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14
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Last Post:
Nov 10, 2009 7:02 PM
Last Post By: yorkhighschool
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Posts:
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Registered:
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Help Finding Center Point of a Curved Plane
Posted:
Nov 5, 2009 2:05 PM
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Hello...I'm trying to find the center point of the curved planes at the bow of my boat. I need to teach my students how to find the center of gravities (longitudinal, traverse, & vertical) so I can help them with some boat designs. I need to find out the x, y, & z distances (same as my CG's) from my reference point (the origin) but cannot figure out how to make a center point on this curve....you'll see I've already made center points in sketches 13 through 15 in this part. I'm also using Inventor 11 so hopefully you all can open this file....thanks for any help and/or ideas anyone can give.
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Posts:
19
Registered:
07/28/08
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Re: Help Finding Center Point of a Curved Plane
Posted:
Nov 5, 2009 3:55 PM
in response to: yorkhighschool
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talking to a math teacher she told me I am looking for the Area Centroid of the curved surface....so does anyone out there know how to find the area centroid in Inventor 11?
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Re: Help Finding Center Point of a Curved Plane
Posted:
Nov 5, 2009 5:44 PM
in response to: yorkhighschool
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At the risk of sounding impertinent, why don't you just use Inventor's built
in ability to calculate volumes, masses and centre of gravity?
The other approach would be to apply some numerical integration method.
Simpson's formula is commonly used in yacht design.
Richard
wrote in message news:6284086@discussion.autodesk.com...
Hello...I'm trying to find the center point of the curved planes at the bow
of my boat. I need to teach my students how to find the center of gravities
(longitudinal, traverse, & vertical) so I can help them with some boat
designs. I need to find out the x, y, & z distances (same as my CG's) from
my reference point (the origin) but cannot figure out how to make a center
point on this curve....you'll see I've already made center points in
sketches 13 through 15 in this part. I'm also using Inventor 11 so hopefully
you all can open this file....thanks for any help and/or ideas anyone can
give.
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Posts:
19
Registered:
07/28/08
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Re: Help Finding Center Point of a Curved Plane
Posted:
Nov 5, 2009 5:58 PM
in response to: Richard Hinterh...
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Thanks for the reply Richard....I did not take your reply as impertinent. Using Simpson's formula is actually exactly what I'm doing as it's required by the contest rules. It requires us to calculate the center of gravity for each plate on a hull or boat design....Inventor 11 can calculate the CG, volume, and mass for the entire part or boat but I do not see how it will calculate it for the faces (hull parts) I need it done on....Keep in mind I have Inventor version 11 on my school computers. I know the newer versions will do as you say and calculate what I need for each face but my students simply do not have access to the newer versions of Inventor. And my school district is not buying new licenses any time soon....so I'm left with trying to figure this out using Version 11.
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Re: Help Finding Center Point of a Curved Plane
Posted:
Nov 5, 2009 6:53 PM
in response to: yorkhighschool
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Quick and dirty answer:
1/ Copy the file to a new name.
2/ Move the End of Part marker up above Extrusion 4
3/ Select the Delete Faces command and remove all faces except the one panel
you want
4/ Thicken that face to the plate thickness.
5/ Use the iProperties to determine the volume and COG. Of course, if you
plugged in the actual material it would also calculate the mass.
6/ Just as a reality check, I added a point in a 3d sketch. By rotating the
viewpoint I could determine whether this made sense or not.
These tools should have been available in release 11.
Richard
wrote in message news:6284310@discussion.autodesk.com...
Thanks for the reply Richard....I did not take your reply as impertinent.
Using Simpson's formula is actually exactly what I'm doing as it's required
by the contest rules. It requires us to calculate the center of gravity for
each plate on a hull or boat design....Inventor 11 can calculate the CG,
volume, and mass for the entire part or boat but I do not see how it will
calculate it for the faces (hull parts) I need it done on....Keep in mind I
have Inventor version 11 on my school computers. I know the newer versions
will do as you say and calculate what I need for each face but my students
simply do not have access to the newer versions of Inventor. And my school
district is not buying new licenses any time soon....so I'm left with trying
to figure this out using Version 11.
