iMechanica - VABS, A Unique Tool for Modeling Composite Beams - Comments

VABS can be requested from hifi-comp.com

Wenbin Yu — Tue, 07 Oct 2008 19:07:05 -0400

All,

If you are interested, you can request VABS through hifi-comp.com.

The limited version, VABS Lite, is free and the full version can be evaluated for free for three months.

Nice to see you too on Imechanica

luciano demasi — Thu, 25 Sep 2008 14:57:01 -0400

Nice to see you too. The new job makes me busy...but who is not busy?

http://www.engineering.sdsu.edu/aerospace/luciano.html

Luciano, Nice to see you

Wenbin Yu — Thu, 25 Sep 2008 11:13:37 -0400

Luciano,

Nice to see you have also signed up for Imechanica. How is your new job? Must be very busy!

Wenbin

Stresses a priori

luciano demasi — Wed, 24 Sep 2008 17:21:31 -0400

If your desire is to have the transverse stresses a priori and without the integration of the indefinite equilibrium equations you can use a mixed vartiational statement such as Reissner's.

Dear Dr.Bin, Thanks a lot

psubbu2000 — Fri, 19 Sep 2008 10:55:20 -0400

Dear Dr.Bin,

Thanks a lot for your clarifications. Currently I am doing research in the field of higher order shear deformation theories, I am unable to share my results with you.

Regards

Subramanian

VABS/VAPAS

Wenbin Yu — Fri, 19 Sep 2008 01:39:54 -0400

blank_page

Subramanian,

Again, I appreciate your comment. The sentence you pointed out states that
based on a priori assumptions a whole spectrum of models can be developed
ranging from the very simple one, Classical Lamination Theory (CLT), to very
complex ones, Higher-Order Layerwise Theories (HOLT). It does not say that
there are no models having better accuracy than CLT and simpler than HOLT. Of
course there are some models in between such as first-order shear-deformation
theory, higher-order shear deformation theory, zigzag theories. This discussion
is more relevant to VAPAS, a sister code of VABS. We have compared our code with
a zigzag-based model in ref. [1], the results of which support the sentence you
pointed out. We have plans to compare with the Generalized Unified Formulation
of Prof. Luciano Demasi at SDSU in the near future. If you are interested, I will
be very glad to collaborate with you to test the performance of either VABS or
VAPAS against your models.

[1] Yu, W.; Kim, J. S.; Hodges, D. H.; and Cho, M.: "Assessment of Two
Reissner-Mindlin Type Models for Composite Laminated Plates," Aerospace
Science and Technology , vol. 12, no. 5, 2008, pp. 408-417. (pdf)

Dear Subramanian, Thanks

Wenbin Yu — Fri, 19 Sep 2008 00:11:21 -0400

Dear Subramanian,

Thanks for your interest. Yes VABS can accurately predict transverse shear and normal stresses without integrating the equilibrium equations. We did a 20-layer example. VABS calculates almost the same results as ANSYS using 3D elements. Please refer to the following paper for more details.

Yu, W. and Hodges, D. H.: "Generalized Timoshenko Theory of the Variational Asymptotic Beam Sectional Analysis, " Journal of the American Helicopter Society, vol. 50, no. 1, 2005, pp. 46-55. (pdf)

Dear Ben, Your

psubbu2000 — Thu, 18 Sep 2008 22:17:50 -0400

Dear Ben,

Your website says "either too simple (CLPT) or too complex (higher order layerwise theories). ........................... thepredictability is not guranteed because". This seems to be incorrect. I have developed a set of simple and highly accurate higher oder shear deformation theories for the analysis of laminated composite structures.

Subramanian

I would like to ask the

psubbu2000 — Thu, 18 Sep 2008 22:07:03 -0400

I would like to ask the following question regarding VABS.

Is VABS capable of accurately predicting transverse shear and normal stress across the thickness of laminated composite beam without integrating the equilibrium equations?.

Subramanian

VABS, A Unique Tool for Modeling Composite Beams

Wenbin Yu — Thu, 18 Sep 2008 19:23:15 -0400

I am glad to introduce VABS, a unique software tool for modeling of composite structures having one dimension much larger than the other two dimensions such as helicopter rotor blades, wind turbine blades, HALE wings, and bridges.

Despite this simple geometry, these slender components could be made out of virtually any material and have very complex internal construction such as modern rotor blades having skins made of hundreds of composite layers, web and D-spar made of active materials and a core filled with foam materials. The efficient, high-fidelity cross-sectional analysis tool, VABS, is capable of realistic modeling of initially curved and twisted anisotropic beams with arbitrary sectional topology and materials. Relative to 3D analyses, two to three orders of magnitude in computing time can be saved using VABS, with little loss of accuracy. VABS is currently used extensively in the rotorcraft industry. Researchers from other industry also begin to use VABS.

The unique features of the VABS methodology are: (1) use of the variational asymptotic method (VAM) as the mathematical foundation for dimensional reduction, incorporating both mathematical rigor and engineering simplicity; (2) absence of ad hoc kinematic assumptions, common in other approaches; (3) decoupling of the original 3D nonlinear problem into two sets of analyses: 2D, linear, cross-sectional analysis and 1D, nonlinear global beam analysis. This allows the global beam analysis to formulate exactly and intrinsically as a general 1D continuum over the reference line and confines all approximations to the cross-sectional analysis, the accuracy of which is guaranteed to be the best by VAM.

Please http://hifi-comp.com for more details on VABS.

Wenbin Yu

http://www.mae.usu.edu/faculty/wenbin