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

This may be helpful: Frank McKenna's thesis on object-oriented finite element software:

www.ce.berkeley.edu/~fmckenna/diss.ps 

http://www.ce.berkeley.edu/~fmckenna/dissertation.html

Dear Wenbin, 

The problem is that no design can take care of all possibilities in an elegant manner.  So parts of the design will be good and parts clunky.  One can hope that the design is flexible enough to be changed dramatically if needed, without excessive effort.  A few things a good design will have are:

1) component architecture that hides tedious details (e.g., message passing for parallel code) from the user/developer

2) modular archictecture that can be rearranged drastically if needed

3) plug-in capability so that users can easily add new elements/material models (think Firefox plug ins)

A good starting point is Tahoe (though I don't like parts of the design too much).  See

 https://tahoe.ca.sandia.gov/public/doxygen/html/hierarchy.php

-- Biswajit 

Wenbin,

Definitely check out Sofea by Professor Krysl.  This is an object oriented toolkit plus a free textbook in PDF.  I like the design a lot, very clean.  It is also very much customizable.

http://hogwarts.ucsd.edu/~pkrysl/sofea

Oscar Mecchan

Wenbin,

If you are seeking for a general purpose object oriented program, I highly recommend you to use FEniCS project (www.fenics.org). This is a project to automate solving PDEs. 

Mehdi