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Additive manufacturing of ceramics offers several advantages over traditional manufacturing methods which include design flexibility, reduced material waste, reduced manufacturing complexity, and the possibility for faster prototyping and production. Despite the growing interests in additively manufactured ceramics (AMCs), their stress state and strain-rate dependent behavior is still not fully understood. This is a significant challenge, as the use of AMCs under complex loading and high strain rate conditions requires a detailed understanding of the underlying mechanisms governing their mechanical behavior and fracture. This study presents a comprehensive look at AMCs focusing on their behaviour under complex loading and high strain rate conditions taking into account: (i) the additive manufacturing techniques and related parameters such as applicability to different ceramic materials, temperature, pressure, sintering, surface finishing, and potential for defects, (ii) experimental characterization using different specimen geometries such as compression, shear compression, indirect tension, and semi-circular under quasi static and dynamic (using a split-Hopkinson Pressure Bar) loading, (iii) evaluation and benchmarking versus ceramics made by traditional methods which includes characterization at microstructure level using EBSD, SEM, and TEM, and comparison of macroscale mechanical properties, and (iv) development of multi-scale numerical models incorporating relevant physics and microstructural features, informed by the experiments at each scale. The simulations are aimed at integrating the information obtained from lower scales (mesocale simulations at grain level and molecular dynamic simulations) to develop more accurate and informed macroscale numerical frameworks. Models also allow for the evaluation of additive manufacturing techniques by considering material orientation, grain size, and porosity on the behavior of the printed ceramic at different, Résumé de la communication présentée lors du congrès international tenu conjointement par Canadian Society for Mechanical Engineering (CSME) et Computational Fluid Dynamics Society of Canada (CFD Canada), à l’Université de Sherbrooke (Québec), du 28 au 31 mai 2023.

A hybrid finite-discrete element model (HFDEM) coupled with Brazilian disk experiments was applied to study the mode I tensile opening failure of an alumina ceramic. In the HFDEM, a phenomenological rate-dependent cohesive law is developed to simulate the crack nucleation, propagation, and fragmentation processes, and tetrahedral elastic elements were used to represent the intact material without flaws. This model also implicitly considered the Weibull distribution of the flaws inside the material by Monte Carlo simulations while modeling processes of crack interactions and coalescence, and predicted the macroscopic variability in failure strength. The proposed model was evaluated by comparing the numerical strain-rate-dependent mode I tensile opening failure process to the Brazilian disk experiments. The simulation results demonstrated that the proposed method could predict the mechanical response of the alumina ceramic under indirect tensile loading. Once validated, this model was applied to explore the mechanism of “overestimation of the tensile strength” and “underestimation of the tensile strength” phenomena in the Brazilian tests. Overall, this study provides an improved qualitative (e.g., fracture and fragmentation behaviour) and quantitative (e.g., stress-strain response) understanding of the alumina ceramic under strain-rate-dependent tensile loading and provides a new insight for the Brazilian tests., Résumé de la communication présentée lors du congrès international tenu conjointement par Canadian Society for Mechanical Engineering (CSME) et Computational Fluid Dynamics Society of Canada (CFD Canada), à l’Université de Sherbrooke (Québec), du 28 au 31 mai 2023.

Advanced ceramics, such as boron carbide, exhibit high strength, abrasion resistance, chemical and thermal stability, and low density making them candidate material for extreme condition applications like body armour, wear-resistant components, and cutting tools. However, the microstructures that initiate these properties are often complex and not fully understood, since they have features at multiple length scales. A major challenge in understanding the relationship between microstructure and properties is the availability and deficiencies of current interatomic potentials used in molecular dynamics (MD) simulations. Additionally, the complex lattice structure of boron carbide consisting of a 12-atom icosahedral cage surrounding a 3-atom linear chain along the (111) rhombohedral axis is challenging to equilibrate due to the covalent bonds between the atoms. Moreover, the small difference between the atomic number of boron and carbon causes the precise composition and distribution of carbon atoms difficult to measure, and this chemical similarity induces substitutional disorder. Improving the accuracy of potentials will facilitate more efficient studies of the effects of different microstructures on material properties and accelerate the development of new ceramics with enhanced properties. Building on these considerations, this research employs machine-learning-based (ML) methods to develop more accurate potentials for advanced ceramics that can capture complex microstructural dynamics relevant to material failure. ML potentials can provide more precise results compared to the traditional potentials since they benefit from high-dimensional representation of underlying potential energy surfaces (PES). ML potentials are composed of three parts: 1. an initial dataset including the energy, force and stress of structures, 2. the descriptor vector defining the atomistic configurations, and 3. numerical regression that maps the initial dataset to the PES. In thi, Résumé de la communication présentée lors du congrès international tenu conjointement par Canadian Society for Mechanical Engineering (CSME) et Computational Fluid Dynamics Society of Canada (CFD Canada), à l’Université de Sherbrooke (Québec), du 28 au 31 mai 2023.

