research
How to form a nolinear TD constitutive relation?
A linear constitutive thermodynamic relation between thermodynamic force f and flux v.
v = Mf, where M is the phenomological coefficient.
How to constitute a nonlinear thermodynamic constitutive relation for an unknown system which we expect to exibit nonlinear behaviour?
Could anyone help on Drucker-Prager model?
I am using exponent Drucker-Prager model at the moment, is there anyone can tell me where the follow exponent D-P eqation comes from originally?
(σ e)(σ e)=λ(σt)(σt)-3(λ-1)σmσt
Where λ= is hydrostatic stress sensitivity parameter and equal to σc/σt, σe is effective stress, σm is hydrostatic stress, σc, σt are stresses under compression and tension, respectively.
Simple strategies to produce perfect long range order in self-assembly
In a recent rapid communication (see attached paper), using principles of pattern formation, we expose some simple stategies to reliably produce perfect long range order in self-assembling systems. Most self-assembling systems exhibit short ranged order. This imperfection is detrimental to several practical applications. It is almost always possible to produce perfect patterns in small domain sizes but self-assembly over a larger areal span results in defects.
Composite analysis using SHELL99
I'm trying to model a composite structure with shell 99 element in Ansys.
I set the thickness and material no. in real constant and prepare an orthotropic material property for that. While ploting the result, as I expect to get the stresses among layers different from other points, but the result is a kind of uniform isotropic graph.
I don't know if any setting other than real constant and material property should be done to get a true result or not. and if I'm true then how can I read the true result.
I will appreciate any help.
Fatigue damage initiation - computational methods
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Dear iMechanicians,
It seems that nobody here is active in fatigue life prediction focused on the initiation period. I believe it should be here and do not understand why the fracture mechanics has its place here but the initiation of cracks has been forgotten. Although cracks are very interesting there is a lot industrial sectors, where they are not wanted. Is not the reason of the current situation that the available computational tools that are free are mostly related to crack growth?
Regards,
Jan Papuga
Measurements of near-ultimate strength for multiwalled carbon nanotubes and irradiation-induced crosslinking improvements
For more than 15 years, carbon nanotubes (CNTs) have been the flagship material of nanotechnology. Researchers have conceived applications for nanotubes ranging from microelectronic devices to cancer therapy. Their atomic structure should, in theory, give them mechanical and electrical properties far superior to most common materials.
Using User Subroutine UMAT in abaqus
Hi,
Iam a new user of abaqus. I have a subroutine written in *.for format. I also have an input file *.inp . Both these programs are in the same folder. When I try to execute the *.inp file using the command
abaqus job=jobname datacheck interactive
I get a message saying "Abaqus/Standard Analysis exited with an error. please see the message file for possible error messages". I looked in the message file and it says ***ERROR: USER SUBROUTINE UMAT IS MISSING.
Then I used the command
abaqus job=jobname user=umat.for
