P. Venini - Academia.edu (original) (raw)

Papers by P. Venini

Computers & Structures, 2016

Annali dell'Università di Ferrara. Sezione 7: Scienze matematiche

A mixed variational formulation with discontinuous displacements and continuous tractions is pro-... more A mixed variational formulation with discontinuous displacements and continuous tractions is pro- posed for the analysis of cohesive-crack propagation in elastic media. Such a formulation gives rise to a peculiar finite-element discretization scheme that is based on the Johnson-Mercier composite elements as to the stresses. Numerical results concerning classical benchmark problems are pro- posed and need for future developments highlighted, including the analysis of elastic-plastic and incompressible media. A new approach for cohesive crack propagation in elastic media is presented. Numerical methods for such kind of problems should be able to resolve discontinuous displacement fields as well as continuous tractions. Among pioneering contributions appeared up to the mid-nineties, the contribution (5) presented a re-meshing approach capable of following post-bifurcation and post-peak regimes, (6) introduced a stable, mesh-insensitive approach for the resolution of localization lines ...

1. Abstract We propose a novel approach for the analysis of cohesive crack propagation in elastic... more 1. Abstract We propose a novel approach for the analysis of cohesive crack propagation in elastic media. Unlike all existing methods that move from continuous displacement formulations that are properly enriched to handle the discontinuity, see e.g. the extended finite element method (XFEM) or the embedded disconti-nuity approaches, inherently discontinuous displacements and H(div, Ω) stresses in a truly mixed setting are herein proposed. The formulation, originally introduced to handle incompressible materials in plane elasticity, is herein extended to the analysis of propagating cohesive cracks in elastic media thanks to a novel variational formulation that is enriched with an interface energy term. Notably, no edge ele-ment is introduced but simply the inherent discontinuity of the displacement field is taken advantage of. Furthermore, stress flux continuity is imposed in an exact fashion within the formulation and not as an additional weak constraint as classically done. Extensi...

Cited By (since 1996):6, Export Date: 9 October 2013, Source: Scopus

. We use biorthogonal B{spline wavelet bases to discretize the dynamic response problem for a str... more . We use biorthogonal B{spline wavelet bases to discretize the dynamic response problem for a straight elasto{plastic rod. In an elastic predictor/plastic corrector method, we use interpolatory wavelets for the stress correction. In several numerical experiments, we show the potential of Wavelet{Galerkin methods for elastoplasticity problems. 1 Introduction The numerical treatement of elastoplasticity problems is still a very challenging eld of active research. Besides classical methods such as Finite Dierences, Finite Elements, Spectral Elements and others, quite recently rst attempts using wavelet bases have been made, [11, 21]. In recent years, signicant progress has been made for using Wavelet{Galerkin methods for the numerical solution of certain operator equations including elliptic partial dierential equations, boundary integral equations and also saddle point problems. In fact, wavelets have been proven to give rise to a diagonal multilevel preconditioner for ellipti...

Minimum compliance topology optimization produces final designs that exhibit optimal stiffness pe... more Minimum compliance topology optimization produces final designs that exhibit optimal stiffness performances without taking care of the stress layout in the material. Even if this procedure generally achieves topological shapes that are mainly made of bars or arch-fashioned members governed by regular stress patterns, final designs may be affected by the arising of stress concentrations in certain parts of the optimal domain. Classical examples refer to cornered regions, as in the well-known benchmark of the L- shaped lamina, or to the ground constraints zones in the domains to be optimized. In both the cases stress singularities generate several difficulties from the point of view of engineering and manufacturing of the pure minimum compliance optimal solutions. To overcome these problems a set of local stress constraints may be introduced in the optimization problem in order to control the concentrations and to produce fully exploitable designs. A classical approach is the stress-c...

In this work we review some applications of wavelet bases for the discretization of non linear pr... more In this work we review some applications of wavelet bases for the discretization of non linear problems arising in engineering materials. In particular, we will consider a Wavelet-Galerkin method coupling with interpolating bases for the numerical treatement of elastoplasticity problems. Here, we use an elastic pre-dictor/plastic corrector method in terms of a stress correction. This correction has to be done pointwise. We use interpolatory wavelets in the correction step and perform (fast) change of bases to switch between the different representations. We show the basic properties of the new numerical approach by some nu-merical test both in dynamical case. Moreover,we consider the possibility to state adaptive algorithms for the computation of the plastic wave. A simple one dimensional problem is used, both in hardening and softening case, for numerical test.

