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VABS, A Unique Tool for Modeling Composite Beams
I am glad to introduceVABS, 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 usingVABS, with little loss of accuracy.VABSis currently used extensively in the rotorcraft industry. Researchers from other industry also begin to useVABS.
The unique features of theVABSmethodology 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 ofad hockinematic 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.
Pleasehttp://hifi-comp.comfor more details onVABS.
Wenbin Yu
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I would like to ask the
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
Dear Subramanian, Thanks
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
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
VABS/VAPAS
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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
ofProf. Luciano Demasi at SDSUin 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 Dr.Bin, Thanks a lot
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
Stresses a priori
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.
Luciano, Nice to see you
Luciano,
Nice to see you have also signed up for Imechanica. How is your new job? Must be very busy!
Wenbin
Nice to see you too on Imechanica
Nice to see you too. The new job makes me busy...but who is not busy?
http://www.engineering.sdsu.edu/aerospace/luciano.html
VABS can be requested from hifi-comp.com
All,
If you are interested, you can request VABS throughhifi-comp.com.
The limited version, VABS Lite, is free and the full version can be evaluated for free for three months.
hellp
hi
please answer me,in 2D analysis of cross section,meshed cross section analysisi of abaqus is better or vabs?wich one,have better result at warpping?(in and out warping)
please answer me with reson,or test,or camparsion analysis witheen abaqus and vabs?
why not try yourself
I am not familar with ABAQUS and do not have access to this software at this moment. However, you are welcome to request VABS to compare for yourself. I am pretty confident that VABS will be better. I will appreciate if you can share your conclusion with us. I am not coming to this site very often. If somebody want a quicker reponse, please send me an email.
We recently made a chart of comparison between VABS and ABAQUS
A student just made a chart for comparing the sectional capability of ABAQUS and VABS. Please refer tohttp://hifi-comp.com/Documents/ABAQUSvsVABS_CrossSectionalCapabilities.pdffor more details.
Assessment of VAPAS
Hi,
If you are interested in the assessment of VAPAS via GUF, I and professor Yu published a conference article on the subject:
L. Demasi, Yu W., “
Assess the Accuracy of the Variational Asymptotic Plate and Shell Analysis
(VAPAS) Using the Generalized Unified Formulation (GUF)”, Presented at
the 50th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics & Materials
Conference, Palm Springs, California, 4-7 May 2009
Luciano
http://attila.sdsu.edu/~demasi/default.htm
Papers on the Generalized Unified Formulation (composites)
If you are interesting in learning more about this powerful technique you can see the following references:
1 ) Generalized Unified Formulation applied to displacement-based theories for composire structures (Advanced Shear Order Deformation Theories, Zig Zag Theories and Layerwise Theories; note that an infinite number of theories is included in the GUF framework and all these formulations can be generated from SIX invariant 1 X 1 arrays):
L. Demasi,An Invariant
Model for any Composite Plate Theory and FEM Applications: the Generalized
Unified Formulation, Presented at the 50th AIAA/ASME/ASCE/AHS/ASC
结构,Structural Dynamics & Materials Conference, Palm Springs,
加州,2009年5月4 - 7。
2) Generalized Unified Formulation applied to the mixed theories based on Reissner's Mixed Variational Theorem (RMVT) (formulation in which all the mixed theories are generated from 13 invariant 1X1 arrays):
L. Demasi,∞6mixed plate theories based on the
Generalized Unified Formulation. Part I: Governing EquationsComposite
结构,Vol. 87, (2009), 1-11.
3)推广统一的配方应用于RMVT-basedLayerwisetheories for composite structures:
L. Demasi,∞6mixed plate theories based on the
Generalized Unified Formulation. Part II: Layerwise theoriesComposite
结构,Vol. 87, (2009), 12-22
4) Generalized Unified Formulation applied to RMVT-basedAdvanced Mixed High Order Shear Deformationtheories andquasi-layerwisetheories:
L. Demasi,∞6mixed plate theories based on the
Generalized Unified Formulation. Part III: Advanced Mixed High Order Shear
Deformation TheoriesComposite Structures, Vol. 87, (2009), 183-194
5) Generalized Unified Formulation applied to RMVT-basedZig-Zagtheories:
L. Demasi,∞6mixed plate theories based on the
Generalized Unified Formulation. Part IV: Zig-Zag TheoriesComposite
结构,Vol. 87, (2009), 195-205
6) RMVT-based theories and theirnumerical performancescompared against theelasticity solution:
L. Demasi,∞6mixed plate theories based on the
Generalized Unified Formulation. Part V: ResultsComposite Structures,
Composite Structures, Vol. 88, (2009), 1-16.
If you are interested in a PhD opportunity on these and other topics please contact me at the following addressldemasi@mail.sdsu.edu
http://attila.sdsu.edu/~demasi/default.htm
VAM Related Query
Respected Professor,
I know i am bit late to add to this discussion butPlease replyif possible as i am knew to VAM and reallywant to learn.
While going through your papers (''Asymptotic construction of Reissner-like composite plate theory with accurate strain recovery'' and few others) ,I noticed thatyou ususally do some transformation into reissner modelalthough in theNeoclassical plate theory by Hodges et.al("Application of the Variational-Asymptotical Method to Laminated Composite Plates")they included the shear strain in the 3-D strain termitself ,In the similar manner 3-D elasticity formulation is done in a paper by Peereswera et.al(Prediction of inter-laminar stresses in composite honeycomb sandwich panels under mechanical loading using Variational Asymptotic Method)
So i just want to understand are these two different theories or the same ,if same then why do we need to go through transformation part.
alsosome links in above discussion doesn't work any more if possible plase provide updated links.