How to Apply Boundary Conditions in Finite Element Analysis Using C++?

[dinaharchery]

Hello all,

I am trying to create a simple finite element program in C++ and have been able to build and assemble the GLOBAL stiffness matrix as well as the load vector. I want to apply the boundary conditions using the elimination approach, can anyone tell me how to do this?

I am sorry for the simplicity of the problem but I have been unable to find any information on this particular issue. Thanks in advance.

 

[dinaharchery]

Well, I figured out the boundary "elimination" approach to the GLOBAL stiffness matrix as well as the vector Load/Heat-Rate (I finally got a book on FEM)

The book has a section on transient heat conduction using a LUMPED capacity matrix - complete with algorithm. However, there is one step in the algorithm that I am not sure about.

The last step before iterating the time-loop again is to "correct" the just determined nodal heat vector (i.e. solution vector at current time) for boundary conditions. Can anyone please explain what is meant by correcting the solution vector for boundary conditions, I thought the bounds were set-up before entering the Time-Loop?

BTW, the algorithm is explicit forward difference for LUMPED capacity matrix. I really need some help if anyone has a hint?

Thank you

 

[dinaharchery]

Anyone?

I just need some kind of hint in the direction to go for the application of boundary corrections at each time step. I am not an engineer but am trying to learn finite element for a program.

Once again, thank you.