Proceedings of the Twelfth International Conference on Computational Structures Technology, 2014

Structural and Multidisciplinary Optimization, 2003

We present a new mortar approach in the spectral context for the analysis and optimization of L-s... more We present a new mortar approach in the spectral context for the analysis and optimization of L-shaped thin composite laminates. Its roots may be found in the (very few) existing mortar approaches for the bi-Laplacian that are herein extended to handle the fourth-order elliptic operator governing thin anisotropic laminates. For the computation of the structural matrices, exact symbolic integration is used rather than more classical Gauss-Lobatto quadrature schemes. Thanks to the underlying spectral approach, considerable CPU times savings are obtained compared with finite-element approaches when the optimal design of the laminates is pursued. A few numerical studies that are concerned with the analysis and the optimization of L-shaped singlelayered plates are described in detail.

Advances in Mechanics and Mathematics, 2004

[7], we propose a fixed-point algorithm for

III European Conference on Computational Mechanics, 2006

We propose a novel approach for the analysis of cohesive crack propagation in elastic media. Unli... more We propose a novel approach for the analysis of cohesive crack propagation in elastic media. Unlike all existing methods that move from continuous displacement formulations that are properly enriched to handle the discontinuity, see e.g. the extended finite element method (XFEM) [Moës et al., 1999] or the embedded discontinuity [Jirásek, 2000] approaches, inherently discontinuous displacements and H(div) stresses in a truly mixed setting are herein proposed. The formulation, originally introduced to handle incompressible materials in plane elasticity, is herein extended to the analysis of propagating cohesive cracks in elastic media thanks to a novel variational formulation that is enriched with an interface energy term. Notably, no edge element is introduced but simply the inherent discontinuity of the displacement field is taken advantage of. Furthermore, stress flux continuity is imposed in an exact fashion within the formulation and not as an additional weak constraint as classically done. Extensive numerical simulations are presented to complete the theoretical framework.

Computational Fluid and Solid Mechanics 2003, 2003

Computational Techniques for Materials, Composites and Composite Structures, 2000

Computational Fluid and Solid Mechanics 2003, 2003

Proceedings of the Ninth International Conference on Computational Structures Technology, 2008

Proceedings of the Eighth International Conference on Computational Structures Technology, 2006

Computers & Structures, 2016

Annali dell'Università di Ferrara. Sezione 7: Scienze matematiche

A mixed variational formulation with discontinuous displacements and continuous tractions is pro-... more A mixed variational formulation with discontinuous displacements and continuous tractions is pro- posed for the analysis of cohesive-crack propagation in elastic media. Such a formulation gives rise to a peculiar finite-element discretization scheme that is based on the Johnson-Mercier composite elements as to the stresses. Numerical results concerning classical benchmark problems are pro- posed and need for future developments highlighted, including the analysis of elastic-plastic and incompressible media. A new approach for cohesive crack propagation in elastic media is presented. Numerical methods for such kind of problems should be able to resolve discontinuous displacement fields as well as continuous tractions. Among pioneering contributions appeared up to the mid-nineties, the contribution (5) presented a re-meshing approach capable of following post-bifurcation and post-peak regimes, (6) introduced a stable, mesh-insensitive approach for the resolution of localization lines ...

1. Abstract We propose a novel approach for the analysis of cohesive crack propagation in elastic... more 1. Abstract We propose a novel approach for the analysis of cohesive crack propagation in elastic media. Unlike all existing methods that move from continuous displacement formulations that are properly enriched to handle the discontinuity, see e.g. the extended finite element method (XFEM) or the embedded disconti-nuity approaches, inherently discontinuous displacements and H(div, Ω) stresses in a truly mixed setting are herein proposed. The formulation, originally introduced to handle incompressible materials in plane elasticity, is herein extended to the analysis of propagating cohesive cracks in elastic media thanks to a novel variational formulation that is enriched with an interface energy term. Notably, no edge ele-ment is introduced but simply the inherent discontinuity of the displacement field is taken advantage of. Furthermore, stress flux continuity is imposed in an exact fashion within the formulation and not as an additional weak constraint as classically done. Extensi...

