User login

Navigation

You are here

research

hyunwoo's picture

Multifunctional “Hydrogel Skins” on Diverse Polymers with Arbitrary Shapes

In this paper, we introduce a new simple yet effective strategy to form "hydrogel skins" on polymer-based medical devices with arbitrary shapes. Hydrogel skins can convert any surface of polymer devices into robust, wet, soft, slippery, antifouling, and ionically conductive without affecting the original properties and geometries.

Abstract

Soft wall-climbing robots

Soft wall-climbing robots

Guoying Gu, Jiang Zou, Ruike Zhao, Xuanhe Zhao and Xiangyang Zhu

Science Robotics, 2018, Vol. 3, Issue 25, eaat2874

keyhani's picture

Energy dissipation in polymer-bonded explosives with various levels of constituent plasticity and internal friction

The ignition of energetic materials (EM) under dynamic loading is mainly controlled by localized temperature spikes known as hotspots. Hotspots occur due to several dissipation mechanisms, including viscoplasticity, viscoelasticity, and internal friction along crack surfaces. To analyze the contributions of these mechanisms, we quantify the ignition probability, energy dissipation, damage evolution, and hotspot characteristics of polymer-bonded explosives (PBXs) with various levels of constituent plasticity of the energetic phase and internal crack face friction.

A novel technology on dynamic interlaminar fracture toughness measurement of composites

Huifang Liu, Hailiang Nie, Chao Zhang, Yulong Li

Composites Sciene and Technology, 2018, https://doi.org/10.1016/j.compscitech.2018.07.040

 

Hailiang Nie, Tao Suo, Xiaopeng Shi, Huifang Liu, Yulong Li, Han Zhao

Antonio Papangelo's picture

Bio-inspired solution for optimal adhesive performance

In recent years there has been a growing interest into high performance bioinspired adhesives. This communication focuses on the adhesive behavior of a rigid cylinder that indents an elastic layer coated on a rigid substrate. With the assumption of short range adhesive interactions (JKR type) the adhesive solution is obtained very easily starting from the adhesiveless one.

Mukunda Madhava Nath's picture

Converting viscoelastic Prony Series terms from ABAQUS to LS-DYNA

Choose a channel featured in the header of iMechanica: 

In Abaqus, 

g(t) = 1 - ∑(gi * (1-exp(-t/taui)); 

in which g and gi are dimensionless. 

 

In LS-DYNA, 

G(t) = ∑( Gi * exp(-betai * t) ); 

in which G and Gi are in N/m2

 

Based on this information, how do we transform the Prony Series terms from one code to another or vice-versa given I don't have the test data available.

 

Also, if I have the test data, what is a recommended process to determine Prony Series terms from the same?

hyunwoo's picture

Our new review on "Hydrogel Bioelectronics"

It is my first blog entry to iMechanica after long period of only reading.

In this review published in Chemical Soceity Reviews, we systematically revealed the design principles for bioelectronics and discussed hydrogels' merits and potential in bioelectronics.

 

Abstract

 

Shuze Zhu's picture

Nanomanufacturing of graphene nanosheets through nano-hole opening and closing

Materials Today, in press, 2018, https://doi.org/10.1016/j.mattod.2018.09.001

Yanan Chen, Yilin Wang, Shuze Zhu, Kun Fu, Xiaogang Han, Yanbin Wang, Bin Zhao, Tian Li , Boyang Liu , Yiju Li , Jiaqi Dai , Hua Xie , Teng Li , John W. Connell , Yi Lin, Liangbing Hu

Fan Xu's picture

A modeling and resolution framework for wrinkling in hyperelastic sheets at finite membrane strain

Wrinkles commonly occur in uniaxially stretched rectangular hyperelastic membranes with clamped-clamped boundaries, and can vanish upon excess stretching. Here we develop a modeling and resolution framework to solve this complex instability problem with highly geometric and material nonlinearities. We extend the nonlinear Foppl-von Karman thin plate model to finite membrane strain regime for various compressible and incompressible hyperelastic materials.

Theories used in Abaqus for composite plate modeling

Choose a channel featured in the header of iMechanica: 

Which plate theories are used in Abaqus for composite plate modeling? 

