Keynote Lectures

The interpenetrating composites (IPCs) are built up of a ceramic skeleton and metallic matrix, which fills the ceramic foam under pressure and high temperature. The specific examples of IPCs analysed in the paper are made of the ceramic skeleton - SiC or Al2O3 - which is a brittle material, whereas the matrix is created by AlSi12 alloy – elasto-plastic material. Both phases of IPCs are crushable and their degradations under the loading are subjected to two different damaging processes. The ceramic foams are brittle throughout the loading process, but the AlSi12 alloy is brittle during the elastic phase; then, its behaviour becomes viscous-plastic. The presentation concerns the experimental testing and simulations of the impact and fragmentation of metal matrix composite - AlSi12/(SiC or Al2O3). The microstructure of the composite is complex and consists of a metallic phase (85%), ceramic skeleton, porosity, and a system of imperfect interfaces. The presented data-driven micromechanical numerical model is based on micro-CT scanning of composite material to get information about the internal structure and the assessment of local thermo-mechanical properties done by Alemnis observations under SEM at nanoscale or microscale using nano- or microindetation technique. The description of the dynamic response of IPCs by impact is investigated in a few scenarios. The exemplary scenario is realised by imposing the initial conditions on the sample that hits a hard elastic barrier. The second one corresponds to SHPB experiments. The last one is the hitting of an elastic impactor against the sample. The influence of the impact velocities and material parameters of the phases on the failure modes is observed. Previously, analyses of the modes of loading application on the micromechanical failure of metal matrix composite were analysed in [1, 2]. An analysis of the empty SiC scaffolds is presented in [3]. The proposed finite element model of the AlSi12/SiC composite behaviour describing gradual degradation under impact loading was tested for different impact scenarios. In all cases, the damage growth in the composite is very realistic. These results conclude that the proposed finite element model is very effective. Acknowledgement The results presented in this paper were obtained within the framework of research grant No. 2019/33/B/ST8/01263 financed by the National Science Centre, Poland. Numerical analyses: PLGRID facilities - ICM UW Warsaw, CI TASK in Gdańsk, CYFRONET, Kraków and LUMI in Kajaani (Finland). References [1] Postek, E. and Sadowski, T. Distributed microcracking process of WC/Co cermet under dynamic impulse compressive loading. Compos. Struct. (2018) 194: 494-508. [2] Postek, E. and Sadowski, T. Qualitative comparison of dynamic compressive pressure load and impact of WC/Co composite. Int. J. Refract. Hard. Met. (2018) 77: 68-81. [3] Postek, E., Sadowski, T. and Bieniaś, J. Simulation of impact and fragmentation of SiC skeleton, Phys. Letters (2021) 24:578-587.

We discuss propagation of surface and interfacial waves in elastic and viscoelastic media possessing surface stresses and surface energy. Nowadays mechanics of media with surface stresses found various applications at small scales as well as at macroscales. The discussed class of models describes of coupled deformations of solids with thin coatings or interface layers. In particular, surface stresses could be responsible for size-effects observed at the nanoscale. With the lecture we discuss a series of boundary-value problems for antiplane motions, see [1-7] for details. These problems illustrate the influence of surface stresses. For example, antiplane surface waves exist in an elastic half-space only if one takes into account surface kinetic energy and surface strain energy in addition to classic constitutive equations in the bulk. Here we discussed the propagation of antiplane waves in an elastic half-space, in an elastic strip perfectly or non-perfectly attached to a half-space. Transverse waves are also studied in an elastic cylinder. Dispersion curves were obtained and analysed. In particular, it was shown that surface waves related to surface stresses propagate with lower speed than others. Finally, viscosity effects were analysed. We demonstrated that even small dissipation essentially changes the behaviour of dispersion curves and the decay with the depth. This is more pronounced for relatively large values of a wave frequency. This work has been supported by the project ``Metamaterials design and synthesis with applications to infrastructure engineering'' funded by the MUR Progetti di Ricerca di Rilevante Interesse Nazionale (PRIN) Bando 2022 - grant 20228CPHN5, Italy. 1. Eremeyev, V.A., Rosi, G. and Naili, S., 2016. Surface/interfacial anti-plane waves in solids with surface energy. Mechanics Research Communications, 74, 8-13. 2. Eremeyev, V.A., Rosi, G. and Naili, S., 2019. Comparison of anti-plane surface waves in strain-gradient materials and materials with surface stresses. Mathematics and mechanics of solids, 24(8), p 2526-2535. 3. Eremeyev, V.A. and Sharma, B.L., 2019. Anti-plane surface waves in media with surface structure: Discrete vs. continuum model. International Journal of Engineering Science, 143, 33-38. 4. Eremeyev, V.A., Rosi, G. and Naili, S., 2020. Transverse surface waves on a cylindrical surface with coating. International Journal of Engineering Science, 147, 103188. 5. Mikhasev, G.I., Botogova, M.G. and Eremeyev, V.A., 2022. Anti-plane waves in an elastic thin strip with surface energy. Philosophical Transactions of the Royal Society A, 380(2231), 20210373. 6. Mikhasev, G., Erbaş, B. and Eremeyev, V.A., 2023. Anti-plane shear waves in an elastic strip rigidly attached to an elastic half-space. International Journal of Engineering Science, 184, 103809. 7. Eremeyev, V.A., 2024. Surface finite viscoelasticity and surface anti-plane waves. International Journal of Engineering Science, 196, 104029.

