Purpose The paper aims to use a switching technique which allows to couple a nonlocal bond-based ... more Purpose The paper aims to use a switching technique which allows to couple a nonlocal bond-based Peridynamic approach to the Meshless Local Exponential Basis Functions (MLEBF) method, based on classical continuum mechanics, to solve planar problems. Design/methodology/approach The coupling has been achieved in a completely meshless scheme. The domain is divided in three zones: one in which only Peridynamics is applied, one in which only the meshless method is applied and a transition zone where a gradual transition between the two approaches takes place. Findings The new coupling technique generates overall grids that are not affected by ghost forces. Moreover, the use of the meshless approach can be limited to a narrow boundary region of the domain, and in this way, it can be used to remove the “surface effect” from the Peridynamic solution applied to all internal points. Originality/value The current study paves the road for future studies on dynamic and static crack propagation p...
Ls-Prepost was used to generate the model. Ls-Dyna was used to simulate the behaviour of this mat... more Ls-Prepost was used to generate the model. Ls-Dyna was used to simulate the behaviour of this material under compressive loads. The objective was to reproduce deformation mechanisms and to compare the numerical load-displacement curves with those obtained from ...
Therefore, the present work proposes a numerical approach to modify the chin bar of a helmet with... more Therefore, the present work proposes a numerical approach to modify the chin bar of a helmet with the aim of reducing the risk of BSF and of satisfying the requirements of the current standards. Two types of FE simulations were carried out in the present work by means of LS‐Dyna software. The first one involved a helmeted HYBRID III head and neck which was hit by a cylindrical impactor on the chin bar of the helmet at a velocity of 3.5 m/s. This simulation was adopted from the test method in for the chin bar in order to measure the induced neck force due to the impact on the chin bar. The second type of FE simulation was the virtual impact test for the chin bar of the full‐face helmet according to ECE 22.05. The proposed approach was developed to optimize the composite chin bar of a full‐face helmet to reduce the risk of BSF, which is one of the most common types of injury among motorcycle accidents but is not clearly addressed in standards. The results show that the developed appro...
Cracks are present in almost all structural components. It is of the highest importance to be abl... more Cracks are present in almost all structural components. It is of the highest importance to be able to describe fatigue crack propagation in engineering structures for a safe use and to define a proper repair and maintenance program. Even though a large amount of analytical work has been performed, the description of the behaviour of actual component geometries under realistic loading conditions require the use of numerical methods. The modeling of damage propagation phenomena is usually a difficult task because it is necessary to have the capability of describing generation and growth of material discontinuities. In the last thirty years, several approaches have been developed to model and simulate fatigue crack growth in structural components such as the boundary element method [1], the finite element method [2], mesh free methods [3], the extended finite element method [4] and the free Galerkin method [5]. In these approaches, it is necessary to define a criterium to predict the ...
This paper aims to define a homogenised constitutive relation for the global behaviour of periodi... more This paper aims to define a homogenised constitutive relation for the global behaviour of periodic composite structures in the case of non-linear material components. Special emphasis is put on the description of the generality of the algorithm which, in principle, can be applied to any kind of nonlinear material behaviour affecting the representative volume element. The method is currently restricted to plane situations with monotonic proportional loading.
Computational Fluid and Solid Mechanics 2003, 2003
Publisher Summary The advent of energy-momentum conserving time integration schemes has introduce... more Publisher Summary The advent of energy-momentum conserving time integration schemes has introduced a class of robust and accurate algorithms to solve geometrically nonlinear structural dynamic problems. The time-discretization of an external force has to be studied carefully to obtain an advantage of the energy conserving based method. This differs from the autonomous dissipative case, where a straightforward application proved useful. An accurate discretized description of the change of energy because of the external force might not be simple to find. This chapter discusses the different discretizations of the external force term in a simple Duffing's oscillator. A comparison of the resulting algorithm is based on the investigations of stable and unstable manifold of a periodic saddle cycle.
