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noyco's picture

Inversion and perversion in twist incompatible isotropic tubes

How can we induce twist in tubular structures without applying a torque?

In nature, such behavior is enabled by material anisotropy. In our new work, we show that isotropic bi-layer tubes with twist incompatible layers can twist upon inflation and extension.
Interestingly, the direction of twist can spontaneously reverse as the load increases!

Check out our new paper at EML:

matthew.grasinger's picture

Flexoelectricity in soft elastomers and the molecular mechanisms underpinning the design and emergence of giant flexoelectricity

Dear colleagues,
We invite you to see the preprint of our new paper "Flexoelectricity in soft elastomers and the molecular mechanisms underpinning the design and emergence of giant flexoelectricity" that will appear in PNAS. Here we present a molecular-to-continuum scale theory for the flexoelectric effect in elastomers. The theory unveils a mechanism for achieving giant flexoelectricity--which finds support in prior experimental results; it is then leveraged for designing elastomers for 1) piezoelectricity, 2) tuning the direction of flexoelectricity, and 3) flexoelectricity which is invariant with respect to spurious deformations (

Matt Pharr's picture

'Sideways' and stable crack propagation in a silicone elastomer

We have discovered a peculiar form of fracture that occurs in a highly stretchable silicone elastomer (Smooth-On Ecoflex 00–30). Under certain conditions, cracks propagate in a direction perpendicular to the initial pre-cut and in the direction of the applied load. In other words, the crack deviates from the standard trajectory and instead propagates perpendicular to that trajectory. The crack arrests stably, and thus the material ahead of the crack front continues to sustain load, thereby enabling enormous stretchabilities. We call this phenomenon 'sideways' and stable cracking.

Guenhael's picture

Ph.D. Candidate Position on “Characterization of the local mechanical behavior of elastomer materials by instrumented nanoindentation”

One Ph.D. candidate position is available in the Fall 2017 in the Elastomer Research Center (Cermel) at the Laboratory of Mechanics and Rheology (LMR) in the Polytechnic School of the University of Tours in France.

Job description

The aim of this Ph.D. is to extend the comprehension of the local mechanisms involved in elastomer materials, in order to faithfully reproduce their behavior in finite element models. The Ph.D. applicant is expected to carry out both theoretical and experimental work.

Stefan E. Schausberger's picture

RSS- -Cost-Efficient Open Source Desktop Size Radial Stretching System With Force Sensor

The rapid and efficient development of soft active materials requires readily available, compact testing equipment. We propose a desktop-sized, cost-efficient, and open source radial stretching system as an alternative to commercially available biaxial and uniaxial stretching devices. It allows for doubling the diameter of an elastomer membrane while measuring the applied force. Our development enables significant cost reduction (<300 €) and increase the availability of equibiaxial deformation measurements for scientific material analysis.

Yeoh Model Parameter


I'm conducting a simple shear test (single lap joint) between aluminum bonded with 3M adhesive. 

Adhesive material is 3M VHB 4930 adhesive (acrylic)

Result obtains = 

Load vs Displacement Curve

True Stress vs Stretch Ratio

From the literature, mostly they used Yeoh model for 3M adhesive (Modeling and simulation of dielectric elastomer actuators,M.Wissler 2005).

The material constant for C10, C20, C30 I get from the curve fitting equation from the True Stress vs Stretch Ratio.

Stephan Rudykh's picture

Analysis of microstructural induced enhancement of electromechanical coupling in soft dielectrics

Electroactive soft elastomers require huge electric field for a meaningful actuation. We demonstrate, by means of numerical simulation, that this can be dramatically reduced and large deformations can be achieved with suitably designed heterogeneous actuators. The mechanism by which the enhancement is attained is illustrated with the aid of both idealized and periodic models.

wvmars's picture

Short Course: Engineering of Durable Elastomeric Structures, 26-27 July 2011, Ann Arbor, Michigan

Elastomers are outstanding in their ability to repeatedly endure large deformations, and they are often applied where fatigue performance is a critical consideration. Because the macromolecular structure of elastomers gives rise to a number of unique behaviors, appropriately specialized methods are needed to characterize, analyze, and design for durability. This 2-day course provides the know-how for engineering durable elastomeric components and systems. The course is taught at Axel Products, and includes live demos of typical behavior.

Cohesive Elements and Soft Materials

I am working on a model in which i have a soft layer of material bonded between to rigid layers of material via cohesive elements following a linear separation-traction law based on a critical fracture energy value I determined from experimental and numerical work. I have the interlayer and cohesive elements as one part with a partitioned face and connected to the two adherends via surface-to-surface ties. I have found that my model runs successfully only if the soft interlayer material is made very stiff.


Why the elastomers are giving large actuation,what is the reason behind it

Amit Acharya's picture

Continuum Mechanics of Line Defects in Liquid Crystals and Liquid Crystal Elastomers

Amit Acharya and Kaushik Dayal

 (To appear in Quarterly of Applied Mathematics)

This paper presents a generalization of traditional continuum approaches to liquid crystals and
liquid crystal elastomers to allow for dynamically evolving line defect distributions. In analogy with
recent mesoscale models of dislocations, we introduce fields that represent defects in orientational
and positional order through the incompatibility of the director and deformation ‘gradient’ fields.

Internship available in FEA of elastomers

Internship Announcement  

Title : FEA of Elastomers

Category: Internship in Industry

Employer: Schlumberger Technology Corporation

Location: Sugar Land, TX, USA

Starting Date: 01/01/2010

Pressure over closure function for Polyurethane or (nearly) incompressible materials in general


Is anyone aware of a pressure-overcosure function for (nearly) incompressible materials.

 I am aware of functions for PE and articular cartilage but they do not work with v=0.5.   I have been trying to find similar functions for elastomers, but can't seem to find anything.

 I am grateful for any input.


Internship available in FEA of Elastomers

An internship position is available in the area of Finite Element Analysis of Elastomers in the Simulation and Modeling Group at Schlumberger, Sugar Land, TX.

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