Bypassing constitutive modeling, the distance-minimizing data-driven computational mechanics has its potential in the modeling and simulation of advanced composite materials and structures. However, the numerous distance calculations between constitutive database and conservation law are extremely heavy in high-dimensional cases, and often consume most of the computational resources. Here, we propose a quantum computing enhanced data-driven framework, where the distance calculation tasks are assigned to a quantum computer. Compared to the classical computing, the use of quantum computing allows to achieve an exponential reduction in computational complexity. This framework has been validated not only on a quantum simulator but also on a real superconducting quantum computer. Furthermore, to address the quantum hardware noise issue, an error mitigation technique is implemented to improve the accuracy of quantum computing. We believe this work represents a promising step towards using the power of quantum computing in the field of composite materials and structures.

It is well known that mechanical stimulation directly affects and controls cell and tissue development in the fractured bones in terms of mechano-regulation theories which correlate mechanical stimuli and bone healing. There are many different types of mechano-regulation algorithms which use different types of mechanical stimuli such as principal strain, fluid velocity, deviatoric strains and so on. External load types and prostheses type may change mechanical condition at the fracture site especially in calluses where the cells and tissues and this controls developing pathways and consequently determines cell and tissue phenotypes. Consequently, flexible composite prostheses may generate appropriate strains which provides positive effect on cell development relative to the high stiffness metal prostheses. The healing performance was compared with according to the prostheses stiffness by using finite element analysis. As a result, it was found if we can find the most appropriate mechanical condition provided by flexible composite prostheses we can accelerate bone healing and also we can use this information for the design of orthopadic implant and orthoses for rehabilitation after bone fracture healing. To accomplish the actual bone healing process modeling of cell’s whole life including cell migration, differentiation and bone resorption, callus configuration and biphasic mechano-regulation algorithm which uses deviatoric strain and fluid velocity as mechanical stimuli were implemented in the finite element analysis. Moreover, devices like orthoses for helping rehabilitation of the healed bones can be designed by using this bone healing simulation technique and this system can precisely detect forces and strains around the fracture site for better healing.