This presentation focuses on the development of a multi-scale hybrid finite element model for composite laminates used as a front and backing layer of a protection system in land armor vehicles. Laminated composites are widely used for impact resistance, energy absorption, stiffness, and structural integrity. A unidirectional carbon fiber reinforced polymer composite laminate is simulated using the MAT_ENHANCED_COMPOSITE_DAMAGE material model in the LS-Dyna® finite element software. The composite model consists of a sub-scaled volume around the impact zone of the protective armor layer, with the remaining areas being a macro-scale homogenous component. The calibrated material model is integrated with other materials to form a structuralscale model that also includes alumina hexagonal tiles and a steel plate which are bonded to the composite layers using a polyurethane adhesive interlayer. Once integrated, this system-scale model is simulated under high-velocity long rod impacts and calibrated with experiments. Overall, this work will give insights towards understanding the influence of the composite layers on the protection system performance and damage propagation through the different layers of the model, which will help in designing improved systems., Résumé de la communication présentée lors du congrès international tenu conjointement par Canadian Society for Mechanical Engineering (CSME) et Computational Fluid Dynamics Society of Canada (CFD Canada), à l’Université de Sherbrooke (Québec), du 28 au 31 mai 2023.

Numerical modeling approaches become effective engineering techniques in the field of structural-scale designs of armor systems under dynamic impact loading and a suitable material model enables to accurately reproduce experiments and investigate impactrelated phenomena (i.e., change of mechanisms). In this study, the Generalized Incremental Stress-State dependent damage MOdel (GISSMO) is applied to explore the dynamic failure and fracture of Armox 500T steel under high-velocity ballistic impact by a longrod projectile in LS-DYNA explicit solver. The Johnson-Cook model is used to describe the behavior of the tungsten heavy alloy projectile and the GISSMO is employed to describe the stress state- and strain rate-fracture behavior of Armox 500T steel target. Here, the GISSMO for Armox 500T is validated and the Johnson-Cook model for tungsten heavy alloy is calibrated against ballistic impact experiments involving depth of penetration measurements on stacked Armox 500T plates. Once validated, the model is used to explore designs of new steel-based armor system configurations for various impact conditions (i.e., impact angle of obliquity, standoff distance, and target span). This work is in collaboration with Defence Research and Development Canada, General Dynamics Land Systems - Canada (GDLS-C), and NP Aerospace., Résumé de la communication présentée lors du congrès international tenu conjointement par Canadian Society for Mechanical Engineering (CSME) et Computational Fluid Dynamics Society of Canada (CFD Canada), à l’Université de Sherbrooke (Québec), du 28 au 31 mai 2023.

Molecular dynamics simulation has been widely used for the research about the fracture behavior of brittle materials. The ceramics of alpha-alumina can also be explored based on this method for the atomic deformation changes under specific loadings. The alumina structures are constructed and validated with theoretical atomic structures first by some typical parameters such as the lattice parameters, and then the validated potential for this material is shown with some material constant such as Young’s modulus, shear modulus and bulk modulus which are from experimental and simulation results. The stress intensity factor of the material is an important parameter to determine the fracture behavior for brittle materials which will be calculated in this paper under the typical loading conditions according to the fracture mechanics. The fracture surface energy of the single-crystal alumina models is also calculated and then used for the calculation of the fracture toughness (KIC) for comparison with the simulation results from theoretical equations and the experimental data. Along this routine, the ultimate fracture strength has been found to be increasing from 44.2 ± 2.6 GPa to 49.5 ± 3.1 GPa with the increase of tension loading rates from 109/s to 1011/s along X-[100] crystal direction, and fracture toughness of alpha-alumina atomic models has been found to be decreasing from 4.22 ± 0.16 MPa(m^1/2) to 3.26 ± 0.18 MPa(m^1/2) with the increasing tension loading rate from 109/s to 1011/s. Other parameters such as stiffness have the similar trends with the fracture strength and fracture toughness. These typical parameters of fracture trends of alpha-alumina models have been explored under the changes of tension loading rate, which can help bridge the microscale modelling of brittle material with the higher-scale experiments., Résumé de la communication présentée lors du congrès international tenu conjointement par Canadian Society for Mechanical Engineering (CSME) et Computational Fluid Dynamics Society of Canada (CFD Canada), à l’Université de Sherbrooke (Québec), du 28 au 31 mai 2023.

The failure behavior of Al-Al2O3 composites additively manufactured by cold spray technology is computationally investigated using 3D microstructure-based physically-informed finite element (FE) models. To inform the model, the microstructural features, including porosity, particle size and content were captured by scanning electron microscope (SEM) images. Representative volume elements (RVEs) were generated by using Digimat software based on microstructural inputs. For the Al metal matrix and the Al2O3 reinforcing particles, stress-state-dependent constitutive material models were incorporated into the RVEs by using VUMAT subroutines in Abaqus/Explicit FE solver. The micromechanical model was validated by the experimental stress-strain curves and the failure mechanisms observed in the SEM images. The microscale failure mechanisms, including matrix/particle debonding, particle cracking, and matrix ductile failure was quantified based on the fraction of fully debonded interfacial nodes, fraction of cracked particles, and the crack volume fraction, respectively, by using Python scripting in Abaqus. The validated model was leveraged to study the effect of Al2O3 particle size and weight fraction, and the stress state on the material behavior. Our analysis based on the quantification of damage mechanisms revealed that the sequence of the activation of failure mechanisms is consistent across different stress states: I. matrix/particle debonding, II. particle cracking, and III. matrix ductile failure. Altogether, the present work provides a better understanding of the evolution of failure in the material and this has implications for the design and improvement of the material. Additionally, our quantitative damage analysis lays the foundation for developing micromechanismbased constitutive models for cold-sprayed additively manufactured metal-ceramic materials in the future., Résumé de la communication présentée lors du congrès international tenu conjointement par Canadian Society for Mechanical Engineering (CSME) et Computational Fluid Dynamics Society of Canada (CFD Canada), à l’Université de Sherbrooke (Québec), du 28 au 31 mai 2023.