iMechanica - Forum topic - Comments

Hi Graham, Thanks for ur

Gurudutt Chandrashekar — Sat, 31 Jul 2010 09:41:20 -0400

Hi Graham,

Thanks for ur suggestion. I have made all my subroutines in F90 . I got a doubt when i read in one of the abaqus documents on "Writing User Subrotines in Abaqus" that we have to specifically use F77 conventions. I should now figure out a way of configuring my Abaqus to use my F90 subroutines.

Dear Adrien

dubuking — Sat, 31 Jul 2010 00:46:13 -0400

HI~. I think your question has been ansered by Kyle. In the explicit code, the time increment is determine by the elemene size and the density of the model material, the time increment decreases as you use finer meshes. Thus, you should check the denominator in the subroutines.

regards,

Sangyul Ha

Have you tried yet?

Mike Graham — Fri, 30 Jul 2010 18:51:57 -0400

I have never done this, but I don't think there should be a problem in general. Make sure you've configured Abaqus to use a Fortran 90-aware compiler and if you're lucky it will Just Work.

I have used Abaqus user subroutines written in C++. In that case I just provide Abaqus the object file instead of the source code and it links it without caring what generated it. When you provide user=something, Abaqus automatically checks to see if it's source code or precompiled.

Writing subroutines in Fortran90 or higher versions

Gurudutt Chandrashekar — Fri, 30 Jul 2010 16:25:43 -0400

Hello everyone,

I am a student of Msc in Computational Engineering at Ruhr University Bochum in Germany. I am implementing a new piezoelectric element as a part of my Master Thesis. I am supposed to write a UEL subroutine and implement it in abaqus.I would like to know whether anyone has written subroutines in Fortran 90 or further versions and implemented them in abaqus. All the Help documents in Abaqus have subroutines written in F77. If it possible in F90, then it will be very helpful if someone could point out the necessary modifications that one has to make to the F90 file to run it in Abaqus. I think many ppl have this question .I myself have been trying to figure out an answer from past 1 month but could not find a convincing solution anywhere.

Dear Thanasis, Thanks for

mremami — Fri, 30 Jul 2010 15:54:29 -0400

Dear Thanasis,

Thanks for the comment. Actually, I want to model the adhesion of a coating to the Aluminum substrate using ABAQUS. I read all the help of ABAQUS to understand this type of modeling. Now, I know that I have to model it by COHESIVE ELEMENT and using "traction-separation constitutive response". The problem is that I need an example of this kind of modeling to find out the modeling procedure.

Would you please send me the procedure of modeling (step by step) during an example?

Thank you in advance.

Hi,Bashir,Thanks for

zhangxiaodong — Fri, 30 Jul 2010 10:21:26 -0400

Hi,Bashir,

Thanks for your attention.

When I say we intend to solve a equation of the form K(u)u =f , I refer to the discretized incremental form of the equation f_int(u) = f_ext. In nonlinear dynamic analysis, the equation system is supposed to be like

Kt(du)du=R

where kt(du) is tangent matrix. My trouble is how to get this tangent matrix.

I did derived some formulations, but the corresponding code does't work well. And I don't know the reason.

The formulations can be found in the attached file. Any advice will be appreciated.

Difficulties when adding image

Peter Cendula — Fri, 30 Jul 2010 10:16:16 -0400

I tried to add an image to my comment, so I uploaded it first with 'Add image' link in separate window and then dragged it to the original window with my comment.

The preview image appears in the comment and I set it up to be a "link to image page". However, when I preview the comment, the image is a link but points to a page like "http://imechanica.org/img_assist/properties/8626", which is the edit page of the image ;-(

The other feature which is not working - "Insert" button does not insert the image anywhere.

We should improve adding images more user-friendly, I'll be glad to help the web administrators.

Thanks

Peter

Thanks for your help

aelias — Fri, 30 Jul 2010 04:52:40 -0400

Thanks for your help Kyle.

I thought about that however the error occurs even when I use a coarse mesh (as long as the mesh density is variable). A regular mesh, even with very small elements, doesn't induce this error. But I will check again the subroutine. Do you have any other idea about what could cause this error?

Thank you

Adrien

Subroutine Problems

kyle.crosby — Thu, 29 Jul 2010 21:37:41 -0400

Adrian,

The subroutine you are using is causing the illegal floating point operation. It is usually caused when a function inside the subroutine is being divided by a really small number. My guess is that when you lower your mesh size, your stresses get small and a function tries to divide by those values, which gives you the floating point error.

Hope this helps.

Kyle

it seems that the input file

Thanasis Zisis — Wed, 28 Jul 2010 11:07:32 -0400

it seems that the input file (test.inp) is not in the same path with that that you are running ABAQUS in.

Hi, I am not sure if

Thanasis Zisis — Wed, 28 Jul 2010 11:04:36 -0400

Hi,

I am not sure if I aunderstand your question completely. I believe you have to be more specific...Anyway there many ways you can do something like this.

One simple way that has worked in the past is to create a part that contains the substrate and the coating and then assign different material properties.

Re: abaqus job=input file name

Biswajit Banerjee — Sun, 25 Jul 2010 22:41:28 -0400

I'd avoid using the command line unless your model contains features that cannot be handled by CAE or you want to run CAE and a job at the same time.

The command line has the form

abaqus job=YourJob input=YourJob.inp

It's hard to say exactly what your problem might be. You haven't provided us with the error messages that you get. "Not working" is not adequate information :)

Windows must be able to find the abaqus executable. Just type "abaqus" and see it it finds abaqus. If not add the location of the abaqus executable to your path. You'll probably find instructions on how to add a path on the web.

If the file "YourJob.inp" can't be found you'll have to run abaqus from the directory in which the input file is kept.

-- Biswajit

Sir, Thank you very much for

Manoj Krishna Majumder — Sat, 24 Jul 2010 08:14:27 -0400

Sir, Thank you very much for your rply. But I need to know in command prompt why this command "abaqus job=input file name" is not working!

Error message probably deceptive

Mike Graham — Fri, 23 Jul 2010 17:25:01 -0400

The UMAT API is very stable and--though I didn't personally check--I highly doubt the message is leading you up the right tree. I have gotten this message before and this was not the actual cause.

Can you explain what process you are using to use this subroutine and what platform you are running on? You might need to install or add-to-the-configuration-file the right compiler and linker. I believe when I ran into this this was the cause.

Problem with updating stress in Vumat while temperature higher

YangTan — Thu, 22 Jul 2010 22:16:49 -0400

hello,all!

In my simulation with vumat, the temperature will be higher than its melting temperature on several integral points, how sholud i update the stress and strain in that situation? Give them zero value? I think pressure shold be exist, but how to calculate it?

anyone can help me with this problem?

thanks