Fiber Reinforced Cementitious Matrix FRCM composites represent a relatively new strengthening technology suitable especially for the reinforcement of masonry, that has gained traction in the last two decades in substitution of the more consolidated external retrofitting with FRP (Fiber Reinforced Polymer). The utilization of an inorganic matrix is probably the main difference with FRP, where the fiber is glued to the substrate with a polymeric adhesive. When compared with FRP, it has many advantages, such as a better compatibility with the substrate, vapor permeability, reversibility. The mechanical performance to debonding is obviously lower, but still adequate to obtain a good seismic upgrading of existing masonry. It is used in particular to reinforced arches and double curvature vaults, because of their reversibility. The experimental literature available for FRCM is nowadays quite comprehensive and mainly deals with (i) coupon and (ii) debonding tests, or (iii) experimentation on entire structural elements (shear walls, arches, vaults). On the contrary, the analytical and numerical counterpart appears still patchy. The aim of the keynote speech is therefore to review and classify what already exists in the field of advanced analytical and numerical modelling for FRCM composites applied to brittle substrates, and to investigate the near future possible developments. Some analytical and semi-analytical approaches will be reviewed when applied in a variety of laboratory experimentation, including coupons and shear tests carried out on FRCM bonded to flat and curved substrates. In the study of such examples, attention will focus on different numerically efficient strategies used to predict the global and local behavior of the FRCM components at progressively increased external loads. A particular insight will be provided for (i) the recursive utilization of the elastic solution when sawtooth constitutive laws for matrix and interfaces are assumed and for (ii) multi-dimensional shooting numerical algorithms generalized to systems of ordinary differential equations. Having clear in mind the limits of applicability of the aforementioned approaches, the keynote will then introduce a new simple truss finite element with 16th degrees of freedom. The finite element is a two-node assemblage of three trusses representing matrix and fiber layers. The interfaces between the layers are modeled with shear and normal springs lumped at the nodes, mutually connecting contiguous trusses and the inner matrix to the substrate. The degrees of freedom, 8 per node, are the longitudinal and transversal displacements of the three layers and of the substrate, evaluated at the nodes. The particularly appealing simplicity and the direct possibility of implementation within already existing FE software dedicated to the advanced analysis of masonry, allows to study the behavior of large-scale structures reinforced with FRCM at a fraction of the computational burden required by a heterogeneous discretization of the reinforcing package. The keynote will end with real scale applications, which include reinforced arches, vaults and in- and out-of-plane loaded panels.

The use of composite materials, particularly fiber reinforced plastics (FRC), is experiencing rapid growth, driven by increasing demand across various industries such as aerospace, automotive, nautical, and wind energy. These materials, known for their high stiffness-to- weight and strength-to-weight ratios, offer significant performance advantages over traditional materials like metals. However, the rapid expansion in the use of composites highlights a critical environmental issue: their recyclability. FRC are generally composed of synthetic fibers embedded in a thermoset matrix, creating a material that is challenging to disassemble and recycle efficiently. This limitation poses significant environmental concerns, as the disposal of composite materials typically results in landfill accumulation or incineration, contributing to pollution and resource depletion. Northern Light Composites, a clean-tech company founded in 2019, is dedicated to making composites more sustainable. NLcomp has developed rComposite, a recyclable composite material that addresses the end- of-life issues of fiberglass and has a lower impact than traditional composites due to the use of thermoplastic resin and natural and recycled fibers. To validate rComposite, NLcomp has built sailing boats, the most notable of which is "ecoracer," a vessel that has won the Italian Championship and numerous international awards.

