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The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Wed, 29 Mar 2023 02:47:24 GMT2023-03-29T02:47:24ZA general multi-scale design strategy for the optimisation of variable stiffness composites
http://hdl.handle.net/10985/11437
A general multi-scale design strategy for the optimisation of variable stiffness composites
MONTEMURRO, Marco; CATAPANO, Anita
The present paper focuses on the development of a multi-scale design strategy for the optimisation of variable angle stiffness laminates. The main goal consists in proving that it is possible to design structures having complex shapes made of variable stiffness composites by taking into account, from the early stages of the design process, the constraints linked to the manufacturing process.
Fri, 01 Jan 2016 00:00:00 GMThttp://hdl.handle.net/10985/114372016-01-01T00:00:00ZMONTEMURRO, MarcoCATAPANO, AnitaThe present paper focuses on the development of a multi-scale design strategy for the optimisation of variable angle stiffness laminates. The main goal consists in proving that it is possible to design structures having complex shapes made of variable stiffness composites by taking into account, from the early stages of the design process, the constraints linked to the manufacturing process.A multi-scale approach for the simultaneous shape and material optimisation of sandwich panels with cellular core
http://hdl.handle.net/10985/10674
A multi-scale approach for the simultaneous shape and material optimisation of sandwich panels with cellular core
MONTEMURRO, Marco; CATAPANO, Anita; DOROSZEWSKI, Dominique
This work deals with the problem of the optimum design of a sandwich panel made of carbon-epoxy skins and a metallic cellular core. The proposed design strategy is a multi-scale numerical optimisation procedure that does not make use of any simplifying hypothesis to obtain a true global optimum configuration of the system. To face the design of the sandwich structure at both meso and macro scales, a two-level optimisation strategy is employed: at the first level the goal is the determination of the optimum shape of the unit cell of the core (meso-scale) together with the material and geometric parameters of the laminated skins (macro-scale), while at the second level the objective is the design of the skins stacking sequence (skin meso-scale) meeting the geometrical and material parameters provided by the first-level problem. The two-level strategy is founded on the polar formalism for the description of the anisotropic behaviour of the laminates, on the NURBS basis functions for representing the shape of the unit cell and on the use of a genetic algorithm as optimisation tool to perform the solution search. To prove its effectiveness, the multi-scale strategy is applied to the least-weight design of a sandwich plate subject to constraints of different nature: on the positive-definiteness of the stiffness tensor of the core, on the admissible material properties of the laminated faces, on the local buckling load of the unit cell, on the global buckling load of the panel and geometrical as well as manufacturability constraints related to the fabrication process of the cellular core.
Fri, 01 Jan 2016 00:00:00 GMThttp://hdl.handle.net/10985/106742016-01-01T00:00:00ZMONTEMURRO, MarcoCATAPANO, AnitaDOROSZEWSKI, DominiqueThis work deals with the problem of the optimum design of a sandwich panel made of carbon-epoxy skins and a metallic cellular core. The proposed design strategy is a multi-scale numerical optimisation procedure that does not make use of any simplifying hypothesis to obtain a true global optimum configuration of the system. To face the design of the sandwich structure at both meso and macro scales, a two-level optimisation strategy is employed: at the first level the goal is the determination of the optimum shape of the unit cell of the core (meso-scale) together with the material and geometric parameters of the laminated skins (macro-scale), while at the second level the objective is the design of the skins stacking sequence (skin meso-scale) meeting the geometrical and material parameters provided by the first-level problem. The two-level strategy is founded on the polar formalism for the description of the anisotropic behaviour of the laminates, on the NURBS basis functions for representing the shape of the unit cell and on the use of a genetic algorithm as optimisation tool to perform the solution search. To prove its effectiveness, the multi-scale strategy is applied to the least-weight design of a sandwich plate subject to constraints of different nature: on the positive-definiteness of the stiffness tensor of the core, on the admissible material properties of the laminated faces, on the local buckling load of the unit cell, on the global buckling load of the panel and geometrical as well as manufacturability constraints related to the fabrication process of the cellular core.On the effective integration of manufacturability constraints within the multi-scale methodology for designing variable angle-tow laminates
