Brice Bognet

Bio: Brice Bognet is an academic researcher from University of Connecticut. The author has contributed to research in topics: Context (language use) & Discretization. The author has an hindex of 8, co-authored 18 publications receiving 528 citations. Previous affiliations of Brice Bognet include École Centrale Paris & École centrale de Nantes.

Inkjet and inkjet-based 3D printing: connecting fluid properties and printing performance

Abstract: Purpose This paper aims to summarize the latest developments both in terms of theoretical understanding and experimental techniques related to inkjet fluids. The purpose is to provide practitioners a self-contained review of how the performance of inkjet and inkjet-based three-dimensional (3D) printing is fundamentally influenced by the properties of inkjet fluids. Design/methodology/approach This paper is written for practitioners who may not be familiar with the underlying physics of inkjet printing. The paper thus begins with a brief review of basic concepts in inkjet fluid characterization and the relevant dimensionless groups. Then, how drop impact and contact angle affect the footprint and resolution of inkjet printing is reviewed, especially onto powder and fabrics that are relevant to 3D printing and flexible electronics applications. A future outlook is given at the end of this review paper. Findings The jettability of Newtonian fluids is well-studied and has been generalized using a dimensionless Ohnesorge number. However, the inclusion of various functional materials may modify the ink fluid properties, leading to non-Newtonian behavior, such as shear thinning and elasticity. This paper discusses the current understanding of common inkjet fluids, such as particle suspensions, shear-thinning fluids and viscoelastic fluids. Originality/value A number of excellent review papers on the applications of inkjet and inkjet-based 3D printing already exist. This paper focuses on highlighting the current scientific understanding and possible future directions.

First steps towards an advanced simulation of composites manufacturing by automated tape placement

Abstract: Composite materials and their related manufacturing processes involve many modeling and simulation issues, mainly related to their multi-physics and multi-scale nature, to the strong couplings and the complex geometries. In our former works we developed a new paradigm for addressing the solution of such complex models, the so-called Proper Generalized Decomposition based model order reduction. In this work we are summarizing the most outstanding capabilities of such methodology and then all these capabilities will be put together for addressing efficiently the simulation of a challenging composites manufacturing process, the automated tape placement.

The microstructure and mechanical properties of 3D printed carbon nanotube‐polylactic acid composites

Abstract: This article reports 3D printing of carbon nanotube-polylactic acid (CNT-PLA) composites using an extrusion-based Fused Deposition Modeling (FDM) method. CNTs with an average diameter of 128 nm and an average length of 2.5 μm were first compounded with PLA and extruded into feedstock filaments at 0.5%, 2.5%, and 5% (w/w) CNT loadings. CNT aggregates were observed, but no clogging occurred during printing with a 500-μm print nozzle. The rheology of the CNT-PLA samples was characterized to understand the printing-induced alignment of CNTs along the road axis. Additionally, the effect of printing flow rate was explored for a fixed printing gap and nozzle diameter. Higher flow rates reduced the void fraction in the FDM parts, but unexpectedly resulted in less degree of CNT alignment, which is attributed to radial flow and fusion between adjacent roads. The mechanical properties of the CNT-PLA tensile test coupons were characterized. Inclusion of CNTs increased the Young's modulus by 30% at 5% CNT loading, but reduced the tensile strength and overall toughness of the FDM parts. Experimental data were compared against the Rule of Mixtures (RoM) model, the Halpin-Tsai model, and the modified RoM model and were further explained by the void fraction and CNT orientation. POLYM. COMPOS., 2017. © 2017 Society of Plastics Engineers

Separated representations of 3D elastic solutions in shell geometries

Abstract: The solution of 3D models in degenerated geometries in which some characteristic dimensions are much lower than the other ones -e.g. beams, plates, shells,...- is a tricky issue when using standard mesh-based discretization techniques. Separated representations allow decoupling the meshes used for approximating the solution along each coordinate. Thus, in plate or shell geometries 3D solutions can be obtained from a sequence of 2D and 1D problems allowing fine and accurate representation of the solution evolution along the thickness coordinate while keeping the computational complexity characteristic of 2D simulations. In a former work this technique was considered for addressing the 3D solution of thermoelastic problems defined in plate geometries. In this work, the technique is extended for addressing the solution of 3D elastic problems defined in shell geometries. The capabilities of the proposed approach are illustrated by considering some numerical examples involving different degrees of complexity, from simple shells to composite laminates involving stiffeners. The analyzed examples prove the potentiality and efficiency of the proposed strategy, where the computational complexity was found evolving as reported in our former works, proving that 3D solutions can be computed at a 2D cost.

