## Simulation Mechanical and Multiphysics

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# lumped masses

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Hi

I am using beam elements in one of my model.I am using setup--loads--weight to give the beam element its actual weight.

my question is, while defining element definition and material, we do give c/s of the beam and density of the material.

so how does asim calculates the weight of the beam? Assigned weight or calculating the beam volume and multiplying with density or adding both?

your help is appreciated.

ASIMM 2012

# Re: lumped masses

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I'm not very sure about this beam check, but my guess is setup-loads-weight is a kind of load, instead of changing mass/density.

If this response answers your concern, please mark it as "solved".

# Re: lumped masses

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okay.

In my model I do have many beam elements with some elements having actual c/s properties. So ASIM can calculate weight from gravitational multiplier.

But for some other beam elements, I need to assign the weight manually.So I use lumped masses.If asim also adds weight due to gravity, then it means adding up more weight to the beam elements right? or is there any other way around?

ASIMM 2012

# Re: lumped masses

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The "weight" of a beam element equals "cross section area" x "length of element" x "mass density" x "Acceleration due to body force" x "X, Y, and Z multiplier" x "Gravity/Accel Load Case Multiplier". All of these values are entered by the user. The only one that you can make 0 without affecting the weight of the rest of the model is the mass density.

Note that the "Gravity/Accel Load Case Multiplier" is used if performing linear stress analysis. For MES and nonlinear analyses, the Load Curve is used in place of the "Gravity/Accel Load Case Multiplier".

Adding "Setup > Loads > Weight" (formerly known as lumped mass) to a model is adding additional weight. It is similar to adding a force or a distributed load.

John Holtz, P.E.

Senior User Experience Designer, Simulation

Autodesk, Inc.

Current version of Mechanical & Multiphysics: 2013 SP1 (2013.01.00.0012 28-Jun-2012)

# Re: lumped masses

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then john do lumped masses addup in overall weight calculation.

I did find this in the ASIM 2013 wiki

Lumped masses and lumped mass moments of inertia may or may not be included in the weight and center of gravity calculation depending on the analysis type. Also, the results with masses of different values in the X, Y, and Z directions may be based on the X mass only. Refer to the weight and center of gravity summary file (.WCG) to see how it is treated for each situation.

ASIMM 2012