http://hdl.handle.net/10985/11438
On the effective integration of manufacturability constraints within the multi-scale methodology for designing variable angle-tow laminates
MONTEMURRO, Marco; CATAPANO, Anita
In this work a multi-scale two-level (MS2L) optimisation strategy for optimising VAT composites is presented. In the framework of the MS2L methodology, the design problem is split and solved into two steps. At the first step the goal is to determine the optimum distribution of the laminate stiffness properties over the structure (macroscopic scale), while the second step aims at retrieving the optimum fibres-path in each layer meeting all the requirements provided by the problem at hand (mesoscopic scale). The MS2L strategy has been improved in order to integrate all types of requirements (mechanical, manufacturability, geometric, etc.) within the first-level problem.The proposed approach relies on: a) the polar formalism for describing the behaviour of the VAT laminate, b) the iso-geometric surfaces for describing the spatial variation of both the laminate stiffness properties (macro-scale) and the layers fibres-path (meso-scale) and c) an hybrid optimisation tool (genetic and gradient-based algorithms) to perform the solution search. The effectiveness of the MS2L strategy is proven through a numerical example on the maximisation of the first buckling factor of a VAT plate subject to both mechanical and manufacturability constraints.
Sun, 01 Jan 2017 00:00:00 GMThttp://hdl.handle.net/10985/114382017-01-01T00:00:00ZMONTEMURRO, MarcoCATAPANO, AnitaIn this work a multi-scale two-level (MS2L) optimisation strategy for optimising VAT composites is presented. In the framework of the MS2L methodology, the design problem is split and solved into two steps. At the first step the goal is to determine the optimum distribution of the laminate stiffness properties over the structure (macroscopic scale), while the second step aims at retrieving the optimum fibres-path in each layer meeting all the requirements provided by the problem at hand (mesoscopic scale). The MS2L strategy has been improved in order to integrate all types of requirements (mechanical, manufacturability, geometric, etc.) within the first-level problem.The proposed approach relies on: a) the polar formalism for describing the behaviour of the VAT laminate, b) the iso-geometric surfaces for describing the spatial variation of both the laminate stiffness properties (macro-scale) and the layers fibres-path (meso-scale) and c) an hybrid optimisation tool (genetic and gradient-based algorithms) to perform the solution search. The effectiveness of the MS2L strategy is proven through a numerical example on the maximisation of the first buckling factor of a VAT plate subject to both mechanical and manufacturability constraints.Simultaneous shape and material optimization of sandwich panels with honeycomb core for additive manufacturing
http://hdl.handle.net/10985/9922
Simultaneous shape and material optimization of sandwich panels with honeycomb core for additive manufacturing
MONTEMURRO, Marco; CATAPANO, Anita; DOROSZEWSKI, Dominique
This works deals with the problem of the optimum design of a sandwich plate composed of CFRP faces and Al honeycomb core. The proposed design strategy is a multi-scale numerical optimization procedure that does not make use of any simplifying assumption to find a global optimum configuration of the system. The goal of such a procedure consists in simultaneously optimizing the shape of the unit cell of the honeycomb core (meso-scale) and the geometrical as well as the material parameters of the CFRP laminated skins (meso and macro scales). To prove its effectiveness, the multi-scale optimization strategy is applied to the problem of the least-weight design of a sandwich panel subject to constraints of different nature: on the positive-definiteness of the stiffness tensor of the core, on the admissible material properties of the laminated faces, on the local buckling load of the unit cell of the core, on the global buckling load of the panel and geometrical as well as manufacturability constraints linked to the fabrication process of the honeycomb core.
