Estudio de estructuras sometidas a esfuerzos de impacto en régimen elastoplástico y con grandes deformaciones por el método de los elementos finitos. Parte II: Algoritmo de contacto-impacto y ejemplos

En este segundo articulo, se expone el algoritmo de contacto-impacto utilizado para problemas tridimensionales. Se desarrolla fundamentalmente el metodo de las penalizaciones hallando el valor de la máxima rigidez estable. Se incluyen asimismo tres ejemplos de aplicación.Peer Reviewe

Estudio de estructuras sometidas a esfuerzos de impacto en régimen elastoplástico y con grandes deformaciones por el método de los elementos finitos. Parte I: Formulación teórica

Se desarrolla en este primer artículo, la formulación teórica para el estudio tridimensional de cuerpos sometidos a acciones de contacto-impacto. Despues de desarrollar las ecuaciones básicas de equilibrio, se estudian las ecuaciones constitutivas utilizadas. El elemento usado es el hexaedrico de ocho nodos, del cual se establecen algunas propiedades, que serán de utilidad para la integración numérica. En un artículo posterior, se desarrollará el algoritmo de contacto-impacto estudiado, así como varios ejemplos.Peer Reviewe

Updated Lagrangian formulation for corrected smooth particle hydrodynamics

Smooth Particle Hydrodynamics (SPH) are, in general, more robust than finite elements for large distortion problems. Nevertheless, updating the reference configuration may be necessary in some problems involving extremely large distortions. If a standard updated formulation is implemented in SPH zero energy modes are activated and spoil the solution. It is important to note that the updated Lagrangian does not present tension instability but only zero energy modes. Here an stabilization technique is incorporated to the updated formulation to obtain an improved method without mechanisms.Peer ReviewedPostprint (author’s final draft

Strict upper and lower boundswith adaptive remeshing in limit state analysis

By writing the limit state analysis as an optimisation problem, and after resorting to suitable discretisations of the stress and velocity field, we compute strict bounds of the load factor. The optimisation problem is posed as a Second Order Conic Program (SOCP), which can be solved very efficiently using specific algorithms for conic programming. Eventually, the optimum stress and velocity fields of the lower and upper bound problem are used to construct an error measure (elemental gap) employed in an adaptive remeshing strategy. This technique is combined with an additional adaptive nodal remeshing that is able to reproduce fan-type mesh patterns around points with discontinuous surface loads. We paticularise the resulting formulation for twodimensional problems in plane strain, with VonMises andMohr-Coulomb plasticity. We demonstrate the effetiveness of the method with a set of numerical examples extracted from the literature

Bounds and adaptivity for 3D limit analysis

In the present paper we compute upper and lower bounds for limit analysis in two and three dimensions. From the solution of the discretised upper and lower bound problems, and from the optimum displacement rate and stress fields, we compute an error estimate defined at the body elements and at their boundaries, which are applied in an adaptive remeshing strategy. In order to reduce the computational cost in 3D limit analysis, the tightness of the upper bound is relaxed and its computation avoided. Instead, the results of the lower bound are used to estimate elemental and edge errors. The theory has been implemented for Von Mises materials, and applied to two- and three-dimensions examples.Peer Reviewe

An enhanced immersed structural potential method (ISPM) for the simulation of fluid-structure interaction problems

Immersed methods are widely used nowadays for the computational simulation of Fluid-Structure Interaction problems. In this paper, the Immersed Structural Potential Method (ISPM) is coupled with a Runge-Kutta-Chebyshev Projection method in order to increase the overall computational efficiency of the methodology. Application of the framework to large three-dimensional problems is carried out. A series of numerical examples will be presented in order to demonstrate the robustness and flexibility of the proposed methodology

A discontinuous galerkin formulation for solid dynamics

Postprint (published version

Optimal collapse simulator for three-dimensional frames

In this work a limit analysis for 3D structures software package is presented. The goal is to obtain for a certain structure the load factor λ that applied to the external loads induces collapse to the structure. The static theorem of limit analysis is the theoretical basis for the Structural Collapse Simulator (SCS), that is finding a stress distribution in equilibrium that does not violate yield criteria anywhere. The limit analysis is developed and written as a Linear Programming Problem, which consists of the maximization of the collapse load factor subject to equilibrium and yield criteria. The Structural Collapse Simulator has been applied to several types of structures to assess its capabilities on world applications

Estudio de estructuras sometidas a esfuerzos de impacto en régimen elastoplástico y con grandes deformaciones por el método de los elementos finitos. Parte II: Algoritmo de contacto-impacto y ejemplos

En este segundo articulo, se expone el algoritmo de contacto-impacto utilizado para problemas tridimensionales. Se desarrolla fundamentalmente el metodo de las penalizaciones hallando el valor de la máxima rigidez estable. Se incluyen asimismo tres ejemplos de aplicación.Peer Reviewe

A new variational framework for large strain piezoelectric hyperelastic materials

In this paper, a novel nonlinear variational formulation is presented for the numerical modelling of piezo-hyperelastic materials. Following energy principles, a new family of anisotropic extended internal energy density functionals is introduced, dependent upon the deformation gradient tensor and the Lagrangian electric displacement field vector. The requirement to obtain solutions to well defined boundary value problems leads to the definition of energy density functionals borrowing concepts from polyconvex elasticity. Material characterisation of the constitutive models is then carried out by means of experimental matching in the linearised regime (i.e. small strains and small electric field). The resulting variational formulation is discretised in space with the help of the Finite Element Method, where the resulting system of nonlinear algebraic equations is solved via the Newton-Raphson method after consistent linearisation. Finally, a series of numerical examples are presented in order to assess the capabilities of the new formulation