Recent posts

#61

General Mechanics Discussion / Re: Tension Testing

Last post by Mark Barkey - August 30, 2018, 08:41:04 PM

hello, professor sir, I found your experimental video from your channel. Your explanations are awesome and very precise. I have a query on the tension test experiment.

I have a 2mm thickness sheet. I want to find the Poisson's ratio and youngs modulus through experiment. I am following the standard Flat test specimen size as per ASTM  test standard DESIGNATION-E8/E8M. As per standard prescribed thickness range lies within (0.005 ≤ T ≤ 0.75) in. So is there any variation in results if I select a minimum thickness and also variation in the result if I select multiple samples. If variation exists on results then how much variation?

If it is a metallic material, I would suspect that the actual material variation would be rather low for those two material properties.  Having said that, you may get some variation for very thin sheet vs thicker sheet but I think that variation would be due to the test set up.  Very thin sheet can be very easily distorted when clamping it into the testing machine grips.

2 mm is a nice thickness and I don't think you would have a problem with that for metals.  Poisson's ratio can be tricky if you use strain gages, too, in that it will not be very constant.  I think there is a good reason that Poisson's ratio is usually reported to only two significant digits.

Hope that helps.

#62

General Mechanics Discussion / Re: Tension Testing

Last post by SOMANATH MOHANTY - August 30, 2018, 11:39:10 AM

hello, professor sir, I found your experimental video from your channel. Your explanations are awesome and very precise. I have a query on the tension test experiment.

I have a 2mm thickness sheet. I want to find the Poisson's ratio and youngs modulus through experiment. I am following the standard Flat test specimen size as per ASTM  test standard DESIGNATION-E8/E8M. As per standard prescribed thickness range lies within (0.005 ≤ T ≤ 0.75) in. So is there any variation in results if I select a minimum thickness and also variation in the result if I select multiple samples. If variation exists on results then how much variation?

#63

General Mechanics Discussion / Re: Fracture Mechanics Discuss...

Last post by Mark Barkey - August 09, 2018, 02:55:25 AM

1- suppose I want to carry out any fracture experiment in any material then it can be modelled by lEFM/EPFM. Is there any strength related perticular parameter that distinguish both of them prior to experiment?

If I understand your question, you want to test a material and know before you test it if the conditions of LEFM or if EPFM conditions prevail?

The answer is no, you cannot.  If you look at the ASTM test procedure (metals) for conducting plane strain fracture toughness testing (KIc) then there are several conditions that must be met that can only be determined after the test has been conducted.

However, you can look at the ASTM test procedure for JIc testing, which assumes EPFM, and use that instead.   

#64

General Mechanics Discussion / Re: Re: Feel free to post ques...

Last post by SOMANATH MOHANTY - August 07, 2018, 03:16:00 PM

1- suppose I want to carry out any fracture experiment in any material then it can be modelled by lEFM/EPFM. Is there any strength related perticular parameter that distinguish both of them prior to experiment?

#65

General Mechanics Discussion / Re: Re: Feel free to post ques...

Last post by Mark Barkey - August 03, 2018, 02:56:38 AM

2. The asymptotic solution at crack tip gives singularity near that point then what happened to the solution when higher order terms included in the solution?
3.we want to extend LEFM concepts to rock like material then what is the effect of these higher order terms in finding fracture parameters?

The higher order terms are more of an influence away from the crack tip.  I don't think it will affect any fracture toughness parameters unless the process zone of the crack extends more than "usual".

In my opinion, anisotropy of the material may be more of an issue than the higher order terms.  However, please note that I am not an expert in Rock Mechanics.

Thanks,
MEB

#66

General Mechanics Discussion / Fracture Mechanics Discussion

Last post by SOMANATH MOHANTY - July 31, 2018, 01:51:15 PM

2. The asymptotic solution at crack tip gives singularity near that point then what happened to the solution when higher order terms included in the solution?
3.we want to extend LEFM concepts to rock like material then what is the effect of these higher order terms in finding fracture parameters?

[University of Darmstadt Mroz UMAT implementation 1992]

#67

AEM class related files / University of Darmstadt Mroz U...

Last post by Mark Barkey - July 16, 2018, 02:50:01 PM

University of Darmstadt Mroz UMAT implementation 1992

http://forums.mbarkey.com/index.php?action=downloads;sa=view;down=30

#68

Welcome Center / https now available

Last post by Mark Barkey - July 08, 2018, 10:28:58 PM

The server is now supported with https.  I will try to update any links but it may take a while.

#69

General Mechanics Discussion / Feel free to post questions

Last post by Mark Barkey - July 07, 2018, 02:25:56 PM

Ask about videos, lectures, or anything about Mechanics here. 

I will do my best to answer them. 

#70

Questions and Answers about ABAQUS / Determining what version of Fo...

Last post by Mark Barkey - June 27, 2018, 04:29:17 PM

Compilers should be installed before ABAQUS if possible so that the paths can be automatically set up.

It is not impossible to work with if the compilers are installed second, but there is more work involved if you install them second.

To see what Simulia used to test ABAQUS 2018 go to this link:
https://www.3ds.com/support/hardware-and-software/simulia-system-information/abaqus-2018/test-configurations-for-abaqus-2018-products/

and then then expand the Windows link, click on the windows 10 link to get a PDF with the test configuration.

Here is what it says for compilers:

Date: Mon Nov 13 14:35:09 2017
[some info deleted]
Processor: Intel(R) Xeon(R) CPU E5-1620 0 @ 3.60GHz
Number of CPUs: 4
Physical Memory: 16311 MB
Virtual Memory: 12179 Available / 18744 Total Mbytes
OS Version: Windows 10 Enterprise (Build 14393) C++
Compiler: Microsoft Visual C++ 14.0.24215.1
Linker Version: Microsoft (R) Incremental Linker Version 14.00.24215.1
Fortran Compiler: Intel Fortran Compiler 16.0
MPI: MS-MPI 5.0.12435.6
Browser: Internet Explorer 11.0.14393.1715

... so it looks like Fortran 16.0 is needed. Lastly, here is a link that tells you that Fortran 16.0 is Intel Fortran 2016.
https://software.intel.com/en-us/articles/intel-compiler-and-composer-update-version-numbers-to-compiler-version-number-mapping


For other versions of ABAQUS, follow similar steps.