Cited By (since 1996):6, Export Date: 9 October 2013, Source: Scopus

. We use biorthogonal B{spline wavelet bases to discretize the dynamic response problem for a str... more . We use biorthogonal B{spline wavelet bases to discretize the dynamic response problem for a straight elasto{plastic rod. In an elastic predictor/plastic corrector method, we use interpolatory wavelets for the stress correction. In several numerical experiments, we show the potential of Wavelet{Galerkin methods for elastoplasticity problems. 1 Introduction The numerical treatement of elastoplasticity problems is still a very challenging eld of active research. Besides classical methods such as Finite Dierences, Finite Elements, Spectral Elements and others, quite recently rst attempts using wavelet bases have been made, [11, 21]. In recent years, signicant progress has been made for using Wavelet{Galerkin methods for the numerical solution of certain operator equations including elliptic partial dierential equations, boundary integral equations and also saddle point problems. In fact, wavelets have been proven to give rise to a diagonal multilevel preconditioner for ellipti...

Minimum compliance topology optimization produces final designs that exhibit optimal stiffness pe... more Minimum compliance topology optimization produces final designs that exhibit optimal stiffness performances without taking care of the stress layout in the material. Even if this procedure generally achieves topological shapes that are mainly made of bars or arch-fashioned members governed by regular stress patterns, final designs may be affected by the arising of stress concentrations in certain parts of the optimal domain. Classical examples refer to cornered regions, as in the well-known benchmark of the L- shaped lamina, or to the ground constraints zones in the domains to be optimized. In both the cases stress singularities generate several difficulties from the point of view of engineering and manufacturing of the pure minimum compliance optimal solutions. To overcome these problems a set of local stress constraints may be introduced in the optimization problem in order to control the concentrations and to produce fully exploitable designs. A classical approach is the stress-c...

In this work we review some applications of wavelet bases for the discretization of non linear pr... more In this work we review some applications of wavelet bases for the discretization of non linear problems arising in engineering materials. In particular, we will consider a Wavelet-Galerkin method coupling with interpolating bases for the numerical treatement of elastoplasticity problems. Here, we use an elastic pre-dictor/plastic corrector method in terms of a stress correction. This correction has to be done pointwise. We use interpolatory wavelets in the correction step and perform (fast) change of bases to switch between the different representations. We show the basic properties of the new numerical approach by some nu-merical test both in dynamical case. Moreover,we consider the possibility to state adaptive algorithms for the computation of the plastic wave. A simple one dimensional problem is used, both in hardening and softening case, for numerical test.

Proceedings of the Twelfth International Conference on Computational Structures Technology, 2014

Structural and Multidisciplinary Optimization, 2003

We present a new mortar approach in the spectral context for the analysis and optimization of L-s... more We present a new mortar approach in the spectral context for the analysis and optimization of L-shaped thin composite laminates. Its roots may be found in the (very few) existing mortar approaches for the bi-Laplacian that are herein extended to handle the fourth-order elliptic operator governing thin anisotropic laminates. For the computation of the structural matrices, exact symbolic integration is used rather than more classical Gauss-Lobatto quadrature schemes. Thanks to the underlying spectral approach, considerable CPU times savings are obtained compared with finite-element approaches when the optimal design of the laminates is pursued. A few numerical studies that are concerned with the analysis and the optimization of L-shaped singlelayered plates are described in detail.

Advances in Mechanics and Mathematics, 2004

[7], we propose a fixed-point algorithm for

III European Conference on Computational Mechanics, 2006

We propose a novel approach for the analysis of cohesive crack propagation in elastic media. Unli... more We propose a novel approach for the analysis of cohesive crack propagation in elastic media. Unlike all existing methods that move from continuous displacement formulations that are properly enriched to handle the discontinuity, see e.g. the extended finite element method (XFEM) [Moës et al., 1999] or the embedded discontinuity [Jirásek, 2000] approaches, inherently discontinuous displacements and H(div) stresses in a truly mixed setting are herein proposed. The formulation, originally introduced to handle incompressible materials in plane elasticity, is herein extended to the analysis of propagating cohesive cracks in elastic media thanks to a novel variational formulation that is enriched with an interface energy term. Notably, no edge element is introduced but simply the inherent discontinuity of the displacement field is taken advantage of. Furthermore, stress flux continuity is imposed in an exact fashion within the formulation and not as an additional weak constraint as classically done. Extensive numerical simulations are presented to complete the theoretical framework.

Computational Fluid and Solid Mechanics 2003, 2003

Computational Techniques for Materials, Composites and Composite Structures, 2000

Computational Fluid and Solid Mechanics 2003, 2003

Proceedings of the Ninth International Conference on Computational Structures Technology, 2008

Proceedings of the Eighth International Conference on Computational Structures Technology, 2006