Thu, 01 Jan 2015 00:00:00 GMThttp://hdl.handle.net/10985/99222015-01-01T00:00:00ZMONTEMURRO, MarcoCATAPANO, AnitaDOROSZEWSKI, DominiqueThis works deals with the problem of the optimum design of a sandwich plate composed of CFRP faces and Al honeycomb core. The proposed design strategy is a multi-scale numerical optimization procedure that does not make use of any simplifying assumption to find a global optimum configuration of the system. The goal of such a procedure consists in simultaneously optimizing the shape of the unit cell of the honeycomb core (meso-scale) and the geometrical as well as the material parameters of the CFRP laminated skins (meso and macro scales). To prove its effectiveness, the multi-scale optimization strategy is applied to the problem of the least-weight design of a sandwich panel subject to constraints of different nature: on the positive-definiteness of the stiffness tensor of the core, on the admissible material properties of the laminated faces, on the local buckling load of the unit cell of the core, on the global buckling load of the panel and geometrical as well as manufacturability constraints linked to the fabrication process of the honeycomb core.A new paradigm for the optimum design of variable angle tow laminates
http://hdl.handle.net/10985/11387
A new paradigm for the optimum design of variable angle tow laminates
MONTEMURRO, Marco; CATAPANO, Anita
In this work the authors propose a new paradigm for the optimum design of variable angle tow (VAT) composites. They propose a generalisation of a multi-scale two-level (MS2L) optimisation strategy already employed to solve optimisation problems of anisotropic structures characterised by a constant stiffness distribution. In the framework of the MS2L methodology, the design problem is split into two sub-problems. At the first step of the strategy the goal is to determine the optimum distribution of the laminate stiffness properties over the structure, while the second step aims at retrieving the optimum fibres-path in each layer meeting all the requirements provided by the problem at hand. The MS2L strategy relies on: a) the polar formalism for describing the behaviour of the VAT laminate, b) the iso-geometric surfaces for describing the spatial variation of the stiffness properties and c) an hybrid optimisation tool (genetic and gradient-based algorithms) to perform the solution search. The effectiveness of the MS2L strategy is proven through a numerical example on the maximisation of the first buckling factor of a VAT plate subject to both mechanical and manufacturability constraints.
Fri, 01 Jan 2016 00:00:00 GMThttp://hdl.handle.net/10985/113872016-01-01T00:00:00ZMONTEMURRO, MarcoCATAPANO, AnitaIn this work the authors propose a new paradigm for the optimum design of variable angle tow (VAT) composites. They propose a generalisation of a multi-scale two-level (MS2L) optimisation strategy already employed to solve optimisation problems of anisotropic structures characterised by a constant stiffness distribution. In the framework of the MS2L methodology, the design problem is split into two sub-problems. At the first step of the strategy the goal is to determine the optimum distribution of the laminate stiffness properties over the structure, while the second step aims at retrieving the optimum fibres-path in each layer meeting all the requirements provided by the problem at hand. The MS2L strategy relies on: a) the polar formalism for describing the behaviour of the VAT laminate, b) the iso-geometric surfaces for describing the spatial variation of the stiffness properties and c) an hybrid optimisation tool (genetic and gradient-based algorithms) to perform the solution search. The effectiveness of the MS2L strategy is proven through a numerical example on the maximisation of the first buckling factor of a VAT plate subject to both mechanical and manufacturability constraints.Optimal design of sandwich plates with honeycomb core
http://hdl.handle.net/10985/8504
Optimal design of sandwich plates with honeycomb core
CATAPANO, Anita; MONTEMURRO, Marco
This work deals with the problem of the optimum design of a sandwich structure composed of two laminated skins and a honeycomb core. The goal is to propose a numerical optimisation procedure that does not make any simplifying hypothesis in order to obtain a true global optimal solution for the considered problem. In order to face the design of the sandwich structure at both meso and macro scales, we use a two-level optimisation strategy. At the first level, we determine the optimum geometry of the unit cell together with the material and geometric parameters of the laminated skins, while at the second level we determine the optimal skins lay-up giving the geometrical and material parameters issued from the first level. We will illustrate the application of our strategy to the least-weight design of a sandwich plate submitted to several constraints: on the first buckling load, on the positive-definiteness of the stiffness tensor of the core, on the ratio between skins and core thickness and on the admissible moduli for the laminated skins.
