Abstract

The use of stabilization methods is becoming an increasingly well-accepted technique due to their success in dealing with numerous numerical pathologies that arise in a variety of applications in computational mechanics.

In this paper a multiscale finite element method technique to deal with pressure stabilization of nearly incompressibility problems in nonlinear solid mechanics at finite deformations is presented. A J2-flow theory plasticity model at finite deformations is considered. A mixed formulation involving pressure and displacement fields is used as starting point. Within the finite element discretization setting, continuous linear interpolation for both fields is considered. To overcome the Babuška–Brezzi stability condition, a multiscale stabilization method based on the orthogonal subgrid scale (OSGS) technique is introduced. A suitable nonlinear expression of the stabilization parameter is proposed. The main advantage of the method is the possibility of using linear triangular or tetrahedral finite elements, which are easy to generate and, therefore, very convenient for practical industrial applications.

Numerical results obtained using the OSGS stabilization technique are compared with results provided by the P1 standard Galerkin displacements linear triangular/tetrahedral element, P1/P1 standard mixed linear displacements/linear pressure triangular/tetrahedral element and Q1/P0 mixed bilinear/trilinear displacements/constant pressure quadrilateral/hexahedral element for 2D/3D nearly incompressible problems in the context of a nonlinear finite deformation J2 plasticity model.

Abstract

The use of stabilization methods is becoming an increasingly well-accepted

technique due to their success in dealing with numerous numerical pathologies

that arise in a variety of applications in computational mechanics. In this monograph a multiscale finite element method technique to deal with pressure stabilization of nearly incompressibility problems in nonlinear solid mechanics at small and finite deformations J2 plasticity is presented. A mixed formulation involving pressure and displacement fields is used as starting point. Within the finite element discretization setting, continuous linear interpolation for both fields is considered. To overcome the Babuˇska-Brezzi stability condition, a multiscale stabilization method based on the Orthogonal Subgrid Scale (OSGS) technique is introduced. Suitable nonlinear expression of the stabilization parameters are proposed. The main advantage of the method is the possibility of using linear triangular or tetrahedral finite elements, which are easy to generate and, therefore, very convenient for practical industrial applications. Numerical results obtained using the OSGS stabilization technique are compared with results provided by the P1 standard Galerkin displacements linear triangular/tehrahedral element, P1/P1 standard mixed linear displacements/ linear pressure triangular/tetrahedral element and Q1/P0 mixed bilinear/ trilinear displacements/constant pressure quadrilateral/hexahedral element for 2D/3D nearly incompressible problems in the context of nonlinear small and finite deformation J2 plasticity models.

Abstract

Additive manufacturing (AM) is a production method with great potential for creating complex geometries and reducing material and energy waste. Numerical simulations are crucial to minimize fabrication failures and optimize designs. Nevertheless, the high computational cost of simulating the multi-scale behaviour of AM processes is a challenge. To address this, an Arlequin-based method is proposed, which uses two distinct meshes to capture the high thermal gradients near the melt pool: a coarse mesh for the entire domain and a fine mesh that moves with the heating source. Additionally, a change of variable simplifies calculations on each time step by transforming the moving fine mesh into a fixed mesh. The proposed methodology has the potential to reduce computational costs and improve the efficiency of AM simulations