One more explicit question

[amar]

hello,
Regarding the previous post I had one more small question. The riveting analysis with hyperelastic material takes a long time to run in explicit. Going through the manuals about "mass scaling" to reduce the computation time. I just had two questions in which I am not clear from the manual. I have aluminum (density 0.00026 lb/in2 sec4) and rubber (density 0.0001 lb/in2sec4). Should one use just one mass scaling factor for both the materials or scale them separately? will this affect the solution? going through the manual there are many options fo rmass scaling. the fixed one seems the most straightforward to apply. How do you decide the factor to scale your mass?
thanks a lot
amar

[Jorgen]

Hmm, are you sure you got the units right for the density, isn't density = mass/volume? One of the best ways to do mass scaling is to use a command like the following example

*Variable mass scaling, freq=1, dt=1.250000E-8, elset=laminate.allE, type=below min

There is no easy way to determine how much you can scale the mass before you start to get inaccurate results. The standard approach is to try different mass scaling constants, using a trial-and-error approach.

[amar]

Hi Dr.Bergstrom,
Yea I will try different mass scaling constants and compare them to the solution without mass scaling so I get an idea when excessive mass scaling is happening. Yea the units for density are lb/in3 but in abaqus you have to multiply by g to obtain lbsec2/in4. I am sorry in my post I wrote it backwards but the numbers are right.
thanks a lot
amar