Force and torque computation from 2-D and 3-D finite element field solutions

The Coulomb virtual work (CVW) method of force and torque calculation is a relatively recent development which has received little publicised appraisal or validation particularly for three-dimensional situations. The authors outline the CVW method and describe its application to a range of force calculation problems, showing that the CVW method can be superior in accuracy and ease of implementation to the Maxwell stress tensor (MST) method. Results of the two-dimensional CVW, twodimensional MST, and three-dimensional CVW are compared against either analytical or measured data. The 2-D CVW calculation produces discrepancies against analytical or test results similar to those obtained with the MST method with centroid paths. Comparisons between 2-D, 3-D and analytical or experimental data show that the force or torque computed from the 3-D analysis is in much better agreement with the analytical or experimental data than that obtained from 2-D.