Can anyone please help me out on the problem with Finite element program I am facing with? The problem is as follows. I have all elemental stiffness matrices, connectivity table with all nodes & elements and Force vector [F]. I want to solve the structure K*X=F for X(Displacement) without writing the Global Stiffness Matrix [K] to the hard disc. This way lot of memory space can be saved. I wonder how commercial FEA software packages solve 200,000 dof structure without occupying much space on the hard disc whereas if it is to store [K] of size(200000,200000) it is a lot of space oh hard disc.

I am not sure, but I guess, at the time of assembling elemental stiffness matrices only, it has to solve the respective no of equations. This way it can write only that particular solution for those equations. Then it can take the next equations to solve from hard disc to the RAM.

If anyone can throw a light on this problem, it will be very great help for me. Any suggestion on FE coding available, any books to refer or any algorithm to assemble and solve the big structures are greately invited. Please help me out. Thanks for your time. Ravi.