The mechanical behaviour of materials endowed with specific microstructure, characterized by complex non-linear behaviour and complex internal sub-structure (micro), strongly depends on their microstructural features. In particular, in the modelling of these materials, such as particle composites, polycrystals with thin or thick interfaces, rock or masonry-like materials and materials with random microstructure, the discrete and heterogeneous nature of the matter must be taken into account because interfaces and/or material internal phases dominate the gross behaviour. This is well established. What is not completely recognized, however, is the possibility of preserving the memory of the microstructure and the presence of material length scales without resorting to discrete modelling, which can often be cumbersome, in terms of non-local continuum descriptions. For materials made of particles of prominent size and/or strongly anisotropic media, lacking in material internal scale parameters and the possibility of accounting for non-symmetries in strains and stresses, the classical Cauchy continuum (Grade 1) does not always seem appropriate for describing the macroscopic behaviour, taking into account the size, orientation, and disposition of the micro-heterogeneities. This necessitates non-classical continuum descriptions [1-3], which can be obtained through multiscale approaches aimed at deducing properties and relations by bridging information at proper underlying sub-levels via energy equivalence criteria. Within such multiscale modelling, the non-local character of the description is crucial for avoiding physical inadequacies and theoretical computational problems, particularly in problems where 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 [5]; where implicit non-locality concerns generalized continua with extra degrees of freedom, such as micromorphic continua or continua with configurational forces. This presentation addresses the modelling and homogenisation of composite materials with varied microstructural characteristics as generalised continua. The numerical analyses begin by focusing on composites considered as polycrystals with grain boundaries or thin interfaces, where a periodic microstructure can be recognised. For these materials, discrete continuum homogenization approaches, derived from the molecular theory of elasticity, have proven effective [6, 8]. The investigation then extends to polycrystals with thick interfaces, employing a statistical homogenization procedure [7, 9] applied to a variety of other composite materials, including fibre-reinforced composites, ceramic/metal matrix composites, concrete, ashlar masonry. The nonlinear modelling of ceramic matrix composite materials is also investigated using a novel method that combines the Virtual Element Method (VEM) with non-linear interface Finite Element approach [10], allowing for a more accurate representation of the material's behaviour under different loading conditions. Keywords: Multiscale approaches, non-local continua, micropolar continua, anisotropic media with internal lengths, non-linear behaviour [1] Capriz G. (1989), Continua with Microstructure, Springer-Verlag, New York [2] Eringen, A.C. (1999), Microcontinuum Field Theories, Springer-Verlag, New York [3] Gurtin, M. E. (2000), Configurational Forces as Basis Concept of Continuum Physics, Springer-Verlag, Berlin. [4] Trovalusci P., Ed. (2016), Materials with Internal Structure. Multiscale and Multifield Modeling and Simulation, P. Trovalusci (Ed.), Springer Tracts in Mechanical Engineering, Vol.18:109-131, Springer. [5] Kunin I.A., (1984) On foundations of the theory of elastic media with microstructure. Int. J. Engn. Sci., 22, pp. 969–978 [6] Trovalusci P. (2014), Molecular approaches for multifield continua: origins and current developments. CISM (Int. Centre for Mechanical Sciences) Series, 556: 211-278, Springer. [7] Trovalusci P., M. Ostoja-Starzewski, M.L. De Bellis, A. Murrali (2015), Scale-dependent homogenization of random composites as micropolar Continua, Eur J Mech A / Solids, 49, 396–407, 2015. [8] Leonetti L., Fantuzzi N., Trovalusci P., Tornabene F. (2019), Scale Effects in Orthotropic Composite Assemblies as Micropolar Continua: A Comparison between Weak- and Strong-Form Finite Element Solutions Materials, 12(5), 758. [9] Homogenization of Random Porous Materials with Low-Order Virtual Elements (2019), ASCE-ASME J Risk and Uncert in Engrg Sys Part B, 5(3) [10] Gatta,C; Pingaro A., Addessi D., Trovalusci, P. (2024), A coupled virtual element-interface model for analysis of fracture propagation in polycrystalline composites. Submitted.

The technology and process behind the production of a CFRP structural component has been developed on decades and has reached a well established and common process. The protocols and workflows are nowadays giving high standard and repeatability of the final component: in our business this is shown by the level of repeatability we measure during the structural proof tests of our structural car parts. All the above is always true factory side, then “Here comes the track”. In motorsport the push to minimize the mass of each component is driven to the limit, sometimes falling on the wrong side of the boundary: some damage (crack/disbonding/delamination) might occur during usual running condition or due to misuse loadcases not accounted in design KPI (e.g. wider-than-usual trajectory). When the car return to the garage, it is always checked by mechanics and our reliability engineer and, in case a damage is experienced, it must be fixed somehow for the next run/session. Fixing a structural damage is not always a straightforward operation, especially on a component which must satisfy a defined aerodynamic shape. The time constraint and the garage environment forced us to find quick and dirty – but working! – ways to put in place repair or reinforcement which can ensure the required strength for the next session, meaning this that the damage analysis and definition (and implementation) of the repair must be completed within hours (two hours in case it happens between first and second Free practice). To successfully complete such a task, a garage-based wet layup workflow has been developed through the year, crossing the experience of technologist, mechanics, engineers. This technical session will show the details of this garage-based technology which is giving us the opportunity to run our F1 car reliably after having experienced unexpected damages on structural car components.