Wed, 01 Jan 2014 00:00:00 GMThttp://hdl.handle.net/10985/85042014-01-01T00:00:00ZCATAPANO, AnitaMONTEMURRO, MarcoThis work deals with the problem of the optimum design of a sandwich structure composed of two laminated skins and a honeycomb core. The goal is to propose a numerical optimisation procedure that does not make any simplifying hypothesis in order to obtain a true global optimal solution for the considered problem. In order to face the design of the sandwich structure at both meso and macro scales, we use a two-level optimisation strategy. At the first level, we determine the optimum geometry of the unit cell together with the material and geometric parameters of the laminated skins, while at the second level we determine the optimal skins lay-up giving the geometrical and material parameters issued from the first level. We will illustrate the application of our strategy to the least-weight design of a sandwich plate submitted to several constraints: on the first buckling load, on the positive-definiteness of the stiffness tensor of the core, on the ratio between skins and core thickness and on the admissible moduli for the laminated skins.Thermo-mechanical homogenisation of cork-based composites: variability in materials properties and propagation of uncertainty
http://hdl.handle.net/10985/16435
Thermo-mechanical homogenisation of cork-based composites: variability in materials properties and propagation of uncertainty
DELUCIA, Marco; CATAPANO, Anita; MONTEMURRO, Marco; PAILHES, Jérôme
The last decades have been characterized by a growth of raw material demand, in particular due to the consumerism in developed countries and to the fast industrialization of emerging economies. Nowadays, with the aim to minimise the environmental impact due to the consistent reduction of primary resources, the main objective in the research field of industrial materials is replacing synthetic and non-renewable materials by natural and renewable ones showing similar or even better properties. In the last years, among natural, renewable and biodegradable materials, cork has attracted the attention of both scientific and industrial communities thanks to its remarkable properties as lightness, excellent thermal and acoustic insulating capabilities mainly due to its honeycomb-like microstructure. Cork is extracted from the outer bark of Quercus Suber L. and in its natural form can be directly exploited to produce small and limited size products, e.g. cork stoppers. With the purpose to extend its field of application, cork is often used in the form of particles embedded in polymeric matrix in order to obtain cork-based agglomerates or composites [1]. Main design parameters as the density, the material properties, the fraction and the size of cork particles, the material of polymeric matrix, the manufacturing process and the overall packing density affect the thermomechanical properties of cork-based agglomerates [2]. The aim of the present work is to propose a general and efficient multi-scale numerical homogenisation strategy capable of determining the effective thermal and mechanical properties of cork-based agglomerates. A 2D (Fig.1) as well as a 3D finite element model (Fig.2) based on Voronoi's tessellation algorithm have been built and the strain energy homogenisation technique has been used for both models to determine the elastic and thermal properties of cork-based composites. In these models, parameters defining the representative volume element (RVE) are: the grain shape, grain orientation, grain matrix and cork material properties, volume fraction of the components, as well as the properties of the grain/matrix interface. Moreover, it must be pointed out that in cork-based composites, some of these parameters, as the mechanical properties of cork as well as the number, size and distribution of pores within the agglomerate, exhibit a high variability. In particular, the variability of density, porosity and chemical composition of the outer bark of Quercus Suber L. (which are strongly affected by the geographical location of cork production) explains the natural variability of the mechanical as well as thermal properties of cork. Therefore this aspect is of paramount importance when modelling and designing cork-based composite structures. For this reason, the variability of the properties mentioned above has been introduced in the FE model through a suitable probability density function [3]. More precisely, the Monte Carlo method has been used to study the effect of the variability of the model inputs on the equivalent thermo-elastic behaviour of the cork-based agglomerate at the macroscopic scale [4]. The result of the analysis has been interpreted in a statistical manner: the probability of every output quantity depends on the input probabilities and their correlations. Effective thermo-mechanical properties of different cork-based composites have been estimated and numerical results have been compared to the experimental ones in order to show the effectiveness of the proposed strategy.
