Mass scaling accuracy 2

[skr3178]

Hi,

I am using mass scaling for my analysis. The documentation for abaqus indicates that mass scaling should be used with caution: "However, you must ensure that changes in the mass and consequent increases in the inertial forces do not alter the solution significantly."
The status file or "DMASS" for the analysis indicate a value of about 225E3. How can one determine if this is too large or acceptable? Should this be 0? How to control it? I would highly appreciate any guidelines on this.

The energy plots indicate that the kinetic energy is at max. 10% of the total internal energy. I found some advise in this post and in the abaqus documentation.
Thanks and Sincerely,
skr3178

 

[FEA way]

The best way would be to compare the results of simulations with and without mass scaling (or with different levels of scaling factors). However, you can also use the ratio of kinetic and internal energy to make sure that the analysis is still quasi-static and that inertia effect are insignificant.

 

[skr3178]

Thank you so much FEAway.
I have been struggling with this problem for quite some time and would appreciate your input.
My energy plot looks as shown below. As you mentioned and also as per manual the KE is roughly 5% of the IE.
DOes this look reasonable? ETotal increases as I am heating it in an oven from 293K to 696K.

 

[skr3178]

Sample .inp file to demonstrate loading conditions

 

[IceBreakerSours]

Although it is a pretty decent one, <5% KE/IE is still a thumb rule. Depending on the level of accuracy required, I might also check where/when the additional mass is added and if those locations/times are critical or not.

*********************************************************
Are you new to this forum? If so, please read these FAQs:

http://www.eng-tips.com/faqs.cfm?fid=376

http://www.eng-tips.com/faqs.cfm?fid=1083