I am studying how delaminations in a composite plate affect its damping properties (by contact friction) and thereby to use for Structural health monitoring. Normally, in a metallic plate, no transverse normal stresses (S33) will be generated during pure bending. But, in a laminated composite plate, around discontinuities, S33 have been observed to be generated. But many plate theories neglect S33. But Reddys Layerwise theory and 3D plate theories consider S33 in the analysis. 

sairajatm's picture

Dislocation pattern formation in finite deformation crystal plasticity

Rajat Arora        Amit Acharya

Stressed dislocation pattern formation in crystal plasticity at finite deformation is demonstrated for the first time. Size effects are also demonstrated within the same mathematical model. The model involves two extra material parameters beyond the requirements of standard classical crystal plasticity theory. The dislocation microstructures shown are decoupled from deformation microstructures, and emerge without any consideration of latent hardening or constitutive assumptions related to cross-slip. Crystal orientation effects on the pattern formation and mechanical response are also demonstrated. The manifest irrelevance of the necessity of a multiplicative decomposition of the deformation gradient, a plastic distortion tensor, and the choice of a reference configuration in our model to describe the micromechanics of plasticity as it arises from the existence and motion of dislocations is worthy of note.

Amit Acharya's picture

On the Structure of Linear Dislocation Field Theory

Amit Acharya          Robin J. Knops         Jeyabal Sivaloganathan

(In JMPS, 130 (2019), 216-244)

Uniqueness of solutions in the linear theory of non-singular dislocations, studied as a special case of plasticity theory, is examined. The status of the classical, singular Volterra dislocation problem as a limit of plasticity problems is illustrated by a specific example that clarifies the use of the plasticity formulation in the study of classical dislocation theory. Stationary, quasi-static, and dynamical problems for continuous dislocation distributions are investigated subject not only to standard boundary and initial conditions, but also to prescribed dislocation density. In particular, the dislocation density field can represent a single dislocation line.

It is only in the static and quasi-static traction boundary value problems that such data are sufficient for the unique determination of stress. In other quasi-static boundary value problems and problems involving moving dislocations, the plastic and elastic distortion tensors, total displacement, and stress are in general non-unique for specified dislocation density. The conclusions are confirmed by the example of a single screw dislocation.

https://www.researchgate.net/publication/328792035_On_the_Structure_of_Linear_Dislocation_Field_Theory

 

 

mohamedlamine's picture

An efficient convergence test for the fixed point method

The fixed point method consists to find the solution of F(X)=X.

One can not get fixed with the convergence condition |F'(X)|<1 because if the function has an optimum then |F'(X)|=0 even if the solution is not yet reached.

 

We introduce an efficient convergence test with the condition:

|Xn+1 - Xn| ≤ epsilon1 And |F(Xn+1)-Xn+1| ≤ epsilon2

Zheng Jia's picture

Will Nemo's balloon burst or not?

Nemo lives in the ocean near the Great Barrier Reef. One day, he bought a hydrogel balloon which is inflated by an inner pressure p. Will the balloon burst eventually or stay safe?

Theories used in Abaqus for composite plate modeling

Choose a channel featured in the header of iMechanica: 

Which plate theories are used in Abaqus for composite plate modelling? 

I am studying how delaminations in a composite plate affect its damping properties (by contact friction) and thereby to use for Structural health monitoring. Normally, in a metallic plate, no transverse normal stresses (S33) will be generated during pure bending. But, in a laminated composite plate, around discontinuities, S33 have been observed to be generated. But many plate theories neglect S33. But Reddys Layerwise theory and 3D plate theories consider S33 in the analysis. 

Yoonho Kim's picture

Untethered soft machines and robots enabled by hard-magnetic soft materials

We introduce our recent works on advanced fabrication and mechanics of hard-magnetic soft materials towards the development of untethered soft machines and robots actuated and controlled by magnetic fields. 

- Abstract

Mike Ciavarella's picture

Questions to experts in Variable Amplitude Loading in Fatigue of metals

As a newcomer in this field, I try to pose some questions to the experts in Variable Amplitude Loading fatigue. The questions are probably trivial, but I don't find any reply in the literature, particularly on the arbitrary choice of frequency cutoff in the spectrum loading, and on the distinction  between cracked and uncracked structures. See attach and please respond if you can, even directly on email at mciava@poliba.it

Pages

Subscribe to RSS - research

Recent comments

More comments

Syndicate

Subscribe to Syndicate