Tue, 01 Jan 2019 00:00:00 GMThttp://hdl.handle.net/10985/164352019-01-01T00:00:00ZDELUCIA, MarcoCATAPANO, AnitaMONTEMURRO, MarcoPAILHES, JérômeThe last decades have been characterized by a growth of raw material demand, in particular due to the consumerism in developed countries and to the fast industrialization of emerging economies. Nowadays, with the aim to minimise the environmental impact due to the consistent reduction of primary resources, the main objective in the research field of industrial materials is replacing synthetic and non-renewable materials by natural and renewable ones showing similar or even better properties. In the last years, among natural, renewable and biodegradable materials, cork has attracted the attention of both scientific and industrial communities thanks to its remarkable properties as lightness, excellent thermal and acoustic insulating capabilities mainly due to its honeycomb-like microstructure. Cork is extracted from the outer bark of Quercus Suber L. and in its natural form can be directly exploited to produce small and limited size products, e.g. cork stoppers. With the purpose to extend its field of application, cork is often used in the form of particles embedded in polymeric matrix in order to obtain cork-based agglomerates or composites [1]. Main design parameters as the density, the material properties, the fraction and the size of cork particles, the material of polymeric matrix, the manufacturing process and the overall packing density affect the thermomechanical properties of cork-based agglomerates [2]. The aim of the present work is to propose a general and efficient multi-scale numerical homogenisation strategy capable of determining the effective thermal and mechanical properties of cork-based agglomerates. A 2D (Fig.1) as well as a 3D finite element model (Fig.2) based on Voronoi's tessellation algorithm have been built and the strain energy homogenisation technique has been used for both models to determine the elastic and thermal properties of cork-based composites. In these models, parameters defining the representative volume element (RVE) are: the grain shape, grain orientation, grain matrix and cork material properties, volume fraction of the components, as well as the properties of the grain/matrix interface. Moreover, it must be pointed out that in cork-based composites, some of these parameters, as the mechanical properties of cork as well as the number, size and distribution of pores within the agglomerate, exhibit a high variability. In particular, the variability of density, porosity and chemical composition of the outer bark of Quercus Suber L. (which are strongly affected by the geographical location of cork production) explains the natural variability of the mechanical as well as thermal properties of cork. Therefore this aspect is of paramount importance when modelling and designing cork-based composite structures. For this reason, the variability of the properties mentioned above has been introduced in the FE model through a suitable probability density function [3]. More precisely, the Monte Carlo method has been used to study the effect of the variability of the model inputs on the equivalent thermo-elastic behaviour of the cork-based agglomerate at the macroscopic scale [4]. The result of the analysis has been interpreted in a statistical manner: the probability of every output quantity depends on the input probabilities and their correlations. Effective thermo-mechanical properties of different cork-based composites have been estimated and numerical results have been compared to the experimental ones in order to show the effectiveness of the proposed strategy.Topography and wettability characterization of surfaces manufactured by SLM and treated by chemical etching
http://hdl.handle.net/10985/19920
Topography and wettability characterization of surfaces manufactured by SLM and treated by chemical etching
THENARD, Thomas; ALLENA, Rachele; CATAPANO, Anita; MESNARD, Michel; SAINTIER, Nicolas; MOHAMED, El May
Selective Laser Melting process represents an interesting opportunity in the biomedical field to fabricate customized implants. However, the surface roughness of components obtained through additive manufacturing is a major limitation and affects the surface wettability. In the present work, chemical etching is adopted to deal with such an issue. To do so, the effects of chemical etching parameters (such as immersion time and composition of the solution) on the surface roughness, weight loss and wettability is analyzed. Different samples (obtained through different printing orientations) are considered. The tests show that the roughness and the wetting of the surfaces are improved thanks to chemical etching. As a major result, the most influencing parameters on surface wetting are two: the roughness and the material properties (which vary with samples depth).
