Comments for d3VIEW & LS-DYNA Blog http://blog.d3view.com Thu, 20 Nov 2008 21:29:59 +0000 http://wordpress.org/?v=2.6 Comment on Features Every LS-DYNA Simulation Must Have by Ganesh Shanbhag http://blog.d3view.com/2007/10/04/features-every-ls-dyna-simulation-must-have/#comment-3724 Ganesh Shanbhag Tue, 18 Nov 2008 09:54:57 +0000 http://blog.d3view.com/2007/10/04/features-every-ls-dyna-simulation-must-have/#comment-3724 Thank you.. We could identify the source of the problem Thank you..

We could identify the source of the problem

]]> Comment on True Total Strain to Effective Plastic Strain by Qian http://blog.d3view.com/2007/05/29/true-total-strain-to-effective-plastic-strain/#comment-3576 Qian Wed, 12 Nov 2008 22:43:58 +0000 http://blog.d3view.com/2007/05/29/true-total-strain-to-effective-plastic-strain/#comment-3576 Sorry, just found the answer myself. Sorry, just found the answer myself.

]]> Comment on True Total Strain to Effective Plastic Strain by Qian http://blog.d3view.com/2007/05/29/true-total-strain-to-effective-plastic-strain/#comment-3575 Qian Wed, 12 Nov 2008 22:37:42 +0000 http://blog.d3view.com/2007/05/29/true-total-strain-to-effective-plastic-strain/#comment-3575 Hello Suri, I have a question about true stress and effective stress. I was under the impression that I should convert true stress data to effective stress for MAT_24. Or I can use true stress values (minus the elastic part) for LCSS curve in MAT_24 directly? Thanks a lot, Hello Suri,

I have a question about true stress and effective stress. I was under the impression that I should convert true stress data to effective stress for MAT_24. Or I can use true stress values (minus the elastic part) for LCSS curve in MAT_24 directly?

Thanks a lot,

]]> Comment on Features Every LS-DYNA Simulation Must Have by Suri Bala http://blog.d3view.com/2007/10/04/features-every-ls-dyna-simulation-must-have/#comment-3544 Suri Bala Tue, 11 Nov 2008 15:21:05 +0000 http://blog.d3view.com/2007/10/04/features-every-ls-dyna-simulation-must-have/#comment-3544 Ganesh, Some things to consider based on information you have provided. 1. Ensure all energy balance options are turned on in CONTROL_ENERGY 2. You could use GLSTAT to output model mass as a function of time. 3. Ensure no nodes exist with initial mass and velocity. When these hit any rigidwalls, the KE could be misleading. 4. Some basic checks of momentum at time zero. Suri Ganesh,

Some things to consider based on information you have provided.

1. Ensure all energy balance options are turned on in CONTROL_ENERGY
2. You could use GLSTAT to output model mass as a function of time.
3. Ensure no nodes exist with initial mass and velocity. When these hit any rigidwalls, the KE could be misleading.
4. Some basic checks of momentum at time zero.

Suri

]]> Comment on Features Every LS-DYNA Simulation Must Have by Ganesh Shanbhag http://blog.d3view.com/2007/10/04/features-every-ls-dyna-simulation-must-have/#comment-3540 Ganesh Shanbhag Tue, 11 Nov 2008 10:21:44 +0000 http://blog.d3view.com/2007/10/04/features-every-ls-dyna-simulation-must-have/#comment-3540 Dear Suri, I am running one of full vehicle impact analysis with rigid wall ( 150 ms run) When I see glstat energy balance, there is sudden drop in kinetic energy curve between 47 - 48 ms. But there is no currusponding increase in global internal energy curve. Total energy curve is fairly constant throughout duration of run. also no other misc. energies in glstat shows the energy drop/hike in that time zone. But the analysis however continues and finishes 150 ms of run successfully I have also checked IE / KE / HE for all parts in matsum plot. I dont see any abnormal energy curve behavior in that time slot Now how to trace this sudden drop in KE energy in our global / partwise energy balance ?? FYI. I have used element fail option for few plastic parts in the model but there is no element failure taking place after 30 ms run as seen in message file I have even extracted B Pillar pulse and I dont see peaks or troughs in pulse also in that ime slot I have discussed this problem with ls dyna suppliers here in India but nobody could really help to resolve the issue Also for your information I am using same model in front ODB impact there the model finishes entire run without any such problem I am writing to you as last resort. Please help me out Best Regards Ganesh Shanbhag Dear Suri,

I am running one of full vehicle impact analysis with rigid wall ( 150 ms run)

When I see glstat energy balance, there is sudden drop in kinetic energy curve between 47 - 48 ms. But there is no currusponding increase in global internal energy curve. Total energy curve is fairly constant throughout duration of run. also no other misc. energies in glstat shows the energy drop/hike in that time zone. But the analysis however continues and finishes 150 ms of run successfully

I have also checked IE / KE / HE for all parts in matsum plot. I dont see any abnormal energy curve behavior in that time slot

Now how to trace this sudden drop in KE energy in our global / partwise energy balance ??

