RESUMO
The Particle Finite Element Method, a lagrangian finite element method based on a continuous Delaunay re-triangulation of the domain, is used to study machining of Ti6Al4V. In this work the method is revised and applied to study the influence of the cutting speed on the cutting force and the chip formation process. A parametric methodology for the detection and treatment of the rigid tool contact is presented. The adaptive insertion and removal of particles are developed and employed in order to sidestep the difficulties associated with mesh distortion, shear localization as well as for resolving the fine-scale features of the solution. The performance of PFEM is studied with a set of different two-dimensional orthogonal cutting tests. It is shown that, despite its Lagrangian nature, the proposed combined finite element-particle method is well suited for large deformation metal cutting problems with continuous chip and serrated chip formation.
RESUMO
When a spin-1/2 nucleus is dipolar coupled to a spin-1 nucleus, the spectrum of the spin-1/2 nucleus can be split into an asymmetric doublet in magic-angle spinning experiments. When the spin-1/2 nucleus is 13C and the spin-1 nucleus is 2H there is also the possibility of this splitting being modified by the indirect (J) coupling. 13C-2H residual dipolar couplings are seen because of the large full dipolar coupling of the nucleus pair. However, this has implications on the spinning speed used in the CP/MAS NMR experiment and the intensities of the isotropic 13C dipolar coupled to 2H. The calculation of side band intensities for slow spinning when the dipolar, quadrupolar and chemical shift tensors are axially symmetric and coaxial is discussed.