6 Replies Latest reply on Mar 25, 2013 11:36 AM by Jared Conway

# Difference in Distributed Mass and Force in Static Sim

I have a quick, possible silly question that I can't find a good answer to.  I have a beam I want to load with a (uniform) distributed load.  What all would be the difference in the three application styles: 1) Force applied to the top face in the total amount desired, 2) Uniform loading with desired specific load calculated, or 3) Distributed mass applied with total amount.  Gravity would be on in all three cases to account for the beam weight.  I'm more interested in comparing 1 & 2.  I understand how a distributed mass can be beneficial in modal analysis, but in static is it more-or-less redundant?

• ###### Re: Difference in Distributed Mass and Force in Static Sim

Justin,

I'm not familiar with how SolidWorks Simulation handles loads applied to a face, but I suspect it is the same as ANSYS. If it is, then a force applied to a face actually results in a uniform pressure being applied to that face, so 1 and 2 give you exactly the same result. I assume that 3 would also give you the same result for a static load.

Jerry S.

• ###### Re: Difference in Distributed Mass and Force in Static Sim

Hai Justin,

Distributed mass will only make a difference when there are inertial forces (i.e. Gravity or centrifugal forces). In your case it doesn't make a difference because gravity is directed downwards. In order to undestrand the difference try this experiement:

- case 1 the beam loaded with a 1000 kg force at one end ( build a split line) and gravity direct ed downwards

- case 2 the beam loaded with a 1000 kg distributed mass, then ad gravity, but this time ad another component ( advanced tab in gravity), for example 50 m/s^2 in the side direction

You will see there will ne a bug difference in the results: the force doesn't "feel" inertial effects, while distributed mass will feel those 50 m/s^2 a lot

Alex

www.solidworkseducation.blogspot.com

• ###### Re: Difference in Distributed Mass and Force in Static Sim

Hi Justin, first thing I'd do is try them all and see what you get. From a learning perspective, you'll get the most from that. Then if they are different, ask yourself why you think they are different and we can start discussing here.

I don't really understand what the difference is between 1 and 2.

I'm surprised you didn't include modeling the part with the mass or a remote load. Those would be others that could be used in this case.

I would suggest you look at this from the perspective of both static and frequency.

Some more information about what your application is and what you want to learn and what assumptions you're ok with or aren't ok with (based on what you want to learn) would be helpful in answering this question unless you're looking specifically to know what the implementation of these features is. In general, I think its better to look at the practical sense.

• ###### Re: Difference in Distributed Mass and Force in Static Sim

I generally use a dummy part to simulate a mass when it's body/bonding strength is necessary, or if it's a concentrated area I split the surface and just apply a force to that spot if I just want the force.  I understand the majority of how things act, but was just curious and haven't a lot of time to conduct quick experiments.  When I do have some time I planned to run a few comparisons, but it doesn't always give you the big picture if you only look at a few aspects and each case may have flaws in certain areas overlooked.  I was asking for general experience into pros/cons for each.

• ###### Re: Difference in Distributed Mass and Force in Static Sim

Pros/cons are based on what assumptions you are ok with and what you want to learn. That would help narrow down from the 5-6 methods down to 1 or 2.