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Calculating wind turbine tower loads - Page 8

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Posted by Curbie on March 3, 2009, 8:24 am
 
On Mon, 2 Mar 2009 15:51:10 -0800 (PST), ralleyrat


It is exactly what I did after reading the first couple replies to the
start of this thread, that and begin study on very basic Trigonometry.
I never took trig in high school (over 30 years ago), but was exactly
what I needed to have any understanding of this stuff.

Thanks,

Curbie

Posted by Curbie on March 3, 2009, 9:43 am
 
I'm drawn to your use of the word "canceling", I've been using the
word "countering" in my notes and I know they're two different words
with essentially the same meaning with no real significants to these
problems, but any excuse to rewrite my notes will force a much needed
review at this point.

I'm still muddy on when to apply which ratio of sine, cosine, or
tangent to solve for a particular force, I not looking for help with
this just "thinking out loud", this answer seems to be the key to
solving these problems and feel I will only properly understand its
application through study and review.

Thank you the efforts of this example, it should be obvious from this
post that I still don't get it, but thanks to the efforts a you and
others, feel like I am sneaking up on it.

Curbie
On Mon, 02 Mar 2009 19:02:45 -0600, david.williams@bayman.org (David
Williams) wrote:




Posted by Tim Jackson on March 3, 2009, 10:36 am
 Curbie wrote:

The mnemonic I learnt for right triangles was

"Old Horses All Have Old Aunties": O/H A/H O/A

Sine = Opposite/Hypotenuse
Cosine = Adjacent/Hypotenuse
Tangent = Opposite/Adjacent

Where Opposite and Adjacent refer to the side's relationship to the
angle in question.

Silly, but I don't forget.

When calculating loading forces for engineering purposes don't forget
that static forces are only half the story, for example the static
lateral force on the base is nominally zero, but if it were unrestrained
the tower wouldn't stand up for long.  Winds can produce unequal drag
above and below the guys (wherever you put them) and can set up bending
and oscillations which will confound your static calculations.  And
maybe you need to allow for a maintenance man climbing the tower.

That's why engineers tend to use large safety margins.


Tim Jackson

Posted by Jim Wilkins on March 3, 2009, 2:23 pm
 
http://darkwing.uoregon.edu/~struct/courseware/461/461_lectures/461_lecture=
7/461_lecture7.html

Find the right words and Google them.

Posted by Curbie on March 3, 2009, 6:05 pm
 On Tue, 3 Mar 2009 06:23:37 -0800 (PST), Jim Wilkins

A cursory review of the lecture looks promising. I'll chase it before
updating my notes. Still haven't revisited Critical Buckling Load of a
columns, but since this stuff applies the loads, any meaningfully
understanding that will depend in this. First things first.

Thanks for the light.

Curbie


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