https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Fri, 15 May 2026 23:42:56 GMT 2026-05-15T23:42:56Z http://hdl.handle.net/10985/8493 A multi-scale approach for the optimum design of sandwich plates with honeycomb core. Part II: the optimisation strategy MONTEMURRO, Marco; CATAPANO, Anita This work deals with the problem of the optimum design of a sandwich panel. The design strategy that we propose is a numerical optimisation procedure that does not make any simplifying assumption to obtain a true global optimum configuration of the system. 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 optimal geometry of the unit cell of the core 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. The two-level strategy relies both on the use of the polar formalism for the description of the anisotropic behaviour of the laminates and on the use of a genetic algorithm as optimisation tool to perform the solution search. To prove its effectiveness, we apply our strategy to the least-weight design of a sandwich plate, satisfying 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 GMT http://hdl.handle.net/10985/8493 2014-01-01T00:00:00Z MONTEMURRO, Marco CATAPANO, Anita This work deals with the problem of the optimum design of a sandwich panel. The design strategy that we propose is a numerical optimisation procedure that does not make any simplifying assumption to obtain a true global optimum configuration of the system. 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 optimal geometry of the unit cell of the core 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. The two-level strategy relies both on the use of the polar formalism for the description of the anisotropic behaviour of the laminates and on the use of a genetic algorithm as optimisation tool to perform the solution search. To prove its effectiveness, we apply our strategy to the least-weight design of a sandwich plate, satisfying 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. http://hdl.handle.net/10985/17329 On the correlation between stiffness and strength properties of anisotropic laminates CATAPANO, Anita; MONTEMURRO, Marco This paper focuses on the analytical formulation of a tensorial laminate-level failure criterion. The criterion is formulated and expressed in the framework of the first-order shear deformation theory (FSDT) in order to take into account the influence of the transverse shear stresses on the failure mechanisms. More precisely the most common polynomial ply-level failure criteria (expressed under a unified matrix formulation) are considered and reformulated at the laminate level. The proposed unified formulation relies on the utilisation of the polar formalism gener- alised to the FSDT framework. Through this approach all the considered criteria can be formulated in terms of tensor invariants. Furthermore, thanks to the polar representation, an important theoretical result is proven: the existence of a set of analytical relationships between the laminate strength and stiffness invariants. Mon, 01 Jan 2018 00:00:00 GMT http://hdl.handle.net/10985/17329 2018-01-01T00:00:00Z CATAPANO, Anita MONTEMURRO, Marco This paper focuses on the analytical formulation of a tensorial laminate-level failure criterion. The criterion is formulated and expressed in the framework of the first-order shear deformation theory (FSDT) in order to take into account the influence of the transverse shear stresses on the failure mechanisms. More precisely the most common polynomial ply-level failure criteria (expressed under a unified matrix formulation) are considered and reformulated at the laminate level. The proposed unified formulation relies on the utilisation of the polar formalism gener- alised to the FSDT framework. Through this approach all the considered criteria can be formulated in terms of tensor invariants. Furthermore, thanks to the polar representation, an important theoretical result is proven: the existence of a set of analytical relationships between the laminate strength and stiffness invariants. http://hdl.handle.net/10985/15155 A contribution to the development of design strategies for the optimisation of lightweight structures MONTEMURRO, Marco The design and optimisation of lightweight structures is of paramount importance in many industrial fields: from automotive to biomedical ones, from naval to aerospace fields. During the last three decades, new manufacturing processes emerged, e.g. the additive layer manufacturing (ALM) technology applied to different materials (metals, ceramics, composites), the automated fibre placement (AFP) technology for tailoring unconventional composites (both thermoplastic and thermoset ones), the compression moulding compound (CMC) technology (well suited for thermoplastic composites), etc. Therefore, the development of new, modern and well-suited design/optimisation methodologies becomes fundamental. Generally speaking, the design/optimisation strategy should be able to provide an optimised but also manufacturable solution. On the one hand, this methodology must be able to include, since the early stage of the design process (i.e. the preliminary design phase), the specificity of such new technologies (and, mostly, the related technological limitations). On the other hand, the design/optimisation strategy must be able to find a solution when the problem is formulated in the most general sense and when the full set of design variables, involved at different scales, is considered. In order to attain this ambitious goal, the