Luca Grigolato | Università degli Studi di Padova (original) (raw)

Papers by Luca Grigolato

Lecture notes in mechanical engineering, 2024

Journal of Functional Biomaterials, Jan 13, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Recent advances in additive manufacturing technologies demand for extremely customized, complex s... more Recent advances in additive manufacturing technologies demand for extremely customized, complex shape and multi-fold functional products. Heterogeneous objects, such as functionally graded materials, represent an attractive solution for researchers and industries in many application fields. Combining geometric modelling and material assignment in a definitive and accessible CAD tool is still a challenge. In this review the key aspects of heterogenous object representation related to additive manufacturing processes are reported. After the presentation of the various methodologies for geometric modelling found in the literature, additive manufacturing applications for heterogeneous objects are summarized.

Springer eBooks, Dec 1, 2021

Applied sciences, Jan 22, 2023

Additive manufacturing, Sep 1, 2022

La sperimentazione che si presenta in questa Tesi ha l’obiettivo di ottimizzare il processo di st... more La sperimentazione che si presenta in questa Tesi ha l’obiettivo di ottimizzare il processo di stampa 3D di un inchiostro a base di polveri di lega di titanio Ti6Al4V tramite Direct Ink Writing, per la realizzazione di strutture scaffold con applicazioni in campo biomedico.

Materials, Jan 14, 2023

Medical Devices : Evidence and Research, Mar 1, 2020

Introduction: Miniscrew-assisted rapid palatal expansion (MARPE) appliances utilize the skeletal ... more Introduction: Miniscrew-assisted rapid palatal expansion (MARPE) appliances utilize the skeletal anchorage to expand the maxilla. One type of MARPE device is the Maxillary Skeletal Expander (MSE), which presents four micro-implants with bicortical engagement of the palatal vault and nasal floor. MSE positioning is traditionally planned using dental stone models and 2D headfilms. This approach presents some critical issues, such as the inability to identify the MSE position relative to skeletal structures, and the potential risk of damaging anatomical structures. Methods: A novel methodology has been developed to plan MSE position using the digital model of dental arches and cone-beam computed tomography (CBCT). A virtual model of MSE appliance with the four micro-implants was created. After virtual planning, a positioning guide is virtually designed, 3D printed, and utilized to model and weld the MSE supporting arms to the molar bands. The expansion device is then cemented in the patient oral cavity and micro-implants inserted. A clinical case of a 12.9-year-old female patient presenting a Class III malocclusion with transverse and sagittal maxillary deficiency is reported. Results: The midpalatal suture was opened with a split of 3.06 mm and 2.8 mm at the anterior and posterior nasal spine, respectively. After facemask therapy, the sagittal skeletal relationship was improved, as shown by the increase in ANB, A-Na perpendicular and Wits cephalometric parameters, and the mandibular plane rotated 1.6°clockwise. Conclusion: The proposed digital methodology represents an advancement in the planning of MSE positioning, compared to the traditional approach. By evaluating the bone morphology of the palate and midface on patient CBCT, the placement of MSE is improved regarding the biomechanics of maxillary expansion and the bone thickness at micro-implants insertion sites. In the present case report, the digital planning was associated with a positive outcome of maxillary expansion and protraction in safety conditions.

Additive manufacturing, Dec 1, 2020

Abstract Recently, the possibility of producing medium-to-large batches has increased the interes... more Abstract Recently, the possibility of producing medium-to-large batches has increased the interest in polymer powder bed fusion technologies such as selective laser sintering (SLS) and multi jet fusion (MJF). Only scant data about the characterization of parts produced by MJF can be found in the literature, and fatigue behavior studies are absent. This study analyzes the material properties of Polyamide 12 (PA12) powders and printed specimens using both SLS and MJF technologies. The morphology, crystalline phases, density, porosity, dimensional accuracy, and roughness are measured and compared; tensile and fatigue tests are performed to assess the effect of the technologies on the mechanical behavior of the produced structures. In addition, lattice structure specimens obtained by different geometric modeling approaches are tested to understand the influence of modeling methods on the fatigue life. The PA12 powders printed by both SLS and MJF mainly show by X-Ray Diffraction γ-phase and a small shoulder of α-phase. The crystallinity decreases after printing the powders both in SLS and MJF technology. The printed parts fabricated using the two technologies present a total porosity of 7.95% for SLS and 6.75% for MJF. The roughness values are similar, Ra ≈ 11 μm along the building direction. During tensile tests, SLS samples appear to be stiffer, with a lower plastic deformation than MJF samples, that are tougher than SLS ones. Fatigue tests demonstrate higher dispersion for MJF specimens and an enhancement of fatigue life for both SLS and MJF printed lattice structures modeled with a novel geometric modeling approach that allows the creation of smoother surfaces at nodal points. Scanning electron microscopy on fracture surfaces shows a brittle failure for the SLS tensile specimens, a more ductile failure for the MJF tensile specimens, a crazing failure mechanism for the SLS fatigue tested samples, and a crack initiation and slow growth and propagation for the MJF fatigue tested samples.

