0Hello, Students!
Answer (taking a static analysis as an example):
This is the method, that makes it easy to calculate displacements. From it calculated the strain & stresses.
In the real world, every single point you would assume on a structure can move in every direction (wholly with 6 DOFs). To make equations of displacements based on these every assumed points would be huge to solve. Also makes it infinite continuum.
Now, we care only on finite points (Nodes) connected by elements ~ Finite elements.
When equations of displacements based out of these finite points, are now finite enough to calculate the real displacements(approximately). Depends on the forces applied & the object stiffness(that resist these forces for displacement). [Delta] = INV[K] X [F] is solved.
The more finite is the problem, less time to solve, but let realistic.
So usually we try to converge numerically the results. So we get to a solution which can be is quite acceptable.