formalisation of new models (or the generalisation of the existing ones) is of capital importance: the problem formulation must be as general as possible and the useless simplifying hypotheses should be totally (or partially) rejected. Of course, the price to pay is an increased problem complexity. This HDR manuscript represents a synthesis of my research activities since September 2013 which are essentially framed into the previous background. This document briefly present my contribution to the development of suitable design strategies for the optimisation of lightweight structures. The work is articulated into four main research axes: - the development of new numerical methods (meta-heuristics) for the resolution of optimisation problems characterised by a variable number of design variables (e.g. the optimisation of modular structures); - the formulation of high-order shear deformation theories based on tensor invariants (for plates and shells) and the development of a multi-scale optimisation strategy for designing unconventional constant stiffness and variable stiffness composites (manufactured through the AFP process); - the development of a new topology optimisation method based on both NURBS hyper-surfaces and density-based schemes (well suited for parts manufactured by ALM technologies); - the development of a general (i.e. problem-independent) optimisation strategy for inverse problems. The effectiveness of these methods has been proven (for each topic) through benchmarks taken from the literature and by means of real-world engineering problems as well. Starting from these encouraging results, some general and meaningful perspectives on both new design/optimisation strategies and new manufacturing process for producing hybrid anisotropic structures (of complex topology) are given at the end of the manuscript. Mon, 01 Jan 2018 00:00:00 GMT http://hdl.handle.net/10985/15155 2018-01-01T00:00:00Z MONTEMURRO, Marco The design and optimisation of lightweight structures is of paramount importance in many industrial fields: from automotive to biomedical ones, from naval to aerospace fields. During the last three decades, new manufacturing processes emerged, e.g. the additive layer manufacturing (ALM) technology applied to different materials (metals, ceramics, composites), the automated fibre placement (AFP) technology for tailoring unconventional composites (both thermoplastic and thermoset ones), the compression moulding compound (CMC) technology (well suited for thermoplastic composites), etc. Therefore, the development of new, modern and well-suited design/optimisation methodologies becomes fundamental. Generally speaking, the design/optimisation strategy should be able to provide an optimised but also manufacturable solution. On the one hand, this methodology must be able to include, since the early stage of the design process (i.e. the preliminary design phase), the specificity of such new technologies (and, mostly, the related technological limitations). On the other hand, the design/optimisation strategy must be able to find a solution when the problem is formulated in the most general sense and when the full set of design variables, involved at different scales, is considered. In order to attain this ambitious goal, the formalisation of new models (or the generalisation of the existing ones) is of capital importance: the problem formulation must be as general as possible and the useless simplifying hypotheses should be totally (or partially) rejected. Of course, the price to pay is an increased problem complexity. This HDR manuscript represents a synthesis of my research activities since September 2013 which are essentially framed into the previous background. This document briefly present my contribution to the development of suitable design strategies for the optimisation of lightweight structures. The work is articulated into four main research axes: - the development of new numerical methods (meta-heuristics) for the resolution of optimisation problems characterised by a variable number of design variables (e.g. the optimisation of modular structures); - the formulation of high-order shear deformation theories based on tensor invariants (for plates and shells) and the development of a multi-scale optimisation strategy for designing unconventional constant stiffness and variable stiffness composites (manufactured through the AFP process); - the development of a new topology optimisation method based on both NURBS hyper-surfaces and density-based schemes (well suited for parts manufactured by ALM technologies); - the development of a general (i.e. problem-independent) optimisation strategy for inverse problems. The effectiveness of these methods has been proven (for each topic) through benchmarks taken from the literature and by means of real-world engineering problems as well. Starting from these encouraging results, some general and meaningful perspectives on both new design/optimisation strategies and new manufacturing process for producing hybrid anisotropic structures (of complex topology) are given at the end of the manuscript. http://hdl.handle.net/10985/19269 Multi-scale optimisation of thin-walled structures by considering a global/local modelling approach IZZI, Michele Iacopo; MONTEMURRO, Marco; CATAPANO, Anita; FANTERIA, Daniele; PAILHES, Jerome In this work, a design strategy for optimising thin-walled structures based on a global-local finite element (FE) modelling approach is presented. The preliminary design of thin-walled