this by first, using a geometric formulation of this problem to show that all the known universal solutions are symmetric with respect to Lie subgroups of the special Euclidean group. Second, we extend this problem to its anelastic version, where the stress-free configuration of the body is a Riemannian manifold.

Surface instability of compliant film/substrate bilayers has raised considerable interests due to its broad applications such as wrinkle-driven surface renewal and antifouling, shape-morphing for camouflaging skins, and micro/nano-scale surface patterning control. However, it is still a challenge to precisely predict and continuously trace secondary bifurcation transitions in the nonlinear post-buckling region. Here, we develop lattice models to precisely capture the nonlinear morphology evolution with multiple mode transitions that occur in the film/substrate systems.

EML Webinar on 16 September 2020 will be given by Prof.  Rob Shepherd, Cornell University, Discussion leader: Jamie Paik, EPFL

In this paper we formulate the problem of elastodynamic transformation cloaking for Kirchhoff-Love plates and elastic plates with both in-plane and out-of-plane displacements. A cloaking transformation maps the boundary-value problem of an isotropic and homogeneous elastic plate (virtual problem) to that of an anisotropic and inhomogeneous elastic plate with a hole surrounded by a cloak that is to be designed (physical problem). For Kirchhoff-Love plates, the governing equation of the virtual plate is transformed to that of the physical plate up to an unknown scalar field.

Dear iMechanicians,

I hope some of you find of interest our latest Acta Mat. paper. We show that the concept of "beneficial traps" can enlarge by an order of magnitude the range of "safe loading frequencies" at which hydrogen embrittlement is not observed. 

Analysis of the influence of microstructural traps on hydrogen assisted fatigue

Rebeca Fernández-Sousa, Covadonga Betegón, Emilio Martínez-Pañeda

Acta Materialia 199, 253-265 (2020). Link

By Yu Zhou and Lihua Jin

Journal: International Journal of Fracture

Abstract: A simple nonlocal field theory of peridynamic type is applied to model brittle fracture. The kinetic relation for the crack tip velocity given by Linear Elastic Fracture Mechanics (LEFM) is recovered directly from the nonlocal dynamics, this is seen both theoretically and in simulations. An explicit formula for the change of internal energy inside a neighborhood enclosing the crack tip is found for the nonlocal model and applied to LEFM.

Usually, roughness destroys adhesion and this is one of the reasons why the "adhesion paradox", i.e. a "sticky Universe", is not real. However, at least with some special type of roughness, there is even the case of adhesion enhancement, as it was shown clearly by Guduru, who considered the contact between a sphere and a wavy axisymmetric single scale roughness, in the limit of short-range adhesion (JKR limit).

https://doi.org/10.1016/j.ijplas.2020.102850

Abstract

The Biofilm Matrix - A Living Engineering Material

Chenxi Zhai, Haoyuan Shi, Tianjiao Li, Liming Zhao, Jingjie Yeo

J2 Lab for Engineering Living Materials, Sibley School of Mechanical and Aerospace Engineering, Cornell University

Introduction

EML Webinar on 2 September 2020 will be given by Prof.  Costantino Creton, ESPCI Paris. Discussion leader: Tian Tang, University of Alberta.

Please check our new article on beam to surface contact modeling, recently accepted in  Computer Methods in Applied Mechanics and Engineering: https://doi.org/10.1016/j.cma.2020.113275 . We have used a previously reported dynamic corotational formulation and added frictional contact terms, which provide a fully consistent formulation.

The synergic combination of smart soft composites with kirigami/origami principles leads to self-deployable systems. To date, the development of soft deployable structures has largely been an empirical process. Focusing on the recently developed shape memory alloy (SMA)-based soft deployable structures, this paper describes an analytical model and a finite element (FE) numerical scheme to investigate deformation and deployment performance of this system.

EASF homepage: https://sites.google.com/view/engapplysciforum/home?authuser=0

Time: Every Sunday

London: 3:00-4:30 pm

Beijing: 10:00-11:30 pm

Composites Design and Manufacturing HUB (cdmHUB) invites you to attend the Global Composites Experts Webinar series. The goal of the series is to accumulate the vast knowledge of composites that has been developed over the past 50 years and to make it available to the global composites community. The inaugural lecture entitled Digital Disruption of Composites Manufacturing and Design will be given by Prof. Anoush Poursartip on September 3rd 11am-12pm EDT. Please visit https://lnkd.in/g9mkRjk for more details.

EML Webinar on 26 August 2020 will be given by Professor Xi-Qiao Feng, Tsinghua University via Zoom meeting. Discussion leader: Professor Wei Yang, Zhejiang University

Title: Dynamics of Collective Cells