ORALS

SESSION: ModellingMonPM2-R8	Trovalusci International Symposium (17th Intl. Symp. on Multiscale & Multiphysics Modelling of 'Complex' Material (MMCM17) )
Mon. 28 Nov. 2022 / Room: Similan 1
Session Chairs: Adnan Ibrahimbegovic; Session Monitor: TBA

15:55: [ModellingMonPM209] OS Plenary
Coarse-graining approaches for complex materials and non classical/non-local local continuum formulations
Patrizia Trovalusci¹ ; ¹Sapienza - University of Rome, Rome, Italy;
Paper Id: 459 [Abstract]

The mechanical behavior of materials endowed with specific microstructure, characterized by complex non-linear behavior and complex internal sub-structure (micro), strongly depends on their microstructural features. In particular, in the modelling of these materials, such as particle composites, that are polycrystals with interfaces or with thin or thick interfaces, as well as rock or masonry-like materials, the discrete and heterogeneous nature of the matter must be taken into account, because interfaces and/or material internal phases dominate the gross behaviour. And this is definitely ascertained. What is not completely recognized instead, is the possibility of preserving memory of the microstructure, and of the presence of material length scales, without resorting to the discrete modelling that can often be cumbersome, in terms of non-local continuum descriptions. In particular, for materials made of particles of prominent size and/or strong anisotropic media, by lacking in material internal scale parameters and in the possibility of accounting non-symmetries in strains and stresses, the classical Cauchy continuum (Grade1) does not always seem appropriate for describing the macroscopic behaviour taking into account the size, the orientation and the disposition of the micro-heterogeneities. This calls for the need of non-classical continuum descriptions [1-3], that can be obtained through multiscale approaches, aimed at deducing properties and relations by bridging information at proper underlying sub-levels via energy equivalence criteria. In the framework of such a multiscale modelling, the non-local character of the description is then crucial for avoiding physical inadequacies and theoretical computational problems. In particular, in problems in which a characteristic internal (material) length is comparable to the macroscopic (structural) length [4]. Among non-local theories, it is useful to distinguish between ‘explicit’ or ‘strong’ and ‘implicit’ or ‘weak’ non-locality [1, 3, 5]; where implicit non-locality concerns generalised continua with extra degrees of freedom, such as micromorphic continua [2] or continua with configurational forces [3]. This talk wants firstly to focus on the origins of multiscale modelling, related to the corpuscular(molecular)-continuous models developed in the 19th century to give explanations ‘per causas’ of elasticity (Cauchy, Voigt, Poincare), in order to find conceptual guidelines for deriving discrete-to scale-dependent continua, that are essentially non-local models with internal length and dispersive properties [5, 6]. Then, a discrete-to-scale dependent continuous formulation, developed for particle composite materials basing on a generalized version of Voigt’s molecular/continuum approach, is proposed. Finally, with the aid of some numerical simulations - concerning ceramic matrix composites (CMC), microcracked media and masonry assemblies – focus will be on the advantages of the micropolar modelling with respect to other generalised continuum formulations [9-12].

References:
[1] Kunin I.A., (1984) Int J Engin Sci, 22, pp. 969–978
[2] Capriz G. (1989), Continua with Microstructure, Springer
[3] Eringen, A.C. (1999), Microcontinuum Field Theories, Springer
[4] Gurtin, M. E. (2000), Configurational Forces as Basis Concept of Continuum Physics, Springer
[5] Trovalusci P., Ed. (2016), Springer Tracts in Mechanical Engineering, 18:109-131, Springer
[6] Trovalusci P., Varano V., Rega G. (2010), J Appl Mech, 77(6):061002/1-11.
[7] Trovalusci P., Pau A. (2014), Acta Mech, 225(1):157-177
[8] Fantuzzi N., Trovalusci P., Dharasura S. (2019), Frontiers, 59 (6):1-11
[9] Settimi, V., Trovalusci P., Rega G. (2019), Cont Mech Thermodyn, 1-18
[10] Tuna M., Trovalusci P. (2020, Mech Res Comm, 103, 103461, 2020
[11] Tuna M., Leonetti L., Trovalusci P., Kirka M. (2020), Meccanica, 55(4), 927-944.
[12] M. Colatosti, F. Shi, N. Fantuzzi, P. Trovalusci (2022), Arch Appl Mech, https://doi.org/10.1007/s00419-022-02142-0

SESSION: ModellingMonPM2-R8	Trovalusci International Symposium (17th Intl. Symp. on Multiscale & Multiphysics Modelling of 'Complex' Material (MMCM17) )
Mon. 28 Nov. 2022 / Room: Similan 1
Session Chairs: Adnan Ibrahimbegovic; Session Monitor: TBA

16:45: [ModellingMonPM211] OS Plenary
Dynamic analysis of Cosserat media for anisotropic homogenized materials
Nicholas Fantuzzi¹ ; Patrizia Trovalusci² ; Marco Colatosti¹ ; ¹University of Bologna, Bologna, Italy; ²Sapienza - University of Rome, Rome, Italy;
Paper Id: 128 [Abstract]

The mechanical behavior of materials with microstructure, such as particle composites, should consider their discontinuous and heterogeneous nature, because interfaces and/or material phases dominate the mechanical behavior. Non-local description is necessary for problems wherein the structural macroscopic scale is comparable with the local microscopic one (see for instance Trovalusci et al. (2017), Tuna et al. (2020), Tuna and Trovalusci (2020)). Non-classical and non-local continuum descriptions can be carried out by multi-scale approaches via energy equivalence criteria, as presented by Trovalusci and Masiani (1999). In this work, anisotropic materials with irregular hexagonal microstructure are considered. This model is capable of accounting for the particle size and orientation, as well as of the asymmetries in strain and stress occurring as a consequence of anisotropy (Fantuzzi et al. (2019a,b)). The present dynamic model is a suitable enrichment of the study presented by Fantuzzi et al. (2019b) where a composite of hexagonal rigid particles interacting through elastic interfaces was derived in a static context. Some paradigmatic cases are discussed, showing how the orientation of the crystal lattice clearly affects the dynamics at the equivalent continuum scale. The reliability of the proposed multiscale strategy is evaluated comparing the results with those provided by finite element simulations.

References:
Fantuzzi, N., Trovalusci, P. and S. Dharasura. Mechanical behavior of anisotropic composite materials as micropolar continua. Frontiers in Materials, 6:59, 2019a. doi: 10.3389/fmats.2019.00059.
Fantuzzi, N., Trovalusci, P. and R. Luciano. Multiscale analysis of anisotropic materials with hexagonal microstructure as micro-polar continua. Journal for Multiscale Computational Engineering, under review, 2019b.
Trovalusci, P., De Bellis, M.L. and R. Masiani. A multiscale description of particle composites: From lattice microstructures to micropolar continua. Composites Part B: Engineering, 128: 64-173, 2017.
Trovalusci, P. and R. Masiani. Material symmetries of micropolar continua equivalent to lattices. International Journal of Solids and Structures, 36(14):2091-2108, 1999.
Tuna, M., Leonetti, L., Trovalusci, P. and Kirca, M. ‘Explicit’ and ‘implicit’ non-local continuous descriptions for a plate with circular inclusion in tension. Meccanica, 55:927–944, 2020
Tuna, M. and Trovalusci, P. Scale dependent continuum approaches for discontinuous assemblies: ‘Explicit’ and ‘implicit’ non-local models. Mechanics Research Communications, 103:103461 (2020)