Stress intensity factor calculation based on the work of external forces

摘要

The external forces method is a numerical methodfor K calculation based on the finite element method. Is uses thework of the external forces W_E for the calculation of the energyrelease rate and is particularly advantageous when that forces areapplied for from the crack front. The method was applied to acorner crack geometry with the objective of study is accuracy.Good results were obtained for a wide range of virtual crackdisplacements (0.03 percent < #DELTA#a/a <6 percent)considering 4 values of W_E along with a polynomial regressionof order 3. For that choice of parameters the inaccuracy of K ismainly due to FEM errors. A great sensitivity of K to FEM errorswas observed, however accurate values of K were obtained, witherrors lower than 2 percent. So, the use of the external forcesmethod for the calculation of K is recommended, considering itssimplicity and accuracy.