Wed, 01 Jan 2020 00:00:00 GMThttp://hdl.handle.net/10985/199202020-01-01T00:00:00ZTHENARD, ThomasALLENA, RacheleCATAPANO, AnitaMESNARD, MichelSAINTIER, NicolasMOHAMED, El MaySelective Laser Melting process represents an interesting opportunity in the biomedical field to fabricate customized implants. However, the surface roughness of components obtained through additive manufacturing is a major limitation and affects the surface wettability. In the present work, chemical etching is adopted to deal with such an issue. To do so, the effects of chemical etching parameters (such as immersion time and composition of the solution) on the surface roughness, weight loss and wettability is analyzed. Different samples (obtained through different printing orientations) are considered. The tests show that the roughness and the wetting of the surfaces are improved thanks to chemical etching. As a major result, the most influencing parameters on surface wetting are two: the roughness and the material properties (which vary with samples depth).Blending constraints for composite laminates in polar parameters space
http://hdl.handle.net/10985/19265
Blending constraints for composite laminates in polar parameters space
PANETTIERI, Enrico; MONTEMURRO, Marco; CATAPANO, Anita
This work proposes a new formulation of blending constraints, in the framework of the multi-scale two-level (MS2L) optimisation strategy for composites. This approach aims to optimise simultaneously both geometrical and mechanical parameters of the laminate at each characteristic scale (macroscopic and mesoscopic ones). In particular, this study deals with the first level of the MS2L optimisation strategy which focuses on the laminate macroscopic scale. At this scale, the behaviour of the laminate is described in terms of the polar parameters of each constitutive stiffness matrix in the framework of the First-order Shear Deformation Theory (FSDT). Therefore, blending constraints are formulated as equivalent mechanical requirements to be imposed to both polar and geometric parameters of the laminate within the first-level problem. The effectiveness of the proposed approach is tested on a meaningful benchmark: the least-weight design of a composite wing-box subject to constraints of different nature. The optimised solutions provided by the MS2L design strategy are characterised by a weight saving of about 12 % (when compared to the reference solution taken from the literature) by meeting the full set of feasibility, manufacturing and mechanical requirements.
Tue, 01 Jan 2019 00:00:00 GMThttp://hdl.handle.net/10985/192652019-01-01T00:00:00ZPANETTIERI, EnricoMONTEMURRO, MarcoCATAPANO, AnitaThis work proposes a new formulation of blending constraints, in the framework of the multi-scale two-level (MS2L) optimisation strategy for composites. This approach aims to optimise simultaneously both geometrical and mechanical parameters of the laminate at each characteristic scale (macroscopic and mesoscopic ones). In particular, this study deals with the first level of the MS2L optimisation strategy which focuses on the laminate macroscopic scale. At this scale, the behaviour of the laminate is described in terms of the polar parameters of each constitutive stiffness matrix in the framework of the First-order Shear Deformation Theory (FSDT). Therefore, blending constraints are formulated as equivalent mechanical requirements to be imposed to both polar and geometric parameters of the laminate within the first-level problem. The effectiveness of the proposed approach is tested on a meaningful benchmark: the least-weight design of a composite wing-box subject to constraints of different nature. The optimised solutions provided by the MS2L design strategy are characterised by a weight saving of about 12 % (when compared to the reference solution taken from the literature) by meeting the full set of feasibility, manufacturing and mechanical requirements.Cellular structures from additive processes: design, homogenization and experimental validation
http://hdl.handle.net/10985/17331
Cellular structures from additive processes: design, homogenization and experimental validation
DE PASQUALE, Giorgio; MONTEMURRO, Marco; CATAPANO, Anita; BERTOLINO, Giulia; REVELLI, Luca
The importance of lightweight structures in many fields of engineering is well known since long time. The innovations in technological processes based on material addiction allow pushing the design towards challenging geometries and associated structural properties. Engineered materials like lattice structures can be theoretically used to modify the local material properties and strength with minimization of the mass of components; in practice, several issues are still to be solved in stabilization of additive processes and achieving repeatable structures able to pass qualification procedures. At this purpose, dedicated experimental and design methods like those reported in this paper are needed.
Mon, 01 Jan 2018 00:00:00 GMThttp://hdl.handle.net/10985/173312018-01-01T00:00:00ZDE PASQUALE, GiorgioMONTEMURRO, MarcoCATAPANO, AnitaBERTOLINO, GiuliaREVELLI, LucaThe importance of lightweight structures in many fields of engineering is well known since long time. The innovations in technological processes based on material addiction allow pushing the design towards challenging geometries and associated structural properties. Engineered materials like lattice structures can be theoretically used to modify the local material properties and strength with minimization of the mass of components; in practice, several issues are still to be solved in stabilization of additive processes and achieving repeatable structures able to pass qualification procedures. At this purpose, dedicated experimental and design methods like those reported in this paper are needed.