AutoCAD

[grizz441]

of course I'm interested.  I have a ton of programs and such on aerodynamic engineering that I'd be happy to share.  Probably not much use in our fields but interesting nonetheless. 

I'm just now getting into the turbine stuff and I have a lot of concerns about the short meeting I took with the program designer.  I'm much more familiar with static loads at the top or top and down the pole. 

Harmonics is funky in this field because it's impossible to predict.  I designed a spread of poles for an AFB a couple of years ago.  Critical stress ratio was 87% and they were in a line not too far apart.  ONE of them started doing the hula due to the harmonics and we wound up putting vibration dampeners on all of them. 

I have to say I'm pretty happy with the fact that when all of those light poles were falling a couple of years ago none of them were mine

I'll shoot you a pm with my email addy <S>

Nono it is not impossible to predict.  You have to be able to estimate your structure's natural frequency, its soil damping, and its material damping, that's all.  Yeah the forcing frequency becomes a probabilistic/cost problem but I'm sure there is an industry standard?

[BrownBaron]

I'd recomend Google Sketch-Up, but that program is a complete joke.

Taking the whole Project Lead the Way I.E.D. thing, eh?

[Dichotomy]

Sadly no Grizz

Again I can put a line of poles up a highway and one in 20 might display vortex shearing due to the harmonics. 

The end user is not going to go to the expense of doing any studies other than requesting the lightest codes that 'might' govern and many of my competitors allow this based on the 'let the buyer beware' philosophy.  In order to offset this I use the most constraining code I can (AASHTO 1994 which uses a base wind speed plus a 3 second gust to 1.3 times the wind speed) to ensure that I'm covered and then run it in the code they requested to ensure that every parameter is met and exceeded.

As I said before I probably lose some business doing it this way but it beats worrying about being retired and finding out one of my poles fell on a bunch of kids.


 

[grizz441]

Sadly no Grizz

Again I can put a line of poles up a highway and one in 20 might display vortex shearing due to the harmonics.  

The end user is not going to go to the expense of doing any studies other than requesting the lightest codes that 'might' govern and many of my competitors allow this based on the 'let the buyer beware' philosophy.  In order to offset this I use the most constraining code I can (AASHTO 1994 which uses a base wind speed plus a 3 second gust to 1.3 times the wind speed) to ensure that I'm covered and then run it in the code they requested to ensure that every parameter is met and exceeded.

As I said before I probably lose some business doing it this way but it beats worrying about being retired and finding out one of my poles fell on a bunch of kids.

You also have to remember though, increasing the mass actually works against you with dynamics.  Your natural frequency goes down the heavier you get, more likely creeping you into the resonance range.  Going stockier typically only helps when dealing with the idealized static forces.  More damping, and increased base stiffness would be my best guess for a more efficient system based on what I know.

[Dichotomy]

interesting thought... I'll need to ponder that.  Instead of going with a heavier design utilizing stiffeners or a collar at the base and gussets on the top plate might alleviate that phenomenon. 

Fortunately, most of the time, a vibration dampener will stop the problem in the field.  $85 fix instead of replacing a 15k pole. 

In high mast that's a bit more of a quandary as you have to change the airflow around the pole.

And then there's seismic forces to deal with.  Fortunately usually the governing code makes the pole substantially more sound than even the most stringent seismic requirements... But I think we've digressed from the original point of the thread.

[grizz441]

interesting thought... I'll need to ponder that.  Instead of going with a heavier design utilizing stiffeners or a collar at the base and gussets on the top plate might alleviate that phenomenon. 

Fortunately, most of the time, a vibration dampener will stop the problem in the field.  $85 fix instead of replacing a 15k pole. 

In high mast that's a bit more of a quandary as you have to change the airflow around the pole.

And then there's seismic forces to deal with.  Fortunately usually the governing code makes the pole substantially more sound than even the most stringent seismic requirements... But I think we've digressed from the original point of the thread.

Well, increasing stiffness is fine, just so as long as the ratio of stiffness increase is larger than the ratio of increase of mass, otherwise you are gaining nothing.  I'm not an expert by any means, just what I have learned about the phenomenon. 

http://www.youtube.com/watch?v=LV_UuzEznHs
Interesting test to shed light on the problem.  The shortest frame has the highest natural frequency since its k is higher.  To excite it, the forcing vibration must be very high and vice versa for the taller frame.

[Dichotomy]

I'll check it out in the morning but I've acted like I have a brain enough for one day.   

OP

Sorry for the hijack but talking engineering is really fun for me especially with someone who knows what they're talking about.

<S> Grizz and thanks for the intellectual stimulation

[grizz441]

I'll check it out in the morning but I've acted like I have a brain enough for one day.   

OP

Sorry for the hijack but talking engineering is really fun for me especially with someone who knows what they're talking about.

<S> Grizz and thanks for the intellectual stimulation

<S>
Check your email too. 

[Dichotomy]

Done and thanks 

[smoe]

May want to take a peak on ebay. Check out any AutoCAD LT versions. The LT versions will surely be cheaper. I think if you get a R14 version or later you will be good to go. R13 will probably work for Win95/98/2000, questionable on XP. I've never used R12, but that may be a DOS version only, who knows, it may work on XP.

If you want to learn ACAD AutoLISP try a R14 manual. These are good enough and cheap on ebay ($15). I've never played around with VBA for AutoCAD, but that seems to be very popular today.

[Stoney]

I use both SolidEdge 2D (free) and Google Sketchup, depending on the application.  Solidedge is a conventional 2D CAD program, but very easy to use, and has almost all the features you need for design work. 

[Babalonian]

Anyone know of an online autoCAD program for FREE?

I just started doing AutoCAD in school and i absolutley love it. So i just need some help finding a decent one.

A)  Sorry if this was already said, kinda got here late and skipping from OP to the end.
B)  You did not hear this from me. 

Find an AutoCAD 2000i release posted somewhere on the intardnets (i - means it's a 2000-instructor/student version).  It's the last plug-n-play, full-version install without any online registration/registry crud, version.  Missing a lot of bells and whistles newer CAD releases have, but if you're trying to learn how to do CAD in your free time at home, this will do.

[jolly22]

Thanks everyone......I use autodesk at school and tried to download it and i barely have neough memory on this comp. to sustain it and it took 9 hours to download............. So im trying to find something similar to that where i can draw my 2D arch. house designs and go into a 3d view so i can see it.

[68ZooM]

Thanks everyone......I use autodesk at school and tried to download it and i barely have neough memory on this comp. to sustain it and it took 9 hours to download............. So im trying to find something similar to that where i can draw my 2D arch. house designs and go into a 3d view so i can see it.

Try PunchPro, it renders 2d and 3d, just make sure you check that it will meet with your systems spec's, you can find it at bestbuy, i use it to rough out the design and show the customers a walk thru of there house and what it looks like with furniture, appliances, HVAC , bathroom layouts, before i go into the time consuming Cad work into blueprint form

[VonMessa]

SolidWorks worked nicely for designing my brewery