Mechanics of Advanced Materials and Structures, 1997
Homogenization theory is applied to the elastic analysis of beams composed of many fibers paralle... more Homogenization theory is applied to the elastic analysis of beams composed of many fibers parallel to the beam axis. We first analyze the microstructure of the beam to define the local perturbation of a global mean behavior, due to nonhomogeneity. We describe this perturbation using first- and second-order terms in the asymptotic expansion of displacements in the power series of
Purpose The paper aims to use a switching technique which allows to couple a nonlocal bond-based ... more Purpose The paper aims to use a switching technique which allows to couple a nonlocal bond-based Peridynamic approach to the Meshless Local Exponential Basis Functions (MLEBF) method, based on classical continuum mechanics, to solve planar problems. Design/methodology/approach The coupling has been achieved in a completely meshless scheme. The domain is divided in three zones: one in which only Peridynamics is applied, one in which only the meshless method is applied and a transition zone where a gradual transition between the two approaches takes place. Findings The new coupling technique generates overall grids that are not affected by ghost forces. Moreover, the use of the meshless approach can be limited to a narrow boundary region of the domain, and in this way, it can be used to remove the “surface effect” from the Peridynamic solution applied to all internal points. Originality/value The current study paves the road for future studies on dynamic and static crack propagation p...
Ls-Prepost was used to generate the model. Ls-Dyna was used to simulate the behaviour of this mat... more Ls-Prepost was used to generate the model. Ls-Dyna was used to simulate the behaviour of this material under compressive loads. The objective was to reproduce deformation mechanisms and to compare the numerical load-displacement curves with those obtained from ...
Therefore, the present work proposes a numerical approach to modify the chin bar of a helmet with... more Therefore, the present work proposes a numerical approach to modify the chin bar of a helmet with the aim of reducing the risk of BSF and of satisfying the requirements of the current standards. Two types of FE simulations were carried out in the present work by means of LS‐Dyna software. The first one involved a helmeted HYBRID III head and neck which was hit by a cylindrical impactor on the chin bar of the helmet at a velocity of 3.5 m/s. This simulation was adopted from the test method in for the chin bar in order to measure the induced neck force due to the impact on the chin bar. The second type of FE simulation was the virtual impact test for the chin bar of the full‐face helmet according to ECE 22.05. The proposed approach was developed to optimize the composite chin bar of a full‐face helmet to reduce the risk of BSF, which is one of the most common types of injury among motorcycle accidents but is not clearly addressed in standards. The results show that the developed appro...
Cracks are present in almost all structural components. It is of the highest importance to be abl... more Cracks are present in almost all structural components. It is of the highest importance to be able to describe fatigue crack propagation in engineering structures for a safe use and to define a proper repair and maintenance program. Even though a large amount of analytical work has been performed, the description of the behaviour of actual component geometries under realistic loading conditions require the use of numerical methods. The modeling of damage propagation phenomena is usually a difficult task because it is necessary to have the capability of describing generation and growth of material discontinuities. In the last thirty years, several approaches have been developed to model and simulate fatigue crack growth in structural components such as the boundary element method [1], the finite element method [2], mesh free methods [3], the extended finite element method [4] and the free Galerkin method [5]. In these approaches, it is necessary to define a criterium to predict the ...
This paper aims to define a homogenised constitutive relation for the global behaviour of periodi... more This paper aims to define a homogenised constitutive relation for the global behaviour of periodic composite structures in the case of non-linear material components. Special emphasis is put on the description of the generality of the algorithm which, in principle, can be applied to any kind of nonlinear material behaviour affecting the representative volume element. The method is currently restricted to plane situations with monotonic proportional loading.
Computational Fluid and Solid Mechanics 2003, 2003
Publisher Summary The advent of energy-momentum conserving time integration schemes has introduce... more Publisher Summary The advent of energy-momentum conserving time integration schemes has introduced a class of robust and accurate algorithms to solve geometrically nonlinear structural dynamic problems. The time-discretization of an external force has to be studied carefully to obtain an advantage of the energy conserving based method. This differs from the autonomous dissipative case, where a straightforward application proved useful. An accurate discretized description of the change of energy because of the external force might not be simple to find. This chapter discusses the different discretizations of the external force term in a simple Duffing's oscillator. A comparison of the resulting algorithm is based on the investigations of stable and unstable manifold of a periodic saddle cycle.
Mechanics of Advanced Materials and Structures, 1997
Homogenization theory is applied to the elastic analysis of beams composed of many fibers paralle... more Homogenization theory is applied to the elastic analysis of beams composed of many fibers parallel to the beam axis. We first analyze the microstructure of the beam to define the local perturbation of a global mean behavior, due to nonhomogeneity. We describe this perturbation using first- and second-order terms in the asymptotic expansion of displacements in the power series of
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Papers by Ugo Galvanetto