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Why getting trouble with Abaqus UMAT subroutine when using interaction features like contact or tie?

Submitted by Rudraprasad Bh… on
software
#ABAQUS

I am implementing a constitutive relation in UMAT subroutine using the commercial software Abaqus. First, I tested the UMAT subroutine with 'one element model' first. Then I tested with comparatively bigger geometry. It worked fine. Now when I am trying to do a models involving contact, i.e. use of the 'Interaction module'. I am getting error of over-constraint warning for 'Split Tension test of concrete cylinder'. The same input file (except the material definition) is running on Abaqus perfectly with Mohr-Coulomb criteria. I can see a reasonable stress and strain contour.

The role of gas pressure on the effective thermal conductivity of pebble beds

Submitted by Dr. Hanaor - D… on
research
thermal
DEM
Pebble bed
heat transport
conductivity
gas pressure
smoluchowski

Influence of gas pressure on the effective thermal conductivity of ceramic breeder pebble beds

https://doi.org/10.1016/j.fusengdes.2017.03.073

 

Contact stiffness of rough surfaces

Submitted by Dr. Hanaor - D… on
research
contact mechanics
contact stiffness
fractal surfaces
emerging
Roughness

Contact stiffness of multiscale surfaces by truncation analysis

 

In this concise piece of work, an effective method is shown to gain new understandings into the role of surface structure in the field of contact mechanics. In particular, normal contact stiffness is correlated to parameters of surfaces' fractal dimension and amplitude. 

3D printing of simulated geomaterials

Submitted by Dr. Hanaor - D… on
research
granular materials
Geotechnical egineering
additive manufacturing
morphology
3D printing
Particle morphology

3D printable geomaterials

https://doi.org/10.1680/jgeot.15.P.034

This work, dating back to 2015 demonstrates the simulation of grain morphologies for subsequent fabrication of surrogate geomaterials 

 

Full text here 

Abstract

 

Funded PhD Fellowship in Multiscale Computational Mechanics of Bone Fragility in T2 Diabetes

Submitted by tedvaughan on

The Biomechanics Research Centre (BioMec) at NUI Galway is seeking applications for a funded-PhD position in Multiscale Mechanics of Bone Fragility in Type-2 Diabetes for a project funded by the European Research Council Starter Grant Scheme, under the supervision of Dr. Ted Vaughan (Google Scholar).

a response (dedicated to John Hutchinson) from Bob McMeeking, M.Ciavarella, G Cricrì and KS Kim on the MCD paradox on sliding and adhesive sphere ---- mixed mode fracture mechanics as applied to contact mechanics

Submitted by Mike Ciavarella on
MCD theory
fracture mechanics
John Hutchinson

Here you find a response to the MCD paradox from McMeeking, M.Ciavarella, G.Cricrì, and KS Kim.  Here.

The paper is dedicated to number one of Mechanical engineering in the world, John Hutchinson from Harvard.

Curvature suppresses tensile wrinkles

Submitted by Fan Xu on
research
hyperelasticity
bifurcation
phase diagram

Transverse wrinkles usually occur in a uniaxially tensile elastic membrane and will be smoothed upon excess stretching. This instability-restabilization response (isola-center bifurcation) can originate from the nonlinear competition between stretching energy and bending energy. Here, we find a crucial factor, the curvature, which can control effectively and precisely the wrinkling and smoothing regimes. When the sheet is bent, the regime of wrinkling amplitude versus membrane elongation is narrowed, with local wrinkling instability coupled with global bending.

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