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Subject: Re: beam188/9 changes from 5.6 to 5.7
Author: K.S. Raghavan
Date: 2002-06-12 14:41:00

Bhashyam,

Some numbers in support of my statements.

Modal analysis of pipe 10 OD, 8 ID 50 long , clamped at both ends analyzed
using five different models. The models are

1. BEAM44 with section properties input (S44).
2. BEAM44 with REAL constants input (R44)
3. BEAM188 elements. (B188)
4. BEAM3 elements. (B3)
5. Harmonic element , mode=1 (P83)

The first four eigenfrequencies for the five models are :

S44 .. 15599 , 32140 , 48199 , 61222
R44 .. 22246 , 57645 , 104015 , 156461
B188 .. 16054 , 35244 , 58596 , 84741
B3 .. 22246 , 57645 , 104015 , 156461
P83 .. 16160 , 35031 , 56738 , 78780

Of the above P83 and B188 are reliable. R44 and B3 bring out the limitation
of the theoretical basis. Results S44 are difficult to digest.

Regards .. raghavan

-----Original Message-----
Sent: Wednesday, June 12, 2002 1:28 PM
To: 'xansys@yahoogroups.com'

Pl. see my comments below

-----Original Message-----
Sent: Wednesday, June 12, 2002 1:08 PM
To: 'xansys@yahoogroups.com'

Bhashyam,

Thanks. I am referring to ANSYS v5.7.

The reason for my asking the question is that theoretical basis of BEAM44
and BEAM188 elements are different. The latter is based on Timoshenko theory
and accounts for shear deformation. BEAM44 , on the other hand , is based on
Euler theory.

An interesting fact is that if static or modal analysis is carried out using
BEAM44 with REAL constants , the results are same as those obtained with
BEAM4 elements. But results obtained from BEAM44 with SECTION properties are
same as those obtained from BEAM188 elements.
Often it appears to me that BEAM44 with shear correction returns more
flexible results (higher deflection or smaller eigenfrequencies) as compared
to BEAM188. This is a bit of surprise and perhaps calls for some
explanation.

>>> BEAM44 uses a higher order polynomial. You might get better
>>> correllation by using BEAM189 or a refined mesh of 188.
>>> I dont understand BEAM44 producing different results when used
>>> with section & real though (assuming it is same properties).
>>> Pl. forward a input to your normal support channel if you suspect
>>> a bug. Regards

Regards .. raghavan

-----Original Message-----
Sent: Wednesday, June 12, 2002 12:08 PM
To: 'xansys@yahoogroups.com'

Raghavan

I think it depends on the version you are using.
I remember seeing this reported as a bug -- and it was
fixed.

Section calculations are independent of element type.

--grb

-----Original Message-----
Sent: Wednesday, June 12, 2002 11:36 AM
To: 'xansys@yahoogroups.com'

Bhashyam,
I have a question in this connection.
In the case of BEAM44 in conjunction with SECTYPE etc., ANSYS calculates
shear factors ( However if REAL constants are used , shear factors are not
computed for BEAM44 element). What is the difference between the shear
factor calculated for BEAM44 and that for BEAM188 ?

Regards .. raghavan ( INFOTECH , India / Pratt & Whitney USA )

-----Original Message-----
Sent: Wednesday, June 12, 2002 10:57 AM
To: 'xansys@yahoogroups.com'

If you do slist in both versions -- you might see the applicable
differences. The shear factors are automatically calculated in
later versions.

Hope that helps.

--grb
-----Original Message-----
[mailto:Kenneth_J_Rasche@e...]
Sent: Wednesday, June 12, 2002 8:18 AM
To: 'xansys@yahoogroups.com'

I have a set (about 15) of .db files I created in 5.6. The models are of
tubing
(modeled with beam188s) that have been used to make many comparisons. I had
continued to use 5.6 to run the model, but recently had to remove it to make
room for 6.1. I recently had to make some more comparisons and when I
resume
the .db files, I get a warning that "Beam sections defined before revision
5.7
will be defined again in the current revision." The problem is that I am
getting significantly different results between the two versions.

I am sure this has been discussed before, but I looked through the archive
and
did not find this particular subject. I also looked (briefly) through class
3
errors and did not find this issue. Could someone point me in the right
direction where I can find a good explanation of the changes to beam188/9?

Thanks,
Ken Rasche
Whirlpool Corp.

Posts possibly associated with message #38728AuthorDateScore
38699beam188/9 changes from 5.6 to 5.7Ken Rasche2002/06/12 
38706Re: beam188/9 changes from 5.6 to 5.7Grama Bhashyam2002/06/12 
38713Re: beam188/9 changes from 5.6 to 5.7K.S. Raghavan2002/06/12 
38717Re: beam188/9 changes from 5.6 to 5.7Grama Bhashyam2002/06/12 
38723Re: beam188/9 changes from 5.6 to 5.7K.S. Raghavan2002/06/12 
38724Re: beam188/9 changes from 5.6 to 5.7Grama Bhashyam2002/06/12 
38728Re: beam188/9 changes from 5.6 to 5.7K.S. Raghavan2002/06/12 
38743Re: beam188/9 changes from 5.6 to 5.7Grama Bhashyam2002/06/12 
38774Re: beam188/9 changes from 5.6 to 5.7K.S. Raghavan2002/06/13 
38780Re: beam188/9 changes from 5.6 to 5.7Sheldon Imaoka2002/06/13 
38785Re: beam188/9 changes from 5.6 to 5.7K.S. Raghavan2002/06/13 
38800Re: beam188/9 changes from 5.6 to 5.7Grama Bhashyam2002/06/13 
38838Re: beam188/9 changes from 5.6 to 5.7K.S. Raghavan2002/06/14 
38840Re: beam188/9 changes from 5.6 to 5.7Grama Bhashyam2002/06/14