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Posts:
11,592
Registered:
04/20/06
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Re: Help Finding Center Point of a Curved Plane
Posted:
Nov 5, 2009 6:54 PM
in response to: yorkhighschool
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It requires us to calculate the center of gravity for each plate on a hull Sounds like you need to model as individual plates. Derive Component the original Body as WorkSurface for each plate and Thicken each plate as needed. |
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Posts:
19
Registered:
07/28/08
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Re: Help Finding Center Point of a Curved Plane
Posted:
Nov 5, 2009 8:34 PM
in response to: JDMather
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It requires us to calculate the center of gravity for each plate on a hull Sounds like you need to model as individual plates. Derive Component the original Body as WorkSurface for each plate and Thicken each plate as needed. JD...can you explain this in a bit more detail? I'm not familar how to use the "derived component" tool. |
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Posts:
11,592
Registered:
04/20/06
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Re: Help Finding Center Point of a Curved Plane
Posted:
Nov 5, 2009 8:42 PM
in response to: yorkhighschool
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Start a new ipt file.
Exit Sketch mode.
Click on the Derived Component tool and select your original file as the component to derive.
Hit the little question mark icon in the lower right corner of the dialog box or F1 on the keyboard.
What you are looking for in information on deriving the body as Worksurfaces.
Follow the Help instructions.
Then click the Thicken/Offset command.
Select the suface to thicken into solid by desire amount.
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Posts:
19
Registered:
07/28/08
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Re: Help Finding Center Point of a Curved Plane
Posted:
Nov 5, 2009 9:04 PM
in response to: JDMather
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Start a new ipt file.
Exit Sketch mode.
Click on the Derived Component tool and select your original file as the component to derive.
Hit the little question mark icon in the lower right corner of the dialog box or F1 on the keyboard.
What you are looking for in information on deriving the body as Worksurfaces.
Follow the Help instructions.
Then click the Thicken/Offset command.
Select the suface to thicken into solid by desire amount.
BEAUTIFUL!!!!! IT WORKED!!!! JDMATHER THANK YOU VERY MUCH FOR YOUR HELP!!!! Richard thanks again for your help as well!! What you suggested does work on my later version. I'VE GOT IT GOING NOW GUYS...THANKS AGAIN FOR ALL YOUR HELP!! I'VE ATTACHED A SCREENSHOT OF MY COG FOR THE CURVED PLATE....YEAH BABY!! |
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Re: Help Finding Center Point of a Curved Plane
Posted:
Nov 5, 2009 6:55 PM
in response to: yorkhighschool
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I meant to send some screen snapshots.
How involved is this competition? Are you expected to produce working
drawings?
Richard
wrote in message news:6284310@discussion.autodesk.com...
Thanks for the reply Richard....I did not take your reply as impertinent.
Using Simpson's formula is actually exactly what I'm doing as it's required
by the contest rules. It requires us to calculate the center of gravity for
each plate on a hull or boat design....Inventor 11 can calculate the CG,
volume, and mass for the entire part or boat but I do not see how it will
calculate it for the faces (hull parts) I need it done on....Keep in mind I
have Inventor version 11 on my school computers. I know the newer versions
will do as you say and calculate what I need for each face but my students
simply do not have access to the newer versions of Inventor. And my school
district is not buying new licenses any time soon....so I'm left with trying
to figure this out using Version 11.
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Posts:
19
Registered:
07/28/08
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Re: Help Finding Center Point of a Curved Plane
Posted:
Nov 5, 2009 8:15 PM
in response to: Richard Hinterh...
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It's a very involved competition....there are detailed drawings required but that's something I don't have a problem teaching. The weight, hydrostatics, waterline, trim, and stability calculations are very involved as well...the sponsor of the competition provides a spreadsheet that calculates most of these for the high school students. But it does not calculate the center of gravities. Students have to do that....either by concept model or by use of a CAD program. I will try your method and let you know how it worked out for me...cheers!