structures can be stated in the form of a constrained non-linear programming problem (CNLPP) involving requirements of different nature intervening at the different scales of the structure. The proposed multi-scale optimisation (MSO) strategy is characterised by two main features. Firstly, the CNLPP is formulated in the most general sense by including all design variables involved at each pertinent scale of the problem. Secondly, two scales (with the related design requirements) are considered: i) the structure macroscopic scale, where low-fidelity FE models are used; ii) the structure mesoscopic scale (or component-level), where more accurate FE models are involved. In particular, the mechanical responses of the structure are evaluated at both global and local scales, avoiding the use of approximated analytical methods. The MSO is here applied to the least-weight design of an aluminium fuselage barrel of a wide-body aircraft. Fully parametric global and local FE models are interfaced with an in-house metaheuristic algorithm. Refined local FE models are created only for critical regions of the structure, automatically detected during the global analysis, and linked to the global one thanks to the implementation of a sub-modelling approach. The whole process is completely automated and, once set, it does not need any further user intervention. Wed, 01 Jan 2020 00:00:00 GMT http://hdl.handle.net/10985/19269 2020-01-01T00:00:00Z IZZI, Michele Iacopo MONTEMURRO, Marco CATAPANO, Anita FANTERIA, Daniele PAILHES, Jerome In this work, a design strategy for optimising thin-walled structures based on a global-local finite element (FE) modelling approach is presented. The preliminary design of thin-walled structures can be stated in the form of a constrained non-linear programming problem (CNLPP) involving requirements of different nature intervening at the different scales of the structure. The proposed multi-scale optimisation (MSO) strategy is characterised by two main features. Firstly, the CNLPP is formulated in the most general sense by including all design variables involved at each pertinent scale of the problem. Secondly, two scales (with the related design requirements) are considered: i) the structure macroscopic scale, where low-fidelity FE models are used; ii) the structure mesoscopic scale (or component-level), where more accurate FE models are involved. In particular, the mechanical responses of the structure are evaluated at both global and local scales, avoiding the use of approximated analytical methods. The MSO is here applied to the least-weight design of an aluminium fuselage barrel of a wide-body aircraft. Fully parametric global and local FE models are interfaced with an in-house metaheuristic algorithm. Refined local FE models are created only for critical regions of the structure, automatically detected during the global analysis, and linked to the global one thanks to the implementation of a sub-modelling approach. The whole process is completely automated and, once set, it does not need any further user intervention. http://hdl.handle.net/10985/17205 Characterisation of composite elastic properties by means of a multi-scale two-level inverse approach CAPPELLI, Lorenzo; GUILLAUMAT, Laurent; MONTEMURRO, Marco; DAU, Frédéric This work deals with the problem of characterising the elastic properties of a composite material at both me- soscopic (ply-level) and microscopic (constitutive phases-level) scales. This goal is attained by means of an adequate multi-scale identification strategy (MSIS) which aims at identifying the constitutive properties, at each relevant scale, by exploiting the information restrained in the macroscopic dynamic response of the composite. In this background, the multi-scale identification problem is split into two interdependent sub-problems which are stated, at both levels, as constrained minimisation problems. At the first level the goal is the characterisation of the lamina properties by minimising the distance between the numerical and the reference harmonic re- sponses of the composite. The second level problem aims at identifying the elastic properties of both fibre and matrix by minimising the distance between the effective elastic properties evaluated through a homogenisation process and those provided by the first-level inverse problem. The MSIS is based on a special global hybrid optimisation tool and on the strain energy homogenisation method of periodic media. Its effectiveness is proven through a meaningful benchmark. Mon, 01 Jan 2018 00:00:00 GMT http://hdl.handle.net/10985/17205 2018-01-01T00:00:00Z CAPPELLI, Lorenzo GUILLAUMAT, Laurent MONTEMURRO, Marco DAU, Frédéric This work deals with the problem of characterising the elastic properties of a composite material at both me- soscopic (ply-level) and microscopic (constitutive phases-level) scales. This goal is attained by means of an adequate multi-scale identification strategy (MSIS) which aims at identifying the constitutive properties, at each relevant scale, by exploiting the information restrained in the macroscopic dynamic response of the composite. In this background, the multi-scale identification problem is split into two interdependent sub-problems which are stated, at both levels, as constrained minimisation problems. At the first level the goal is the characterisation of the lamina properties by minimising the distance between the numerical and the reference harmonic re- sponses of the composite. The second level problem aims at