Can AutoCAD accurately determine the center of gravity for my vehicle design?

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Discussion Overview

The discussion revolves around the ability of AutoCAD to accurately determine the center of gravity (CG) for a vehicle design, with participants exploring methods for calculating CG based on known dimensions and masses of components. The scope includes practical application and technical reasoning related to CAD modeling.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant inquires about locating the center of gravity for their vehicle design, stating that all parts, dimensions, and masses are known.
  • Another participant describes a method involving drawing, creating a region, and using the MASSPROP function in AutoCAD to find the centroid.
  • A question is raised regarding the accuracy of the method and whether the results align with theoretical calculations of the center of gravity.
  • Concerns are expressed about the accuracy of CAD models, noting that they may underestimate the total mass due to missing smaller components and other factors, which could affect the CG position.
  • A request for recommendations on firms that perform modeling in AutoCAD and literature related to the center of gravity is made.
  • One participant suggests that in 2D, the method is sufficiently accurate for practical purposes and encourages testing with a physical model to verify the centroid's position.

Areas of Agreement / Disagreement

Participants express varying opinions on the accuracy of AutoCAD's CG determination, with some acknowledging potential inaccuracies due to model limitations, while others assert that the method is adequate for practical applications. No consensus is reached regarding the reliability of the results.

Contextual Notes

Limitations noted include potential underestimation of mass in CAD models due to omitted components and manufacturing tolerances, which may impact the calculated center of gravity.

RJ2012
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HELLO

Can someone help me locate the center of gravity for my vehicle design? all the parts, dimensions and mass of the parts of the design are known. Is it possible to locate for the COG of it? Thanks!
 
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RJ2012 said:
HELLO

Can someone help me locate the center of gravity for my vehicle design? all the parts, dimensions and mass of the parts of the design are known. Is it possible to locate for the COG of it? Thanks!

The way I always did it in 2D was draw it, REGION it and MASSPROP it. From the massprop, you can drag the figure by the centroid to (0,0).
 
Hello! Is your method accurate? :) Does the result agree with the calculate/ theoretical ( if there's any) center of gravity? thanks buddy!
 
It will be as accurate as your CAD model. Most CAD models give a significant underestimate of the total mass of the object, because they don't contain all the "little" components like nuts and bolts that hold the real structure together, the mass of surface finishes like paint, manufacturing tolerances that produce oversized parts, etc.

That type of thing can easily contribute a few percent to the total mass of the real object, and obviously it can change the CG position as well.
 
Hello AlephZero! thanks for the reply! Do you know a firm (online ) who do modelling and do stuff in AutoCAD, or can you suggest me some readings/ related lit about center of gravity. I keep on looking and looking for different materials for this topic, thank you!
 
RJ2012 said:
Hello! Is your method accurate? :) Does the result agree with the calculate/ theoretical ( if there's any) center of gravity? thanks buddy!

In 2D, it's more accurate than you'll ever need. Try it out with an oddly shaped piece of cardboard or thin plywood (something with constant thickness). You should be able to balance the cardboard or plywood on a nail at the centroid AutoCAD gives you.
 

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