# Wenbin Yu's blog

## Three ways to derive the classical plate model

Attached is part of my lecture notes for a graduate structural mechanics. In
the notes, we derived the classical plate theory, which is also called
the Kirchhoff plate theory, in three ways: Newtonian method, variational
method, and variational asymptotic method, using 3D elasticity theory as the
starting point. The self-contradictions of Kirchhoff assumptions and plane-stress assumptions used in both
Newtonian method and variational method are clearly pointed out. The
variational asymptotic method does not rely on any ad hoc assumptions, ending
in a self-consistent theory. It can be considered as a theoretical

## Three-ways to derive the Euler-Bernoulli-Saint Venant Beam Theory

After having taught graduate structural mechanics for several years, I am finally
able to write down my lecture notes (attached) for teaching the beam theory. In
the notes, we formulated the complete classical beam model
(extension/torsion/bending in two directions), which is also called
Euler-Bernoulli-Saint beam theory, in three ways: Newtonian method, variational
method, and variational asymptotic method, using 3D elasticity theory as the
starting point. Many self-contradictions of the various assumptions used in both
Newtonian method and variational method are clearly pointed out. The

## New Release of General Purpose Micromechanics Code: VAMUCH 3.0

I am writing to let you know the release of VAMUCH 3.0,  the 3rd version of our general-purpose micromechanics code. The main new features are:

1. Multiphysics capability: VAMUCH can be used to homogenize heterogeneous materials which have coupled or uncoupled responses to mechanical field, electric field, magnetic field, and thermal field.  It not only predicts elastic, conductive, dielectric, magnetic, and diffusive properties of heterogeneous materials but also coupled properties such as coefficients of thermal expansion, pyroelectric, pyromagnetic, piezoeletric, piezomagnetic, and/or eletromagnetic properties, as well as the local fields corresponding to these multiphysical responses.

## PhDs/Postdocs in modeling composite structures/materials

Dear All,

I am looking for highly motivated PhDs/PostDocs to join my group to work on various aspects of efficient high-fidelity modeling of composite structures/materials, mainly related with VABS/VAPAS/VAMUCH. The basic qualifications are: basic training in solid mechanics and composite materials, excellent math and programming skills, and good English communication skills. Please let me know if you are interested or if you know somebody is interested.

## DNAD, a simple tool for automatic differentiation

All,

I am writing to introduce DNAD, a Fortran module I wrote for automatic differentiation of analysis codes written in Fortran including those legacy codes written in Fortran 77. Although only implementation using Fortran 90/95 was carried out, it is straightward to translate it to a language you like such as c/c++.

## GEBT, a general-purpose composite beam solver

Dear All,

I am writing to introduce to you a general-purpose composite beam solver, GEBT, which can capture all the geometrical nonlinearity obtainable by the six fundamental deformation modes (extension, torsion, bending in two directions, and shearing in two directions), and the coupling between these fundamental deformantion modes, such as extension-twist coupling commonly existing in initially twisted rotorblades. The features of GEBT are:

1. GEBT can analyze any structure which can be modeled as an assembly of beams made of arbitrary material and arbitrarily oriented in the 3D space.

## Help for explaining a strange problem related with beam shear stiffness

There is a very strange problem puzzled quite a few in the rotor blades (including helicopter blades and wind turbine blades) community. We hope some mechanician on this board can help us explain the situation.

## Can somebody suggest a general-purpose object oriented design of the finite element?

I am looking into object oriented programing of the finite element method. I don't know whether somebody can provide a general-purpose oop design of a general finite element program, say a linear static analysis of a 3D solid. Or somebody who are experienced in this field point out some good references for this purpose. It will be better if the oop design is language free, i.e. not directly related with implementation in a specific language such as c++. Thanks in advance.

## VABS, A Unique Tool for Modeling Composite Beams

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.

## Faculty Research in Solid Mechanics, review starts on 01/07/2008

Dear Fellow Mechanicians:

If you know somebody (including yourself) are looking for faculty jobs, please encourage them to apply to Utah State University. We are filling two tenure-track positions in the broad sense of solid mechanics or thermal science. At least one position for solid mechanics. For details of the job descriptions, please refer to my previous post. You need to apply through the online system at jobs.usu.edu. We will start reviewing the applicants on January 7th, 2008.

Best regards,

## Hello, all iMechanicians

This is Wenbin Yu from Utah State University, more details can be found from my website (www.mae.usu.edu/faculty/wenbin). I browsed through this site several times and felt like home here, particularly seeing so many of my friends  and so many of my role-model mechanicians. I finally made the decision to register and became part of the iMechanicians family.  Zhigang, thanks a lot for providing such a wonderful platform for mechanicians to network and exchange their ideas. This post may not belong to the research channel. I am just try to see whether I can post.