“…Recently several studies have indicated the efficiency of the GFEM and others methods based on the Partition of Unity Method in problems such as analysis of cracks (Xiao & Karihaloo, 2007;Abdelaziz & Hamouine, 2008;Duarte & Kim, 2008;Nistor et al, 2008), dislocations based on interior discontinuities (Gracie et al, 2007), large deformation of solid mechanics (Khoei et al, 2008) and Helmholtz equation (Strouboulis et al, 2006a;Strouboulis et al, 2008). In structural dynamics, the Partition of Unity Method was applied by De Bel et al (2005), Hazard & Bouillard (2007) to numerical vibration analysis of plates and by Arndt et al (2010) to free vibration analysis of bars and trusses. Among the main challenges in developing the GFEM to a specific problem are: (a) choosing the appropriate space of functions to be used as local approximation and (b) the imposition of essential boundary conditions, since the degrees of freedom used in GFEM generally do not correspond to the nodal ones.…”