Springer eBooks, Sep 25, 2022

Springer eBooks, 2021

Thanks to the great diffusion of additive manufacturing technologies, the interest in lattice str... more Thanks to the great diffusion of additive manufacturing technologies, the interest in lattice structures is growing. Among them, minimal surfaces are characterized by zero mean curvature, allowing enhanced properties such as mechanical response and fluidynamic behavior. Recent works showed a method for geometric modeling triply periodic minimal surfaces (TPMS) based on subdivision surface. In this paper, the deviation between the subdivided TPMS and the implicit defined ones is investigated together with mechanical properties computed by numerical methods. As a result, a model of mechanical properties as a function of the TPMS thickness and relative density is proposed.

Lecture Notes in Computer Science, 2020

In the orthodontic field, UX concerns can take an important role in boosting innovation from the ... more In the orthodontic field, UX concerns can take an important role in boosting innovation from the designers, engineers, dentists, dental technicians and patients’ points of view. In the last months, these concerns spread over the development of functional orthodontic appliances for the correction of skeletal class II malocclusions. This paper focuses on two phases: the data collection before starting the development and the evaluation of the design results. The UX concerns developed through the involvement of the Quality Function Deployment and the irMMs-based UX evaluation method 2.0, including the meQUE questionnaire 2.0. This paper describes the UX role, the related activities and the impact of its involvement in the design process.

International Journal of Applied Ceramic Technology, Aug 23, 2022

Pastes based on preceramic polymers have a great potential for direct ink writing of bioceramic s... more Pastes based on preceramic polymers have a great potential for direct ink writing of bioceramic scaffolds. In this paper, we discuss the fabrication of phase pure sphene (CaTiSiO5) bioceramics, developed by firing, at 1300°C, of silicone‐based printed scaffolds containing CaCO3and TiO2as active fillers. As a proof of the flexibility of the combination of preceramic polymers and additive manufacturing technologies, several lattice geometries of increasing complexity were successfully explored. In particular, the approach allowed the fabrication of sphene scaffolds with gyroid‐like structure exhibiting an impressive compressive strength, given the high porosity. Moreover, different lattice topologies of sphene scaffolds were compared also in terms of permeability.

Applied sciences, Mar 13, 2021

Journal of The European Ceramic Society, Oct 1, 2022

Materials

Material extrusion additive manufacturing enables us to combine more materials in the same nozzle... more Material extrusion additive manufacturing enables us to combine more materials in the same nozzle during the deposition process. This technology, called material coextrusion, generates an expanded range of material properties, which can gradually change in the design domain, ensuring blending or higher bonding/interlocking among the different materials. To exploit the opportunities offered by these technologies, it is necessary to know the behavior of the combined materials according to the materials fractions. In this work, two compatible pairs of materials, namely Polylactic Acid (PLA)-Thermoplastic Polyurethane (TPU) and Acrylonitrile Styrene Acrylate (ASA)-TPU, were investigated by changing the material fractions in the coextrusion process. An original model describing the distribution of the materials is proposed. Based on this, the mechanical properties were investigated by analytical and numerical approaches. The analytical model was developed on the simplified assumption tha...

Applied Sciences

Nowadays, the use of 3D printing is becoming a key process for on-demand and customized manufactu... more Nowadays, the use of 3D printing is becoming a key process for on-demand and customized manufacturing. One of the most flexible 3D printing techniques is fused deposition modeling (FDM), where the combination of multiple materials was recently introduced. A quantum leap in part design is possible by integrating local variations between materials that allow for expanded functionality to be built into a single part. Therefore, the process of co-extrusion and material mixing is becoming more and more popular. The process of management and design of the engineered part are still complicated, and there are no commercially available tools that follow the process from design to production of these highly engineered products. This paper proposes a methodology to fill this gap and allow any designer to be able to produce multi-material parts by editing a G-code (computer numerical control programming language) with engineered gradients for FDM technology. More specifically, the proposed appr...