FYI. I have used element fail option for few plastic parts in the model but there is no element failure taking place after 30 ms run as seen in message file

I have even extracted B Pillar pulse and I dont see peaks or troughs in pulse also in that ime slot

I have discussed this problem with ls dyna suppliers here in India but nobody could really help to resolve the issue

Also for your information I am using same model in front ODB impact there the model finishes entire run without any such problem

I am writing to you as last resort. Please help me out

Best Regards

Ganesh Shanbhag

]]> Comment on Packing LS-DYNA Input Files for Easy Distribution (v1.1a) by Airfoil http://blog.d3view.com/2008/10/15/packing-ls-dyna-input-files-for-distribution/#comment-3483 Airfoil Fri, 07 Nov 2008 04:23:06 +0000 http://blog.d3view.com/?p=428#comment-3483 Suri, Thank you. I can't wait for the release. Airfoil Suri,
Thank you. I can’t wait for the release.

Airfoil

]]> Comment on Packing LS-DYNA Input Files for Easy Distribution (v1.1a) by Suri Bala http://blog.d3view.com/2008/10/15/packing-ls-dyna-input-files-for-distribution/#comment-3476 Suri Bala Thu, 06 Nov 2008 18:37:21 +0000 http://blog.d3view.com/?p=428#comment-3476 Hi Airfoil, Thanks for your note. I have made that change among others and the new version will be avaible shortly. Suri Hi Airfoil,

Thanks for your note. I have made that change among others and the new version will be avaible shortly.

Suri

]]> Comment on Modified Crushable Foam by Sandeep http://blog.d3view.com/2008/01/17/modified-crushable-foam/#comment-3474 Sandeep Thu, 06 Nov 2008 13:52:02 +0000 http://blog.d3view.com/2008/01/17/modified-crushable-foam/#comment-3474 Hi Pls tell me how do i model MAT57 for foam shell mesh Hi Pls tell me how do i model MAT57 for foam shell mesh

]]> Comment on Packing LS-DYNA Input Files for Easy Distribution (v1.1a) by Airfoil http://blog.d3view.com/2008/10/15/packing-ls-dyna-input-files-for-distribution/#comment-3454 Airfoil Tue, 04 Nov 2008 05:11:52 +0000 http://blog.d3view.com/?p=428#comment-3454 Hi Suri, Thank you for the script. I have been using your script since v1.0. My problem is that, my include files always two directory away from my header. example: ../BIW/biw.key ../DOOR/door.key. It will be nice if V1.1a can maintain the header file but only alter the directory line such as: ../BIW/biw.key to BIW/biw.key. Regards, Airfoil Hi Suri,
Thank you for the script. I have been using your script since v1.0. My problem is that, my include files always two directory away from my header. example:
../BIW/biw.key
../DOOR/door.key.
It will be nice if V1.1a can maintain the header file but only alter the directory line such as:
../BIW/biw.key to BIW/biw.key.

Regards,
Airfoil

]]> Comment on Damage modeling using GURSON by Suri Bala http://blog.d3view.com/2008/10/13/gurson-parameters/#comment-3133 Suri Bala Wed, 22 Oct 2008 14:23:17 +0000 http://blog.d3view.com/2008/10/13/gurson-parameters/#comment-3133 Tom, A closer look at the material card may provide some insight. If the material has time or strain based failure, this could happen but it is highly unlikely that the entire part could disappear at the same time. Since you are posing this question under the post, I presume the material the part belongs is GURSON in which case, a component analysis like a uniaxial test can be performed to see if the failure is pre-mature. Just some best guesses and I could be misleading. Suri Bala Tom,

A closer look at the material card may provide some insight. If the material has time or strain based failure, this could happen but it is highly unlikely that the entire part could disappear at the same time. Since you are posing this question under the post, I presume the material the part belongs is GURSON in which case, a component analysis like a uniaxial test can be performed to see if the failure is pre-mature. Just some best guesses and I could be misleading.

Suri Bala

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