An estimator for force errors in finite-element analysis

If the net force on a body is calculated from a finite-element analysis using the single-solution virtual work method, it is possible to estimate the error in this force from a virtual movement of the layer of nodes on the outer surface of the first annulus of air around the body. Two electrostatic examples are used to investigate the estimate: two flat, parallel, conducting plates with a potential difference between them and three conducting wires. The examples show that the error estimated in this way approximates the true error over a wide range.