A Short Review on Model Order Reduction Based on Proper Generalized Decomposition

Abstract: This paper revisits a new model reduction methodology based on the use of separated representations, the so called Proper Generalized Decomposition—PGD. Space and time separated representations generalize Proper Orthogonal Decompositions—POD—avoiding any a priori knowledge on the solution in contrast to the vast majority of POD based model reduction technologies as well as reduced bases approaches. Moreover, PGD allows to treat efficiently models defined in degenerated domains as well as the multidimensional models arising from multidimensional physics (quantum chemistry, kinetic theory descriptions,…) or from the standard ones when some sources of variability are introduced in the model as extra-coordinates.

A review on stereolithography and its applications in biomedical engineering

Abstract: Stereolithography is a solid freeform technique (SFF) that was introduced in the late 1980s Although many other techniques have been developed since then, stereolithography remains one of the most powerful and versatile of all SFF techniques It has the highest fabrication accuracy and an increasing number of materials that can be processed is becoming available In this paper we discuss the characteristic features of the stereolithography technique and compare it to other SFF techniques The biomedical applications of stereolithography are reviewed, as well as the biodegradable resin materials that have been developed for use with stereolithography Finally, an overview of the application of stereolithography in preparing porous structures for tissue engineering is given

PGD-Based Computational Vademecum for Efficient Design, Optimization and Control

Abstract: In this paper we are addressing a new paradigm in the field of simulation-based engineering sciences (SBES) to face the challenges posed by current ICT technologies. Despite the impressive progress attained by simulation capabilities and techniques, some challenging problems remain today intractable. These problems, that are common to many branches of science and engineering, are of different nature. Among them, we can cite those related to high-dimensional problems, which do not admit mesh-based approaches due to the exponential increase of degrees of freedom. We developed in recent years a novel technique, called Proper Generalized Decomposition (PGD). It is based on the assumption of a separated form of the unknown field and it has demonstrated its capabilities in dealing with high-dimensional problems overcoming the strong limitations of classical approaches. But the main opportunity given by this technique is that it allows for a completely new approach for classic problems, not necessarily high dimensional. Many challenging problems can be efficiently cast into a multidimensional framework and this opens new possibilities to solve old and new problems with strategies not envisioned until now. For instance, parameters in a model can be set as additional extra-coordinates of the model. In a PGD framework, the resulting model is solved once for life, in order to obtain a general solution that includes all the solutions for every possible value of the parameters, that is, a sort of computational vademecum. Under this rationale, optimization of complex problems, uncertainty quantification, simulation-based control and real-time simulation are now at hand, even in highly complex scenarios, by combining an off-line stage in which the general PGD solution, the vademecum, is computed, and an on-line phase in which, even on deployed, handheld, platforms such as smartphones or tablets, real-time response is obtained as a result of our queries.

3D Printing of Additive-Free 2D Ti3C2Tx (MXene) Ink for Fabrication of Micro-Supercapacitors with Ultra-High Energy Densities.

Abstract: Recent advances in the development of self-powered devices and miniaturized electronics have increased the demand for on-chip energy storage devices that can deliver high power and energy densities in a limited footprint area. Here, we report the fabrication of all-solid-state micro-supercapacitors (MSCs) through a three-dimensional (3D) printing of additive-free and water-based MXene ink. The fabricated MSCs benefit from the high electrical conductivity and excellent electrochemical properties of two-dimensional (2D) Ti3C2Tx MXene and a 3D interdigital electrode architecture to deliver high areal and volumetric energy densities. We demonstrate that a highly concentrated MXene ink shows desirable viscoelastic properties for extrusion printing at room temperature and therefore can be used for scalable fabrication of MSCs with various architectures and electrode thicknesses on a variety of substrates. The developed printing process can be readily used for the fabrication of flexible MSCs on polymer and paper substrates. The printed solid-state devices show exceptional electrochemical performance with very high areal capacitance of up to ∼1035 mF cm-2. Our study introduces Ti3C2Tx MXene as an excellent choice of electrode material for the fabrication of 3D MSCs and demonstrates 3D printing of MXene inks at room temperature.