NURBS distance fields for extremely curved cracks

This paper presents the first methodology that combines a meshless method and the exact representation of cracks using Non-Uniform Rational B-Splines (NURBS). The methodology consists on developing an enrichment function based on distance functions to NURBS curves.The examples show the potential of the proposed approach and demonstrate the applicability to problems involving complex cracks that appear in sol-gel films

Transient analysis of tube rolling processes by a semi‐analytical formulation

A semi‐analytical formulation is presented for transient metal‐forming processes which, being axisymmetric in geometry, are subjected to non‐axisymmetric loads and boundary conditions. The problems are described in terms of the flow formulation, and the pseudo‐concentration method (two material based) is used to account for time integration and non‐axisymmetric free surfaces. Proper Fourier series expansion of both the scalar fields defined to identify the free surfaces and of all the variables of the mechanical problem allows the performance of an advective transport–corresponding to time integration–for a non‐axisymmetric velocity field. A block diagonal matrix is obtained for each harmonic component, as it has been achieved for the constant time solution. The new configuration found as a result of this analysis is taken to calculate the velocity field for the incremented time, which in turn is used to perform the following time ste

Using pseudo-concentrations in the analysis of transient forming processes

The pseudo‐concentration method is applied to the analysis of transient processes. A simple, easy‐to‐handle model is obtained by keeping an Eulerian description: it does not require remeshing after a certain amount of plastic deformation. The range of applicability of the method is extended to non‐confined (even with several free surfaces) processes. It is shown the need of distinct handling of free surfaces according to their orientation to the direction of the flow. A seamless tube rolling process, a cylinder upsetting and a backward extrusion are modelled. Experimental data and results obtained by other methods are used to compare and discuss the performance of the model

Metal forming analysis by fourier series expansion and further uses of pseudo-concentrations

An analysis of metal forming processes with axial geometry is performed by an expansion in Fourier series on the circumferential direction. For that purpose, an incremental form is presented on the basis of the flow formulation. For every increment of the non-null imposed boundary conditions an algebraic system is formed in which the non-linearity due to the visco-plastic properties of the material is placed as part of the load term. In this way, the global stiffness matrix is block diagonal, the coupling due to material non-linearity being included on the right-hand side. Free surfaces are treated as an interface inside the elements, as an extension of the pseudo-concentration method

A particle finite element method (PFEM) for coupled thermal analysis of quasi and fully incompressible flows and fluid-structure interaction problems

This book presents and discusses mathematical models, numerical methods and computational techniques used for solving coupled problems in science and engineering. It takes a step forward in the formulation and solution of real-life problems with a multidisciplinary vision, accounting for all of the complex couplings involved in the physical description. Simulation of multifaceted physics problems is a common task in applied research and industry. Often a suitable solver is built by connecting together several single-aspect solvers into a network. In this book, research in various fields was selected for consideration: adaptive methodology for multi-physics solvers, multi-physics phenomena and coupled-field solutions, leading to computationally intensive structural analysis. The strategies which are used to keep these problems computationally affordable are of special interest, and make this an essential book.Postprint (published version