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Re: Help Finding Center Point of a Curved Plane
Posted:
Nov 5, 2009 8:38 PM
in response to: yorkhighschool
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Next impertinent question. Assuming the intent is that each of the hull
panels, bulkeads, stringers, decks and so forth are to be designed as
separate panels which will be prefabricated (I'm guessing welded aluminum),
why are you modelling this as a part being milled out of a 9,000 lb aluminum
block?
Wouldn't a series of assemblies representing the various weldments better
resemble the design intent? It would make detailing a lot easier.
Hydrostatic and stability calculations aren't hard to get out of IV
(valuable way to double check the spreadsheet calculations for errors).
Richard
wrote in message news:6284413@discussion.autodesk.com...
It's a very involved competition....there are detailed drawings required but
that's something I don't have a problem teaching. The weight, hydrostatics,
waterline, trim, and stability calculations are very involved as well...the
sponsor of the competition provides a spreadsheet that calculates most of
these for the high school students. But it does not calculate the center of
gravities. Students have to do that....either by concept model or by use of
a CAD program. I will try your method and let you know how it worked out for
me...cheers!
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Posts:
19
Registered:
07/28/08
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Re: Help Finding Center Point of a Curved Plane
Posted:
Nov 5, 2009 8:56 PM
in response to: Richard Hinterh...
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Next impertinent question. Assuming the intent is that each of the hull
panels, bulkeads, stringers, decks and so forth are to be designed as
separate panels which will be prefabricated (I'm guessing welded aluminum),
why are you modelling this as a part being milled out of a 9,000 lb aluminum
block?
Wouldn't a series of assemblies representing the various weldments better
resemble the design intent? It would make detailing a lot easier.
Hydrostatic and stability calculations aren't hard to get out of IV
(valuable way to double check the spreadsheet calculations for errors).
Richard Good catch...I got a chuckle from that one. The truth needs to come out...here it is...this part is actually an older entry from the same competition from 2007. Back then, they did not require the amount of calculations that they do now. So basically our entry from a few years ago consisted of this part and my students really didn't care what it was made out of just so they could get their drawings made from it. However, this year the competition has "ratcheted up" so-to-speak with the calculations portion and I'm simply trying to use an older model to make changes too and show my students how to meet the competion specs....what I was doing was working well up until the point I ran into a curved plane. I do have a last resort....my laptop at home does have a newer version which will calculate what my students need easily...I'm leaning toward simply bringing it in to my class and letting them open their models in the newer version to get the math figures they need. However I was trying to find a way around this by using the existing software in my classroom but it doesn't look good...I tried your earlier method and was really hoping it would work but it didn't...the center of gravity still stayed in the same location as the original boat. |
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Re: Help Finding Center Point of a Curved Plane
Posted:
Nov 8, 2009 2:18 AM
in response to: yorkhighschool
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I don't know how far you're going with the detailing on this competition,
but the way the originator of this hull created the curved bow panel results
in a subtle kink at the transition to the flat side panels. To the
untrained eye, the construction of this feature looks like the curve should
be tangent to the flat, but it's not.
The curve at the interface (highlighted in blue) is the red flag. Failure
to create a proper flat pattern confirmed my suspicion.
Richard
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Posts:
19
Registered:
07/28/08
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Re: Help Finding Center Point of a Curved Plane
Posted:
Nov 10, 2009 7:01 PM
in response to: Richard Hinterh...
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I don't know how far you're going with the detailing on this competition,
but the way the originator of this hull created the curved bow panel results
in a subtle kink at the transition to the flat side panels. To the
untrained eye, the construction of this feature looks like the curve should
be tangent to the flat, but it's not.
The curve at the interface (highlighted in blue) is the red flag. Failure
to create a proper flat pattern confirmed my suspicion.
Richard
Thank you Richard but this entry was from the competition two years ago...I was using it to re-teach myself the concepts I needed in order to better help my students be successful in this contest....here is an address to the contest if interested: http://www.sname.org/SNAME/DesignCompetition/HomeEdited by: yorkhighschool on Nov 10, 2009 11:01 AM |
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