identifying the elastic properties of both fibre and matrix by minimising the distance between the effective elastic properties evaluated through a homogenisation process and those provided by the first-level inverse problem. The MSIS is based on a special global hybrid optimisation tool and on the strain energy homogenisation method of periodic media. Its effectiveness is proven through a meaningful benchmark. http://hdl.handle.net/10985/17330 A 2D topology optimisation algorithm in NURBS framework with geometric constraints COSTA, Giulio; MONTEMURRO, Marco; PAILHES, Jerome In this paper, the Solid Isotropic Material with Penalisation (SIMP) method for Topology Optimisation (TO) of 2D problems is reformulated in the Non-Uniform Rational BSpline (NURBS) framework. This choice implies several advantages, such as the definition of an implicit filter zone and the possibility for the designer to get a geometric entity at the end of the optimisation process. Therefore, important facilities are provided in CAD postprocessing phases in order to retrieve a consistent and well connected final topology. The effect of the main NURBS parameters (degrees, control points, weights and knot-vector components) on the final optimum topology is investigated. Classic geometric constraints, as the minimum and the maximum member size have been integrated and reformulated according to the NURBS formalism. Furthermore, a new constraint on the local curvature radius has been developed thanks to the NURBS formalism and properties. The effectiveness and the robustness of the proposed method are tested and proven through some benchmarks taken from literature and the results are compared with those provided by the classical SIMP approach. Sun, 01 Jan 2017 00:00:00 GMT http://hdl.handle.net/10985/17330 2017-01-01T00:00:00Z COSTA, Giulio MONTEMURRO, Marco PAILHES, Jerome In this paper, the Solid Isotropic Material with Penalisation (SIMP) method for Topology Optimisation (TO) of 2D problems is reformulated in the Non-Uniform Rational BSpline (NURBS) framework. This choice implies several advantages, such as the definition of an implicit filter zone and the possibility for the designer to get a geometric entity at the end of the optimisation process. Therefore, important facilities are provided in CAD postprocessing phases in order to retrieve a consistent and well connected final topology. The effect of the main NURBS parameters (degrees, control points, weights and knot-vector components) on the final optimum topology is investigated. Classic geometric constraints, as the minimum and the maximum member size have been integrated and reformulated according to the NURBS formalism. Furthermore, a new constraint on the local curvature radius has been developed thanks to the NURBS formalism and properties. The effectiveness and the robustness of the proposed method are tested and proven through some benchmarks taken from literature and the results are compared with those provided by the classical SIMP approach. http://hdl.handle.net/10985/17338 A general multi-scale two-level optimisation strategy for designing composite stiffened panels MONTEMURRO, Marco; PAGANI, Alfonso; FIORDILINO, Giacinto Alberto; PAILHES, Jerome; CARRERA, Erasmo This work deals with the problem of the least-weight design of a composite stiffened panel subject to constraints of different nature (mechanical, geometrical and manufacturability requirements). To face this problem, a multi-scale two-level (MS2L) design methodology is proposed. This approach aims at optimising simultaneously both geometrical and mechanical parameters for skin and stiffeners at each characteristic scale (mesoscopic and macroscopic ones). In this background, at the first level (macroscopic scale) the goal is to find the optimum value of geometric and mechanical design variables of the panel minimising its mass and meeting the set of imposed constraints. The second-level problem focuses on the laminate mesoscopic scale and aims at finding at least one stacking sequence (for each laminate composing the panel) meeting the geometrical and material parameters provided by the first-level problem. The MS2L optimisation approach is based on the polar formalism to describe the macroscopic behaviour of the composites and on a special genetic algorithm to perform optimisation calculations. The quality of the optimum configurations is investigated, a posteriori, through a refined finite element model of the stiffened panel making use of elements with different kinematics and accuracy in the framework of the Carrera's Unified Formulation (CUF). Mon, 01 Jan 2018 00:00:00 GMT http://hdl.handle.net/10985/17338 2018-01-01T00:00:00Z MONTEMURRO, Marco PAGANI, Alfonso FIORDILINO, Giacinto Alberto PAILHES, Jerome CARRERA, Erasmo This work deals with the problem of the least-weight design of a composite stiffened panel subject to constraints of different nature (mechanical, geometrical and manufacturability requirements). To face this problem, a multi-scale two-level (MS2L) design methodology is proposed. This approach aims at optimising simultaneously both geometrical and mechanical parameters for skin and stiffeners at each characteristic scale (mesoscopic and macroscopic ones). In this background, at the first level (macroscopic scale) the goal is to find the optimum value of geometric and mechanical design variables of the panel minimising its mass and meeting the set of imposed constraints. The second-level problem focuses on the laminate mesoscopic scale and aims at finding at least one stacking sequence (for each laminate composing the panel) meeting the geometrical and material parameters provided by the first-level problem. The MS2L optimisation approach is based on the polar formalism to describe the macroscopic behaviour of the composites and on a special genetic algorithm to perform optimisation calculations. The quality of the optimum configurations is investigated, a posteriori, through a refined finite element model of the stiffened panel making use of elements with different kinematics and accuracy in the framework of the Carrera's Unified Formulation (CUF). http://hdl.handle.net/10985/16436 Determination of the effective thermoelastic properties of cork-based agglomerates DELUCIA, Marco; CATAPANO, Anita; MONTEMURRO, Marco; PAILHES, Jerome In this paper, a general numerical homogenisation scheme coupled with an efficient modelling strategy for predicting the effective thermoelastic properties of cork-based agglomerates is presented. In order to generate a realistic representation of the geometry and distribution of particles for the representative volume element (RVE) of the agglomerate at the mesoscopic scale, a general parametric model based on the Voronoi’s tesselation (VT) has been developed. However, the classical algorithm for VT has been enhanced by adding a full parametrization of the RVE. The grains composing the RVE are generated by considering the full set of design variables involved at this scale, i.e. the material properties of the constitutive phases (grains and matrix) and the main geometric parameters related to the grain (volume fraction, average diameter, geometric and material orientations). Numerical results show that the macroscopic effective thermoelastic properties of the cork-based agglomerate are strongly affected by the previous parameters in perfect agreement with experimental results available in literature. Tue, 01 Jan 2019 00:00:00 GMT http://hdl.handle.net/10985/16436 2019-01-01T00:00:00Z DELUCIA, Marco CATAPANO, Anita MONTEMURRO, Marco PAILHES, Jerome In this paper, a general numerical homogenisation scheme coupled with an efficient modelling strategy for predicting the effective thermoelastic properties of cork-based agglomerates is presented. In order to generate a realistic representation of the geometry and distribution of particles for the representative volume element (RVE) of the agglomerate at the mesoscopic scale, a general parametric model based on the Voronoi’s tesselation (VT) has been developed. However, the classical algorithm for VT has been enhanced by adding a full parametrization of the RVE. The grains composing the RVE are generated by considering the full set of design variables involved at this scale, i.e. the material properties of the constitutive phases (grains and matrix) and the main geometric parameters related to the grain (volume fraction, average diameter, geometric and material orientations). Numerical results show that the macroscopic effective thermoelastic properties of the cork-based agglomerate are strongly affected by the previous parameters in perfect agreement with experimental results available in literature. http://hdl.handle.net/10985/17334 Quasi-trivial stacking sequences for the design of thick laminates GARULLI, Torquato; CATAPANO, Anita; MONTEMURRO, Marco; JUMEL, Julien; FANTERIA, Daniele Quasi-trivial (QT) sequences have largely proven to be an extremely powerful tool in the design and optimisation of composites laminates. In this paper new interesting properties of this class of stacks are derived. These properties allow to obtain QT sequences by superposing (according to some prescribed rules) any number of QT elementary stacks. In this way, QT solutions with arbitrary large number of plies can be readily obtained, overcoming the computational issues arising in the search of QT solutions with huge number of layers. Moreover, a general version of the combinatorial algorithm to find QT stacks is proposed in this work. It is also proven that the previous estimation of the number of QT solutions, for a given number of plies and saturated groups, is not correct because a larger number of solutions has been found in this study. Mon, 01 Jan 2018 00:00:00 GMT http://hdl.handle.net/10985/17334 2018-01-01T00:00:00Z GARULLI, Torquato CATAPANO, Anita MONTEMURRO, Marco JUMEL, Julien FANTERIA, Daniele Quasi-trivial (QT) sequences have largely proven to be an extremely powerful tool in the design and optimisation of composites laminates. In this paper new interesting properties of this class of stacks are derived. These properties allow to obtain QT sequences by superposing (according to some prescribed rules) any number of QT elementary stacks. In this way, QT solutions with arbitrary large number of plies can be readily obtained, overcoming the computational issues arising in the search of QT solutions with huge number of layers. Moreover, a general version of the combinatorial algorithm to find QT stacks is proposed in this work. It is also proven that the previous estimation of the number of QT solutions, for a given number of plies and saturated groups, is not correct because a larger number of solutions has been found in this study. 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, Jerome 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 GMT http://hdl.handle.net/10985/16435 2019-01-01T00:00:00Z DELUCIA, Marco CATAPANO, Anita MONTEMURRO, Marco PAILHES, Jerome 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.